Αστρονομική Εικόνα της Ημέρας από τη NASA

Προηγούμενες Αστρονομικές Εικόνες της Ημέρας από τη NASA

Blue Arcs Toward Andromeda

04/08/2025

What are these gigantic blue arcs near the Andromeda Galaxy (M31)? Discovered in 2022 by amateur astronomers, the faint arcs -- dubbed SDSO 1 -- span nearly the same angular size as M31 itself. At first, their origin was a mystery: are they actually near the Andromeda Galaxy, or alternatively near to our Sun? Now, over 550 hours of combined exposure and a collaboration between amateur and professional astronomers has revealed strong evidence for their true nature: SDSO 1 is not intergalactic, but a new class of planetary nebula within our galaxy. Dubbed a Ghost Planetary Nebula (GPN), SDSO 1 is the first recognized member of a new subclass of faded planetary nebulas, along with seven others also recently identified. Shown in blue are extremely faint oxygen emission from the shock waves, while the surrounding red is a hydrogen-emitting trail that indicates the GPN's age.

Milky Way and Exploding Meteor

03/08/2025

In about a week the Perseid Meteor Shower will reach its maximum. Grains of icy rock will streak across the sky as they evaporate during entry into Earth's atmosphere. These grains were shed from Comet Swift-Tuttle. The Perseids result from the annual crossing of the Earth through Comet Swift-Tuttle's orbit, and are typically the most active meteor shower of the year. Although it is hard to predict the level of activity in any meteor shower, in a clear dark sky an observer might see a meteor a minute. This year's Perseids peak just a few days after full moon, and so some faint meteors will be lost to the lunar skyglow. Meteor showers in general are best seen from a relaxing position, away from lights. Featured here is a meteor caught exploding during the 2015 Perseids above Austria next to the central band of our Milky Way Galaxy.

Fireflies, Meteors, and Milky Way

02/08/2025

Taken on July 29 and July 30, a registered and stacked series of exposures creates this dreamlike view of a northern summer night. Multiple firefly flashes streak across the foreground as the luminous Milky Way arcs above the horizon in the Sierra de Órganos national park of central Mexico, The collection of bright streaks aligned across the sky toward the upper left in the timelapse image are Delta Aquariid meteors. Currently active, the annual Delta Aquarid meteor shower shares August nights though, overlapping with the better-known Perseid meteor shower. This year that makes post-midnight, mostly moonless skies in early August very popular with late night skygazers. How can you tell a Delta Aquariid from a Perseid meteor? The streaks of Perseid meteors can be traced back to an apparent radiant in the constellation Perseus. Delta Aquariids appear to emerge from the more southerly constellation Aquarius, beyond the top left of this frame. Of course, the bioluminescent flashes of fireflies are common too on these northern summer nights. But how can you tell a firefly from a meteor? Just try to catch one.

Small Dark Nebula

01/08/2025

A small, dark, nebula looks isolated near the center of this telescopic close-up. The wedge-shaped cosmic cloudlet lies within a relatively crowded region of space though. About 7,000 light-years distant and filled with glowing gas and an embedded cluster of young stars, the region is known as M16 or the Eagle Nebula. Hubble's iconic images of the Eagle Nebula include the famous star-forming Pillars of Creation, towering structures of interstellar gas and dust 4 to 5 light-years long. But this small dark nebula, known to some as a Bok globule, is a fraction of a light-year across. The Bok globule stands out in silhouette against the expansive background of M16's diffuse glow. Found scattered within emission nebulae and star clusters, Bok globules are small interstellar clouds of cold molecular gas and obscuring dust that also form stars within their dense, collapsing cores.

Supernova 2025rbs in NGC 7331

31/07/2025

A long time ago in a galaxy 50 million light-years away, a star exploded. Light from that supernova was first detected by telescopes on planet Earth on July 14th though, and the extragalactic transient is now known to astronomers as supernova 2025rbs. Presently the brightest supernova in planet Earth's sky, 2025rbs is a Type Ia supernova, likely caused by the thermonuclear detonation of a white dwarf star that accreted material from a companion in a binary star system. Type Ia supernovae are used as standard candles to establish the distance scale of the universe. The host galaxy of 2025rbs is NGC 7331. Itself a bright spiral galaxy in the northern constellation Pegasus, NGC 7331 is often touted as an analog to our own Milky Way.

Coronal Loops on the Sun

30/07/2025

Our Sun frequently erupts in loops. Hot solar plasma jumps off the Sun's surface into prominences, with the most common type of prominence being a simple loop. The loop shape originates from the Sun's magnetic field, which is traced by spiraling electrons and protons. Many loops into the Sun's lower corona are large enough to envelop the Earth and are stable enough to last days. They commonly occur near active regions that also include dark sunspots. The featured panel shows four loops, each of which was captured near the Sun's edge during 2024 and 2025. The images were taken by a personal telescope in Mantova, Italy and in a very specific color of light emitted primarily by hydrogen. Some solar prominences suddenly break open and eject particles into the Solar System, setting up a space weather sequence that can affect the skies and wires of Earth. Jigsaw Universe: Astronomy Puzzle of the Day

A Helix Nebula Deep Field

29/07/2025

Is the Helix Nebula looking at you? No, not in any biological sense, but it does look quite like an eye. The Helix Nebula is so named because it also appears that you are looking down the axis of a helix. In actuality, it is now understood to have a surprisingly complex geometry, including radial filaments and extended outer loops. The Helix Nebula (aka NGC 7293) is one of brightest and closest examples of a planetary nebula, a gas cloud created at the end of the life of a Sun-like star. The remnant central stellar core, destined to become a white dwarf star, glows in light so energetic it causes the previously expelled gas to fluoresce. The featured picture, taken in red, green, and blue but highlighted by light emitted primarily by hydrogen was created from 12 hours of exposure through a personal telescope located in Greece. A close-up of the inner edge of the Helix Nebula shows complex gas knots the origin of which are still being researched. Portal Universe: Random APOD Generator

Lightning over the Volcano of Water

27/07/2025

Have you ever watched a lightning storm in awe? You're not alone. Details of what causes lightning are still being researched, but it is known that inside some clouds, internal updrafts cause collisions between ice and snow that slowly separate charges between cloud tops and bottoms. The rapid electrical discharges that are lightning soon result. Lightning usually takes a jagged course, rapidly heating a thin column of air to about three times the surface temperature of the Sun. The resulting shock wave starts supersonically and decays into the loud sound known as thunder. On average, around the world, about 6,000 lightning bolts occur between clouds and the Earth every minute. Pictured in July 2019 in a two-image composite, lightning stems from communication antennas near the top of Volcán de Agua (Volcano of Water) in Guatemala. Sky Surprise: What picture did APOD feature on your birthday? (post 1995)

Η Αστρονομική Εικόνα της Ημέρας από τη NASA

Robert Goddard and Nell

28/03/2026