Αστρονομική Εικόνα της Ημέρας από τη NASA

Προηγούμενες Αστρονομικές Εικόνες της Ημέρας από τη NASA

NGC 6946 and NGC 6939

04/07/2025

Face-on spiral galaxy NGC 6946 and open star cluster NGC 6939 share this cosmic snapshot, composed with over 68 hours of image data captured with a small telescope on planet Earth. The field of view spans spans about 1 degree or 2 full moons on the sky toward the northern constellation Cepheus. Seen through faint interstellar dust couds near the plane of our Milky Way galaxy, the stars of open cluster NGC 6939 are 5,600 light-years in the distance, near bottom right in the frame. Face-on spiral galaxy NGC 6946 is at top left, but lies some 22 million light-years away. In the last 100 years, 10 supernovae have been discovered in NGC 6946, the latest one seen in 2017. By comparison, the average rate of supernovae in our Milky Way is about 1 every 100 years or so. Of course, NGC 6946 is also known as The Fireworks Galaxy.

Nova V462 Lupi Now Visible

03/07/2025

If you know where to look, you can see a thermonuclear explosion from a white dwarf star. Possibly two. Such explosions are known as novas and the detonations are currently faintly visible with the unaided eye in Earth's southern hemisphere -- but are more easily seen with binoculars. Pictured, Nova Lupi 2025 (V462 Lupi) was captured toward the southern constellation of the Wolf (Lupus) last week near the central plane of our Milky Way galaxy. Nova Lupi 2025 was originally discovered on June 12 and peaked in brightness about a week later. Similarly, Nova Velorum 2025, toward the southern constellation of the Ship Sails (Vela), was discovered on June 25 and peaked a few days later. A nova somewhere in our Galaxy becomes briefly visible to the unaided eye only every year or two, so it is quite unusual to have two novas visible simultaneously. Meanwhile, humanity awaits even a different nova: T Coronae Borealis, which should become visible in northern skies and is expected to become even brighter.

Milky Way Through Otago Spires

02/07/2025

Does the Milky Way always rise between these two rocks? No. Capturing this stunning alignment took careful planning: being in the right place at the right time. In the featured image taken in June 2024 from Otago, New Zealand, the bright central core of our Milky Way Galaxy, home to the many of our Galaxy's 400 billion stars, can be seen between two picturesque rocks spires. For observers in Earth's Northern Hemisphere, the core is only visible throughout the summer. As Earth orbits the Sun, different parts of the Milky Way become visible at different angles at different times of the night. As Earth rotates, the orientation of the Milky Way in the sky also shifts -- sometimes standing vertically as seen in the featured image, and other times stretching parallel to the horizon, making it harder to see. In early June, observers can watch it emerge low on the horizon after sunset and gradually arc upward to reveal its full grandeur.

Eye Sky a Dragon

01/07/2025

What do you see when you look into this sky? In the center, in the dark, do you see a night sky filled with stars? Do you see a sunset to the left? Clouds all around? Do you see the central band of our Milky Way Galaxy running down the middle? Do you see the ruins of an abandoned outpost on a hill? (The outpost is on Askold Island, Russia.) Do you see a photographer with a headlamp contemplating surreal surroundings? (The featured image is a panorama of 38 images taken last month and compiled into a Little Planet projection.) Do you see a rugged path lined with steps? Or do you see the eye of a dragon?

NGC 4651: The Umbrella Galaxy

30/06/2025

It's raining stars. What appears to be a giant cosmic umbrella is now known to be a tidal stream of stars stripped from a small satellite galaxy. The main galaxy, spiral galaxy NGC 4651, is about the size of our Milky Way, while its stellar parasol appears to extend some 100 thousand light-years above this galaxy's bright disk. A small galaxy was likely torn apart by repeated encounters as it swept back and forth on eccentric orbits through NGC 4651. The remaining stars will surely fall back and become part of a combined larger galaxy over the next few million years. The featured deep image was captured in long exposures from Saudi Arabia. The Umbrella Galaxy lies about 50 million light-years distant toward the well-groomed northern constellation of Berenice's Hair (Coma Berenices). APOD in a Modern Format StellarSnap

Dark Sand Cascades on Mars

29/06/2025

Are these trees growing on Mars? No. Groups of dark brown streaks have been photographed by the Mars Reconnaissance Orbiter on melting pinkish sand dunes covered with light frost. The featured image was taken in 2008 April near the North Pole of Mars. At that time, dark sand on the interior of Martian sand dunes became more and more visible as the spring Sun melted the lighter carbon dioxide ice. When occurring near the top of a dune, dark sand may cascade down the dune leaving dark surface streaks -- streaks that might appear at first to be trees standing in front of the lighter regions but cast no shadows. Objects about 25 centimeters across are resolved on this image spanning about one kilometer. Close ups of some parts of this image show billowing plumes indicating that the sand slides were occurring even while the image was being taken. Celestial Surprise: What picture did APOD feature on your birthday? (post 1995)

Lunar Farside

28/06/2025

Tidally locked in synchronous rotation, the Moon always presents its familiar nearside to denizens of planet Earth. From lunar orbit, the Moon's farside can become familiar, though. In fact this sharp picture, a mosaic from the Lunar Reconnaissance Orbiter's wide angle camera, is centered on the lunar farside. Part of a global mosaic of over 15,000 images acquired between November 2009 and February 2011, the highest resolution version shows features at a scale of 100 meters per pixel. Surprisingly, the rough and battered surface of the farside looks very different from the nearside covered with smooth dark lunar maria. A likely explanation is that the farside crust is thicker, making it harder for molten material from the interior to flow to the surface and form dark, smooth maria.

Messier 109

27/06/2025

Big beautiful barred spiral galaxy Messier 109 is the 109th entry in Charles Messier's famous catalog of bright Nebulae and Star Clusters. You can find it just below the Big Dipper's bowl in the northern constellation Ursa Major. In fact, bright dipper star Phecda, Gamma Ursa Majoris, produces the glare at the upper right corner of this telescopic frame. M109's prominent central bar gives the galaxy the appearance of the Greek letter "theta", θ, a common mathematical symbol representing an angle. M109 spans a very small angle in planet Earth's sky though, about 7 arcminutes or 0.12 degrees. But that small angle corresponds to an enormous 120,000 light-year diameter at the galaxy's estimated 60 million light-year distance. The brightest member of the now recognized Ursa Major galaxy cluster, M109 (aka NGC 3992) is joined by spiky foreground stars. Three small, fuzzy bluish galaxies also on the scene, identified (top to bottom) as UGC 6969, UGC 6940 and UGC 6923, are possibly satellite galaxies of the larger barred spiral galaxy Messier 109.

Η Αστρονομική Εικόνα της Ημέρας από τη NASA

Ou4: The Giant Squid Nebula

05/07/2025