Explanation: Taken on the same night, from the same place, with the same telescope and camera, these postcards from our Solar System are shown at the same scale to provide an interesting comparison of apparent sizes. Spanning about half a degree in planet Earth's sky, the Moon is a stitched mosaic of six images. The others are the result of digitally stacked frames or simple single exposures, with the real distances to the objects indicated along the bottom of each insert. Most of the Solar System's planets with their brighter moons, and Pluto were captured during the telescopic expedition, but elusive Mercury was missed because of clouds near the horizon. The International Space Stationwas successfully hunted, though. The night was July 21st. Telescope and camera were located at the Centro Astronomico de Tiedra Observatory in Spain.
Explanation: Look opposite the Sun in the sky tonight and you'll see Mars at its brightest. Also within days of its closest approach Mars rises at sunset, near its brightest and best for telescopic observers too, except for the dust storm still blanketing the Red Planet. These two Hubble Space Telescope images compare Mars' appearance near its 2016 and 2018 oppositions. In 2016 the martian atmosphere was clear. Captured just days ago, the 2018 image shows almost the same face of Mars. Surface features obscured by dust, the planet's cloud enshrouded south pole is tilted more toward the Sun. Increased heat in the southern hemisphere spring and summer likely triggers planet wide dust storms. Of course, if you look opposite the Sun in the sky tonight, you'll also see a Full Moon near Mars. Skygazers NOT located in North America could see the Red Planet near a Red Moon during a Total Lunar Eclipse.
Explanation: These dark markings on the sky can just be found in silhouette against a rich, luminous background of stars. Seen toward the southern constellation of Lupus the Wolf, the dusty, obscuring clouds are part of the Lupus Molecular Cloud some 500 light-years distant. Packs of low mass stars are forming within them, from collapsing cores only visible at long infrared wavelengths. Still, colorful stars in Lupus add to this pretty galactic skyscape. It spans about 8 degrees, not far from the central Milky Way.
Explanation: What kind of celestial object is this? A relatively normal galaxy -- but seen from its edge. Many disk galaxies are actually just as thin as NGC 5866, pictured here, but are not seen edge-on from our vantage point. A perhaps more familiar galaxy seen edge-on is our own Milky Way Galaxy. Cataloged as M102 and NGC 5866, the Spindle galaxy has numerous and complex dust lanes appearing dark and red, while many of the bright stars in the disk give it a more blue underlying hue. The blue disk of young stars can be seen extending past the dust in the extremely thin galactic plane. There is evidence that the Spindle galaxy has cannibalized smaller galaxies over the past billion years or so, including multiple streams of faint stars, dark dust that extends away from the main galactic plane, and a surrounding group of galaxies (not shown). In general, many disk galaxies become thin because the gas thatforms them collides with itself as it rotates about the gravitational center. The Spindle galaxy lies about 50 million light years distant toward the constellation of the Dragon (Draco).
Clouds of Earth and Sky Image Credit & Copyright: Angelo Perrone
Explanation: If you go high enough, you may find yourself on a picturesque perch between the water clouds of the Earth and the star clouds of the Milky Way. Such was the case last month for one adventurous alpinist astrophotographer. Captured here in the foreground above white clouds are mountain peaks in the Dolomite range in northern Italy. This multi-exposure image was captured from Lagazuoi, one of the Dolomites. Hundreds of millions of years ago, the Dolomites were not mountains but islands an ancient sea that rose through colliding tectonic plates. The Dolomites divergent history accounts for its unusually contrasting features, which include jagged crests and ancient marine fossils. High above even the Dolomites, and far in the distance, dark dust lanes streak out from the central plane of our Milky Way Galaxy. The stars and dust are dotted with bright red clouds of glowing hydrogen gas -- such as the Lagoon Nebula just above and to the left of center.
Explanation: The Fermi Science Playoffs celebrate 10 years of the Fermi Gamma-ray Space Telescope's exploration of the high-energy universe. Surviving all early rounds of voting, these two finalists in the competion square off at last. Digital illustrations from a list of 16 of Fermi's top scientific discoveries, they represent the competition's two top seeds, defeating 12th seed New Clues to Dark Matter and 14th seed Starquakes in Magnetar Storm in the semifinal round. On the left are unprecedented, unpredicted, 25,000 light-year tall Gamma-ray Bubbles above and below the plane of our Milky Way galaxy. On the right, violently merging Neutron Stars Collide to create the first gamma-ray detected gravitational wave event. Pick one now and cast your vote here to crown the most popular science result from Fermi's first decade.
Explanation: You can see it change in brightness with just binoculars over the course of a year. Variable star R Aquarii is actually an interacting binary star system, two stars that seem to have a close, symbiotic relationship. About 710 light years away, this intriguing system consists of a cool red giant star and hot, dense white dwarf star in mutual orbit around their common center of mass. The binary system's visible light is dominated by the red giant, itself a Mira-type long period variable star. But material in the cool giant star's extended envelope is pulled by gravity onto the surface of the smaller, denser white dwarf, eventually triggering a thermonuclear explosion and blasting material into space. Thefeatured image from the Hubble Space Telescope shows the still-expanding ring of debris which spans less than a light year and originated from a blast that would have been seen in the early 1770s. The evolution of less understood energetic events producing high energy emission in the R Aquarii system has been monitored since 2000 using Chandra X-ray Observatory data.
Explanation: Have you seen a panorama from another world lately? Assembled from high-resolution scans of the original film frames, this one sweeps across the magnificent desolation of the Apollo 11 landing site on the Moon's Sea of Tranquility. The images were taken by Neil Armstrong looking out his window of the Eagle Lunar Module shortly after the July 20, 1969 landing. The frame at the far left (AS11-37-5449) is the first picture taken by a person on another world. Toward the south, thruster nozzles can be seen in the foreground on the left, while at the right, the shadow of the Eagle is visible to the west. For scale, the large, shallow crater on the right has a diameter of about 12 meters. Frames taken from the Lunar Module windows about an hour and a half after landing, before walking on the lunar surface, were intended to initially document the landing site in case an early departure was necessary.
Tous les curieux du ciel, et bien sûr les astronomes amateurs, sont gâtés pour ce mois de juillet : quasiment toutes les planètes du Système solaire sont visibles au cours des douces nuits de l’été. Cinq le sont à l’œil nu. S’y ajoute l’astéroïde Vesta. Mais il n’y a pas que ça ! Événement céleste à ne pas rater : la plus longue éclipse de Lune du siècle le même jour que l’opposition de Mars ! Et en plus, ce sera la plus petite distance entre la Terre et la Planète rouge depuis 2003 ! Un beau festival de planètes.
Ce mois de juillet 2018 va combler tous les observateurs du ciel, que vous soyez simple curieux ou astronome amateur chevronné. C’est en effet un vrai défilé de planètes, du crépuscule à l’aube. Un paradis pour tous les amateurs de planètes qui souhaitent les contempler ou les photographier. Et ce n’est pas tout : la Lune se donnera en spectacle à la fin du mois pour une longue éclipse. Cerise sur la gâteau, la planète rouge sera alors visible à côté d’elle, le jour de son opposition (le 27 juillet). Et cette année, c’est un grand cru.
Notre satellite naturel a rendez-vous avec toutes ces planètes au fil de sa lunaison. Les 5 visibles à l’œil nu, auxquelles s’ajoutent les lointaines Uranus et Neptune et l’astéroïde Vesta, le deuxième plus gros corps de la Ceinture d’astéroïdes. Alors, si d’aventure vous hésitiez encore à acheter uninstrument d’observation — et/ou du matériel pour photographier le ciel —, ce mois de juillet (avec les vacances) est peut-être le bon moment. Vous pourrez ainsi admirer au cours des douces nuits d’été, le croissant de Vénus, les bandes colorées de Jupiter (et ses satellites), Saturne et ses anneaux, Vesta… ! Enfin, Pluton, une ex-planète classée maintenant comme planète naine, sera en opposition le 12 juillet. Il y a 3 ans, le 14 juillet 2015, New Horizons réalisait son survol historique de l’astre et de ses compagnons. Des images qu’on n’est pas prêt d’oublier !
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