Announcements - Astronomical News

7 things to know about the NASA rover about to land on Mars

With only about 50 million miles (80 million kilometers) left to go in its 293-million-mile (471-million-kilometer) journey, NASA's Mars 2020 Perseverance rover is nearing its new planetary home. The spacecraft has begun its approach to the Red Planet and in 43 days, on Feb. 18, 2021, Perseverance will blaze through Mars' atmosphere at about 12,100 mph (19,500 kph), touching down gently on the surface about seven minutes later.

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If a planet has a lot of methane in its atmosphere, life is the most likely cause

The ultra-powerful James Webb Space Telescope will launch soon. Once it's deployed and in position at the Earth-Sun Lagrange Point 2, it'll begin work. One of its jobs is to examine the atmospheres of exoplanets and look for biosignatures. It should be simple, right? Just scan the atmosphere until you find oxygen, then close your laptop and head to the pub: Fanfare, confetti, Nobel prize. Of course, Universe Today readers know it's more complicated than that. Much more complicated. In fact, the presence of oxygen is not necessarily reliable. It's methane that can send a stronger signal indicating the presence of life. Oxygen might seem like the obvious thing to look for in a planet's atmosphere when searching for signs of life, but that's not the case. Its presence or lack thereof is not a reliable indicator. Earth's history makes that clear.

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Huge Puerto Rico radio telescope to close in blow to science

The National Science Foundation announced Thursday that it will close the huge telescope at the renowned Arecibo Observatory in Puerto Rico in a blow to scientists worldwide who depend on it to search for planets, asteroids and extraterrestrial life. The independent, federally funded agency said it's too dangerous to keep operating the single dish radio telescope—one of the world's largest—given the significant damage it recently sustained. An auxiliary cable broke in August and tore a 100-foot hole in the reflector dish and damaged the dome above it. Then on Nov. 6, one of the telescope's main steel cables snapped, leading officials to warn that the entire structure could collapse.

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First study with exoplanet satellite data describes one of the most extreme planets in the universe

CHEOPS keeps its promise: Observations with the space telescope have revealed details of the exoplanet WASP-189b—one of the most extreme planets known. CHEOPS is a joint mission by the European Space Agency (ESA) and Switzerland, under the aegis of the University of Bern in collaboration with the University of Geneva. Eight months after the space telescope CHEOPS started its mission, the first scientific publication using data from CHEOPS has been issued. CHEOPS is the first ESA mission dedicated to characterizing known exoplanets, those orbiting stars outside the solar system. Exoplanets were first found in 1995 by two Swiss astronomers, Michel Mayor and Didier Queloz, who were last year awarded the Nobel Prize for this discovery. CHEOPS was developed as part of a partnership between ESA and Switzerland. Under the leadership of the University of Bern and ESA, a consortium of more than 100 scientists and engineers from 11 European states was involved in constructing the satellite over five years. The Science Operations Center of CHEOPS is located at the observatory of the University of Geneva.

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Hubble views edge of stellar blast

While appearing as a delicate and light veil draped across the sky, this image from the NASA/ESA Hubble Space Telescope actually depicts a small section of the Cygnus supernova blast wave, located around 2,400 light-years away. The name of the supernova remnant comes from its position in the northern constellation of Cygnus (the Swan), where it covers an area 36 times larger than the full moon. The original supernova explosion blasted apart a dying star about 20 times more massive than our sun between 10,000 and 20,000 years ago. Since then, the remnant has expanded 60 light-years from its center. The shockwave marks the outer edge of the supernova remnant and continues to expand at around 220 miles per second.

Cygnus supernova blast wave. (Credit: ESA/Hubble & NASA, W. Blair; acknowledgment: Leo Shatz)

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Betelgeuse's mysterious dimming is due to an outburst

Recent observations of Betelgeuse have revealed that the star's unexpected and significant dimming periods in late 2019 and early 2020 were most likely caused by the ejection and cooling of dense hot gases, and that the star may be going through another dimming period more than a year early. Between October and November 2019, Hubble Space Telescope observed dense, heated material moving outward through the star's extended atmosphere at 200,000 miles per hour. The following month, several ground-based telescopes observed a decrease in brightness in Betelgeuse's southern hemisphere, as if something was blocking light in this region of the star. By February 2020, the star had lost more than two-thirds of its brilliance, a dimming visible even to the naked eye, creating buzz that the star might be going supernova. Continued ultraviolet light spectroscopic observations with Hubble provided a timeline for researchers to follow, like breadcrumbs leading back through time to pinpoint the source of the mysterious dimming.

This four-panel graphic illustrates how the southern region of the rapidly evolving, bright red supergiant star Betelgeuse may have suddenly become fainter for several months during late 2019 and early 2020. In the first two panels, as seen in ultraviolet light with the Hubble Space Telescope, a bright, hot blob of plasma is ejected from the emergence of a huge convection cell on the star's surface. In panel three, the outflowing expelled gas rapidly expands outward. It cools to form an enormous cloud of obscuring dust grains. The final panel reveals the huge dust cloud blocking the light (as seen from Earth) from a quarter of the star's surface. (Credit: NASA, ESA, and E. Wheatley (STScI))

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Betelgeuse's mysterious dimming is due to an outburst

One of the biggest challenges in Earth-based astronomy is overcoming the effect of atmospheric turbulence on telescope image quality. This turbulence makes stars twinkle, and measurement of its impact is referred to as 'seeing'. The less turbulence (the lower the seeing number) the better. "The thinner boundary layer at Dome A makes it less challenging to locate a telescope above it, thereby giving greater access to the free atmosphere," said UBC astronomer Bin Ma, lead author on the paper. Currently, the highest performing observatories are located in high-altitude locations along the equator (Chile and Hawai'i) and offer seeing in the range of 0.6 to 0.8 arcseconds. In general, the Antarctic has the potential for better seeing, owing to weaker turbulence in the free atmosphere, with an estimated range of 0.23 to 0.36 arcseconds at a location called Dome C.

The highest ice dome on the Antarctic Plateau could offer the clearest view on Earth of the stars at night, according to new research by an international team from China, Australia and the University of British Columbia. (Credit: Zhaohui Shang)

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Super-Earths discovered orbiting nearby red dwarf

The nearest exoplanets to us provide the best opportunities for detailed study, including searching for evidence of life outside the solar system. In research led by the University of Göttingen, the RedDots team of astronomers has detected a system of super-Earth planets orbiting the nearby star Gliese 887, the brightest red dwarf star in the sky. Super-Earths are planets which have a mass higher than the Earth's but substantially below those of our local ice giants, Uranus and Neptune. The newly discovered super-Earths lie close to the red dwarf's habitable zone, where water can exist in liquid form, and could be rocky worlds. The results were published in the journal Science. The RedDots team of astronomers monitored the red dwarf, using the HARPS spectrograph at the European Southern Observatory in Chile. They used a technique known as "Doppler wobble," which enables them to measure the tiny back and forth wobbles of the star caused by the gravitational pull of the planets. The regular signals correspond to orbits of just 9.3 and 21.8 days, indicating two super-Earths—Gliese 887b and Gliese 887c—both larger than the Earth yet moving rapidly, much faster even than Mercury. Scientists estimate the temperature of Gliese 887c to be around 70° C.

Artist's impression of the multiplanetary system of newly discovered super-Earths orbiting nearby red dwarf Gliese 887. (Credit: Mark Garlick)

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One billion stars and counting—the sky according to Gaia's second data release

Launched in 2013, ESA's Gaia satellite has been scanning the sky to measure the positions, distances and motions of more than one billion stars in our galaxy, the Milky Way. The goal of the mission is to create the most detailed galactic map ever made, in order to investigate the Milky Way's past and future history like never before. This animation shows the satellite as it scans great circles around the sky. Eventually, the sky is unfolded to reveal the view of the Milky Way and neighbouring galaxies, based on measurements of nearly 1.7 billion stars from the second Gaia data release. The map shows the total brightness and colour of stars observed by Gaia in each portion of the sky between July 2014 and May 2016.

Artist's impression of our Milky Way. (Credit: CC0 Public Domain)

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Spitzer Telescope Reveals the Precise Timing of a Black Hole Dance

The recently retired infrared observatory was the only telescope to spot a far-off flash of light that holds clues about the physical characteristics of these cosmic mysteries. Black holes aren't stationary in space; in fact, they can be quite active in their movements. But because they are completely dark and can't be observed directly, they're not easy to study. Scientists have finally figured out the precise timing of a complicated dance between two enormous black holes, revealing hidden details about the physical characteristics of these mysterious cosmic objects. The OJ 287 galaxy hosts one of the largest black holes ever found, with over 18 billion times the mass of our Sun. Orbiting this behemoth is another black hole with about 150 million times the Sun's mass. Twice every 12 years, the smaller black hole crashes through the enormous disk of gas surrounding its larger companion, creating a flash of light brighter than a trillion stars - brighter, even, than the entire Milky Way galaxy. The light takes 3.5 billion years to reach Earth. Orbital and ground-based observations have been combined, in order to unveil the fast changing orbit. The University of Athens Observatory (UOAO) has a significant contribution on this study, as it observes OJ287 since 2006 in the frame of 'BOSS Project', which monitors photometrically the brightest blazars. "It is important to black hole scientists that we prove or disprove the no-hair theorem. Without it, we cannot trust that black holes as envisaged by Hawking and others exist at all," said Mauri Valtonen, an astrophysicist at University of Turku in Finland and a coauthor on the paper.

The original publication paper can be found here: (publication)

This image shows two massive black holes in the OJ 287 galaxy. The smaller black hole orbits the larger one, which is also surrounded by a disk of gas. When the smaller black hole crashes through the disk, it produces a flare brighter than 1 trillion stars. (Credit: NASA/JPL-Caltech)

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NASA's James Webb Space Telescope full mirror deployment a success

In a recent test, NASA's James Webb Space Telescope fully deployed its primary mirror into the same configuration it will have when in space. As Webb progresses towards liftoff in 2021, technicians and engineers have been diligently checking off a long list of final tests the observatory will undergo before being packaged for delivery to French Guiana for launch. Performed in early March, this procedure involved commanding the spacecraft's internal systems to fully extend and latch Webb's iconic 21 feet 4-inch (6.5 meter) primary mirror, appearing just like it would after it has been launched to orbit. The observatory is currently in a cleanroom at Northrop Grumman Space Systems in Redondo Beach, California.

The primary mirror of NASA's James Webb Space Telescope is planned to be deployed only once more on Earth, before being packaged for delivery to South America. (Credit: NASA/Chris Gunn)

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How interferometry works, and why it's so powerful for astronomy

When astronomers talk about an optical telescope, they often mention the size of its mirror. That's because the larger your mirror, the sharper your view of the heavens can be. It's known as resolving power, and it is due to a property of light known as diffraction. When light passes through an opening, such as the opening of the telescope, it will tend to spread out or diffract. The smaller the opening, the more the light spreads, making your image more blurry. This is why larger telescopes can capture a sharper image than smaller ones.

The Five-hundred-metre Aperture Spherical Telescope (FAST) has just finished construction in the southwestern province of Guizhou. (Credit: FAST)

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TESS mission uncovers its first world with two stars

In 2019, when Wolf Cukier finished his junior year at Scarsdale High School in New York, he joined NASA's Goddard Space Flight Center in Greenbelt, Maryland, as a summer intern. His job was to examine variations in star brightness captured by NASA's Transiting Exoplanet Survey Satellite (TESS) and uploaded to the Planet Hunters TESS citizen science project.

TOI 1338 b is silhouetted by its host stars. TESS only detects transits from the larger star. (Credit: NASA's Goddard Space Flight Center/Chris Smith)

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New evidence shows that the key assumption made in the discovery of dark energy is in error

The most direct and strongest evidence for the accelerating universe with dark energy is provided by the distance measurements using type Ia supernovae (SN Ia) for the galaxies at high redshift. This result is based on the assumption that the corrected luminosity of SN Ia through the empirical standardization would not evolve with redshift.

Luminosity evolution mimicking dark energy in supernova (SN) cosmology. The Hubble residual is the difference in SN luminosity with respect to the cosmological model without dark energy (the black dotted line). The cyan circles are the binned SN data from Betoule et al. (2014). The red line is the evolution curve based on our age dating of early-type host galaxies. The comparison of our evolution curve with SN data shows that the luminosity evolution can mimic Hubble residuals used in the discovery and inference of the dark energy (the black solid line). (Credit: Yonsei University)

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Blazar variability

Active galactic nuclei (AGN) are supermassive black holes at the centers of galaxies that are accreting material. These AGN emit jets of charged particles that move at speeds close to that of light, transporting huge amounts of energy away from the central black hole region and radiating across the electromagnetic spectrum. Blazars are extreme examples of AGN in which the collimated jets are coincidentally aligned towards us. Blazar jets have two peak emission wavelengths, one that spans the range from the radio to the X-ray, the result of charged particle acceleration, and one at extremely short wavelength, high energy gamma ray bands usually (and somewhat controversially) attributed to the charged particles scattering infrared "seed" photons from a variety of other sources. All these bands manifest strong and unpredictable variability. Simultaneous, long-term observations across multiple bands therefore, by modeling the relative timing of flares and other variable emission, offer a valuable way to investigate the numerous possible physical mechanisms at work.

An artist's conception of a blazar, a galay powered by an active nucleus. Blazars are the most common sources detected by NASA's Fermi gamma-ray spacecraft. Astronomers have modeled the bright, variable emission from the blazar CTA102 between 2013-2017 using data taken from the gamma-ray to radio bands. They are able to explain the multiuwavelegnth variability observed using a geometrical model for the rapidly moving jets. (Credit: M. Weiss/CfA)

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Annular Solar Eclipse from Sultanate of Oman

The last solar eclipse in 2019, as observed by Dr. Kosmas Gazeas from the dessert in Ghalat area, at the Sultanate of Oman.(Credit: Kosmas Gazeas)

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Evidence suggests some super-puffs might be ringed exoplanets

A pair of researchers from the Observatories of the Carnegie Institution for Science and the California Institute of Technology have reported evidence that some super-puff exoplanets might be ringed exoplanets. Anthony Piro and Shreyas Vissapragada have written a paper describing their theory and the evidence supporting it and have posted it on the arXiv preprint server.

Transit of a ringed planet and the resulting light curves. The upper panel shows an example of the images considered for the transit calculations with the planet at seven different positions. The middle panel shows the resulting transit (normalized to the stellar flux) with the points corresponding to each of the planet positions shown in the upper panel. The bottom shows the difference between a ringed transit and a bare star with the same surface area. (Credit: arXiv:1911.09673)

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Mercury skips across sun's vast glare in rare transit

Mercury skipped across the vast, glaring face of the sun Monday in a rare celestial transit. Stargazers used solar-filtered binoculars and telescopes to spot Mercury—a tiny black dot—as it passed directly between Earth and the sun on Monday. The eastern U.S. and Canada got the whole 5 ½-hour show, weather permitting, along with Central and South America. The rest of the world, except for Asia and Australia, got just a sampling. Mercury is the solar system's smallest, innermost planet. The next transit isn't until 2032, and North America won't get another shot until 2049.

This still image from video issued by NASA's Solar Dynamics Observatory shows Mercury as it passes between Earth and the sun on Monday, Nov. 11, 2019. The solar system's smallest, innermost planet resembles a tiny black dot during the transit, which began at 7:35 a.m. EST (1205 UTC). (NASA Solar Dynamics Observatory via AP)

(Credit: Kosmas Gazeas)

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TESS reveals an improbable planet

Using asteroseismology, a team led by an Instituto de Astrofísica e Ciências do Espaço (IA) researcher studied two red-giant stars known to have exoplanets, and around one of them, found a seemingly improbable planet. The team studied the red-giant stars HD 212771 and HD 203949. These are the first detections of oscillations in previously known exoplanet-host stars by TESS. The result was published today in an article in the Astrophysical Journal.

TESS Satellite mission. (Credit: Instituto de Astrofísica e Ciências do Espaço)

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Frequent flaring of Proxima Centauri means bad news for its rocky planet

Proxima Centauri is a cool red dwarf with about one-eighth of the sun's mass. Although it is the closest star to the sun, located just 4.2 light-years from the solar system in the triple star system of alpha Centauri, it is not visible to the naked eye. What makes this star particularly interesting is the recent discovery of an Earth-like exoplanet in its habitable zone: a region around the central star where the presence of liquid water is possible on a planetary surface.

Yellow triangles mark every flare event identified in the TESS light curve of Proxima Centauri. The inserts zoom in on the two largest events (green triangles). (Credit: Krisztián Vida, Konkoly Observatory)

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Rare ISS transit in front of the Sun

The International Space Station (ISS) orbits our planet every 92.7 minutes. We can observe it quite frequently as a bright satellite in the night sky, but it is quite rare to cross in front of the lunar or solar disk. The image shows the transit of ISS in front of the Sun on 29 August 2019, in a rare occation for the people leaving in Attica to observe the ISS projection in front of the solar disk. The observation was obtained by Dr. Kosmas Gazeas, with portable astronomical equipment from Ktima Syggrou in Kifisia. Images were captured with a rate of 30 fps, while the transit duration was only 0.7 sec.

The transit video can be downloaded here.

Silhuette of ISS, as it passes in front of the Sun on 29 August 2019 from Athens, Greece. (Credit: Kosmas Gazeas)

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Discovering the shortest orbital period eclipsing binary known

Observations made with a new instrument developed for use at the 2.1-meter (84-inch) telescope at the National Science Foundation's Kitt Peak National Observatory have led to the discovery of the fastest eclipsing white dwarf binary yet known. The system consists of two white dwarfs orbiting each other in an orbit so close that the whole binary could fit completely inside of the planet Saturn. Clocking in with an orbital period of only 6.91 minutes, the rapidly orbiting stars are expected to be one of the strongest sources of gravitational waves detectable with LISA, the future space-based gravitational wave detector.

The original published article can be found here

Artist's design, depicting the eclipsing binary ZTF J1530+5027, which is comprised of two extremely dense objects (white dwarfs) that orbit each other roughly every seven minutes. The smaller white dwarf is slightly larger than Earth and is the more massive of the two, with about 60% the mass of the sun. Its companion is larger but less massive, with only about 20% the mass of the sun. The orbital separation of these objects is shrinking by about 26 centimeters per day due to the emission of gravitational waves. (Credit: Caltech/IPAC)

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The total solar eclipse of the year

Only a few hours are left before the great aastronomical event of the year.
On Thuesday 2 July 2019 a total solar eclipse will occur, with a duration of 4 minutes and 33 seconds.
The central phase of the eclipse will occur in Pacific Ocean, while only a few part of continental Latin America will be shadowed by the Moon, covering the Sun for a few minutes. The lunar shadow will cross the Pacific Ocean without passing any island on its way, until it reaches Latin America at the end of its path. Chile and Argentina will have the opportunity to witness a total solar eclipse for only 2 minutes and 30 seconds.
The eclipse will not be visible from Greece, as the Moon will not cover the solar disk for this region.
Thousands of people are visiting the wider area of Chile and Argentina in order to observe the rare phenomenon. These days, Kosmas Gazeas from the University of Athens, Greece, is in Argentina in order to observe and record the solar eclipse from the area of Bella Vista in San Juan Province.

The total solar eclipse of 20 March 2015, as observed from Svalbard, Norway. (Credit: Kosmas Gazeas)

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NASA's TESS mission finds its smallest planet yet

NASA's Transiting Exoplanet Survey Satellite (TESS) has discovered a world between the sizes of Mars and Earth orbiting a bright, cool, nearby star. The planet, called L 98-59b, marks the tiniest discovered by TESS to date. Two other worlds orbit the same star. While all three planets' sizes are known, further study with other telescopes will be needed to determine if they have atmospheres and, if so, which gases are present. The L 98-59 worlds nearly double the number of small exoplanets—that is, planets beyond our solar system—that have the best potential for this kind of follow-up.

The three planets discovered in the L98-59 system by NASA's Transiting Exoplanet Survey Satellite (TESS) are compared to Mars and Earth in order of increasing size in this illustration. (Credit: NASA's Goddard Space Flight Center)

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A family of comets reopens the debate about the origin of Earth's water

Where did the Earth's water come from? Although comets, with their icy nuclei, seem like ideal candidates, analyses have so far shown that their water differs from that in our oceans. Now, however, an international team, bringing together CNRS researchers at the Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres (Paris Observatory - PSL/CNRS/ Sorbonne University/University of Cergy-Pontoise) and the Laboratory of Space Studies and Instrumentation in Astrophysics (Paris Observatory - PSL/CNRS/Sorbonne University/University of Paris), has found that one family of comets, the hyperactive comets, contains water similar to terrestrial water. The study, published in the journal Astronomy & Astrophysics on May 20, 2019, is based in particular on measurements of comet 46P/Wirtanen carried out by SOFIA, NASA's Stratospheric Observatory for Infrared Astronomy.

The comet 46P/Wirtanen on January 3, 2019. (Credit: Nicolas Biver)

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Curiosity captured two solar eclipses on Mars

When NASA's Curiosity Mars rover landed in 2012, it brought along eclipse glasses. The solar filters on its Mast Camera (Mastcam) allow it to stare directly at the Sun. Over the past few weeks, Curiosity has been putting them to good use by sending back some spectacular imagery of solar eclipses caused by Phobos and Deimos, Mars' two moons. Phobos, which is about 7 miles (11.5 kilometers) across, was imaged on March 26, 2019 (the 2,359th sol, or Martian day, of Curiosity's mission); Deimos, which is about 1.5 miles (2.3 kilometers) across, was photographed on March 17, 2019 (Sol 2350). Phobos doesn't completely cover the Sun, so it would be considered an annular eclipse. Because Deimos is so small compared to the disk of the Sun, scientists would say it's transiting the Sun.

This series of images shows the Martian moon Phobos as it crossed in front of the Sun, as seen by NASA's Curiosity Mars rover on Tuesday, March 26, 2019 (Sol 2359). (Credit: NASA/JPL-Caltech/MSSS)

This series of images shows the Martian moon Deimos as it crossed in front of the Sun, as seen by NASA's Curiosity Mars rover on Sunday, March 17, 2019 (Sol 2350). (Credit: NASA/JPL-Caltech/MSSS)

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Data flows from NASA's TESS Mission, leads to discovery of Saturn-sized planet

Astronomers who study stars are providing a valuable assist to the planet-hunting astronomers pursuing the primary objective of NASA's new TESS Mission. In fact, asteroseismologists—stellar astronomers who study seismic waves (or "starquakes") in stars that appear as changes in brightness—often provide critical information for finding the properties of newly discovered planets. This teamwork enabled the discovery and characterization of the first planet identified by TESS for which the oscillations of its host star can be measured.

A "hot Saturn" passes in front of its host star in this illustration. Astronomers who study stars used "starquakes" to characterize the star, which provided critical information about the planet. (Credit: Gabriel Perez Diaz, Instituto de Astrofísica de Canarias)

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Tiny Object Found at the Edge of the Solar System

The Kuiper Belt, or the Edgeworth-Kuiper Belt, is home to ancient rocks. Kuiper Belt Objects, or KBOs, are remnants of the early planet-formation days of our Solar System. Small KBOs, in the 1 km. diameter range, have been theorized about for decades, but nobody’s every found one.
Until now.
Planets form when bits of dust conglomerate into rocks, which conglomerate into boulders, which conglomerate into larger and larger objects. In our inner Solar System, we can see many of these larger rocks, or asteroids. We can study them, but they’re not the same as the distant, ancient KBOs. Asteroids in our neighbourhood have been changed by exposure to solar radiation, by collisions, and by interacting with the gravity of the planets.

An artist's impression of the newly-discovered object. (Credit: Ko Arimatsu)

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NASA rings in New Year with historic flyby of faraway world

NASA rang in the New Year on Tuesday with a historic flyby of the farthest, and quite possibly the oldest, cosmic body ever explored by humankind—a tiny, distant world called Ultima Thule—in the hopes of learning more about how planets took shape. It was 07:33 am (05:33 GMT) when the New Horizons spacecraft aimed its cameras at the space rock four billion miles (6.4 billion kilometers) away in a dark and frigid region of space known as the Kuiper Belt. Offering scientists the first up-close look at an ancient building block of planets, the flyby took place about a billion miles beyond Pluto, which was until now the most faraway world ever visited up close by a spacecraft. Real-time video of the actual flyby was impossible, since it takes more than six hours for a signal sent from Earth to reach the spaceship, and another six hours for the response to arrive.

This artist's illustration obtained from NASA shows the New Horizons spacecraft encountering 2014 MU69 –- nicknamed "Ultima Thule" –- a Kuiper Belt object that orbits one billion miles (1.6 billion kilometers) beyond Pluto. (Credit: NASA)

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Astronomers discover nine new variable stars

A team of astronomers from Chile has detected nine new variable stars in the globular cluster NGC 6652 and its background stream. Six of the newly found stars were classified as eclipsing binaries, one as an SX Phoenicis star, and two remain unclassified. Variable stars could offer important hints into aspects of stellar structure and evolution. They could be also helpful for better understanding of the distance scale of the universe. In particular, studies of variable stars in star clusters are of special interest for astronomers as they have the potential to help identify systematic errors that affect stellar distance indicators. However, although stellar variability in globular clusters (GCs) of the Milky Way galaxy is one of the oldest branches of astronomy, there are still many galactic GCs in which the census of their variable star content is far from complete.

A finding chart for the discovered variables in the NGC 6652 field, based on a GMOS r-band image. The position of V14 is also indicated. The fov is 5.5x5.5 arcmin. North is up, East to the left. (Credit: Salinas et al., 2018)

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Mars touchdown: NASA spacecraft survives supersonic plunge

A NASA spacecraft designed to drill down into Mars' interior landed on the planet Monday after a perilous, supersonic plunge through its red skies, setting off jubilation among scientists who had waited in white-knuckle suspense for confirmation to arrive across 100 million miles of space. Flight controllers at NASA's Jet Propulsion Laboratory in Pasadena, California, leaped out of their chairs, screaming, dancing and hugging, upon learning that InSight had arrived on Mars, the graveyard for a multitude of previous missions. "Touchdown confirmed!" a flight controller called out just before 3 p.m. EST, instantly dispelling the anxiety that had gripped the control room as the spacecraft made its six-minute descent.

This illustration made available by NASA in October 2016 shows an illustration of NASA's InSight lander about to land on the surface of Mars. NASA's InSight spacecraft will enter the Martian atmosphere at supersonic speed, then hit the brakes to get to a soft, safe landing on the alien red plains. After micromanaging every step of the way, flight controllers will be powerless over what happens at the end of the road, nearly 100 million miles away. (NASA/JPL-Caltech via AP)

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Ultra-close stars discovered inside a planetary nebula

An international team of astronomers have discovered two stars in a binary pair that complete an orbit around each other in a little over three hours, residing in the planetary nebula M3-1. Remarkably, the stars could drive a nova explosion, an entirely unexpected event based on our current understanding of binary star evolution.

An image obtained with the Hubble Space Telescope of the planetary nebula M3-1, the central star of which is actually a binary system with one of the shortest orbital periods known. (Credit: David Jones / Daniel López – IAC)

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How Does a Black Hole Form?

There's something inherently fascinating about black holes. Maybe it's that they're invisible beasts lurking in space that sometimes rip passing stars in half and scatter their remains. Whatever it is, these strange cosmic objects continue to captivate scientists and laypeople alike. But where do black holes come from? How do they form, and what gives them such awesome destructive power?

Supermassive black holes blast winds outward in a spherical shape, as depicted here in this artist's conception of a black hole. (Credit: NASA/JPL-Caltech)

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NASA's Opportunity Rover on Mars Still Silent 2 Months into Epic Dust Storm

It's now been more than two months since NASA's long-lived Opportunity Mars rover last phoned home. Opportunity hasn't made a peep since June 10, when dust in the Red Planet's air got so thick that the solar-powered rover couldn't recharge its batteries. Opportunity's handlers think the six-wheeled robot has put itself into a sort of hibernation, and they still hope to get a ping once the dust storm has petered out.

These side-by-side images, captured several months apart by NASA's Mars Reconnaissance Orbiter, show the dramatic effects of the dust storm currently blanketing the Red Planet. (Credit: NASA/JPL-Caltech/MSSS)

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First confirmed image of newborn planet

Astronomers led by a group at the Max Planck Institute for Astronomy in Heidelberg, Germany have captured a spectacular snapshot of planetary formation around the young dwarf star PDS 70. By using the SPHERE instrument on ESO's Very Large Telescope (VLT)—one of the most powerful planet-hunting instruments in existence—the international team has made the first robust detection of a young planet, named PDS 70b, cleaving a path through the planet-forming material surrounding the young star.

This spectacular image from the SPHERE instrument on ESO's Very Large Telescope is the first clear image of a planet caught in the very act of formation around the dwarf star PDS 70. The planet stands clearly out, visible as a bright point to the right of the center of the image, which is blacked out by the coronagraph mask used to block the blinding light of the central star. (Credit: ESO/A. Müller et al.)

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How solar prominences vibrate

An international team led by researchers from the Instituto de Astrofísica de Canarias (IAC) and the Universidad de La Laguna (ULL) has cataloged around 200 oscillations of the solar prominences during the first half of 2014. Its development has been possible thanks to the GONG network of telescopes, of which one of them is located in the Teide Observatory. When we look at the surface of the Sun the solar prominences are seen as dark filaments that populate the disk or as a blaze of plasma above it. Solar prominences are very dense plasma structures that levitate in the solar atmosphere. It is generally believed that the star's magnetic field supports them so that they do not fall on the surface due to their own weight. These magnetic structures can accumulate a large amount of energy that, when released, produces eruptions ejecting the prominence material into the interplanetary space.

(Credit: Instituto de Astrofísica de Canarias)

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Ushering in the next phase of exoplanet discovery

Ever since scientists discovered the first planet outside of our solar system, 51 Pegasi b, the astronomical field of exoplanets has exploded, thanks in large part to the Kepler Space Telescope. Now, with the successful launch of the Transiting Exoplanet Survey Satellite (TESS), scientists see a revolution not only in the amount of new planetary data to analyze, but also in the potential for new avenues of scientific discovery. So far, scientists have confirmed 3,717 exoplanets in 2,773 systems. As an all-sky survey, TESS will build on this, observing 85 percent of the cosmos containing more than 200,000 nearby stars, and researchers expect to identify some 20,000 exoplanets.

An artist concept depicts TESS in front of a lava planet orbiting its host star. (Credit: Credit: NASA Goddard Space Flight Center)

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ExoMars returns first images from new orbit

The ExoMars Trace Gas Orbiter has returned the first images of the Red Planet from its new orbit. The spacecraft arrived in a near-circular 400 km altitude orbit a few weeks ago ahead of its primary goal to seek out gases that may be linked to active geological or biological activity on Mars. The orbiter's Colour and Stereo Surface Imaging System, CaSSIS, took this stunning image, which features part of an impact crater, during the instrument's test period. The camera was activated on 20 March and was tested for the start of its main mission on 28 April.

The image captures a 40 km-long segment of Korolev Crater located high in the northern hemisphere. The bright material on the rim of the crater is ice. It is assembled from three images in different colours that were taken almost simultaneously on 15 April. (Credit: ESA)

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70-year-old mystery of how magnetic waves heat the Sun cracked

Scientists at Queen's University Belfast have led an international team to the ground-breaking discovery that magnetic waves crashing through the Sun may be key to heating its atmosphere and propelling the solar wind. The Sun is the source of energy that sustains all life on Earth but much remains unknown about it. However, a group of researchers at Queen's have now unlocked some mysteries in a research paper, which has been published in Nature Physics. In 1942, Swedish physicist and engineer Hannes Alfvén predicted the existence of a new type of wave due to magnetism acting on a plasma, which led him to obtain the Nobel Prize for Physics in 1970. Since his prediction, Alfvén waves have been associated with a variety of sources, including nuclear reactors, the gas cloud that envelops comets, laboratory experiments, medical MRI imaging and in the atmosphere of our nearest star -- the Sun. Scientists have suggested for many years that these waves may play an important role in maintaining the Sun's extremely high temperatures but until now had not been able to prove it.

A view of a sunspot on the solar surface, visible here as a dark collection of plasma with magnetic field strengths similar to those found in modern hospital MRI machines. However, it is the size of the sunspot, which is comparable to that of our own Earth (see the scale Earth depicted in the lower-right corner), that gives these structures immense power and energy. The recent work published in Nature Physics reveals first-time evidence for how a rare breed of magnetic waves, which originate within the centre of sunspots, can form shockwaves that heat the surrounding plasma by thousands of degrees. (Credit: Image courtesy of Queen's University, Belfast)

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Eclipse season starts for NASA's SDO

On Sunday, Feb. 11, 2018, NASA's Solar Dynamics Observatory, or SDO, saw a total solar eclipse in space when Earth crossed its view of the Sun. Also known as a transit, Earth's passage was brief, lasting from 2:10 a.m. to 2:41 a.m. EST and covering the entire face of the Sun. So marks the beginning of SDO's eclipse season—as well as the mission's eighth launch anniversary. SDO's eclipse season is a three-week period that comes twice a year near the equinoxes during which Earth blocks SDO's view of the Sun for a short while each day. The eclipses are fairly short near the beginning and end of the season but ramp up to 72 minutes in the middle. Most spacecraft observing the Sun from an orbit around Earth have to contend with such eclipses. SDO's orbit is designed to maximize the amount of data the spacecraft can send back to Earth, but twice a year Earth gets in the way of the spacecraft's view. The spring eclipse season began on Feb. 10 with a partial eclipse and concludes March 5, 2018.

On Sunday, Feb. 11, 2018, NASA's SDO saw a total solar eclipse in space. These images were taken in a wavelength of extreme ultraviolet light, a type of light that is typically invisible to our eyes, but is colorized here in purple. Credit: NASA's Goddard Space Flight Center/SDO/Joy Ng

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A better way to weigh millions of solitary stars

Astronomers have come up with a new and improved method for measuring the masses of millions of solitary stars, especially those with planetary systems. Getting accurate measurements of how much stars weigh not only plays a crucial role in understanding how stars are born, evolve and die, but it is also essential in assessing the true nature of the thousands of exoplanets now known to orbit most other stars. The method is tailor-made for the European Space Agency's Gaia Mission, which is in the process of mapping the Milky Way galaxy in three dimensions, and NASA's upcoming Transiting Exoplanet Survey Satellite (TESS), which is scheduled for launch next year and will survey the 200,000 brightest stars in the firmament looking for alien earths. "We have developed a novel method for 'weighing' solitary stars," said Stevenson Professor of Physics and Astronomy Keivan Stassun, who directed the development. "First, we use the total light from the star and its parallax to infer its diameter. Next, we analyze the way in which the light from the star flickers, which provides us with a measure of its surface gravity. Then we combine the two to get the star's total mass."

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Discovery of new planet reveals distant solar system to rival our own

The discovery of an eighth planet circling the distant star Kepler-90 by University of Texas at Austin astronomer Andrew Vanderburg and Google's Christopher Shallue overturns our solar system's status as having the highest number of known planets. We're now in a tie. The newly discovered Kepler-90i—a sizzling hot, rocky planet orbiting its star once every 14.4 days—was found using computers that "learned" to find planets in data from NASA's Kepler space telescope. Kepler finds distant planets beyond the solar system, or exoplanets, by detecting the minuscule change in brightness when a planet transits (crosses in front of) a star. Vanderburg, a NASA Sagan fellow at UT Austin, and Shallue, a Google machine learning researcher, teamed up to train a computer to learn how to identify signs of an exoplanet in the light readings from distant stars recorded by Kepler. Similar to the way neurons connect in the human brain, this "neural network" sifted through the Kepler data to identify the weak transit signals from a previously missed eighth planet orbiting Kepler-90, a sun-like star 2,545 light-years from Earth in the constellation Draco. "For the first time since our solar system planets were discovered thousands of years ago, we know for sure that our solar system is not the sole record holder for the most planets," Vanderburg said.

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Fifty years ago, Jocelyn Bell discovered pulsars!

A pulsar is a small, spinning star – a giant ball of neutrons, left behind after a normal star has died in a fiery explosion. With a diameter of only 30 km, the star spins up to hundreds of times a second, while sending out a beam of radio waves (and sometimes other radiation, such as X-rays). When the beam is pointed in our direction and into our telescopes, we see a pulse. 2017 marks 50 years since pulsars were discovered. In that time, we have found more than 2600 pulsars (mostly in the Milky Way), and used them to hunt for low-frequency gravitational waves, to determine the structure of our galaxy and to test the general theory of relativity. The discovery In mid-1967, when thousands of people were enjoying the summer of love, a young PhD student at the University of Cambridge in the UK was helping to build a telescope. It was a poles-and-wires affair – what astronomers call a "dipole array". It covered a bit less than two hectares, the area of 57 tennis courts. By July it was built. The student, Jocelyn Bell (now Dame Jocelyn Bell Burnell), became responsible for running it and analysing the data it churned out. The data came in the form of pen-on-paper chart records, more than 30 metres of them each day. Bell analysed them by eye.

CSIRO Parkes radio telescope has discovered around half of all known pulsars. (Credit: Wayne England, Author provided)

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Dwarf planet Haumea has rings!

While watching a tiny planet eclipse a very distant star, astronomers made an unexpected discovery: The elongated dwarf planet Haumea hosts a 43-mile-wide ring of particles and debris. Haumea is now the first official dwarf planet found to host a ring system, while we knew that this was only a priviledge of the four giant planets of our Solar System (Jupiter, Saturn, Uranus, Neptune) and of the small asteroid Chariklo. The discovery also marks the first time anyone has found rings around an object in the Kuiper belt, a region of icy bodies out beyond the orbit of Neptune.

The University of Athens Observatory (UOAO), and more specifically Dr. K. Gazeas and the student L. Tzouganatos, participated to this observing campaign, while the scientific results are published through the refereed journal Nature.

The original paper can be found here.

A thin band of debris circles the dwarf planet Haumea in an illustration based on the latest discovery. (Illustration by IAA-CSIC/UHU)

Read more here: wiki and here: (information)

Fly me to the Moon

By 2040, a hundred people will live on the Moon, melting ice for water, 3D-printing homes and tools, eating plants grown in lunar soil, and competing in low-gravity, "flying" sports. To those who mock such talk as science fiction, experts such as Bernard Foing, ambassador of the European Space Agency-driven "Moon Village" scheme, reply the goal is not only reasonable but feasible too. At a European Planetary Science Congress in Riga this week, Foing spelt out how humanity could gain a permanent foothold on Earth's satellite, and then expand.

The 1969-72 Apollo landings left us with an image of a lunar environment that was hostile and sterile. But scientists today says there is bounty in the Moon that can be unlocked with advanced technology, opening the way to a permanent human colony.

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Partial Lunar Eclipse - 7 August 2017

On August 7, 2017 we will witness a partial lunar eclipse, which will be visible from Greece. The precentage of coverage will reach 25%, meaning that the Earth's shadow will cover only 1/4 of the lunar surface. This phenomenon will be visible during the early night hours, when the fullmoon will rise from eastern horizon. The moonrise is expected to occur at 20:20 (local time), simultaneously with the beginning of the eclipse. The maximum phase will occur at 21:22, when the moon will be a few degrees higher, while it will end at 22:20 when the Moon exits Earth's shadow. The eclipse will be visible from all parts of Greece, while the fullmoon will normally shine afterwards at the night sky for the entire night. Get ready to watch the August fullmoon, together with the partial lunar eclipse, wherever you are!

The partial lunar eclipse, as observed from the University of Athens, Greece on 25 April 2013 by Dr. K. Gazeas.

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Total Solar Eclipse - 21 August 2017

On August 21, 2017, people across the United States will see the sun disappear behind the moon, turning daylight into twilight, causing the temperature drop rapidly and revealing massive streamers of light streaking through the sky around the silhouette of the moon. On that day, USA will fall under the path of a total solar eclipse. The so-called "Great American Total Solar Eclipse" will darken skies all the way from Oregon to South Carolina, along a stretch of land about 70 miles (113 kilometers) wide. People who descend upon this "path of totality" for the big event are in for an unforgettable experience.

The total solar eclipse, as observed from Svalbard, Norway on 20 March 2015 by Dr. K. Gazeas.

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Four new short-period giant planets discovered

Astronomers have detected four new giant exoplanets as part of the Hungarian-made Automated Telescope Network-South (HATSouth) exoplanet survey. The newly found alien worlds are about the size of Jupiter, but less massive. They transit moderately bright stars and have short orbital periods. The findings were presented July 22 in a paper published on HATSouth is a network of six astrograph telescope systems located in South America, Africa, and Australia. These telescopes are designed to detect transiting extrasolar planets in orbit around relatively bright stars visible from the Southern hemisphere. Since its launch in 2009, the network has already detected dozens of transiting exoplanets.

Unbinned transit light curves for HATS-43. Credit: Brahm et al., 2017.

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Japan reveals plans to put a man on moon by 2030

Japan has revealed ambitious plans to put an astronaut on the Moon around 2030 in new proposals from the country's space agency. This is the first time the Japan Aerospace Exploration Agency (JAXA) has said it aims to send an astronaut beyond the International Space Station, an agency spokeswoman told AFP on Friday. The idea is to first join a NASA-led mission in 2025 to build a space station in the moon's orbit, as part of a longer-term effort by NASA to reach Mars. Tokyo hopes that contributing to the multinational mission and sharing Japanese technology will land it a coveted spot at the station, from which it could eventually send an astronaut to the Moon, the spokeswoman said.

Japan has unveiled ambitious plans to put an astronaut on the moon around 2030 under new proposals from the country's space agency.

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Construction begins on the world's first super telescope

Scientists are a step closer to understanding the inner-workings of the universe following the laying of the first stone, and construction starting on the world's largest optical and infrared telescope. With a main mirror 39 metres in diameter, the Extremely Large Telescope (ELT), is going to be, as its name suggests, enormous. Unlike any other before it, ELT is also designed to be an adaptive telescope and has the ability to correct atmospheric turbulence, taking telescope engineering to another level. To mark the construction's milestone, a ceremony was held at ESO's Paranal residencia in northern Chile, close to the site of the future giant telescope which will be on top of Cerro Armazones, a 3046-metre peak mountain.

Artist's impression of the European Extremely Large Telescope (E-ELT) in its enclosure on Cerro Armazones. A 3046-metre mountaintop in Chile's Atacama Desert. The 39-metre E-ELT will be the largest optical/infrared telescope in the world.

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Brown dwarf binary discovered by microlensing

Using gravitational microlensing, astronomers have recently found a binary star composed of two brown dwarfs. The newly discovered system is the third brown-dwarf binary detected with this technique. The finding was presented in a paper published May 16 on the arXiv pre-print server. Gravitational microlensing is an invaluable method of detecting new extrasolar planets and brown dwarfs, regardless of the light they emit. This technique is therefore sensitive to the mass of the objects, rather than their luminosity, which allows astronomers to study objects that emit little or no light at all. Hence, due to their extremely low luminosities, brown-dwarf systems seem to be ideal targets for microlensing observations.

Light curve of the microlensing event OGLE-2016-BLG-1469. The upper panel shows the enlarged view of the anomaly around the peak.

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Επιτυχία του ΕΚΠΑ στον διαγωνισμό του Europlanet

Φοιτητές του Τμ. Φυσικής του ΕΚΠΑ σημείωσαν μεγάλη επιτυχία στον διαγωνισμό που διοργανώθηκε φέτος από το ευρωπαϊκό δίκτυο πλανητολογίας Europlanet. Στο πλαίσιο του φετινού διαγωνισμού Europlanet Funding Scheme 2017 βραβεύτηκαν δύο ομάδες, με την ομάδα του ΕΚΠΑ να λαμβάνει μια από τις δύο πρώτες θέσεις σε πανευρωπαϊκό επίπεδο.

Το Europlanet θα χρηματοδοτήσει τους φοιτητές του Τμήματός μας με το ποσό των 7000 ευρώ για την υλοποίηση της πρότασης με τίτλο "Planets in Your Hand" και τη προσομοίωση των διαφορετικών συνθηκών που επικρατούν σε κάθε πλανήτη του Ηλιακού μας Συστήματος.

Η ομάδα αποτελείται από προπτυχιακούς και μεταπτυχιακούς φοιτητές του Τμήματος Φυσικής του ΕΚΠΑ. Συγκεκριμένα, στην πρόταση αυτή συμμετέχουν οι φοιτητές: Αθανασόπουλος Δημήτριος, Καραμπότσιου Σέβη, Κεφαλά Κυριακή, Κωνσταντίνου Άννα, Παλαφούτα Σόφη, Παπαδάμη Αργυρώ, Σκλήρης Βασίλης, Τζουγανάτος Λευτέρης, Τριβυζά Μαρίλια, Χλιάρας Βαγγέλης, Χριστοπούλου Έλενα. Επιστημονικός υπεύθυνος για την υλοποίηση της πρότασης είναι ο Κοσμάς Γαζέας, Λέκτορας Παρατηρησιακής Αστροφυσικής του ΕΚΠΑ.

Στον φετινό διαγωνισμό, οι φοιτητές πρότειναν να κατασκευάσουν μακέτες πλανητικών επιφανειών, με τη μορφή κάδρων, παρουσιάζοντας τις ιδιαιτερότητες που έχει ο κάθε πλανήτης του Ηλιακού μας Συστήματος. Το σύνολο των κατασκευών θα παρουσιαστεί σε διάφορους χώρους (σχολεία, πανεπιστήμια, ιδρύματα κτλ) και θα λειτουργεί ως διαδραστικό έκθεμα. Έτσι θα δοθεί η δυνατότητα σε όλους τους επισκέπτες, ακόμη και σε άτομα με ειδικές ανάγκες, να δουν, να μάθουν και να αντιληφθούν δια της αφής και της όρασης τις ιδιαιτερότητες του κάθε πλανήτη.

Η χρηματοδότηση της πρότασης και η έναρξη των κατασκευών θα γίνει άμεσα, με σκοπό την έναρξη της έκθεσης το Σεπτέμβριο του 2017 και τη λειτουργία της για ένα χρόνο.

Στο πλαίσιο της υλοποίησης της πρότασης, θα δημιουργηθεί ιστοσελίδα ενημέρωσης, καθώς και επικοινωνίας μέσω των διαφόρων social media. Για την πρόοδο και την εξέλιξη της πρότασης θα γίνονται σχετικές ανακοινώσεις μέσω των παραπάνω μέσων ενημέρωσης.

Διαβάστε περισσότερα εδώ: Planets In Your Hand

Πληροφορίες για το διαγωνισμό: Europlanet

Mercury Transit on 9 May 2016

Planetary transits in front of the solar disk are rare phenomena. In our Solar System only Mercury and Venus can be projected on the solar disk, since their orbit has smaller radius than Earth has. Mercury orbits the Sun in an elliptical orbit every 88 days. The combination of orbital period, inclination and distace from the Sun and Earth, creates the ideal circumstances for a planetary transit 13 or 14 times every century. The most recent Mercury Transits occured in 2003 (visible from Greece), and 2006 (invisible from Greece), while the next will occur in 9 May 2016. Given that the next transit will occur in 2019 (partially visible from Greece) and then in 2032, it is clear that Mercury Transit does not occur very often. The University of Athens Observatory at the Department of Physics of the National and Kapodistrian University of Athens organizes a daily educational activity, taking advantage of this event. Mercury Transit will occur between 11:12-18:42 UT (14:12-21:42 local time). The activity will take place on 9 May 2016 at Physics Department, National and Kapodistrian University of Athens between 16:00 and 22:00.

Mosaic image of Mercury Transit in 2003.

Read more here: (Press Release) (Poster)

Evidence for a habitable region within Saturn's moon Enceladus

Scientists from Southwest Research Institute (SwRI) have discovered hydrogen gas in the plume of material erupting from Saturn's moon Enceladus. Analysis of data from NASA's Cassini spacecraft indicates that the hydrogen is best explained by chemical reactions between the moon's rocky core and warm water from its subsurface ocean. The SwRI-led team's discovery suggests that Enceladus' ocean floor could include features analogous to hydrothermal vents on Earth, which are known to support life on the seafloor.

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NASA tests robotic ice tools

Since 2015, NASA's Jet Propulsion Laboratory in Pasadena, California, has been developing new technologies for use on future missions to ocean worlds. That includes a subsurface probe that could burrow through miles of ice, taking samples along the way; robotic arms that unfold to reach faraway objects; and a projectile launcher for even more distant samples.

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Comet 45P/Honda-Mrkos-Pajdušáková is coming!

Comet hunters still have a chance to see comet 45P/Honda-Mrkos-Pajdušáková in the next few days using binoculars or a telescope. It's the first of a trio of comets that will-between now and the end of 2018-pass close enough to Earth for backyard observers to try to spot and for scientists to study using ground-based instruments. Comet 45P will come closest to Earth on the morning of Saturday, Feb. 11, when it passes by at a distance of about 7.7 million miles (12.4 million kilometers), or more than roughly 30 times the distance between Earth and the moon. It is currently in the early morning eastern sky, though the full moon may make the comet more difficult to spot. Ground-based observations also are planned for comet 41P/Tuttle-Giacobini-Kresak, which will pass closest to Earth on April 1, 2017, and for comet 46P/Wirtanen, passing closest to Earth on Dec. 16, 2018.

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A contact binary will explode in 2022!

Calvin College professor Larry Molnar and his students along with colleagues from Apache Point Observatory (Karen Kinemuchi) and the University of Wyoming (Henry Kobulnicky) are predicting a change to the night sky that will be visible to the naked eye. Molnar's prediction is that a binary star he is monitoring will merge and explode in 2022, give or take a year; at which time the star will increase its brightness ten thousand fold, becoming one of the brighter stars in the heavens for a time. The star will be visible as part of the constellation Cygnus, and will add a star to the recognizable Northern Cross star pattern.

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NASA seeks planets like those in 'Star Wars: Rogue One'

In the "Star Wars" universe, ice, ocean and desert planets burst from the darkness as your ship drops out of light speed. But these worlds might be more than just science fiction. Some of the planets discovered around stars in our own galaxy could be very similar to arid Tatooine, watery Scarif and even frozen Hoth, according to NASA scientists. Sifting through data on the more than 3,400 confirmed alien worlds, scientists apply sophisticated computer modeling techniques to tease out the colors, light, sunrise and sunsets we might encounter if we could pay them a visit. Some of these distant worlds are even stranger than those that populate the latest Star Wars film, "Rogue One: A Star Wars Story." And others are eerily like the fictional planets from a galaxy far, far away.

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New crater on the Moon!

The moon's surface is being "gardened" by small impacts—more than 100 times faster than scientists previously thought. This means that surface features believed to be young are perhaps even younger than assumed. It also means that any structures placed on the moon as part of human expeditions will need better protection. This new discovery comes from more than seven years of high-resolution lunar images studied by a team of scientists from Arizona State University and Cornell University. The team is led by ASU's Emerson Speyerer, who is also the lead author of the scientific paper published Oct. 13 in Nature. When the team examined the new craters found by the LROC survey, they noticed that the craters were surrounded by starburst patterns that obviously formed during the impact. While the pattern details are complex, the researchers found that an impact throws out several kinds of debris. Some of it lands nearby. But impacts also throw small amounts of debris in hyper-velocity jets at speeds of 16 kilometers (10 miles) per second. This material—vaporized and molten rock—shoots over the surface, disturbing the upper layer of lunar soil and changing its brightness.

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Penumbral Lunar Eclipse visible from Athens

A Penumbral Lunar Eclipse will be visible from Athens Greece on Friday 16 September 2016! The Moon will start hiding behind the terrestrial shadow at 19:55 (Local Time) and the maximum eclipse will occur at 21:54 (Local Time). The phenomenon will last until 23:54 (Local Time), when the Fullmoon will shine again in the night sky of Athens. During the maximum phase, the penumbra will hide a small fraction of the lunar light and one might not notice great difference. Don't forget to take a look or even take photo of this event! The next Penumbral Lunar Eclipse will occur in 11 February 2017.

Read more here... (details) and here... (map)

Supercomputer model of an impossibly bright 'monster pulsar'

Ultra Luminous X-ray sources (ULX), which are remarkably bright X-ray sources, were thought to be powered by black holes. But in 2014, the X-ray space telescope "NuSTAR" detected unexpected periodic pulsed emissions in a ULX named M82 X-2. The discovery of this object named "ULX-pulsar" has puzzled astrophysicists. Black holes can be massive enough to provide the energy needed to create ULXs, but black holes shouldn't be able to produce pulsed emissions. In contrast, "pulsars," a kind of neutron star, are named for the pulsed emissions they produce, but they are much fainter than ULXs. A new theory is needed to explain "ULX-pulsar."

Read more here... (article)

China's lunar-based telescope observes a binary star system

China's Chang'e-3 mission landed on the moon in December 2013 and deployed a lunar rover known as Yutu or Jade Rabbit; it also carried a robotic telescope designed to observe various celestial objects such as galaxies, active galactic nuclei, variable stars, binaries, novae, quasars and blazars in the near-ultraviolet band. The Lunar-based Ultraviolet Telescope (LUT) was recently used by a team of Chinese astronomers to observe a peculiar binary star designated V921 Her.

One can compare the light curve of the very same binary system with the one observed from the University of Athens Observatory here: (paper)

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First atmospheric study of Earth-sized exoplanets reveals rocky worlds

On May 2, scientists from MIT, the University of Liege, and elsewhere announced they had discovered a planetary system, a mere 40 light years from Earth, that hosts three potentially habitable, Earth-sized worlds. Judging from the size and temperature of the planets, the researchers determined that regions of each planet may be suitable for life.

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Theft Behind Planet 9 in Our Solar System

Through a computer-simulated study, astronomers at Lund University in Sweden show that it is highly likely that the so-called Planet 9 is an exoplanet. This would make it the first exoplanet to be discovered inside our own solar system. The theory is that our sun, in its youth some 4.5 billion years ago, stole Planet 9 from its original star.

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Astronomers find giant planet around very young star

In contradiction to the long-standing idea that larger planets take longer to form, U.S. astronomers today announced the discovery of a giant planet in close orbit around a star so young that it still retains a disk of circumstellar gas and dust. The planet, CI Tau b, is at least eight times larger than Jupiter and orbits a 2 million-year-old star about 450 light years from Earth in the constellation Taurus. Johns-Krull and a dozen co-authors from Rice, Lowell Observatory, the University of Texas at Austin, NASA and Northern Arizona University made the peer-reviewed study available online this week.

Read more here... (article)

Earth-like planet may exist in a nearby star system

An Earth-like planet may be lurking in a star system located just 16 light years away, according to a new research. The star, named Gliese 832, was recently investigated by a team of astronomers searching for additional exoplanets that may be residing between the two currently known alien worlds in this system. Gliese 832 is a red dwarf and has just under half the mass and radius of our sun. The star is orbited by a giant Jupiter-like exoplanet designated Gliese 832b and by a super-Earth mass planet Gliese 832c. The gas giant, with a mass of 0.64 Jupiter masses, is orbiting the star at a distance of 3.53 AU, while the other planet is potentially a rocky world, around five times more massive than the Earth, residing very close its host star—about 0.16 AU.

Read more here... (article)

Dance of Two Monster Black Holes

OJ 287 is one of the largest supermassive black holes known, weighing in at 18 billion solar masses. Located about 3.5 billion light-years away, this monster quasar is bright enough that it was first observed as early as the 1890s. This past December, researchers all over the world watched an outburst from the enormous black hole in OJ 287, an outburst that had been predicted years ago using the general theory of relativity. The University of Athens participates actively on photometric observations of this highly interesting target since 2006. The daily variations of OJ287 and the corresponding light curve is uptaded very frequently.

image credit: S. Zola & NASA/JPL

Read more here... (article) (article) (article) ...and here... (light curve)

Hubble breaks cosmic distance record

Using the NASA/ESA Hubble Space Telescope an international team of astronomers has measured the distance to this new galaxy, named GN-z11. This galaxy existed just 400 million years after the Big Bang and provides new insights into the first generation of galaxies. This is the first time that the distance of an object so far away has been measured from its spectrum, which makes the measurement extremely reliable.

Read more here... (full article)

Gravitational waves have been detected!

After 100 years of searching, an international team of physicists has confirmed the existence of Einstein's gravitational waves, marking one of the biggest astrophysical discoveries of the past century. It's a huge deal, because it not only improves our understanding of how the Universe works, it also opens up a whole new way of studying it.

Read more here... (full article)

James Webb Space Telescope mirror halfway complete

The 9th flight mirror was installed onto JWST structure with a robotic arm at NASA's Goddard Space Flight Center. This marks the halfway completion point for the James Webb Space Telescope's segmented primary mirror. The JWST team has been working tirelessly to install all 18 of Webb's mirror segments onto the telescope structure. The full installation is expected to be complete early in 2016.

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Hubble checks out a home for old stars

This image, taken with the Wide Field Planetary Camera 2 on board the NASA/ESA Hubble Space Telescope, shows the globular cluster Terzan 1. Lying around 20,000 light-years from us in the constellation of Scorpius (The Scorpion), it is one of about 150 globular clusters belonging to our galaxy, the Milky Way. Terzan 1, like many globular clusters, is a source of X-rays. It is likely that these X-rays come from binary star systems that contain a dense neutron star and a normal star. The neutron star drags material from the companion star, causing a burst of X-ray emission. The system then enters a quiescent phase in which the neutron star cools, giving off X-ray emission with different characteristics, before enough material from the companion builds up to trigger another outburst.

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LRO finds Apollo 16 booster rocket impact site

After decades of uncertainty, the Apollo 16 S-IVB impact site on the lunar surface has been identified. S-IVBs were portions of the Saturn V rockets that brought astronauts to the moon. The site was identified in imagery from the high-resolution LROC Narrow Angle Camera aboard NASA's Lunar Reconnaissance Orbiter. Beginning with Apollo 13, the S-IVB rocket stages were deliberately impacted on the lunar surface after they were used. Seismometers placed on the moon by earlier Apollo astronauts measured the energy of these impacts to shed light on the internal lunar structure. Locations of the craters that the boosters left behind were estimated from tracking data collected just prior to the impacts. Earlier in the LRO mission, the Apollo 13, 14, 15 and 17 impact sites were successfully identified, but Apollo 16's remained elusive. In the case of Apollo 16, radio contact with the booster was lost before the impact, so the location was only poorly known. Positive identification of the Apollo 16 S-IVB site took more time than the other four impact craters because the location ended up differing by about 30 km (about 19 miles) from the Apollo-era tracking estimate. (For comparison, the other four S-IVB craters were all within 7 km—about four miles—of their estimated locations.)

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New Horizons returns new images of Pluto

NASA's New Horizons spacecraft has sent back the first in a series of the sharpest views of Pluto it obtained during its July flyby – and the best close-ups of Pluto that humans may see for decades. Each week the piano-sized New Horizons spacecraft transmits data stored on its digital recorders from its flight through the Pluto system on July 14. These latest pictures are part of a sequence taken near New Horizons' closest approach to Pluto, with resolutions of about 250-280 feet (77-85 meters) per pixel – revealing features less than half the size of a city block on Pluto's diverse surface. In these new images, New Horizons captured a wide variety of cratered, mountainous and glacial terrains.

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First photo of planet in making captured

There are 450 light-years between Earth and LkCa15, a young star with a transition disk around it, a cosmic whirling dervish, a birthplace for planets. Despite the disk's considerable distance from Earth and its gaseous, dusty atmosphere, University of Arizona researchers captured the first photo of a planet in the making, a planet residing in a gap in LkCa15's disk. Of the roughly 2,000 known exoplanets—planets that orbit a star other than our sun—only about 10 have been imaged, and that was long after they had formed, not when they were in the making. This is the first time that we've imaged a planet that we can say is still forming.

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The extreme binary system VFTS 352

Using ESO's Very Large Telescope, an international team of astronomers have found the hottest and most massive double star with components so close that they touch each other. The two stars in the extreme system VFTS 352 could be heading for a dramatic end, during which the two stars either coalesce to create a single giant star, or form a binary black hole.

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The Curious Case of KIC 8462852

For the past few days, the media has been abuzz with one of the most peculiar astronomical observations for many years. As described in a recent paper, a faint star in the northern constellation Cygnus has been seen acting incredibly strangely.

Read more here... (full article) ...and here... (full article)

Update your desktop!

Are you fed up with the same photos all over the network? Here you can find two photographic mosaics from the recent astronomical expeditions for recording total solar eclipses. The first (left) is taken from Gabon on 3 November 2013 while the second (right) is taken from Svalbard Island at North Pole on 20 Marceh 2015. If you wish to re-use them for any purpose (announcement/publication/post), please inform me and give all credits to the owner.

Office hours - How you can find me

I am at Physics Faculty almost daily for several hours, basically from 12 at noon until late at night. Usually I am at the University Observatory (4th floor at bulding IV of Physics Faculty), or at the Laboratory of Astronomy and Applied Optics, or at the Laboratory of Astrophysics (2th floor at bulding IV of Physics Faculty).

If you need to leave a message or documents, you can place in on my mailbox (against the Secretariat of the Department of Astrophysics, Astronomy and Mechanics) or leave it at the secretary with a note.

The webpage is ready

With the beginning of the winter semester 2015-2016 I created the current webpage, with the aim to inform the students of Faculty of Physics on various topics related to the Faculty, the University Observatory and the wider research field of mine. All documents, texts, announcemets and photos will be updated frequently and I hope that you will find all information useful.

I would like to ask the users to be careful when they use material from this webpage. Any full or partial re-use of documents, photographs and/or other personal information without the written permission by the owner, is strictly prohibited. I will be glad to share documents and photographs with you, as long as you preserve, fully document and acknowledge the source and owner. For a detailed description of copyright matters, please see the World Intellectual Property Organization (WIPO) Copyright Treaty (Geneva, December 2-20, 1996) and/or the latest text of the Berne Convention for the Protection of Literary and Artistic Works.


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