Αστρονομική Εικόνα της Ημέρας από τη NASA

Προηγούμενες Αστρονομικές Εικόνες της Ημέρας από τη NASA

Unusually Smooth Sections of Asteroid Itokawa

30/06/2026

Why are parts of this asteroid's surface so smooth? The answer seems likely to do with the dynamics of an asteroid that is a loose pile of rubble rather than a solid rock. The unusual asteroid Itokawa was visited by the Japanese spacecraft Hayabusa in 2005 which imaged and documented its unusual structure and mysterious lack of craters. Analyses of the border regions between smooth and rugged sections indicate that jostling of the asteroid might be creating segregation between large and small rocks near the surface, like the Brazil nut effect. The robotic Hayabusa actually touched down on one of the smooth patches, dubbed the MUSES Sea, and collected soil samples. These samples were returned to Earth and are not only giving clues to the ancient history of this unusual asteroid, but also about the early years of our entire Solar System. Computer simulations show that 500-meter asteroid Itokawa may impact the Earth within the next few million years. Rocking Space: Today is Asteroid Day

M82: Galaxy with a Supergalactic Wind

29/06/2026

Why is the Cigar Galaxy billowing red smoke? M82, as this starburst galaxy is also known, was stirred up by a recent pass near large spiral galaxy M81. This doesn't fully explain the source of the red-glowing outwardly expanding gas and dust, however. Evidence indicates that this gas and dust is being driven out by the combined emerging particle winds of many stars, together creating a galactic superwind. The dust particles are thought to originate in M82's interstellar medium and are actually similar in size to particles in cigar smoke. The featured photographic mosaic combines images taken in visible light from the Hubble Space Telescope and images taken in infrared light from James Webb Space Telescope. It shows the light-colored central galaxy nearly edge on across the image center with tremendous orange and red colored filaments of gas and dust extending both up and down. The filaments extend for over 10,000 light years. The 12-million light-year distant Cigar Galaxy is the brightest galaxy in the sky in infrared light and can be seen in visible light with a small telescope towards the constellation of the Great Bear (Ursa Major).

AR 4478: Giant Sunspot Group

28/06/2026

Right now, one of the largest sunspot groups in recent history is crossing the Sun. Active Region 4478 is not only big -- it's violent, showing tangled magnetic fields capable of throwing off huge clouds of particles into the Solar System. Some of these CMEs might impact the Earth. At the extreme, these solar storms could cause some Earth-orbiting satellites to malfunction, the Earth's atmosphere to slightly distort, and electrical power grids to surge. When impacting Earth's upper atmosphere, these particles can produce beautiful auroras. Pictured here, AR 4478 and its dark sunspots were captured in visible light a few days ago from Barcelona, Spain. Almost as large as AR 3664 was in 2024, the AR 4478 sunspot group is so big that it is visible just with glasses specially designed to view solar eclipses. This week, skygazing enthusiasts all over the globe will not only be tracking AR 4478 during the day -- but keenly watching night skies for its corresponding bright auroras. Sky Surprise: What picture did APOD feature on your birthday? (after 1995)

Mars Marathon by Perseverance

27/06/2026

In this recent HiRISE view from the Mars Reconnaissance Orbiter, the little green dot indicated on the surface of the big Red Planet is the Perseverance Mars rover. Recorded on June 13, the car-sized, six-wheeled robot was imaged a day before completing a Martian marathon, traveling a total distance of 26.218 miles (42.195 kilometers) since it began exploring the surface of Mars. That equivalent marathon distance was achieved by Perseverance on its mission sol (Martian day) 1,890, after about 5 Earth years and 4 Earth months of driving. Perseverance is continuing to hunt for biosignatures. In the HiRISE image, the Mars rover's tracks can be seen leading to its location in an area west of its landing site in Jezero crater near an ancient river delta.

Milky Way Urban Style

26/06/2026

In a cosmic vista you can never see, the Milky Way arcs through the night above Seoul, South Korea. Remarkably, this urban night skyscape reveals our galaxy's faintly luminous central region and dark obscuring dust clouds in spite of the brilliant city lights. To overcome the extreme light pollution of the metropolitan area and record faint cosmic details, an infrared filter was used to capture the night scene in a single exposure. While the filter transmits predominately infrared light, it still passes some visible light to give the scene a natural appearance. The view is from Seoul's Ttukseom Hangang Park, with the Han River and a well lit railway bridge across the foreground. The 123 story Lotte World Tower looms in the distance, the tallest building in South Korea.

Anticrepuscular Rays over Sicily

25/06/2026

The Sun has just set... in the opposite side of the sky. Pictured here are anticrepuscular rays apparently converging in the east in this image of the limestone plateau in the heart of the Hyblaean Mountains of southeastern Sicily, in Italy. How were these anticrepuscular rays formed, if the Sun wasn't there? After the Sun set (in the west, as usual) its light still illuminated a cloud higher up in the sky. Partially blocked by the cloud, the sunlight produced patterns of light and shadow, crossing the sky in parallel lines. Perspective makes it look like they converge in the east, in the same way that train tracks appear to meet in the distance. This effect can also happen at sunrise, only the directions are exchanged. In rare cases, both crepuscular and anticrepuscular rays can be seen at the same time.

M27: The Dumbbell Nebula

22/06/2026

Is this what will become of our Sun? Quite possibly. The first hint of our Sun's future was discovered inadvertently in 1764. At that time, Charles Messier was compiling a list of diffuse objects not to be confused with comets. The 27th object on Messier's list, now known as M27 or the Dumbbell Nebula, is a planetary nebula, one of the brightest planetary nebulas on the sky and visible with binoculars toward the constellation of the Fox (Vulpecula). It takes light about 1000 years to reach us from M27, featured here in colors enhanced by red for hydrogen and blue for oxygen. We now know that in about 6 billion years, our Sun will shed its outer gases into a planetary nebula like M27, while its remaining center will become an X-ray hot white dwarf star. Understanding the physics and significance of M27 was well beyond 18th century science, though. Even today, many things remain mysterious about planetary nebulas, including how their intricate shapes are created.

Starry Night II

19/06/2026

Does this scene look familiar? It is a modern recreation of the famous painting Starry Night by Vincent van Gogh. Both the image and the painting depict a tall tree on the left, a crescent moon on the upper right, the planet Venus just to the right of the tree, a foreground horizon rising from left to right, and clouds above the horizon. Differences include that the photograph was taken in mid-April earlier this year in Cascavel, Brazil, while the painting was composed in Saint-Rémy-de-Provence, France, in 1889. The original Starry Night is considered by many to be one of the three most famous paintings in the world today and a statement about the wonders of the night sky. Today is (roughly) the anniversary of the morning that van Gogh saw the sky that he later painted in his version of Starry Night. Night Sky Jigsaw: Astronomy Puzzle of the Day

Η Αστρονομική Εικόνα της Ημέρας από τη NASA

Barnards Loop over Twin Volcanoes

28/07/2026