Αστρονομική Εικόνα της Ημέρας από τη NASA

Προηγούμενες Αστρονομικές Εικόνες της Ημέρας από τη NASA

The ISS Meets Venus

11/04/2025

Made with a telescope shaded from bright sunlight by an umbrella, on April 5 a well-planned video captured a crescent Venus shining in clear daytime skies from Shoreline, Washington, USA at 11:57AM Pacific Time. It also caught the International Space Station in this single video frame. In close conjunction with the bright planet, the faint outline of the orbital outpost seen at a range of about 400 kilometers appears to be similar in size to the slender planetary crescent. Of course the ISS is much smaller than Venus. Now appearing as planet Earth's brilliant morning star and climbing above the eastern horizon in predawn skies, inner planet Venus was nearly 45 million kilometers from Shoreline.

38 Hours with the M81 Group

10/04/2025

From a garden on planet Earth, 38 hours of exposure with a camera and small telescope produced this cosmic photo of the M81 galaxy group. In fact, the group's dominant galaxy M81 is near the center of the frame sporting grand spiral arms and a bright yellow core. Also known as Bode's galaxy, M81 itself spans some 100,000 light-years. Near the top is cigar-shaped irregular galaxy M82. The pair have been locked in gravitational combat for a billion years. Gravity from each galaxy has profoundly affected the other during a series of cosmic close encounters. Their last go-round lasted about 100 million years and likely raised density waves rippling around M81, resulting in massive star forming regions arrayed along M81's spiral arms. M82 was left with violent star forming regions too, and colliding gas clouds so energetic that the galaxy glows in X-rays. In the next few billion years, their continuing gravitational encounters will result in a merger, and a single galaxy will remain. Another group member, NGC 3077 is below and left of the large spiral M81. Far far away, about 12 million light-years distant the M81 group galaxies are seen toward the northern constellation Ursa Major (the Great Bear). But in the closer foreground the wide-field image is filled with integrated flux nebulae whose faint, dusty interstellar clouds reflect starlight above the plane of our own Milky Way galaxy.

HH 49: Interstellar Jet from Webb

09/04/2025

What's at the tip of this interstellar jet? First let's consider the jet: it is being expelled by a star system just forming and is cataloged as Herbig-Haro 49 (HH 49). The star system expelling this jet is not visible -- it is off to the lower right. The complex conical structure featured in this infrared image by the James Webb Space Telescope also includes another jet cataloged as HH 50. The fast jet particles impact the surrounding interstellar gas and form shock waves that glow prominently in infrared light -- shown here as reddish-brown ridges. This JWST image also resolved the mystery of the unusual object at HH 49's tip: it is a spiral galaxy far in the distance. The blue center is therefore not one star but many, and the surrounding circular rings are actually spiral arms. Jump Around the Universe: Random APOD Generator

Moon Visits Sister Stars

08/04/2025

Sometimes, the Moon visits the Pleiades. Technically, this means that the orbit of our Moon takes it directly in front of the famous Pleiades star cluster, which is far in the distance. The technical term for the event is an occultation, and the Moon is famous for its rare occultations of all planets and several well-known bright stars. The Moon's tilted and precessing orbit makes its occultations of the Seven Sisters star cluster bunchy, with the current epoch starting in 2023 continuing monthly until 2029. After that, though, the next occultation won't occur until 2042. Taken from Cantabria, Spain on April 1, the featured image is a composite where previous exposures of the Pleiades from the same camera and location were digitally added to the last image to bring up the star cluster's iconic blue glow. Jigsaw Challenge: Astronomy Puzzle of the Day

NGC 4414: A Flocculent Spiral Galaxy

07/04/2025

How much mass do flocculent spirals hide? The featured image of flocculent spiral galaxy NGC 4414 was taken with the Hubble Space Telescope to help answer this question. Flocculent spirals -- galaxies without well-defined spiral arms -- are a quite common form of galaxy, and NGC 4414 is one of the closest. Stars and gas near the visible edge of spiral galaxies orbit the center so fast that the gravity from a large amount of unseen dark matter must be present to hold them together. Understanding the matter and dark matter distribution of NGC 4414 helps humanity calibrate the rest of the galaxy and, by deduction, flocculent spirals in general. Further, calibrating the distance to NGC 4414 helps humanity calibrate the cosmological distance scale of the entire visible universe.

Moonquakes Surprisingly Common

06/04/2025

Why are there so many moonquakes? Analyses of seismometers left on the moon during the Apollo moon landings reveal a surprising number of moonquakes occurring within 100 kilometers of the surface. In fact, 62 moonquakes were detected in data recorded between 1972 and 1977. Many of these moonquakes are not only strong enough to move furniture in a lunar apartment, but the stiff rock of the moon continues to vibrate for many minutes, significantly longer than the softer rock earthquakes on Earth. The cause of the moonquakes remains unknown, but a leading hypothesis include tidal gravity from -- and relative heating by -- our Earth. Regardless of the source, future moon dwellings need to be built to withstand the frequent shakings. Pictured here, Apollo 11 astronaut Buzz Aldrin stands beside a recently deployed lunar seismometer, looking back toward the lunar landing module. Explore Your Universe: Random APOD Generator

The Gargoyles' Eclipse

05/04/2025

In dramatic silhouette against a cloudy daytime sky over Paris, France, gargoyles cast their monstrous gaze outward from the west facade of Notre Dame Cathedral. Taken on March 29, this telephoto snapshot also captures the dramatic silhouette of a New Moon against the bright solar disk in a partial solar eclipse. Happening high in Parisian skies, the partial eclipse was close to its maximum phase of about 23 percent. Occurring near the end of the first eclipse season of 2025, this partial solar eclipse followed the total eclipse of the Full Moon on March 13/14. The upcoming second eclipse season of 2025 will see a total lunar eclipse on September 7/8 and partial solar eclipse on September 21. The partial solar eclipse will be seen only from locations in planet Earth's southern hemisphere.

Hickson 44 in Leo

04/04/2025

Scanning the skies for galaxies, Canadian astronomer Paul Hickson and colleagues identified some 100 compact groups of galaxies, now appropriately called Hickson Compact Groups. The four prominent galaxies seen in this intriguing telescopic skyscape are one such group, Hickson 44. The galaxy group is about 100 million light-years distant, far beyond the spiky foreground Milky Way stars, toward the constellation Leo. The two spiral galaxies in the center of the image are edge-on NGC 3190 with its distinctive, warped dust lanes, and S-shaped NGC 3187. Along with the bright elliptical, NGC 3193 (above and left) they are also known as Arp 316. The spiral toward the lower right corner is NGC 3185, the 4th member of the Hickson group. Like other galaxies in Hickson groups, these show signs of distortion and enhanced star formation, evidence of a gravitational tug of war that will eventually result in galaxy mergers on a cosmic timescale. The merger process is now understood to be a normal part of the evolution of galaxies, including our own Milky Way. For scale, NGC 3190 is about 75,000 light-years across at the estimated distance of Hickson 44.

Η Αστρονομική Εικόνα της Ημέρας από τη NASA

Comet R3 PanSTARRS Behind Satellite Trails

27/04/2026