"O cantar é de quem canta"
2017-02-08
Astronomy picture of the day - 2017 February 8 - The Butterfly Nebula from Hubble
Image Credit: NASA, ESA, Hubble, HLA; Reprocessing & Copyright: Jesús M.Vargas & Maritxu Poyal
Explanation: The bright clusters and nebulae of planet Earth's night sky are often named for flowers or insects. Though its wingspan covers over 3 light-years, NGC 6302 is no exception. With an estimated surface temperature of about 250,000 degrees C, the dying central star of this particular planetary nebula has become exceptionally hot, shining brightly in ultraviolet light but hidden from direct view by a dense torus of dust. This sharp close-up of the dying star's nebula was recorded by the Hubble Space Telescope and is presented here in reprocessed colors. Cutting across a bright cavity of ionized gas, the dust torus surrounding the central star is near the center of this view, almost edge-on to the line-of-sight. Molecular hydrogen has been detected in the hot star's dusty cosmic shroud. NGC 6302 lies about 4,000 light-years away in the arachnologically correct constellation of the Scorpion (Scorpius).
2017-02-07
Astronomy picture of the day - 2017 February 7 - NGC 6357: The Lobster Nebula
Image Credit: ESO, VLT Survey Telescope
Explanation: Why is the Lobster Nebula forming some of the most massive stars known? No one is yet sure. Near the more obvious Cat's Paw nebula on the upper right, the Lobster Nebula, on the lower left and cataloged as NGC 6357, houses the open star cluster Pismis 24, home to these tremendously bright and blue stars. The overall red glow near the inner star forming region results from the emission of ionized hydrogen gas. The surrounding nebula, featured here, holds a complex tapestry of gas, dark dust, stars still forming, and newly born stars. The intricate patterns are caused by complex interactions between interstellar winds, radiation pressures, magnetic fields, and gravity. The fullzoomable version of this image contains about two billion pixels, making it one of the largest space images ever released. NGC 6357 spans about 400 light years and lies about 8,000 light years away toward the constellation of theScorpion.
2017-02-06
Astronomy picture of the day - 2017 February 6 - The Porpoise Galaxy from Hubble
Image Credit: NASA, ESA, Hubble, HLA; Reprocessing & Copyright: Raul Villaverde
Explanation: What's happening to this spiral galaxy? Just a few hundred million years ago, NGC 2936, the upper of the two large galaxies shown, was likely a normal spiral galaxy -- spinning, creating stars -- and minding its own business. But then it got too close to the massive elliptical galaxy NGC 2937 below and took a dive. Dubbed the Porpoise Galaxy for its iconic shape, NGC 2936 is not only being deflected but also being distorted by the close gravitational interaction. A burst of young blue stars forms the nose of the porpoise toward the right of the upper galaxy, while the center of the spiral appears as an eye. Alternatively, the galaxy pair, together known as Arp 142, look to some like a penguin protecting an egg. Either way, intricate dark dust lanes and bright blue star streams trail the troubled galaxy to the lower right. The featured re-processed image showing Arp 142 in unprecedented detail was taken by the Hubble Space Telescope last year. Arp 142 lies about 300 million light years away toward the constellation, coincidently, of the Water Snake (Hydra). In a billion years or so the two galaxies will likely merge into one larger galaxy.
2017-02-05
Astronomy picture of the day - 2017 February 5 - Odysseus Crater on Tethys
Image Credit: Cassini Imaging Team, SSI, JPL, ESA, NASA
Explanation: Some moons wouldn't survive the collision. Tethys, one of Saturn's larger moons at about 1000 kilometers in diameter, survived the collision, but today exhibits the resulting expansive impact crater Odysseus. Sometimes called the Great Basin, Odysseus occurs on the leading hemisphere of Tethys and shows its great age by the relative amount of smaller craters that occur inside its towering walls. The density of Tethys is similar to water-ice. Thefeatured image was captured in November by the robotic Cassini spacecraft in orbit around Saturn as it swooped past the giant ice ball. Cassini has now started on its Grand Finale Tour which will take it inside Saturn's rings andculminate in September with a dive into Saturn's thick atmosphere.
2017-02-04
Fotografia - Lisboa noturna - Praça dos Restauradores e avenida da Liberdade
Estúdio Horácio Novais, Praça dos Restauradores e avenida da Liberdade, Lisboa, sem data Colecções da Fundação Calouste Gulbenkian, Lisboa, Portugal (Flickr Commons)
Astronomy picture of the day - 2017 February 4 - Conjunction of Four
Image Credit & Copyright: Maxime Oudoux
Explanation: On January 31, a waxing crescent Moon, brilliant Venus, and fainter Mars gathered in the fading twilight, hanging above the western horizon just after sunset on planet Earth. In this combined evening skyscape, the lovely celestial triangle is seen through clouds and haze. Still glinting in sunlight, from low Earth orbit the International Space Station briefly joined the trio that evening in skies near Le Lude, France. The photographer's line-of-sight to the space station was remarkably close to Mars as the initial exposure began. As a result, the station's bright streak seems to leap from the Red Planet, moving toward darker skies at the top of the frame.
2017-02-03
Astronomy picture of the day - 2017 February 3 - Milky Way with Airglow Australis
Image Credit & Copyright: Yuri Beletsky (Carnegie Las Campanas Observatory, TWAN)
Explanation: Captured last April after sunset on a Chilean winter's night an exceptionally intense airglow flooded this scene. The panoramic skyscape is also filled with stars, clusters, and nebulae along the southern Milky Way including the Large and Small Magellanic clouds. Originating at an altitude similar to aurorae, the luminous airglow is due to chemiluminescence, the production of light through chemical excitation. Commonly recorded with a greenish tinge by sensitive digital cameras, both red and green airglow emission here is predominately from atmospheric oxygen atoms at extremely low densities and has often been present in southern hemisphere nights during the last few years. Like theMilky Way on that dark night the strong airglow was visible to the eye, but seen without color. Mars, Saturn, and bright star Antares in Scorpius form the celestial triangle anchoring the scene on the left. The road leads toward the 2,600 meter high mountain Cerro Paranal and the European Southern Observatory's Very Large Telescopes.
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