Η Αστρονομική Εικόνα της Ημέρας από τη NASA
CTB 1: The Medulla Nebula
19/01/2026
What powers this unusual nebula? CTB 1 is the expanding gas shell that was left when a massive star toward the constellation of Cassiopeia exploded about 10,000 years ago. The star likely detonated when it ran out of elements, near its core, that could create stabilizing pressure with nuclear fusion. The resulting supernova remnant, nicknamed the Medulla Nebula for its brain-like shape, still glows in visible light because of the heat generated by its collision with confining interstellar gas. Why the nebula also glows in X-ray light, though, remains a topic of research. One hypothesis holds that an energetic pulsar was created and powers the nebula with a fast outwardly moving wind. Following this lead, a pulsar was found in radio waves that appears to have been expelled by the supernova explosion at over 1000 kilometers per second. Although the Medulla Nebula appears as large as a full moon, it is so faint that it took 84-hours of exposure with a small telescope in Texas, USA, to create the featured image.
Copyright: NASA
Προηγούμενες Αστρονομικές Εικόνες της Ημέρας από τη NASA
Rubin's First Look: A Sagittarius Skyscape
25/06/2025
This interstellar skyscape spans over 4 degrees across crowded starfields toward the constellation Sagittarius and the central Milky Way. A First Look image captured at the new NSF–DOE Vera C. Rubin Observatory, the bright nebulae and star clusters featured include famous stops on telescopic tours of the cosmos: Messier 8 and Messier 20. An expansive star-forming region over a hundred light-years across, Messier 8 is also known as the Lagoon Nebula. About 4,000 light-years away the Lagoon Nebula harbors a remarkable cluster of young, massive stars. Their intense radiation and stellar winds energize and agitate this cosmic lagoon's turbulent depths. Messier 20's popular moniker is the Trifid. Divided into three parts by dark interstellar dust lanes, the Trifid Nebula's glowing hydrogen gas creates its dominant red color. But contrasting blue hues in the colorful Trifid are due to dust reflected starlight. The Rubin Observatory visited the Trifid-Lagoon field to acquire all the image data during parts of four nights (May 1-4). At full resolution, Rubin's magnificent Sagittarius skyscape is 84,000 pixels wide and 51,500 pixels tall.
Copyright: NASA
In the Center of Spiral Galaxy M61
24/06/2025
Is there a spiral galaxy in the center of this spiral galaxy? Sort of. Image data from the Hubble Space Telescope, the European Southern Observatory, and smaller telescopes on planet Earth are combined in this detailed portrait of face-on spiral galaxy Messier 61 (M61) and its bright center. A mere 55 million light-years away in the Virgo Cluster of Galaxies, M61 is also known as NGC 4303. It's considered to be an example of a barred spiral galaxy similar to our own Milky Way. Like other spiral galaxies, M61 also features sweeping spiral arms, cosmic dust lanes, pinkish star forming regions, and young blue star clusters. Its core houses an active supermassive black hole surrounded by a bright nuclear spiral -- infalling star-forming gas that itself looks like a separate spiral galaxy. APOD Turns 30!: Free public lecture in Cork, Ireland TONIGHT (Tuesday) at 7 pm
Copyright: NASA
W5: Pillars of Star Formation
23/06/2025
How do stars form? Images of the star forming region W5 like those in the infrared by NASA's Wide Field Infrared Survey Explorer (WISE, later NEOWISE) satellite provide clear clues with indications that massive stars near the center of empty cavities are older than stars near the edges. A likely reason for this is that the older stars in the center are actually triggering the formation of the younger edge stars. The triggered star formation occurs when hot outflowing gas compresses cooler gas into knots dense enough to gravitationally contract into stars. In the featured scientifically colored infrared image, spectacular pillars left slowly evaporating from the hot outflowing gas provide further visual clues. W5 is also known as Westerhout 5 (W5) and IC 1848. Together with IC 1805, the nebulas form a complex region of star formation popularly dubbed the Heart and Soul Nebulas. The featured image highlights a part of W5 spanning about 2,000 light years that is rich in star forming pillars. W5 lies about 6,500 light years away toward the constellation of Cassiopeia. APOD Turns 30!: Free public lecture in Cork, Ireland tomorrow (Tuesday) at 7 pm
Copyright: : Francesco Antonucci
A Berry Bowl of Martian Spherules
22/06/2025
How were these unusual Martian spherules created? Thousands of unusual gray spherules made of iron and rock and dubbed blueberries were found embedded in and surrounding rocks near the landing site of the robot Opportunity rover on Mars in 2004. To help investigate their origin, Opportunity found a surface dubbed the Berry Bowl with an indentation that was rich in the Martian orbs. The Berry Bowl is pictured here, imaged during rover's 48th Martian day. The average size of a Martian blueberry rock is only about 4 millimeters across. By analyzing a circular patch in the rock surface to the left of the densest patch of spherules, Opportunity obtained data showing that the underlying rock has a much different composition than the hematite rich blueberries. This information contributes to the growing consensus that these small, strange, gray orbs were slowly deposited from a bath of dirty water. APOD Turns 30!: Free Public Lecture in Cork, Ireland on Tuesday, June 24 at 7 pm
Copyright: NASA
Two Worlds, Two Analemmas
21/06/2025
Sure, that figure-8 shaped curve you get when you mark the position of the Sun in Earth's sky at the same time each day over one year is called an analemma. On the left, Earth's figure-8 analemma was traced by combining wide-angle digital images recorded during the year from December 2011 through December 2012. But the shape of an analemma depends on the eccentricity of a planet's orbit and the tilt of its axis of rotation, so analemma curves can look different for different worlds. Take Mars for example. The Red Planet's axial tilt is similar to Earth's, but its orbit around the same sun is more eccentric (less circular) than Earth's orbit. As seen from the Martian surface, the analemma traced in the right hand panel is shaped more like a tear drop. The Mars rover Opportunity captured the images used over the Martian year corresponding to Earth dates July 2006 to June 2008. Of course, each world's solstice dates still lie at the top and bottom of their different analemma curves. The last Mars northern summer solstice was May 29, 2025. Our fair planet's 2025 northern summer solstice is at June 21, 2:42 UTC.
Copyright: Tunc Tezel
Major Lunar Standstill 2024-2025
20/06/2025
dmonton, Alberta, Canada, planet Earth lies on the horizon. in this stack of panoramic composite images. In a monthly time series arranged vertically top to bottom the ambitious photographic project follows the annual north-south swing of sunrise points, from June solstice to December solstice and back again. It also follows the corresponding, but definitely harder to track, Full Moon rise. Of course, the north-south swing of moonrise runs opposite sunrise along the horizon. But these rising Full Moons also span a wider range on the horizon than the sunrises. That's because the well-planned project (as shown in this video) covers the period June 2024 to June 2025, centered on a major lunar standstill. Major lunar standstills represent extremes in the north-south range of moonrise driven by the 18.6 year precession period of the lunar orbit.
Copyright: Luca Vanzella
NGC 3521: Galaxy in a Bubble
19/06/2025
Gorgeous spiral galaxy NGC 3521 is a mere 35 million light-years away, toward the northern springtime constellation Leo. Relatively bright in planet Earth's sky, NGC 3521 is easily visible in small telescopes but often overlooked by amateur imagers in favor of other Leo spiral galaxies, like M66 and M65. It's hard to overlook in this colorful cosmic portrait though. Spanning some 50,000 light-years the galaxy sports characteristic patchy, irregular spiral arms laced with dust, pink star forming regions, and clusters of young, blue stars. The deep image also finds NGC 3521 embedded in fainter, gigantic, bubble-like shells. The shells are likely tidal debris, streams of stars torn from satellite galaxies that have undergone mergers with NGC 3521 in the distant past.
Copyright: Vikas Chander
Space Station Silhouette on the Moon
18/06/2025
What's that unusual spot on the Moon? It's the International Space Station. Using precise timing, the Earth-orbiting space platform was photographed in front of a partially lit gibbous Moon in 2019. The featured image was taken from Palo Alto, California, USA with an exposure time of only 1/667 of a second. In contrast, the duration of the transit of the ISS across the entire Moon was about half a second. A close inspection of this unusually crisp ISS silhouette will reveal the outlines of numerous solar panels and trusses. The bright crater Tycho is visible on the lower left, as well as comparatively rough, light colored terrain known as highlands and relatively smooth, dark colored areas known as maria. Downloadable apps can tell you when the International Space Station will be visible from your area. APOD Turns 30!: Free Public Lecture in Cork, Ireland on June 24
Copyright: Eric Holland
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.