Swimming on Jupiter - Astronomy picture of the day - 2018 December 14

Swimming on Jupiter 
Image Credit: NASA, JPL-Caltech, SwRI, MSSS; Processing: Brian Swift, Sean Doran

Explanation: On October 29, the Juno spacecraft once again dove near the turbulent Jovian cloud tops. Its 16th orbital closest approach or perijove passage, brought Juno within 3,500 kilometers of the Solar System's largest planetary atmosphere. These frames, recorded by JunoCam while the spacecraft cruised 20 - 50 thousand kilometers above the planet's middle southern latitudes, seem to follow a swirling cloud shaped remarkably like a dolphin. Swimming along Jupiter's darker South South Temperate Belt, this dolphin is itself planet-sized though, some thousands of kilometers across. Juno's next perijove passage will be December 21.

M43: Orion Falls - Astronomy picture of the day - 2018 December 12

M43: Orion Falls  
Image Credit & Copyright: Zhuoqun Wu, Chilescope Telescope 2

Explanation: Is there a waterfall in Orion? No, but some of the dust in M43 appears similar to a waterfall on Earth. M43, part of the Orion Molecular Cloud Complex, is the often imaged but rarely mentioned neighbor of the more famous M42. M42, which includes many bright stars from the Trapezium cluster, lies above the featured scene. M43 is itself a star forming region and although laced with filaments of dark dust, is composed mostly of glowing hydrogen. The entire Orion field, located about 1600 light years away, is inundated with many intricate and picturesque filaments of dust. Opaque to visible light, dark dust is created in the outer atmosphere of massive cool stars and expelled by a strong outer wind of protons and electrons.

Arp 188 and the Tadpole's Tail - Astronomy picture of the day - 2018 December 11

Arp 188 and the Tadpole's Tail   Image Credit: Hubble Legacy Archive, ESA, NASA; Processing: Faus Márquez (AAE)

Explanation: Why does this galaxy have such a long tail? In this stunning vista, based on image data from the Hubble Legacy Archive, distant galaxies form a dramatic backdrop for disrupted spiral galaxy Arp 188, the Tadpole Galaxy. The cosmic tadpole is a mere 420 million light-years distant toward the northern constellation of the Dragon (Draco). Its eye-catching tail is about 280 thousand light-years long and features massive, bright blue star clusters. One story goes that a more compact intruder galaxy crossed in front of Arp 188 - from right to left in this view - and was slung around behind the Tadpole by their gravitational attraction. During the close encounter, tidal forces drew out the spiral galaxy's stars, gas, and dust forming the spectacular tail. The intruder galaxy itself, estimated to lie about 300 thousand light-years behind the Tadpole, can be seen through foreground spiral arms at the upper right.Following its terrestrial namesake, the Tadpole Galaxy will likely lose its tail as it grows older, the tail's star clusters forming smaller satellites of the large spiral galaxy.

Sound and Light Captured by Mars InSight - Astronomy picture of the day - 2018 December 10

Sound and Light Captured by Mars InSight 

Image Credit: NASA/JPL-Caltech

Explanation: Your arm on Mars has unusual powers. For one thing it is nearly 2 meters long, has a scoop and grapple built into its hand, and has a camera built into its forearm. For another, it will soon deploy your ear -- a sensitive seismometer that will listen for distant rumblings -- onto the surface of Mars. Your SEISmomet-ear is the orange box in the foreground, while the gray dome behind it will be its protective cover. Your arm is attached to the InSight robotic lander that touched down on Mars two weeks ago. Somewhat unexpectedly, your ear has already heard something -- slight vibrations caused by the Martian wind flowing over the solar panels. Light from the Sun is being collected by the solar panels, part of one being visible on the far right. Actually, at the present time, you have two arms operating on Mars, but they are separated by about 600 kilometers. That's because your other active arm is connected to the Curiosity rover exploring a distant crater. Taken a week ago, rusty soil and rocks are visible in the featured image beyond Insight, as well as the orange sky of Mars.

Aurora Shimmer, Meteor Flash - Astronomy picture of the day - 2018 December 9

Aurora Shimmer, Meteor Flash 
Image Credit & Copyright: Bjørnar G. Hansen

Explanation: Some night skies are serene and passive -- others shimmer and flash. The later, in the form of auroras and meteors, haunted skies over the island of Kvaløya, near Tromsø Norway on 2009 December 13. This 30 second long exposure records a shimmering auroral glow gently lighting the wintery coastal scene. A study in contrasts, the image also captures the sudden flash of a fireball meteor from the excellent Geminid meteor shower of 2009. Streaking past familiar stars in the handle of the Big Dipper, the trail points back toward the constellation Gemini, off the top of the view. Both auroras and meteors occur in Earth's upper atmosphere at altitudes of 100 kilometers or so, but auroracaused by energetic charged particles from the magnetosphere, while meteors are trails of cosmic dust. Nine years after this photograph was taken, toward the end of this week, the yearly 2018 Geminids meteor shower will peak again, although this time their flashes will compete with the din of a half-lit first-quarter moon during the first half of the night.

Tiny Planet Timelapse - Astronomy picture of the day - 2018 December 8

Tiny Planet Timelapse Video Credit & Copyright: Brian Haidet - Music Credit: Space Walk - Silent Partner

Explanation: You can pack a lot of sky watching into 30 seconds on this tiny planet. Of course, the full spherical image timelapse video was recorded on planet Earth, from Grande Pines Observatory outside Pinehurst, North Carolina. It was shot in early September with a single camera and circular fisheye lens, digitally combining one 24-hour period with camera and lens pointed up with one taken with camera and lens pointed down. The resulting image data is processed and projected onto a flat frame centered on the nadir, the point directly below the camera. Watch as clouds pass, shadows creep, and the sky cycles from day to night when stars swirl around the horizon. Keep watching, though. In a second sequence the projected center is the south celestial pole, planet Earth's axis of rotation below the tiny planet horizon. Holding the stars fixed, the horizon itself rotates as the tiny planet swings around the frame, hiding half the sky through day and night.

December's Comet Wirtanen - Astronomy picture of the day - 2018 December 7

December's Comet Wirtanen  
Image Credit & Copyright: Juan Carlos Casado (TWAN, Earth and Stars)

Explanation: Coming close in mid-December, Comet 46P Wirtanen hangs in this starry sky over the bell tower of a Romanesque church. In the constructed vertical panorama, a series of digital exposures capture its greenish coma on December 3 from Sant Llorenc de la Muga, Girona, Catalonia, Spain, planet Earth. With an orbital period that is now about 5.4 years, the periodic comet's perihelion, its closest approach, to the Sun will be on December 12. On December 16 it will be closest to Earth, passing at a distance of about 11.6 million kilometers or 39 light-seconds. That's close for a comet, a mere 30 times the Earth-Moon distance. A good binocular target for comet watchers, Wirtanen could be visible to the unaided eye from a dark sky site. To spot it after dusk on December 16, look close on the sky to the Pleiades star cluster in Taurus.

Highlights of the North Winter Sky - Astronomy picture of the day - 2018 December 5

Highlights of the North Winter Sky  
Image Credit & Copyright: Universe2go.com

Explanation: What can you see in the night sky this season? The featured graphic gives a few highlights for Earth's northern hemisphere. Viewed as a clock face centered at the bottom, early (northern) winter sky events fan out toward the left, while late winter events are projected toward the right. Objects relatively close to Earth are illustrated, in general, as nearer to the cartoon figure with the telescope at the bottom center -- although almost everything pictured can be seen without a telescope. As happens during any season, constellations appear the same year to year, and, as usual, the Geminids meteor shower will peak in mid-December. Also as usual, the International Space Station (ISS) can be seen, at times, as a bright spot drifting across the sky after sunset. Less usual, the Moon is expected to pass nearly in front of several planets in early January. A treat this winter is Comet 46P/Wirtanen, already bright, will pass only 36 lunar distances from the Earth in mid-December, potentially making it easily visible to the unaided eye.

Rocket Launch between Mountains - Astronomy picture of the day - 2018 December 4

Rocket Launch between Mountains Image Credit & Copyright: Yudong Jiang

Explanation: What's happening between those mountains? A rocket is being launched to space. Specifically, a Long March 3B Carrier Rocket was launched from Xichang Satellite Launch Center in Sichuan Province in China about two week ago. The rocket lifted two navigation satellites to about 2,000 kilometers above the Earth's surface, well above the orbit of the International Space Station, but well below the orbit of geostationary satellites. China's Chang'e 3 mission that landed the robotic Yutu rover on the Moon was launched from Xichang in 2013. The featured image was taken about 10 kilometers from the launch site and is actually a composite of nine exposures, including a separate background image.

Spiraling Supermassive Black Holes - Astronomy picture of the day - 2018 December 3

Spiraling Supermassive Black Holes  
Video Credit: NASA's Goddard Space Flight Center; Music: In the Hall of the Mountain King by Edvard Grieg

Explanation: Do black holes glow when they collide? When merging, co-orbiting black holes are sure to emit a burst of unusual gravitational radiation, but will they emit light, well before that, if they are surrounded by gas? To help find out, astrophysicists created a sophisticated computer simulation. The simulation and featured resulting video accurately depicts two spiraling supermassive black holes, including the effects of Einstein's general relativity on the surrounding gas and light. The video first shows the system from the top, and later from the side where unusual gravitational lens distortions are more prominent. Numerical results indicate that gravitational and magnetic forces should energize the gas to emit high-energy light from the ultraviolet to the X-ray. The emission of such light may enable humanity to detect and study supermassive black hole pairs well before they spiral together.