NASA Astronomy Picture of the Day:

It is one of the more unusual rocks yet found on Mars. Smaller than a penny, the rock has several appendages that make it look, to some, like a flower. Although it would be a major discovery if the rock was truly a fossilized ancient Martian flower, there are less spectacular -- and currently preferred -- explanations for its unusual structure. One theory that has emerged is that the rock is a type of concretion created by minerals deposited by water in cracks or divisions in existing rock. These concretions can be compacted together, can be harder and denser than surrounding rock, and can remain even after the surrounding rock erodes away. The flower structure may also be caused by crystal clusters. The small rock, named Blackthorn Salt, has similarities to previously imaged Martian pebbles. The featured image was taken by the Curiosity rover on Mars in late February. Scientists will continue to study data and images taken of this -- and similar -- surprising Martian rocks. Review: Last Year in Space Pictures

NASA Astronomy Picture of the Day:

Which moon is this? It's Earth's moon -- but in inverted colors. Here, the pixel values corresponding to light and dark areas have been translated in reverse, or inverted, producing a false-color representation reminiscent of a black and white photographic negative. However, this is an inverted color image -- where the muted colors of the moon are real but digitally exaggerated before inversion. Normally bright rays from the large crater Tycho dominate the southern (bottom) features as easily followed dark green lines emanating from the 85-kilometer diameter impact site. Normally dark lunar mare appear light and silvery. The image was acquired in Southend-on-Sea, England, UK. Historically, astronomical images recorded on photographic plates were directly examined on inverted-color negatives because it helped the eye pick out faint details.

Photo by Dawid Glawdzin

NASA Astronomy Picture of the Day:

Yes, but can you see the lion? A deep exposure shows the famous dark indentation that looks like a horse's head, visible just left and below center, and known unsurprisingly as the Horsehead Nebula. The Horsehead Nebula (Barnard 33) is part of a vast complex of dark absorbing dust and bright glowing gas. To bring out details of the Horsehead's pasture, an astrophotographer artistically combined light accumulated for over 20 hours in hydrogen (orange), oxygen (blue), and sulfur (green). The resulting spectacular picture captured from Raachine, Lebanon, details an intricate tapestry of gaseous wisps and dust-laden filaments that were created and sculpted over eons by stellar winds and ancient supernovas. The featured composition brings up another pareidolic animal icon -- that of a lion's head -- in the expansive orange colored gas above the horse's head. The Flame Nebula is visible just to the left of the Horsehead. The Horsehead Nebula lies 1,500 light years distant towards the constellation of Orion.

Photo by Maroun Mahfoud

NASA Astronomy Picture of the Day:

This was a very unusual type of solar eclipse. Typically, it is the Earth's Moon that eclipses the Sun. In 2012, though, the planet Venus took a turn. Like a solar eclipse by the Moon, the phase of Venus became a continually thinner crescent as Venus became increasingly better aligned with the Sun. Eventually the alignment became perfect and the phase of Venus dropped to zero. The dark spot of Venus crossed our parent star. The situation could technically be labeled a Venusian annular eclipse with an extraordinarily large ring of fire. Pictured here during the occultation, the Sun was imaged in three colors of ultraviolet light by the Earth-orbiting Solar Dynamics Observatory, with the dark region toward the right corresponding to a coronal hole. Hours later, as Venus continued in its orbit, a slight crescent phase appeared again. The next Venusian transit across the Sun will occur in 2117.

NASA Astronomy Picture of the Day:

From somewhere else in the Milky Way galaxy, Comet 2I/Borisov was just visiting the Solar System. Discovered by amateur astronomer Gennady Borisov on August 30, 2019, the first known interstellar comet is seen in these two Hubble Space Telescope images from November and December 2019. On the left, a distant background galaxy near the line-of-sight to Borisov is blurred as Hubble tracked the speeding comet and dust tail about 327 million kilometers from Earth. At right, 2I/Borisov appears shortly after perihelion, its closest approach to Sun. European Southern Observatory observations indicate that this comet may never have passed close to any star before its 2019 perihelion passage. Borisov's closest approach to our fair planet, a distance of about 290 million kilometers, came on December 28, 2019. Even though Hubble's sharp images don't resolve the comet's nucleus, they did lead to estimates of less than 1 kilometer for its diameter.

NASA Astronomy Picture of the Day:

The Crab Nebula is cataloged as M1, the first object on Charles Messier's famous list of things which are not comets. In fact, the Crab is now known to be a supernova remnant, expanding debris from massive star's death explosion, witnessed on planet Earth in 1054 AD. This brave new image offers a 21st century view of the Crab Nebula by presenting image data from across the electromagnetic spectrum as wavelengths of visible light. From space, Chandra (X-ray) XMM-Newton (ultraviolet), Hubble (visible), and Spitzer (infrared), data are in purple, blue, green, and yellow hues. From the ground, Very Large Array radio wavelength data is shown in red. One of the most exotic objects known to modern astronomers, the Crab Pulsar, a neutron star spinning 30 times a second, is the bright spot near picture center. Like a cosmic dynamo, this collapsed remnant of the stellar core powers the Crab's emission across the electromagnetic spectrum. Spanning about 12 light-years, the Crab Nebula is 6,500 light-years away in the constellation Taurus.

NASA Astronomy Picture of the Day:

A mere 46 million light-years distant, spiral galaxy NGC 2841 can be found in the northern constellation of Ursa Major. This deep view of the gorgeous island universe was captured during 32 clear nights in November, December 2021 and January 2022. It shows off a striking yellow nucleus, galactic disk, and faint outer regions. Dust lanes, small star-forming regions, and young star clusters are embedded in the patchy, tightly wound spiral arms. In contrast, many other spirals exhibit grand, sweeping arms with large star-forming regions. NGC 2841 has a diameter of over 150,000 light-years, even larger than our own Milky Way. X-ray images suggest that resulting winds and stellar explosions create plumes of hot gas extending into a halo around NGC 2841.

Photo by Vitali Pelenjow

NASA Astronomy Picture of the Day:

What's happened to our Sun? Last month, it produced the largest prominence ever imaged together with a complete solar disk. The record image, featured, was captured in ultraviolet light by the Sun-orbiting Solar Orbiter spacecraft. A quiescent solar prominence is a cloud of hot gas held above the Sun's surface by the Sun's magnetic field. This solar prominence was huge -- spanning a length rivaling the diameter of the Sun itself. Solar prominences may erupt unpredictably and expel hot gas into the Solar System via a Coronal Mass Ejection (CME). When a CME strikes the Earth and its magnetosphere, bright auroras may occur. This prominence did produce a CME, but it was directed well away from the Earth. Although surely related to the Sun's changing magnetic field, the energy mechanism that creates and sustains a solar prominence remains a topic of research.

NASA Astronomy Picture of the Day:

What are these two bands in the sky? The more commonly seen band is the one on the right and is the central band of our Milky Way galaxy. Our Sun orbits in the disk of this spiral galaxy, so that from inside, this disk appears as a band of comparable brightness all the way around the sky. The Milky Way band can also be seen all year -- if out away from city lights. The less commonly seem band, on the left, is zodiacal light -- sunlight reflected from dust orbiting the Sun in our Solar System. Zodiacal light is brightest near the Sun and so is best seen just before sunrise or just after sunset. On some evenings in the north, particularly during the months of March and April, this ribbon of zodiacal light can appear quite prominent after sunset. It was determined only this century that zodiacal dust was mostly expelled by comets that have passed near Jupiter. Only on certain times of the year will the two bands be seen side by side, in parts of the sky, like this. The featured image, including the Andromeda galaxy and a meteor, was captured in late January over a frozen lake in Kanding, Sichuan, China.

Photo by Jeff DaiTWAN

NASA Astronomy Picture of the Day:

You don't have to look through a telescope to know where it's pointing. Allowing the telescope to project its image onto a large surface can be useful because it dilutes the intense brightness of very bright sources. Such dilution is useful for looking at the Sun, for example during a solar eclipse. In the featured single-exposure image, though, it is a too-bright full moon that is projected. This February full moon occurred two weeks ago and is called the Snow Moon by some northern cultures. The projecting instrument is the main 62-centimeter telescope at the Saint-Véran Observatory high in the French Alps. Seeing a full moon directly is easier because it is not too bright, although you won't see this level of detail. Your next chance will occur on March 17.

Photo by Jeff Graphy

NASA Astronomy Picture of the Day:

"Oh my God! Look at that picture over there! Here's the Earth coming up. Wow is that pretty!" Soon after that pronouncement, 50 years ago today, one of the most famous images ever taken was snapped from the orbit of the Moon. Now known as "Earthrise", the iconic image shows the Earth rising above the limb of the Moon, as taken by the crew of Apollo 8. But the well-known Earthrise image was actually the second image taken of the Earth rising above the lunar limb -- it was just the first in color. With modern digital technology, however, the real first Earthrise image -- originally in black and white -- has now been remastered to have the combined resolution and color of the first three images. Behold! The featured image is a close-up of the picture that Apollo 8 astronaut Bill Anders was talking about. Thanks to modern technology and human ingenuity, now we can all see it. (Historical note: A different historic black & white image of the Earth setting behind the lunar limb was taken by the robotic Lunar Orbiter 1 two years earlier.)

NASA Astronomy Picture of the Day:

Large spiral galaxy NGC 4945 is seen nearly edge-on in this cosmic galaxy close-up. It's almost the size of our Milky Way Galaxy. NGC 4945's own dusty disk, young blue star clusters, and pink star forming regions stand out in the colorful telescopic frame. About 13 million light-years distant toward the expansive southern constellation Centaurus, NGC 4945 is only about six times farther away than Andromeda, the nearest large spiral galaxy to the Milky Way. Though this galaxy's central region is largely hidden from view for optical telescopes, X-ray and infrared observations indicate significant high energy emission and star formation in the core of NGC 4945. Its obscured but active nucleus qualifies the gorgeous island universe as a Seyfert galaxy and home to a central supermassive black hole.

Photo by Dietmar Hager