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NASA Astronomy Picture of the Day:

It was just last July. If you could see the stars of the Big Dipper, you could find Comet NEOWISE in your evening sky. After sunset denizens of the north could look for the naked-eye comet below the bowl of that famous celestial kitchen utensil and above the northwestern horizon. The comet looked like a fuzzy 'star' with a tail, though probably not so long a tail as in this memorable skyview recorded from the Czech Republic on July 23th, 2020, near the comet's closest approach to planet Earth. Photographs of C/2020 F3 (NEOWISE) often did show the comet's broad dust tail and fainter but separate bluish ion tail extending farther than the eye could follow. Skygazers around the world were delighted to witness Comet NEOWISE, surprise visitor from the outer Solar System. Notable Comet NEOWISE Images 2020: July 31 30, 29, 28, 27, 26, 25, 24

Photo by Petr Horalek

NASA Astronomy Picture of the Day:

Peering from the shadows, the Saturn-facing hemisphere of Mimas lies in near darkness alongside a dramatic sunlit crescent. The mosaic was captured near the Cassini spacecraft's final close approach on January 30, 2017. Cassini's camera was pointed in a nearly sunward direction only 45,000 kilometers from Mimas. The result is one of the highest resolution views of the icy, crater-pocked, 400 kilometer diameter moon. An enhanced version better reveals the Saturn-facing hemisphere of the synchronously rotating moon lit by sunlight reflected from Saturn itself. To see it, slide your cursor over the image (or follow this link). Other Cassini images of Mimas include the small moon's large and ominous Herschel Crater.

NASA Astronomy Picture of the Day:

This tall telescopic field of view looks out along the plane of our Milky Way Galaxy toward the nebula rich constellation Cygnus the Swan.

Photo by Carlos Uriarte

NASA Astronomy Picture of the Day:

NASA Astronomy Picture of the Day:

Chaotic in appearance, these tangled filaments of shocked, glowing gas are spread across planet Earth's sky toward the constellation of Cygnus as part of the Veil Nebula. The Veil Nebula itself is a large supernova remnant, an expanding cloud born of the death explosion of a massive star. Light from the original supernova explosion likely reached Earth over 5,000 years ago. The glowing filaments are really more like long ripples in a sheet seen almost edge on, remarkably well separated into the glow of ionized hydrogen atoms shown in blue and oxygen in red hues. Also known as the Cygnus Loop and cataloged as NGC 6979, the Veil Nebula now spans about 6 times the diameter of the full Moon. The length of the wisp corresponds to about 30 light years, given its estimated distance of 2,400 light years. Often identified as Pickering's Triangle for a director of Harvard College Observatory, it is also named for its discoverer, astronomer Williamina Fleming, as Fleming's Triangular Wisp.

Photo by Anthony Saab

NASA Astronomy Picture of the Day:

Can a gas cloud grab a galaxy? It's not even close. The "claw" of this odd looking "creature" in the featured photo is a gas cloud known as a cometary globule. This globule, however, has ruptured. Cometary globules are typically characterized by dusty heads and elongated tails. These features cause cometary globules to have visual similarities to comets, but in reality they are very much different. Globules are frequently the birthplaces of stars, and many show very young stars in their heads. The reason for the rupture in the head of this object is not yet known. The galaxy to the left of the globule is huge, very far in the distance, and only placed near CG4 by chance superposition.

Photo by Nicolas RollandMartin Pugh

NASA Astronomy Picture of the Day:

Gliding silently through the outer Solar System, the Voyager 2 spacecraft camera captured Neptune and Triton together in crescent phase. The elegant picture of the gas giant planet and its cloudy moon was taken from behind just after closest approach in 1989. It could not have been taken from Earth because Neptune never shows a crescent phase to sunward Earth. The unusual vantage point also robs Neptune of its familiar blue hue, as sunlight seen from here is scattered forward, and so is reddened like the setting Sun. Neptune is smaller but more massive than Uranus, has several dark rings, and emits more light than it receives from the Sun.

NASA Astronomy Picture of the Day:

Where does space begin? For purposes of spaceflight some would say at the Karman line, currently defined as an altitude of 100 kilometers (60 miles). Others might place a line 80 kilometers (50 miles) above Earth's mean sea level. But there is no sharp physical boundary that marks the end of atmosphere and the beginning of space. In fact, the Karman line itself is near the transition between the upper mesophere and lower thermosphere. Night shining or noctilucent clouds are high-latitude summer apparitions formed at altitudes near the top of the mesophere, up to 80 kilometers or so, also known as polar mesopheric clouds. Auroral bands of the northern (and southern) lights caused by energetic particles exciting atoms in the thermosphere can extend above 80 kilometers to over 600 kilometers altitude. Taken from a cockpit while flying at an altitude of 10 kilometers (33,000 feet) in the realm of stratospheric aeronautics, this snapshot captures both noctilucent clouds and aurora borealis under a starry sky, looking toward planet Earth's horizon and the edge of space.

Photo by Ralf Rohner

NASA Astronomy Picture of the Day:

Sprawling emission nebulae IC 1396 and Sh2-129 mix glowing interstellar gas and dark dust clouds in this 10 degree wide field of view toward the northern constellation Cepheus the King. Energized by its bluish central star IC 1396 (left) is hundreds of light-years across and some 3,000 light-years distant. The nebula's intriguing dark shapes include a winding dark cloud popularly known as the Elephant's Trunk below and right of center. Tens of light-years long, it holds the raw raw material for star formation and is known to hide protostars within. Located a similar distance from planet Earth, the bright knots and swept back ridges of emission of Sh2-129 on the right suggest its popular name, the Flying Bat Nebula. Within the Flying Bat, the most recently recognized addition to this royal cosmic zoo is the faint bluish emission from Ou4, the Giant Squid nebula.

Photo by Patrick Hsieh

NASA Astronomy Picture of the Day:

Point your telescope toward the high flying constellation Pegasus and you can find this expanse of Milky Way stars and distant galaxies. NGC 7814 is centered in the pretty field of view that would almost be covered by a full moon. NGC 7814 is sometimes called the Little Sombrero for its resemblance to the brighter more famous M104, the Sombrero Galaxy. Both Sombrero and Little Sombrero are spiral galaxies seen edge-on, and both have extensive halos and central bulges cut by a thin disk with thinner dust lanes in silhouette. In fact, NGC 7814 is some 40 million light-years away and an estimated 60,000 light-years across. That actually makes the Little Sombrero about the same physical size as its better known namesake, appearing smaller and fainter only because it is farther away. In this telescopic view from July 17, NGC 7814 is hosting a newly discovered supernova, dominant immediately to the left of the galaxy's core. Cataloged as SN 2021rhu, the stellar explosion has been identified as a Type Ia supernova, useful toward calibrating the distance scale of the universe.

Photo by CHART32 Team

NASA Astronomy Picture of the Day:

What if you could see, separately, all the colors of the Ring? And of the surrounding stars? There's technology for that. The featured image shows the Ring Nebula (M57) and nearby stars through such technology: in this case, a prism-like diffraction grating. The Ring Nebula is seen only a few times because it emits light, primarily, in only a few colors. The two brightest emitted colors are hydrogen (red) and oxygen (blue), appearing as nearly overlapping images to the left of the image center. The image just to the right of center is the color-combined icon normally seen. Stars, on the other hand, emit most of their light in colors all across the visible spectrum. These colors, combined, make a nearly continuous streak -- which is why stars appear accompanied by multicolored bars. Breaking object light up into colors is scientifically useful because it can reveal the elements that compose that object, how fast that object is moving, and how distant that object is.

NASA Astronomy Picture of the Day:

Thor not only has his own day (Thursday), but a helmet in the heavens.  Popularly called Thor's Helmet, NGC 2359 is a hat-shaped cosmic cloud with wing-like appendages. Heroically sized even for a Norse god, Thor's Helmet is about 30 light-years across. In fact, the cosmic head-covering is more like an interstellar bubble, blown with a fast wind from the bright, massive star near the bubble's center. Known as a Wolf-Rayet star, the central star is an extremely hot giant thought to be in a brief, pre-supernova stage of evolution. NGC 2359 is located about 15,000 light-years away toward the constellation of the Great Overdog. This remarkably sharp image is a mixed cocktail of data from broadband and narrowband filters, capturing not only natural looking stars but details of the nebula's filamentary structures. The star in the center of Thor's Helmet is expected to explode in a spectacular supernova sometime within the next few thousand years. Almost Hyperspace: Random APOD Generator

Photo by Bernard Miller