Αστρονομική Εικόνα της Ημέρας από τη NASA

Προηγούμενες Αστρονομικές Εικόνες της Ημέρας από τη NASA

A Messier Moment for Tempel 2

08/08/2026

Which of these is not a comet? You guessed it - the one on the right is a globular star cluster. The diffuse greenish coma of periodic comet 10P/Tempel 2 is at left in the frame. In fact the globular star cluster is Messier 30, also known as M30, or the 30th entry in astronomer Charles Messier's catalog of things which are not comets. The well-known 18th century astronomer kept a list of objects he observed, now his famous Messier Catalogue of Nebulae and Star Clusters, which did not move from night to night against the background stars and so were not the comets he was hunting for. So the famous comet hunter would get the correct answer too, even though his telescope would show both 10P/Tempel 2 and distant star cluster as similar looking faint and fuzzy objects in his field of view. Recorded on July 29, this modern telescopic image captures periodic comet Tempel 2 as it briefly swept close on the sky to M30. While the periodic comet's faint, narrow, orbital dust trail seems to pierce the globular star cluster, Tempel 2 was a mere 3.5 light-minutes away. Messier 30 is some 28,000 light-years distant.

Rubin's COSMOS field

07/08/2026

There are more than half a million galaxies in the central panel of this image from the NSF-DOE Vera C. Rubin Observatory in Chile. This is the COSMOS field, a patch of sky several times larger than the full moon, first observed by Hubble. It has also been observed by Webb and other telescopes because it contains comparatively few bright stars from our own galaxy, offering a relatively unimpeded view of other galaxies outside the Milky Way. The outer panels, numbered 1-10, show zoomed-in views of the corresponding small regions highlighted in the central panel. The variety of galaxy shapes and sizes is astonishing. Some of them are so far away that their light has traveled for billions of years before reaching Earth. Rubin will come back every couple of days to the COSMOS field as part of its ten-year Legacy Survey of Space and Time. It will allow a dynamic view of the COSMOS field and how the sky changes over time.

New Sharpest Image of the Sun Uncovers Instability

06/08/2026

What does the new sharpest image of our Sun show? Instability. To be clear, a certain kind of interactive process called the Kelvin-Helmholtz instability (KHI). This instability can create waves and swirls when two streams flow past each other -- in this case variable streams of solar magnetic plasma. Long hypothesized to occur on the Sun's surface, KHI streaks and swirls were confirmed in just-released dramatic high-resolution images taken recently by the Inouye Solar Telescope in Hawaii, USA. The featured false-yellow image, actually taken in deep blue, is the highest resolution image yet of the Sun in visible light. It spans about the radius of the Earth, but its finest details are city sized. Visible are several smooth tops of changing solar granules, while the edges of the flower-like structures have been found to harbor multiple KHI swirls. Future research may investigate how the KHI helps move energy, magnetic fields, and may even heat the surrounding solar corona.

Spokes on Saturn's B Ring

05/08/2026

Don’t get spooked by Saturn’s ghostly spokes! Today we feature a nearly two-hour timelapse of Saturn and its rings looping forwards and backwards. A day on Saturn is only 10 hours long, so two hours of observation covers quite a bit of its rotation. If you look closely, a ghoulish shadow appears and disappears as Saturn’s B ring rotates. Decades of observation with Voyager 2, Cassini, and Hubble show the appearance of Saturn’s spokes varies with the planet’s seasons. Like Earth, Saturn’s spin axis is tilted compared to the plane of its orbit around the Sun. During Saturn’s equinox, the rings are less tilted away from the Sun and the planet receives more evenly distributed sunlight and solar wind. Although their origin is still uncertain, Saturn’s spokes may be shadows of and reflections off of dust and ice levitating above the rings caused by electromagnetic interactions between the solar wind and the planet’s magnetic field. Find dark skies and look up this August to witness the Perseid meteor shower uninhibited by the Moon!

Curious Cometary Knots in the Helix Nebula

04/08/2026

What causes unusual knots of gas and dust in planetary nebulas? Seen also in the Ring Nebula, the Dumbbell Nebula and NGC 2392, the knots' existence was not initially predicted, and their origins are still not well understood. Pictured here is a fascinating image of part of the Helix Nebula by the James Webb Space Telescope showing tremendous detail in infrared light. The cometary knots have masses similar to the Earth but have sizes typically several times the orbit of Pluto. One hypothesis for the fragmentation and evolution of the knots includes existing gas being driven out by a less dense but highly energetic stellar wind of the central evolving star. The Helix Nebula is one of the closest examples of a planetary nebula created at the end of the life of a Sun-like star. Given a technical designation of NGC 7293, the Helix Nebula lies about 650 light-years away towards the constellation of Water Carrier (Aquarius). Open Science: Browse 4,000+ codes in the Astrophysics Source Code Library

Vaporizing Meteor Photobombs the Lacerta Nebula

03/08/2026

What's happening to this meteor? This bright meteor streak appeared and disappeared quickly during a long exposure of the Great Lacerta Nebula, seen faintly in red toward the center of the image. The meteoroid, likely a small pebble, creates its glow partly by heating and exciting surrounding air in Earth's atmosphere, but itself vaporizes and leaves wind-blown gas and dust with colors that give clues to its composition. The featured image was captured last month from Death Valley Observatories in Nevada, USA. This month, though, is particularly good for seeing meteors. Presently there are three meteor showers ongoing, although they are currently competing for visibility with the glow of a bright gibbous Moon. The most active of these showers, the Perseids, will be busiest in about 10 days -- after the Moon has dimmed considerably. This year, the Perseids peak nearly coincides with not only a new Moon, but, from some locations, one that totally eclipses the Sun. Sky Surprise: What picture did APOD feature on your birthday? (after 1995)

A Fire Rainbow over West Virginia

02/08/2026

What's happening to this cloud? Ice crystals in a distant cirrus cloud are acting like little floating prisms. Known informally as a fire rainbow for its flame-like appearance, a circumhorizon arc appears parallel to the horizon. For a circumhorizontal arc to be visible, the Sun must be at least 58 degrees high in a sky where cirrus clouds present below -- in this case cirrus fibratus. The numerous, flat, hexagonal ice-crystals that compose the cirrus cloud must be aligned horizontally to properly refract sunlight in a collectively similar manner. Therefore, circumhorizontal arcs are somewhat unusual to see. The featured fire rainbow was photographed in 2021 near North Fork Mountain in West Virginia, USA. Sky Surprise: What picture did APOD feature on your birthday? (after 1995)

Buck Moon and Belt of Venus

01/08/2026

The Buck Moon is a traditional name for the full moon of July. In this colorful Adriatic sea and skyscape captured on July 28 from Krk Island along the coast of Croatia, a full Buck Moon is just rising over distant mountains. Since a full moon rises as the Sun sets, Earth's shadow also rises in the twilight scene, a diffuse gray band extending above the mountainous southeastern horizon. Above Earth's shadow band is the pinkish antitwilight arch. That subtly tinted band of backscattered sunlight is more widely known as the Belt of Venus. But as it shares the eastern horizon with the atmospheric shadow of Earth and Belt of Venus, this full Buck Moon seems to set the stage for the New Moon to come. The New Moon of August 12 will cast its shadow on planet Earth in a much anticipated total solar eclipse.

Η Αστρονομική Εικόνα της Ημέρας από τη NASA

Contemplating the Sun

09/08/2026