Η Αστρονομική Εικόνα της Ημέρας από τη NASA
Earthset from Orion
20/11/2024
ght billion people are about to disappear in this snapshot from space taken on 2022 November 21. On the sixth day of the Artemis I mission, their home world is setting behind the Moon's bright edge as viewed by an external camera on the outbound Orion spacecraft. Orion was headed for a powered flyby that took it to within 130 kilometers of the lunar surface. Velocity gained in the flyby maneuver was used to reach a distant retrograde orbit around the Moon. That orbit is considered distant because it's another 92,000 kilometers beyond the Moon, and retrograde because the spacecraft orbited in the opposite direction of the Moon's orbit around planet Earth. Orion entered its distant retrograde orbit on November 25. Swinging around the Moon, Orion reached a maximum distance (just over 400,000 kilometers) from Earth on November 28, exceeding a record set by Apollo 13 for most distant spacecraft designed for human space exploration. The Artemis II mission, carrying 4 astronauts around the moon and back again, is scheduled to launch no earlier than September 2025.
Copyright: NASA
Προηγούμενες Αστρονομικές Εικόνες της Ημέρας από τη NASA
The Unusual Tails of Comet Tsuchinshan-Atlas
11/11/2024
What created an unusual dark streak in Comet Tsuchinshan-Atlas's tail? Some images of the bright comet during mid-October not only caught its impressively long tail and its thin anti-tail, but a rather unexpected feature: a dark streak in the long tail. The reason for the dark streak is currently unclear and a topic of some debate. Possible reasons include a plume of dark dust, different parts of the bright tail being unusually superposed, and a shadow of a dense part of the coma on smaller dust particles. The streak is visible in the featured image taken on October 14 from Texas, USA. To help future analyses, if you have taken a good image of the comet that clearly shows this dark streak, please send it in to APOD. Comet Tsuchinshan–ATLAS has now faded considerably and is returning to the outer Solar System. Gallery: Comet Tsuchinshan-ATLAS in 2024
Copyright: Bray Falls
Valles Marineris: The Grand Canyon of Mars
10/11/2024
The largest canyon in the Solar System cuts a wide swath across the face of Mars. Named Valles Marineris, the grand valley extends over 3,000 kilometers long, spans as much as 600 kilometers across, and delves as much as 8 kilometers deep. By comparison, the Earth's Grand Canyon in Arizona, USA is 800 kilometers long, 30 kilometers across, and 1.8 kilometers deep. The origin of the Valles Marineris remains unknown, although a leading hypothesis holds that it started as a crack billions of years ago as the planet cooled. Several geologic processes have been identified in the canyon. The featured mosaic was created from over 100 images of Mars taken by Viking Orbiters in the 1970s.
Copyright: NASA
Neptune at Night
09/11/2024
Ice giant Neptune is faint in Earth's night sky. Some 30 times farther from the Sun than our fair planet, telescopes are needed to catch a glimpse of the dim and distant world. This dramatic view of Neptune's night just isn't possible for telescopes in the vicinity of planet Earth though. Peering out from the inner Solar System they can only bring Neptune's day side into view. In fact this night side image with Neptune's slender crescent next to the crescent of its large moon Triton was captured by Voyager 2. Launched from planet Earth in 1977 the Voyager 2 spacecraft made a close fly by of the Solar System's outermost planet in 1989, looking back on Neptune as the robotic spacecraft continued its voyage to interstellar space.
Copyright: Voyager
Helping Hand in Cassiopeia
08/11/2024
Drifting near the plane of our Milky Way galaxy these dusty molecular clouds seem to extend a helping hand on a cosmic scale. Part of a local complex of star-forming interstellar clouds they include LDN 1358, 1357, and 1355 from American astronomer Beverly Lynds' 1962 Catalog of Dark Nebulae. Presenting a challenging target for astro-imagers, the obscuring dark nebulae are nearly 3,000 light-years away, toward rich starfields in the northern constellation Cassiopeia. At that distance, this deep, telescopic field of view would span about 80 light-years.
Copyright: Francesco Radici
Shell Galaxies in Pisces
07/11/2024
This spectacular intergalactic skyscape features Arp 227, a curious system of galaxies from the 1966 Atlas of Peculiar Galaxies. Some 100 million light-years distant within the boundaries of the constellation Pisces, Arp 227 consists of the two galaxies prominent above and left of center, the shell galaxy NGC 474 and its blue, spiral-armed neighbor NGC 470. The readily apparent shells and star streams of NGC 474 are likely tidal features originating from the accretion of another smaller galaxy during close gravitational encounters that began over a billion years ago. The large galaxy on the bottom righthand side of the deep image, NGC 467, appears to be surrounded by faint shells and streams too, evidence of another merging galaxy system. Intriguing background galaxies are scattered around the field that also includes spiky foreground stars. Of course, those stars lie well within our own Milky Way Galaxy. The telescopic field of view spans 25 arc minutes or just under 1/2 degree on the sky.
Copyright: George Williams
Comet Tsuchinshan-Atlas over the Dolomites
06/11/2024
Comet Tsuchinshan-Atlas is now headed back to the outer Solar System. The massive dusty snowball put on quite a show during its trip near the Sun, resulting in many impressive pictures from planet Earth during October. The featured image was taken in mid-October and shows a defining visual feature of the comet -- its impressive anti-tail. The image captures Comet C/2023 A3 (Tsuchinshan–ATLAS) with impressively long dust and ion tails pointing up and away from the Sun, while the strong anti-tail -- composed of more massive dust particles -- trails the comet and points down and (nearly) toward the recently-set Sun. In the foreground is village of Tai di Cadore, Italy, with the tremendous Dolomite Mountains in the background. Another comet, C/2024 S1 (ATLAS), once a candidate to rival Comet Tsuchinshan-Atlas in brightness, broke up last week during its close approach to our Sun. Growing Gallery: Comet Tsuchinshan-ATLAS in 2024
Copyright: Alessandra Masi
Milky Way over Easter Island
05/11/2024
Why were the statues on Easter Island built? No one is sure. What is sure is that over 900 large stone statues called moais exist there. The Rapa Nui (Easter Island) moais stand, on average, over twice as tall as a person and have over 200 times as much mass. It is thought that the unusual statues were created about 600 years ago in the images of local leaders of a vibrant and ancient civilization. Rapa Nui has been declared by UNESCO to a World Heritage Site. Pictured here, some of the stone giants were imaged last month under the central band of our Milky Way galaxy. Previously unknown moais are still being discovered. Alternative Multi-APOD Front Page: MyUniverseHub.com
Copyright: Josh Dury
M42: The Great Nebula in Orion
04/11/2024
The Great Nebula in Orion, an immense, nearby starbirth region, is probably the most famous of all astronomical nebulas. Here, glowing gas surrounds hot young stars at the edge of an immense interstellar molecular cloud only 1500 light-years away. In the featured deep image in assigned colors highlighted by emission in oxygen and hydrogen, wisps and sheets of dust and gas are particularly evident. The Great Nebula in Orion can be found with the unaided eye near the easily identifiable belt of three stars in the popular constellation Orion. In addition to housing a bright open cluster of stars known as the Trapezium, the Orion Nebula contains many stellar nurseries. These nurseries contain much hydrogen gas, hot young stars, proplyds, and stellar jets spewing material at high speeds. Also known as M42, the Orion Nebula spans about 40 light years and is located in the same spiral arm of our Galaxy as the Sun.
Copyright: Fényes Lóránd
Η Αστρονομική Εικόνα της Ημέρας από τη NASA (NASA Astronomy Picture of the Day) είναι μια δωρεάν υπηρεσία που παρέχει καθημερινά μια εντυπωσιακή εικόνα από το σύμπαν, την λήψη της οποίας έχει πραγματοποιήσει κάποιος από τους αστρονόμους της NASA ή από κάποιον από τους δορυφόρους ή τα τηλεσκόπια που η NASA λειτουργεί. Οι εικόνες που εμφανίζονται καλύπτουν μια ευρεία γκάμα από θέματα, συμπεριλαμβανομένων των αστερισμών, των γαλαξιών, των πλανητικών συστημάτων, των κομητών, των αστρικών σωμάτων και των παρατηρητηρίων. Κάθε εικόνα συνοδεύεται από μια σύντομη εξήγηση και πληροφορίες σχετικά με το τι παρατηρείται στην εικόνα.