Αστρονομική Εικόνα της Ημέρας από τη NASA

Προηγούμενες Αστρονομικές Εικόνες της Ημέρας από τη NASA

Saturn's Rings Appear to Disappear

29/04/2025

Where are Saturn's ears? Galileo is credited, in 1610, as the first person to see Saturn's rings. Testing out Lipperhey's recently co-invented telescope, Galileo did not know what they were and so called them "ears". The mystery deepened in 1612, when Saturn's ears mysteriously disappeared. Today we know exactly what happened: from the perspective of the Earth, Saturn's rings had become too thin to see. The same drama plays out every 15 years because Saturn, like Earth, undergoes tilt-driven seasons. This means that as Saturn goes around the Sun, its equator and rings can tilt noticeably toward the Sun and inner Solar System, making them easily visible, but from other orbital locations will appear almost not at all. The featured picture from Brasilia, Brazil shows a modern version of this sequence: the top ring-dominated image was taken in 2020, while the bottom ring-obscure image taken earlier in 2025. Make Saturn's Rings Musical: Play them like a harp!

Gum 37 and the Southern Tadpoles

28/04/2025

This cosmic skyscape features glowing gas and dark dust clouds alongside the young stars of NGC 3572. A beautiful emission nebula and star cluster, it sails far southern skies within the nautical constellation Carina. Stars from NGC 3572 are toward top center in the telescopic frame that would measure about 100 light-years across at the cluster's estimated distance of 9,000 light-years. The visible interstellar gas and dust, shown in colors of the Hubble palette, is part of the star cluster's natal molecular cloud, itself cataloged as Gum 37. Dense streamers of material within the nebula, eroded by stellar winds and radiation, clearly trail away from the energetic young stars. They are likely sites of ongoing star formation with shapes reminiscent of the Tadpoles of IC 410 -- better known to northern skygazers. In the coming tens to hundreds of millions of years, gas and stars in the cluster will be dispersed though, by gravitational tides and by violent supernova explosions that end the short lives of the massive cluster stars.

IC 418: The Spirograph Nebula

27/04/2025

What is creating the strange texture of IC 418? Dubbed the Spirograph Nebula for its resemblance to drawings from a cyclical drawing tool, planetary nebula IC 418 shows patterns that are not well understood. Perhaps they are related to chaotic winds from the variable central star, which changes brightness unpredictably in just a few hours. By contrast, evidence indicates that only a few million years ago, IC 418 was probably a well-understood star similar to our Sun. Only a few thousand years ago, IC 418 was probably a common red giant star. Since running out of nuclear fuel, though, the outer envelope has begun expanding outward leaving a hot remnant core destined to become a white-dwarf star, visible in the image center. The light from the central core excites surrounding atoms in the nebula causing them to glow. IC 418 lies about 2000 light-years away and spans 0.3 light-years across. This false-color image taken from the Hubble Space Telescope reveals the unusual details.

Barred Spiral Galaxy NGC 5335

26/04/2025

This stunning portrait of NGC 5335 was captured by the Hubble Space Telescope. Some 170,000 light-years across and over 200 million light-years away toward the constellation Virgo, the magnificent spiral galaxy is seen face-on in Hubble's view. Within the galactic disk, loose streamers of star forming regions lie along the galaxy's flocculent spiral arms. But the most striking feature of NGC 5335 is its prominent central bar. Seen in about 30 percent of galaxies, including our Milky Way, bar structures are understood to channel material inward toward the galactic center, fueling star formation. Of course, distant background galaxies are easy to spot, scattered around the sharp Hubble image. Launched in 1990, Hubble is now celebrating its 35th year exploring the cosmos from orbit around planet Earth.

Asteroid Donaldjohanson

25/04/2025

Main belt asteroid 52246 Donaldjohanson is about 8 kilometers long and 3.5 kilometers across. On April 20, this sharp close-up of the asteroid was captured at a distance of about 1100 kilometers by the Lucy spacecraft's long range camera during its second asteroid encounter. Named after American paleoanthropologist Donald Johanson, discoverer of the Lucy hominid fossil, the elongated asteroid was likely formed about 150 million years ago from a gentle collision of two smaller bodies creating its characteristic contact binary shape. Launched in October of 2021, the Lucy spacecraft will continue its travels through the main asteroid belt in 2025, but is on its way to explore Jupiter's swarm of Trojan asteroids. Lucy is expected to encounter its first Trojan asteroid target, 3548 Eurybates, in August 2027.

NGC 6164: A Dragon's Egg

24/04/2025

Beautiful emission nebula NGC 6164 was created by a rare, hot, luminous O-type star, some 40 times as massive as the Sun. Seen at the center of the cosmic cloud, the star is a mere 3 to 4 million years old. In another three to four million years the massive star will end its life in a supernova explosion. Spanning around 4 light-years, the nebula itself has a bipolar symmetry. That makes it similar in appearance to more common and familiar planetary nebulae - the gaseous shrouds surrounding dying sun-like stars. Also like many planetary nebulae, NGC 6164 has been found to have an extensive, faint halo, revealed in this deep image of the region. Expanding into the surrounding interstellar medium, the material in the halo is likely from an earlier active phase of the O star. This gorgeous telescopic view is a composite of extensive narrow-band image data, highlighting glowing atomic hydrogen gas in red and oxygen in greenish hues, with broad-band data for the surrounding starfield. Also known as the Dragon's Egg nebula, NGC 6164 is 4,200 light-years away in the right-angled southern constellation of Norma.

An Almost Everything Sky

23/04/2025

This surprising sky has almost everything. First, slanting down from the upper left and far in the distance is the central band of our Milky Way Galaxy. More modestly, slanting down from the upper right and high in Earth's atmosphere is a bright meteor. The dim band of light across the central diagonal is zodiacal light: sunlight reflected from dust in the inner Solar System. The green glow on the far right is aurora high in Earth's atmosphere. The bright zigzagging bright line near the bottom is just a light that was held by the scene-planning astrophotographer. This "almost everything" sky was captured over rocks on Castle Hill, New Zealand late last month. The featured finished frame is a combination of 10 exposures all taken with the same camera and from the same location. But what about the astrophotographer himself? He's pictured too -- can you find him? Jigsaw Fun: Astronomy Puzzle of the Day

Terminator Moon: A Moonscape of Shadows

22/04/2025

What's different about this Moon? It's the terminators. In the featured image, you can't directly see any terminator -- the line that divides the light of day from the dark of night. That's because the featured image is a digital composite of many near-terminator lunar strips over a full Moon. Terminator regions show the longest and most prominent shadows -- shadows which, by their contrast and length, allow a flat photograph to appear three-dimensional. The overlay images were taken over two weeks in early April. Many of the Moon's craters stand out because of the shadows they all cast to the right. The image shows in graphic detail that the darker regions known as maria are not just darker than the rest of the Moon -- they are also flatter. Dial-A-Moon: Find the Moon phase on your birthday this year

Η Αστρονομική Εικόνα της Ημέρας από τη NASA

NGC 2685: The Helix Galaxy

14/07/2025