Astronomy Picture of the Day 🪐

🔭 Rosetta's Selfie Credit: ESA/Rosetta/Philae/CIVA ap261024

🔭 Noctilucent Clouds over Sweden Credit & Copyright: V. Höfer, D. Večerník & B. Večerníková ap261027

here as they appeared in early August, a network of blue noctilucent clouds was captured in the distant sky above a field of green grass near Linköping, Sweden, with trees in stark silhouette across the horizon. Much about noctilucent clouds has been discovered only in the past two decades, while

how they form and evolve remains a topic of active research.

🔭 Noctilucent Clouds over Sweden Credit & Copyright: V. Höfer, D. Večerník & B. Večerníková ap261027

Sometimes it's night on the ground but day in the air. As the Earth rotates to eclipse the Sun, sunset rises upfrom the ground. Therefore, at sunset on the ground, sunlight still shines on clouds above. Under usual circumstances, a pretty sunset might be visible, but unusual noctilucent clouds float

so high up they can be seen well after dark. Normally too dim to be seen, they may become visible just after sunset during the summer when illuminated by sunlight from below the horizon. Noctilucent clouds are the highest clouds and are known more technically as polar mesospheric clouds. Featured

Astronomy Picture of the Day 🪐 reposted

🔭 Andromeda in Southern Spring Credit & Copyright: Lucy Yunxi Hu ap261023

Astronomy Picture of the Day 🪐 reposted

🔭 The First Green Star, WD J1330+6435 Credit & Copyright: Mark A. Garlick/University of Warwick ap261022

Astronomy Picture of the Day 🪐 reposted

🔭 New Ghosts Revealed in Cassiopeia Credit & Copyright: Louis Leroux-Géré, Thibault Rouillée, Vincent Martin, Cédric de Decker (Starfront Observatories) ap261021

🔭 Rosetta's Selfie Credit: ESA/Rosetta/Philae/CIVA ap261024

Philae lander. Its chosen primary landing site was on the visible hemisphere of the smaller lobe of the nucleus. This was the last image from Philae's camera before the lander separated from Rosetta on November 12. Shortly after separation Philae took another image looking back toward the orbiter

and began its descent to the nucleus of the comet.

🔭 Rosetta's Selfie Credit: ESA/Rosetta/Philae/CIVA ap261024

This Rosetta spacecraft selfie was snapped on October 7th, 2014. At the time the comet-chasing spacecraft was about 472 million kilometers from planet Earth, but only 16 kilometers from the surface of comet 67P/Churyumov-Gerasimenko. Looming beyond the spacecraft near the top of the frame, dust and

gas stream away from the comet's curious double-lobed nucleus. Bright sunlight glints off one of Rosetta's 14 meter long solar arrays. In fact, two exposures, one short and one long, were combined to record the dramatic high contrast scene using the CIVA camera system on Rosetta's still-attached

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🔭 An Anticrepuscular Rainbow Fan Credit & Copyright: Aurelia Degli Esposti ap261020

🔭 Andromeda in Southern Spring Credit & Copyright: Lucy Yunxi Hu ap261023

exposures were used to reveal the spiral galaxy in tantalizing detail as it climbed above rolling Australian hills. Also known as M31, the Andromeda Galaxy is one of the brightest objects in the Messier catalog, but is only visible to the unaided eye as a small, faint, fuzzy patch. Digitally tracked

and stacked frames were combined with a foreground shot in the deep astro-image composite to reveal the galaxy's greater extent in planet Earth's night. In the springtime night skyscape,the closest large spiral galaxy spans nearly 6 full moons.

🔭 Andromeda in Southern Spring Credit & Copyright: Lucy Yunxi Hu ap261023

Looking toward the north from Mullion, New South Wales, Australia, the Andromeda Galaxy never gets more than a few degrees above the horizon. During the southern hemisphere spring, Andromeda is highest in the sky around midnight though. And in this telephoto scene from October 10/11, multiple

🔭 The First Green Star, WD J1330+6435 Credit & Copyright: Mark A. Garlick/University of Warwick ap261022

recently found that some white dwarf stars, despite their name, would appear yellow, green, cyan, pink, or purple. In these cases, trace elements that were accreted to these stars interact with the stellar atmosphere and shift its normally white color. But, alas! I wish I may, I wish I might, but

they are too faint to see tonight...

🔭 The First Green Star, WD J1330+6435 Credit & Copyright: Mark A. Garlick/University of Warwick ap261022

Star light, star bright: is there a green star out tonight? Other than the Sun, all stars are so far from Earth that they appear as points in the sky. They are mostly white, but sometimes noticeably red or blue. This color typically relates to the temperature: blue stars are hotter than red stars.

What about other colors? The featured image is an illustration showing WD J1330+6435, a white dwarf star, surrounded by an accretion disk with gas and rocks orbiting the star. White dwarfs are small, faint stars that are left over when a star like the Sun exhausts its nuclear fuel. Astronomers

Astronomy Picture of the Day 🪐 reposted

youtube.comSonified: Eagle Nebula PillarsYouTube video by APOD Videos

🔭 Sonified: Eagle Nebula Pillars Credit: Image Credit: NASA, ESA, & The Hubble Heritage Project (STScI/AURA); Sonification: NASA, CXC, SAO, K. Arcand, M. Russo & A. Santaguida ap261018

🔭 New Ghosts Revealed in Cassiopeia Credit & Copyright: Louis Leroux-Géré, Thibault Rouillée, Vincent Martin, Cédric de Decker (Starfront Observatories) ap261021

speeding boat, γ Cassiopeia may be piling up material as the system moves through interstellar gas and dust. It follows that Object 3 may be the compressed and heated oxygen of that bow shock. Object 1 could be a planetary nebula if a central white dwarf is identified. The origins of these

astronomical apparitions remain a mystery to be solved.

🔭 New Ghosts Revealed in Cassiopeia Credit & Copyright: Louis Leroux-Géré, Thibault Rouillée, Vincent Martin, Cédric de Decker (Starfront Observatories) ap261021

Jinkies, look at all those ghosts! It took 100 hours of observation and a special oxygen filter for today’s image to capture three faint nebulas hidden in the Cassiopeia constellation. IC 59 and IC 63, the original Ghosts of Cassiopeia, haunt the region near multi-star system γ Cassiopeia.

Energetic light from γ Cassiopeia causes the hydrogen gas in IC 59 and 63 to glow red. Their dust reflects and scatters some blue-ish white starlight. Newly discovered Objects 1, 2, and 3 appear as blue phantoms, revealing the presence of ionized oxygen. But ionized by what? Like at the bow of a

Astronomy Picture of the Day 🪐 reposted

🔭 3D 67P Credit: ESA , Rosetta , MPS , OSIRIS - Stereo Anaglyph: Philippe Lamy and The Team ap261017

🔭 An Anticrepuscular Rainbow Fan Credit & Copyright: Aurelia Degli Esposti ap261020

how rainbows work. Rainbows involve a backward reflection from falling rain, so that the Sun must really be behind you. In this case, gaps between clouds near the setting Sun allowed rays to cross the entire sky and appear to converge in front, an unusual phenomenon called anticrepuscular rays. The

photo was taken with a phone last week at sunset in Presenzano, Italy. The seemingly reverse rainbow was noticed when hanging up laundry.

🔭 An Anticrepuscular Rainbow Fan Credit & Copyright: Aurelia Degli Esposti ap261020

This is an unusual rainbow. For one thing, the rainbow is not complete, appearing only in a sunlit fan -- but that by itself is not very unusual. What is most unusual is the fake location of the Sun. The Sun appears to be toward the front, just below those hills -- but it is not. That is not

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🔭 Chasing the International Space Station Video Credit: Eric Holland ap261016

Astronomy Picture of the Day 🪐 reposted

🔭 The Milky Way over Manhattan Credit & Copyright: Jason Kurth, Ty Buckley ap261015

youtube.comSonified: Eagle Nebula PillarsYouTube video by APOD Videos

🔭 Sonified: Eagle Nebula Pillars Credit: Image Credit: NASA, ESA, & The Hubble Heritage Project (STScI/AURA); Sonification: NASA, CXC, SAO, K. Arcand, M. Russo & A. Santaguida ap261018

spectacular details are captured in this combined Hubble (visible) and Chandra (X-ray) image, is likely similar to the environment that formed our own Sun. In the featured video, listen for stars and dust sounding off as the line of sonification moves left to right, with vertical position

determining pitch.

youtube.comSonified: Eagle Nebula PillarsYouTube video by APOD Videos

🔭 Sonified: Eagle Nebula Pillars Credit: Image Credit: NASA, ESA, & The Hubble Heritage Project (STScI/AURA); Sonification: NASA, CXC, SAO, K. Arcand, M. Russo & A. Santaguida ap261018

Yes, but have you ever experienced the Eagle Nebula with your ears? The famous nebula M16 is best known for the feast it gives your eyes, highlighting bright young stars forming deep inside dark towering structures. These light-years long columns of cold gas and dust are some 6,500 light-years

distant toward the constellation of the Serpent (Serpens). Sculpted and eroded by the energetic ultraviolet light and powerful winds from M16's cluster of massive stars, the cosmic pillars themselves are destined for destruction. But the turbulent environment of star formation within M16, whose

Astronomy Picture of the Day 🪐 reposted