ePrivacy and GPDR Cookie Consent by Cookie Consent

Η Αστρονομική Εικόνα της Ημέρας από τη NASA

The Retrograde Dance of Saturn and Neptune

The Retrograde Dance of Saturn and Neptune

06/05/2026

What does it mean for Saturn and Neptune to be in retrograde? Featured is a composite of images taken over 34 nights from May 2025 to February 2026 tracing Saturn (brighter, foreground) and Neptune (dimmer, background). Over that time, the two planets exhibited retrograde motion, meaning they appeared to move backward in the sky. This apparent backwards motion occurs when Earth overtakes the slower outer planets as they orbit the Sun. Imagine the Solar System is a running track. Earth "runs" faster along the inside of the track compared to the outer planets. As Earth approaches, aligns, and then "laps" the outer planets, they change position from ahead to behind from the Earth's perspective. This perspective shift is what causes the outer planets to change position in the night sky. An animation corresponding to today’s image shows Saturn and Neptune’s months-long dance across the northern night sky. Saturn stepped from the Pisces constellation into Aquarius and back again while Neptune remained in Pisces. This is the closest Saturn and Neptune have been in the sky since their last conjunction in 1989.

Copyright: Tunç Tezel (TWAN) Text: Keighley Rockcliffe (NASA GSFC, UMBC CSST, CRESST II)

Προηγούμενες Αστρονομικές Εικόνες της Ημέρας από τη NASA

Messier 87

Messier 87

20/02/2025

rmous elliptical galaxy Messier 87 is about 50 million light-years away. Also known as NGC 4486, the giant galaxy holds trillions of stars compared to the mere billions of stars in our large spiral Milky Way. M87 reigns as the large central elliptical galaxy in the Virgo galaxy cluster. An energetic jet from the giant galaxy's core is seen to stretch outward for about 5,000 light-years in this sharp optical and near-infrared view from the Hubble Space Telescope. In fact, the cosmic blow torch is seen across the electromagnetic spectrum from gamma-rays to radio wavelengths. Its ultimate power source is M87's central, supermassive black hole. An image of this monster in the middle of M87 has been captured by planet Earth's Event Horizon Telescope.

Copyright: NASA

HH 30: A Star System with Planets Now Forming

HH 30: A Star System with Planets Now Forming

19/02/2025

How do stars and planets form? New clues have been found in the protoplanetary system Herbig-Haro 30 by the James Webb Space Telescope in concert with Hubble and the Earth-bound ALMA. The observations show, among other things, that large dust grains are more concentrated into a central disk where they can form planets. The featured image from Webb shows many attributes of the active HH-30 system. Jets of particles are being expelled vertically, shown in red, while a dark dust-rich disk is seen across the center, blocking the light from the star or stars still forming there. Blue-reflecting dust is seen in a parabolic arc above and below the central disk, although why a tail appears on the lower left is currently unknown. Studying how planets form in HH 30 can help astronomers better understand how planets in our own Solar System once formed, including our Earth.

Copyright: NASA

Thor's Helmet versus the Seagull

Thor's Helmet versus the Seagull

18/02/2025

Seen as a seagull and a duck, these nebulae are not the only cosmic clouds to evoke images of flight. But both are winging their way across this broad celestial landscape, spanning almost 7 degrees across planet Earth's night sky toward the constellation of the Big Dog (Canis Major). The expansive Seagull (top center) is itself composed of two major cataloged emission nebulas. Brighter NGC 2327 forms the head with the more diffuse IC 2177 as the wings and body. Impressively, the Seagull's wingspan would correspond to about 250 light-years at the nebula's estimated distance of 3,800 light-years. At the lower right, the Duck appears much more compact and would span only about 50 light-years given its 15,000 light-year distance estimate. Blown by energetic winds from an extremely massive, hot star near its center, the Duck nebula is cataloged as NGC 2359. Of course, the Duck's thick body and winged appendages also lend it the slightly more dramatic popular moniker, Thor's Helmet. Portal Universe: Random APOD Generator

Copyright: Nicolas Martino, Adrien Soto, Louis Leroux & Yann Sainty

SpaceX Rocket Launch Plume over California

SpaceX Rocket Launch Plume over California

17/02/2025

What's happened to the sky? Last Monday, the photogenic launch plume from a SpaceX rocket launch created quite a spectacle over parts of southern California and Arizona. Looking at times like a giant space fish, the impressive rocket launch from Vandenberg Air Force Base near Lompoc, California, was so bright because it was backlit by the setting Sun. The Falcon 9 rocket successfully delivered to low Earth orbit 23 Starlink communications satellites. The plume from the first stage is seen on the right, while the soaring upper stage rocket is seen at the apex of the plume toward the left. Venus appears at the top of the frame, while a bright streetlight shines on the far right. The featured image was captured toward the west after sunset from near Phoenix, Arizona.

Copyright: Martin LaMontagne

Parhelia at Abisko

Parhelia at Abisko

15/02/2025

Three suns seem to hug the horizon in this otherworldly winterscape. But the evocative scene was captured during a February 3rd snowmobile exploration of the mountainous region around Abisko National Park, northern Sweden, planet Earth. The two bright spots on either side of Earth's Sun are parhelia (singular parhelion), also known as mock suns or sun dogs. The parhelia are caused by hexagonal ice crystals suspended in the hazy atmosphere that reflect and refract sunlight. Commonly seen in winter and at high latitudes, the bright parhelia lie along the visible 22 degree ice halo of the Sun.

Copyright: planet Earth

A Cosmic Rose: NGC 2237 in Monoceros

A Cosmic Rose: NGC 2237 in Monoceros

14/02/2025

The Rosette Nebula, NGC 2237, is not the only cosmic cloud of gas and dust to evoke the imagery of flowers, but it is probably the most famous. At the edge of a large molecular cloud in Monoceros some 5,000 light years away, the petals of this cosmic rose are actually a stellar nursery. The lovely, symmetric shape is sculpted by the winds and radiation from its central cluster of hot young, O-type stars. Stars in the energetic cluster, cataloged as NGC 2244, are only a few million years young, while the central cavity in the Rosette Nebula, is about 50 light-years in diameter. The nebula can be seen with a small telescope toward the constellation of Monoceros, the Unicorn. This natural appearing telescopic portrait of the Rosette Nebula was made using broadband color filters, but sometimes roses aren't red.

Copyright: Harry Karamitsos

Reflections on VdB 31

Reflections on VdB 31

13/02/2025

Riding high in the constellation of Auriga, beautiful, blue VdB 31 is the 31st object in Sidney van den Bergh's 1966 catalog of reflection nebulae. It shares this well-composed celestial still life with dark, obscuring clouds B26, B27, and B28, recorded in Edward E. Barnard's 1919 catalog of dark markings in the sky. All are these nebulae are interstellar dust clouds. Barnard's dark nebulae block the light from background stars. For VdB 31 the dust preferentially reflects bluish starlight from embedded, hot, variable star AB Aurigae. Exploring the environs of AB Aurigae with the Hubble Space Telescope has revealed the several million year young star is itself surrounded by a flattened dusty disk with evidence for the ongoing formation of a planetary system. AB Aurigae is about 470 light-years away. At that distance this cosmic canvas would span about eight light-years.

Copyright: Roberto Marinoni

The Spider and the Fly

The Spider and the Fly

11/02/2025

Will the spider ever catch the fly? Not if both are large emission nebulas toward the constellation of the Charioteer (Auriga). The spider-shaped gas cloud in the image center is actually an emission nebula labelled IC 417, while the smaller fly-shaped cloud on the left is dubbed NGC 1931 and is both an emission nebula and a reflection nebula. About 10,000 light-years distant, both nebulas harbor young star clusters. For scale, the more compact NGC 1931 (Fly) is about 10 light-years across. The featured deep image, captured over 20 hours during late January in Berkshire UK, also shows more diffuse and red-glowing interstellar gas and dust. Explore Your Universe: Random APOD Generator

Copyright: Dave Boddington

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.