Η Αστρονομική Εικόνα της Ημέρας από τη NASA
Active Sunspot Region 4366 Crosses the Sun
08/02/2026
An unusually active sunspot region is now crossing the Sun. The region, labelled AR 4366, is much larger than the Earth and has produced several powerful solar flares over the past ten days. In the featured image, the region is marked by large and dark sunspots toward the upper right of the Sun's disk. The image captured the Sun over a hill in Zacatecas, Mexico, 5 days ago. AR 4366 has become a candidate for the most active solar region in this entire 11-year solar cycle. Active solar regions are frequently associated with increased auroral activity on the Earth. Now reaching the edge, AR 4366 will begin facing away from the Earth during the coming week. It is not known, though, if the active region will survive long enough to reappear in about two weeks' time, as the Sun rotates.
Copyright: Daniel Korona
Προηγούμενες Αστρονομικές Εικόνες της Ημέρας από τη NASA
Prominences and Filaments on the Active Sun
15/06/2024
This colorized and digitally sharpened image of the Sun is composed of frames recording emission from hydrogen atoms in the solar chromosphere on May 15. Approaching the maximum of solar cycle 25, a multitude of planet-dwarfing active regions and twisting, snake-like solar filaments are seen to sprawl across the surface of the active Sun. Suspended in the active regions' strong magnetic fields, the filaments of plasma lofted beyond the Sun's edge appear as bright solar prominences. The large prominences seen near 4 o'clock, and just before 9 o'clock around the solar limb are post flare loops from two powerful X-class solar flares that both occurred on that day. In fact, the 4 o'clock prominence is associated with the monster active region AR 3664 just rotating off the Sun's edge.
Copyright: solar cycle 25
RCW 85
14/06/2024
From the 1960 astronomical catalog of Rodgers, Campbell and Whiteoak, emission region RCW 85 shines in southern night skies between bright stars Alpha and Beta Centauri. About 5,000 light years distant, the hazy interstellar cloud of glowing hydrogen gas and dust is faint. But detailed structures along well-defined rims within RCW 85 are traced in this cosmic skyscape composed of 28 hours of narrow and broadband exposures. Suggestive of dramatic shapes in other stellar nurseries where natal clouds of gas and dust are sculpted by energetic winds and radiation from newborn stars, the tantalizing nebula has been called the Devil's Tower. This telescopic frame would span around 100 light-years at the estimated distance of RCW 85.
Copyright: Martin Pugh
Messier 66 Close Up
13/06/2024
Big, beautiful spiral galaxy Messier 66 lies a mere 35 million light-years away. The gorgeous island universe is about 100 thousand light-years across, similar in size to the Milky Way. This Hubble Space Telescope close-up view spans a region about 30,000 light-years wide around the galactic core. It shows the galaxy's disk dramatically inclined to our line-of-sight. Surrounding its bright core, the likely home of a supermassive black hole, obscuring dust lanes and young, blue star clusters sweep along spiral arms dotted with the tell-tale glow of pinkish star forming regions. Messier 66, also known as NGC 3627, is the brightest of the three galaxies in the gravitationally interacting Leo Triplet.
Copyright: NASA
Aurora over Karkonosze Mountains
12/06/2024
It was the first time ever. At least, the first time this photographer had ever seen aurora from his home mountains. And what a spectacular aurora it was. The Karkonosze Mountains in Poland are usually too far south to see any auroras. But on the amazing night of May 10 - 11, purple and green colors lit up much of the night sky, a surprising spectacle that also appeared over many mid-latitude locations around the Earth. The featured image is a composite of six vertical exposures taken during the auroral peak. The futuristic buildings on the right are part of a meteorological observatory located on the highest peak of the Karkonosze Mountains. The purple color is primarily due to Sun-triggered, high-energy electrons impacting nitrogen molecules in Earth's atmosphere. Our Sun is reaching its maximum surface activity over the next two years, and although many more auroras are predicted, most will occur over regions closer to the Earth's poles.
Copyright: Daniel Koszela
Colorful Stars and Clouds near Rho Ophiuchi
11/06/2024
Why is the sky near Antares and Rho Ophiuchi so colorful, yet dusty? The colors result from a mixture of objects and processes. Fine dust -- illuminated by starlight -- produces blue reflection nebulae. Gaseous clouds whose atoms are excited by ultraviolet starlight produce reddish emission nebulae. Backlit dust clouds block starlight and so appear dark. Antares, a red supergiant and one of the brighter stars in the night sky, lights up the yellow-red clouds on the upper right of the featured image. The Rho Ophiuchi star system lies at the center of the blue reflection nebula on the left, while a different reflection nebula, IC 4605, lies just below and right of the image center. These star clouds are even more colorful than humans can see, emitting light across the electromagnetic spectrum. Open Science: Browse 3,400+ codes in the Astrophysics Source Code Library
Copyright: Craig Stocks
Sh2-132: The Lion Nebula
10/06/2024
Is the Lion Nebula the real ruler of the constellation Cepheus? This powerful feline appearing nebula is powered by two massive stars, each with a mass over 20 times greater than our Sun. Formed from shells of ionized gas that have expanded, the nebula's energetic matter not only glows, but is dense enough to contract gravitationally and form stars. The angular size of the Lion Nebula, officially named Sh2-132, is slightly greater than that of the full moon. The gaseous iconic region resides about 10,000 light years away in a constellation named after the King of Aethopia in Greek mythology. Your Sky Surprise: What picture did APOD feature on your birthday? (post 1995)
Copyright: Imran Badr; Text: Natalia Lewandowska (SUNY Oswego)
How to Identify that Light in the Sky
09/06/2024
What is that light in the sky? The answer to one of humanity's more common questions may emerge from a few quick observations. For example -- is it moving or blinking? If so, and if you live near a city, the answer is typically an airplane, since planes are so numerous and so few stars and satellites are bright enough to be seen over the glare of artificial city lights. If not, and if you live far from a city, that bright light is likely a planet such as Venus or Mars -- the former of which is constrained to appear near the horizon just before dawn or after dusk. Sometimes the low apparent motion of a distant airplane near the horizon makes it hard to tell from a bright planet, but even this can usually be discerned by the plane's motion over a few minutes. Still unsure? The featured chart gives a sometimes-humorous but mostly-accurate assessment. Dedicated sky enthusiasts will likely note -- and are encouraged to provide -- polite corrections. Chart translations: Italian, German, Latvian, Persian, Polish, Slovenian, Spanish, and Turkish
Copyright: HK (The League of Lost Causes)
Pandora's Cluster of Galaxies
08/06/2024
This deep field mosaicked image presents a stunning view of galaxy cluster Abell 2744 recorded by the James Webb Space Telescope's NIRCam. Also dubbed Pandora's Cluster, Abell 2744 itself appears to be a ponderous merger of three different massive galaxy clusters. It lies some 3.5 billion light-years away, toward the constellation Sculptor. Dominated by dark matter, the mega-cluster warps and distorts the fabric of spacetime, gravitationally lensing even more distant objects. Redder than the Pandora cluster galaxies many of the lensed sources are very distant galaxies in the early Universe, their lensed images stretched and distorted into arcs. Of course distinctive diffraction spikes mark foreground Milky Way stars. At the Pandora Cluster's estimated distance this cosmic box spans about 6 million light-years. But don't panic. You can explore the tantalizing region in a 2 minute video tour.
Copyright: NASA
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.