Astronomy picture of the day - 2017 November 1 - Thor's Helmet Emission Nebula

Thor's Helmet Emission Nebula 
Image Credit & Copyright: Adam Block, Mt. Lemmon SkyCenter, U. Arizona

Explanation: This helmet-shaped cosmic cloud with wing-like appendages is popularly called Thor's Helmet. Heroically sized even for a Norse god, Thor's Helmet spans about 30 light-years across. In fact, the helmet is more like an interstellar bubble, blown as a fast wind -- from the bright star near the center of the bubble's blue-hued region -- sweeps through a surrounding molecular cloud. This star, a Wolf-Rayet star, is a massive and extremely hot giant starthought to be in a brief, pre-supernova stage of evolution. Cataloged as NGC 2359, the emission nebula is located about 12,000 light-years away toward the constellation of the Big Dog (Canis Major). The sharp image, made using broadband and narrowband filters, captures striking details of the nebula's filamentary gas and dust structures. The blue color originates from strong emission from oxygen atoms in the nebula.

Astronomy picture of the day - 2017 October 31 - Dark Matter in a Simulated Universe

Dark Matter in a Simulated Universe 
Illustration Credit & Copyright Tom Abel & Ralf Kaehler (KIPAC, SLAC), AMNH

Explanation: Is our universe haunted? It might look that way on this dark matter map. The gravity of unseen dark matter is the leading explanation for why galaxies rotate so fast, why galaxies orbit clusters so fast, why gravitational lenses so strongly deflect light, and why visible matter is distributed as it is both in the local universe and on the cosmic microwave background. The featured image from the American Museum of Natural History’s Hayden PlanetariumSpace Show Dark Universe highlights one example of how pervasive dark matter might haunt our universe. In this frame from a detailed computer simulation, complex filaments of dark matter, shown in black, are strewn about the universe like spider webs, while the relatively rare clumps of familiar baryonic matter are colored orange. These simulations are good statistical matches to astronomical observations. In what is perhaps a scarier turn of events, dark matter -- although quite strange and in an unknown form -- is no longer thought to be the strangest source of gravity in the universe. That honor now falls to dark energy, a more uniform source of repulsive gravity that seems to now dominate the expansion of the entire universe.

Pintores Portugueses - Fernando Gaspar

Astronomy pictures of the day - 2017 October 30 - Orionid Meteors from Orion

Orionid Meteors from Orion 
Image Credit & Copyright: Lu Shupei

Explanation: Meteors have been shooting out from the constellation of Orion. This was expected, as October is the time of year for the Orionids Meteor Shower. Pictured here, over a dozen meteors were caught in successively added exposures last weekend over Wulan Hada volcano in Inner Mongolia, China. The featured image shows multiple meteor streaks that can all be connected to a single small region on the sky called the radiant, here visible just above and to the left of the belt of Orion, The Orionids meteors started as sand sized bits expelled from Comet Halley during one of its trips to the inner Solar System. Comet Halley is actually responsible for two known meteor showers, the other known as the Eta Aquarids and visible every May. Next month, the Leonids Meteor Shower from Comet Tempel-Tuttle should also result in some bright meteor streaks.

Aaron - "U turn" (Lili) - Video - Music

"U turn (Lili)"

Astronomy picture of the day - 2017 October 29 - Night on a Spooky Planet

Night on a Spooky Planet 
Image Credit & Copyright: Stéphane Vetter (Nuits sacrées)

Explanation: What spooky planet is this? Planet Earth of course, on a dark and stormy night in 2013 at Hverir, a geothermally active area along the volcanic landscape in northeastern Iceland. Geomagnetic storms produced the auroral display in the starry night sky while ghostly towers of steam and gas venting from fumaroles danced against the eerie greenish light. Tonight, there is also a chance for geomagnetic storms triggered by recent solar activity, so high-latitude skygazers should beware. Ghostly shapes may dance in your neighborhood pretty soon, too.

Astronomy picture of the day - 2017 October 28 - NGC 6369: The Little Ghost Nebula

NGC 6369: The Little Ghost Nebula 
Image Credit: Hubble Heritage Team, NASA

Explanation: Wraithlike NGC 6369 is a faint apparition in night skies popularly known as the Little Ghost Nebula. It was discovered by 18th century astronomer Sir William Herschel as he used a telescope to explore the medicinalconstellation Ophiucus. Herschel historically classified the round and planet-shaped nebula as a Planetary Nebula. But planetary nebulae in general are not at all related to planets. Instead they are gaseous shrouds created at the end of a sun-like star's life, the dying star's outer layers expanding into space while its core shrinks to become a white dwarf. The transformed white dwarf star, seen near the center, radiates strongly at ultraviolet wavelengths and powers the expanding nebula's glow. Surprisingly complex details and structures of NGC 6369 are revealed in this tantalizing image composed from Hubble Space Telescope data. The nebula's main round structure is about a light-year across and the glow from ionized oxygen, hydrogen, and nitrogen atoms are colored blue, green, and red respectively. Over 2,000 light-years away, the Little Ghost Nebula offers a glimpse of the fate of our Sun, which could produce its own planetary nebula about 5 billion years from now.

Astronomy picture of the day - 2017 October 27 - Mirach's Ghost

Mirach's Ghost 
Image Credit & Copyright: Kent Wood

Explanation: As far as ghosts go, Mirach's Ghost isn't really that scary. Mirach's Ghost is just a faint, fuzzy galaxy, well known to astronomers, that happens to be seen nearly along the line-of-sight to Mirach, a bright star. Centered inthis star field, Mirach is also called Beta Andromedae. About 200 light-years distant, Mirach is a red giant star, cooler than the Sun but much larger and so intrinsically much brighter than our parent star. In most telescopic views, glare and diffraction spikes tend to hide things that lie near Mirach and make the faint, fuzzy galaxy look like a ghostly internal reflection of the almost overwhelming starlight. Still, appearing in this sharp image just above and to the left of Mirach, Mirach's Ghost is cataloged as galaxy NGC 404 and is estimated to be some 10 million light-years away.

Imagens do mundo - Peso da Régua, Portugal

Margens do Douro

Astronomy picture of the day - 2017 October 25 - Marius Hills and a Hole in the Moon

Marius Hills and a Hole in the Moon 
Image Credit: NASA, Lunar Orbiter 2; Inset: Lunar Reconnaissance Orbiter

Explanation: Could humans live beneath the surface of the Moon? This intriguing possibility was bolstered in 2009 when Japan's Moon-orbiting SELENE spacecraft imaged a curious hole beneath the Marius Hills region on the Moon, possibly a skylight to an underground lava tube. Follow-up observations by NASA's Lunar Reconnaissance Orbiter (LRO) indicated that the Marius Hills Hole (MHH) visually extends down nearly 100 meters and is several hundred meters wide. Most recently, ground penetrating radar data from SELENE has been re-analyzed to reveal a series of intriguing second echoes -- indicators that the extensive lava tubes exist under Marius Hills might extend down even kilometers and be large enough to house cities. Such tubes could shelter a future Moon colony from large temperature swings, micro-meteor impacts, and harmful solar radiation. Potentially, underground lava tubes might even be sealed to contain breathable air. These lava tubes likely formed when lunar volcanos were active billions of years ago. Pictured, the surface of Marius Hills region was captured in the 1960s by NASA's Lunar Orbiter 2 mission, while an inset image of the MHH is shown from NASA's continuing LRO. Several volcanic domes are visible, while Marius Crater is visible on the upper right.