Αστρονομική Εικόνα της Ημέρας από τη NASA

Προηγούμενες Αστρονομικές Εικόνες της Ημέρας από τη NASA

Peculiar Galaxies of Arp 273

09/01/2025

The colorful, spiky stars are in the foreground of this image taken with a small telescope on planet Earth. They lie well within our own Milky Way Galaxy. But the two eye-catching galaxies in the frame lie far beyond the Milky Way, at a distance of over 300 million light-years. The galaxies' twisted and distorted appearance is due to mutual gravitational tides as the pair engage in close encounters. Cataloged as Arp 273 (also as UGC 1810), these galaxies do look peculiar, but interacting galaxies are now understood to be common in the universe. Closer to home, the large spiral Andromeda Galaxy is known to be some 2 million light-years away and inexorably approaching the Milky Way. In fact the far away peculiar galaxies of Arp 273 may offer an analog of the far future encounter of Andromeda and Milky Way. Repeated galaxy encounters on a cosmic timescale ultimately result in a merger into a single galaxy of stars. From our perspective, the bright cores of the Arp 273 galaxies are separated by only a little over 100,000 light-years.

Supernova Remnants Big and Small

08/01/2025

What happens after a star explodes? A huge fireball of hot gas shoots out in all directions. When this gas slams into the existing interstellar medium, it heats up so much it glows. Two different supernova remnants (SNRs) are visible in the featured image, taken at the Oukaïmeden Observatory in Morocco. The blue soccer ball-looking nebula toward the upper left is SNR G179.0+02.6, which appears to be the smaller one. This supernova, about 11,000 light years distant, detonated about 50,000 years ago. Although composed mostly of hydrogen gas, the blue light is emitted by a trace amount of oxygen. The seemingly larger SNR, dominating the lower right of the frame, is the Spaghetti Nebula, cataloged as Simeis 147 and sh2-240. This supernova, only about 3,000 light years away, exploded about 40,000 years ago. Comparatively, even though they appear different sizes, both supernova remnants are not only roughly the same age, but about the same size, too.

A New Year's Aurora and SAR Arc

07/01/2025

It was a new year, and the sky was doubly red. The new year meant that the Earth had returned to its usual place in its orbit on January 1, a place a few days before its closest approach to the Sun. The first of the two red skyglows, on the left, was a red aurora, complete with vertical rays, caused by a blast from the Sun pushing charged particles into Earth's atmosphere. The second red glow, most prominent on the far right, was possibly a SAR arc caused by a river of charged particles flowing across Earth's atmosphere. Although both appear red, the slight color difference is likely due to the aurora being emitted by both oxygen and nitrogen, whereas the higher SAR arc was possibly emitted more purely by atmospheric oxygen. The featured image was taken on January 1 from near Pieve di Cadore in Italy. Portal Universe: Random APOD Generator

Colliding Spiral Galaxies from Webb and Hubble

06/01/2025

Billions of years from now, only one of these two galaxies will remain. Until then, spiral galaxies NGC 2207 and IC 2163 will slowly pull each other apart, creating tides of matter, sheets of shocked gas, lanes of dark dust, bursts of star formation, and streams of cast-away stars. The featured image in scientifically assigned colors is a composite of Hubble exposures in visible light and Webb exposures in infrared light. Astronomers predict that NGC 2207, the larger galaxy on the right, will eventually incorporate IC 2163, the smaller galaxy on the left. In the most recent encounter that about peaked 40 million years ago, the smaller galaxy is swinging around counter-clockwise and is now slightly behind the larger galaxy. The space between stars is so vast that when galaxies collide, the stars in them usually do not collide. Jigsaw Challenge: Astronomy Puzzle of the Day

Welcome to Perihelion

04/01/2025

rth's orbit around the Sun is not a circle, it's an ellipse. The point along its elliptical orbit where our fair planet is closest to the Sun is called perihelion. This year perihelion is today, January 4, at 13:28 UTC, with the Earth about 147 million kilometers from the Sun. For comparison, at aphelion on last July 3 Earth was at its farthest distance from the Sun, some 152 million kilometers away. But distance from the Sun doesn't determine Earth's seasons. It's only by coincidence that the beginning of southern summer (northern winter) on the December solstice - when this H-alpha picture of the active Sun was taken - is within 14 days of Earth's perihelion date. And it's only by coincidence that Earth's perihelion date is within 11 days of the historic perihelion of NASA's Parker Solar Probe. Launched in 2018, the Parker Solar Probe flew within 6.2 million kilometers of the Sun's surface on 2024 December 24, breaking its own record for closest perihelion for a spacecraft from planet Earth.

Eclipse Pair

03/01/2025

clipses tend to come in pairs. Twice a year, during an eclipse season that lasts about 34 days, Sun, Moon, and Earth can nearly align. Then the full and new phases of the Moon, separated by just over 14 days, create a lunar and a solar eclipse. But only rarely is the alignment at both new moon and full moon phases during a single eclipse season close enough to produce a pair with both total (or a total and an annular) lunar and solar eclipses. More often, partial eclipses are part of any eclipse season. In fact, the last eclipse season of 2024 produced this fortnight-separated eclipse pair: a partial lunar eclipse on 18 September and an annular solar eclipse on 2 October. The time-lapse composite images were captured from Somerset, UK (left) and Rapa Nui planet Earth. The 2025 eclipse seasons will see a total lunar eclipse on 14 March paired with a partial solar eclipse on 29 March, and a total lunar eclipse on 8 September followed by a partial solar eclipse on 21 September.

Solar Analemma 2024

02/01/2025

Recorded during 2024, this year-spanning series of images reveals a pattern in the seasonal drift of the Sun's daily motion through planet Earth's sky. Known to some as an analemma, the figure-eight curve was captured in exposures taken only at 1pm local time on clear days from Kayseri, Turkiye. Of course the Sun's position on the 2024 solstice dates was at the top and bottom of the curve. They correspond to the astronomical beginning of summer and winter in the north. The points along the curve half-way between the solstices, but not the figure-eight curve crossing point, mark the 2024 equinoxes and the start of spring and fall. Regional peaks and dormant volcano Mount Erciyes lie along the southern horizon in the 2024 timelapse skyscape.

Alpha Centauri: The Closest Star System

01/01/2025

The closest star system to the Sun is the Alpha Centauri system. Of the three stars in the system, the dimmest -- called Proxima Centauri -- is actually the nearest star. The bright stars Alpha Centauri A and B form a close binary as they are separated by only 23 times the Earth- Sun distance - slightly greater than the distance between Uranus and the Sun. The Alphasystem is not visible in much of the northern hemisphere. Alpha Centauri A, also known as Rigil Kentaurus, is the brightest star in the constellation of Centaurus and is the fourth brightest star in the night sky. Sirius is the brightest even though it is more than twice as far away. By an exciting coincidence, Alpha Centauri A is the same type of star as our Sun, and Proxima Centauri is now known to have a potentially habitable exoplanet.

Η Αστρονομική Εικόνα της Ημέρας από τη NASA

NGC 4372 and the Dark Doodad

31/07/2026