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NASA Astronomy Picture of the Day:

How does weather on the Sun affect humanity? To help find out, the European Space Agency (ESA) and NASA have just launched the Solar Orbiter. This Sun-circling robotic spaceship will monitor the Sun's changing light, solar wind, and magnetic field not only from the usual perspective of Earth but also from above and below the Sun. Pictured, a long duration exposure of the launch of the Solar Orbiter shows the graceful arc of the bright engines of United Launch Alliance's Atlas V rocket as they lifted the satellite off the Earth. Over the next few years, the Solar Orbiter will use the gravity of Earth and Venus to veer out of the plane of the planets and closer to the Sun than Mercury. Violent weather on the Sun, including solar flares and coronal mass ejections, has shown the ability to interfere with power grids on the Earth and communications satellites in Earth orbit. The Solar Orbiter is expected to coordinate observations with the also Sun-orbiting Parker Solar Probe launched in 2018. Solar Orbiter to Space: Watch the Launch

Photo by Derek Demeter

NASA Astronomy Picture of the Day:

What's happening behind that camel? A partial eclipse of the Sun. About six and a half weeks ago, the Moon passed completely in front of the Sun as seen from a narrow band on the Earth. Despite (surely) many camels being located in this narrow band, only one found itself stationed between this camera, the distant Moon, and the even more distant Sun. To create this impressive superposition, though, took a well-planned trip to the United Arab Emirates, careful alignments, and accurate timings on the day of the eclipse. Although the resulting featured image shows a partially eclipsed Sun rising, the Moon went on to appear completely engulfed by the Sun in an annular eclipse known as a ring of fire. Forward scattering of sunlight, dominated by quantum mechanical diffraction, gives the camel hair and rope fray an unusual glow. The next solar eclipse is also an annular eclipse and will occur this coming June. News: Solar Orbiter Launched

Photo by Joshua Cripps

NASA Astronomy Picture of the Day:

What would it be like to fly free in space? At about 100 meters from the cargo bay of the space shuttle Challenger, Bruce McCandless II was living the dream -- floating farther out than anyone had ever been before. Guided by a Manned Maneuvering Unit (MMU), astronaut McCandless, pictured, was floating free in space. McCandless and fellow NASA astronaut Robert Stewart were the first to experience such an "untethered space walk" during Space Shuttle mission 41-B in 1984. The MMU worked by shooting jets of nitrogen and was used to help deploy and retrieve satellites. With a mass over 140 kilograms, an MMU is heavy on Earth, but, like everything, is weightless when drifting in orbit. The MMU was later replaced with the SAFER backpack propulsion unit.

NASA Astronomy Picture of the Day:

Interstellar clouds of hydrogen gas and dust abound in this gorgeous skyscape. The 3 degree wide field of view stretches through the faint but fanciful constellation Monoceros, the Unicorn. A star forming region cataloged as NGC 2264 is centered, a complex jumble of cosmic gas, dust and stars about 2,700 light-years distant. It mixes reddish emission nebulae excited by energetic light from newborn stars with dark dust clouds. Where the otherwise obscuring dust clouds lie close to hot, young stars they also reflect starlight, forming blue reflection nebulae. A few light-years across, a simple sculpted shape known as the Cone Nebula is near center. Outlined by the red glow of hydrogen gas, the cone points toward the left and bright, blue-white S Monocerotis. Itself a multiple system of massive, hot stars S Mon is adjacent to bluish reflection nebulae and the convoluted Fox Fur nebula. Expansive dark markings on the sky are silhouetted by a larger region of fainter emission with yellowish open star cluster Trumpler 5 near the top of the frame. The curious compact cometary shape right of center is known as Hubble's Variable Nebula.

Photo by Bray Falls

NASA Astronomy Picture of the Day:

Big, beautiful spiral galaxy NGC 7331 is often touted as an analog to our own Milky Way. About 50 million light-years distant in the northern constellation Pegasus, NGC 7331 was recognized early on as a spiral nebula and is actually one of the brighter galaxies not included in Charles Messier's famous 18th century catalog. Since the galaxy's disk is inclined to our line-of-sight, long telescopic exposures often result in an image that evokes a strong sense of depth. In this Hubble Space Telescope close-up, the galaxy's magnificent spiral arms feature dark obscuring dust lanes, bright bluish clusters of massive young stars, and the telltale reddish glow of active star forming regions. The bright yellowish central regions harbor populations of older, cooler stars. Like the Milky Way, a supermassive black hole lies at the core of spiral galaxy NGC 7331.

NASA Astronomy Picture of the Day:

The Moon's south pole is near the top of this detailed telescopic view. Looking across the rugged southern lunar highlands it was captured from southern California, planet Earth. At the Moon's third quarter phase the lunar terminator, the sunset shadow line, is approaching from the left. The scene's foreshortened perspective heightens the impression of a dense field of craters and makes the craters themselves appear more oval shaped close to the lunar limb. Below and left of center is sharp-walled crater Tycho, 85 kilometers in diameter. Young Tycho's central peak is still in sunlight, but casts a long shadow across the crater floor. The large prominent crater to the south (above) Tycho is Clavius. Nearly 231 kilometers in diameter its walls and floor are pocked with smaller, more recent, overlaying impact craters. Mountains visible along the lunar limb at the top can rise about 6 kilometers or so above the surrounding terrain.

Photo by Tom Glenn

NASA Astronomy Picture of the Day:

Do we all see the same Moon? Yes, but we all see it differently. One difference is the apparent location of the Moon against background stars -- an effect known as parallax. We humans use the parallax between our eyes to judge depth. To see lunar parallax, though, we need eyes placed at a much greater separations -- hundreds to thousands of kilometers apart. Another difference is that observers around the Earth all see a slightly different face of our spherical Moon -- an effect known as libration. The featured image is a composite of many views across the Earth, as submitted to APOD, of the total lunar eclipse of 2019 January 21. These images are projected against the same background stars to illustrate both effects. The accurate superposition of these images was made possible by a serendipitous meteorite impact on the Moon during the lunar eclipse, labeled here L1-21J -- guaranteeing that these submitted images were all taken within a split second.

NASA Astronomy Picture of the Day:

Seeing mountain peaks glow red from inside the Grand Canyon was one of the most incredible sunset experiences of this amateur photographer's life. They appeared even more incredible later, when digitally combined with an exposure of the night sky -- taken by the same camera and from the same location -- an hour later. The two images were taken last August from the 220 Mile Canyon campsite on the Colorado River, Arizona, USA. The peaks glow red because they were lit by an unusually red sunset. Later, high above, the band of the Milky Way Galaxy angled dramatically down, filled with stars, nebula, and dark clouds of dust. To the Milky Way's left is the planet Saturn, while to the right is the brighter Jupiter. Although Jupiter and Saturn are now hard to see, Venus will be visible and quite bright to the west in clear skies, just after sunset, for the next two months. Astrophotography with Your Computer: NASA's Astrophoto Challenges

Photo by Robert Q. Fugate

NASA Astronomy Picture of the Day:

Why does the Sun's surface keep changing? The help find out, the US National Science Foundation (NSF) has built the Daniel K. Inouye Solar Telescope in Hawaii, USA. The Inouye telescope has a larger mirror that enables the capturing of images of higher resolution, at a faster rate, and in more colors than ever before. Featured are recently-released first-light images taken over 10 minutes and combined into a 5-second time-lapse video. The video captures an area on the Sun roughly the size of our Earth, features granules roughly the size of a country, and resolves features as small as 30-kilometers across. Granule centers are bright due to the upwelling hot solar plasma, while granule edges are dim due to the cooled plasma falling back. Some regions between granules edges are very bright as they are curious magnetic windows into a deep and hotter solar interior. How the Sun's magnetic field keeps changing, channeling energy, and affecting the distant Earth, among many other topics, will be studied for years to come using data from the new Inouye telescope. Astrophysicists: Browse 2,100+ codes in the Astrophysics Source Code Library

NASA Astronomy Picture of the Day:

Like a ship plowing through cosmic seas, runaway star Zeta Ophiuchi produces the arcing interstellar bow wave or bow shock seen in this stunning infrared portrait. In the false-color view, bluish Zeta Oph, a star about 20 times more massive than the Sun, lies near the center of the frame, moving toward the left at 24 kilometers per second. Its strong stellar wind precedes it, compressing and heating the dusty interstellar material and shaping the curved shock front. What set this star in motion? Zeta Oph was likely once a member of a binary star system, its companion star was more massive and hence shorter lived. When the companion exploded as a supernova catastrophically losing mass, Zeta Oph was flung out of the system. About 460 light-years away, Zeta Oph is 65,000 times more luminous than the Sun and would be one of the brighter stars in the sky if it weren't surrounded by obscuring dust. The image spans about 1.5 degrees or 12 light-years at the estimated distance of Zeta Ophiuchi. Last week, NASA placed the Spitzer Space Telescope in safe mode, ending its 16 successful years of studying our universe. News: NASA’s Spitzer Space Telescope Ends Mission of Astronomical Discovery

NASA Astronomy Picture of the Day:

When leaving lunar orbit in February 1971, the crew of Apollo 14 watched this Earthrise from their command module Kittyhawk. With Earth's sunlit crescent just peaking over the lunar horizon, the cratered terrain in the foreground is along the lunar farside. Of course, while orbiting the Moon, the crew could watch Earth rise and set, but the Earth hung stationary in the sky over Fra Mauro Base, their landing site on the lunar surface. Rock samples brought back by the Apollo 14 mission included a 20 pound rock nicknamed Big Bertha, later determined to contain a likely fragment of a meteorite from planet Earth.

NASA Astronomy Picture of the Day:

The Goldilocks zone is the habitable zone around a star where it's not too hot and not too cold for liquid water to exist on the surface of orbiting planets. This intriguing infographic includes relative sizes of those zones for yellow G stars like the Sun, along with orange K dwarf stars and red M dwarf stars, both cooler and fainter than the Sun. M stars (top) have small, close-in Goldilocks zones. They are also seen to live long (100 billion years or so) and are very abundant, making up about 73 percent of the stars in the Milky Way. Still, they have very active magnetic fields and may produce too much radiation harmful to life, with an estimated X-ray irradiance 400 times the quiet Sun. Sun-like G stars (bottom) have large Goldilocks zones and are relatively calm, with low amounts of harmful radiation. But they only account for 6 percent of Milky Way stars and are much shorter lived. In the search for habitable planets, K dwarf stars could be just right, though. Not too rare they have 40 billion year lifetimes, much longer than the Sun. With a relatively wide habitable zone they produce only modest amounts of harmful radiation. These Goldilocks stars account for about 13 percent of the stars of the Milky Way.