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NASA Astronomy Picture of the Day:

Does the Moon ever engulf Mars? Yes, but only in the sense that it moves in front, which happens on rare occasions. This happened just yesterday, though, as seen from some locations in North America and western Africa. This occultation was notable not only because the Moon was a fully lit Wolf Moon, but because Mars was near its largest and brightest, moving to opposition -- the closest to the Earth in its orbit -- only tomorrow. The engulfing, more formally called an occultation, typically lasting about an hour. The featured image was taken from near Chicago, Illinois, USA just as Earth's largest satellite was angularly moving away from the much more distant red planet. Our Moon occasionally moves in front of all of the Solar System's planets. Given the temporary alignment of orbital planes, the next time our Moon eclipses Mars will be a relatively soon February 9. Growing Gallery: Moon-Mars Occultation in January 2025

Photo by Imran Sultan

NASA Astronomy Picture of the Day:

Why is Polaris called the North Star? First, Polaris is the nearest bright star toward the north spin axis of the Earth. Therefore, as the Earth turns, stars appear to revolve around Polaris, but Polaris itself always stays in the same northerly direction -- making it the North Star. Since no bright star is near the south spin axis of the Earth, there is currently no bright South Star. Thousands of years ago, Earth's spin axis pointed in a slightly different direction so that Vega was the North Star. Although Polaris is not the brightest star on the sky, it is easily located because it is nearly aligned with two stars in the cup of the Big Dipper. Polaris is near the center of the five-degree wide featured image, a digital composite of hundreds of exposures that brings out faint gas and dust of the Integrated Flux Nebula (IFN) all over the frame. The surface of Cepheid Polaris slowly pulsates, causing the famous star to change its brightness by a few percent over the course of a few days. Today: Zoom APOD Lecture hosted by the Amateur Astronomers of Association of New York

Photo by Davide Coverta

NASA Astronomy Picture of the Day:

Comet ATLAS is really bright now, but also really close to the Sun. Outside the glow of the Sun, Comet C/2024 G3 (ATLAS) would be one of the more remarkable comet sights of recent years, reflecting about as much sunlight to Earth as Comet Tsuchinshan-ATLAS did in October, and now rivaling even planet Venus. But the giant snowball is now so close to the Sun that it can only be seen through the light of the early morning dawn or the early evening dusk. Today, Comet ATLAS is at perihelion -- its closest ever to the Sun. Although the future brightness of comets is notoriously hard to predict, there is hope that Comet ATLAS will survive its close pass near the Sun and remain bright enough to be seen with the unaided eye over the next few days -- and possibly a good camera comet for weeks. The featured image was taken early yesterday morning near Tornaľa, Slovakia. Tomorrow: Zoom APOD Lecture hosted by the Amateur Astronomers of Association of New York

Photo by Petr Horalek / Institute of Physics in Opava

NASA Astronomy Picture of the Day:

Whatever hit Mimas nearly destroyed it. What remains is one of the largest impact craters on one of Saturn's smallest round moons. Analysis indicates that a slightly larger impact would have destroyed Mimas entirely. The huge crater, named Herschel after the 1789 discoverer of Mimas, Sir William Herschel, spans about 130 kilometers and is featured here. Mimas' low mass produces a surface gravity just strong enough to create a spherical body but weak enough to allow such relatively large surface features. Mimas is made of mostly water ice with a smattering of rock - so it is accurately described as a big dirty snowball. The featured image was taken during the closest-ever flyby of the robot spacecraft Cassini past Mimas in 2010 while in orbit around Saturn. Interactive: Take a trek across Mimas January 14: Zoom APOD Lecture hosted by the Amateur Astronomers of Association of New York

NASA Astronomy Picture of the Day:

Only Mercury is missing from a Solar System parade of planets in this early evening skyscape. Rising nearly opposite the Sun, bright Mars is at the far left. The other naked-eye planets Jupiter, Saturn, and Venus, can also be spotted, with the positions of too-faint Uranus and Neptune marked near the arcing trace of the ecliptic plane. On the far right and close to the western horizon after sunset is a young crescent Moon whose surface is partly illuminated by earthshine. In the foreground of the composite panorama captured on 2 January, planet Earth is represented by Mount Etna's lower Silvestri Crater. Of course Earth's early evening skies are full of planets for the entire month of January. On 13 January, a nearly Full Moon will appear to pass in front of Mars for skywatchers in the continental U.S. and Eastern Canada.

Photo by Dario Giannobile

NASA Astronomy Picture of the Day:

An unassuming region in the constellation Taurus holds these dark and dusty nebulae. Scattered through the scene, stars in multiple star systems are forming within their natal Taurus molecular cloud complex some 450 light-years away. Millions of years young and still going through stellar adolescence, the stars are variable in brightness and in the late phases of their gravitational collapse. Known as T-Tauri class stars they tend to be faint and take on a yellowish hue in the image. One of the brightest T-Tauri stars in Taurus, V773 (aka HD283447) is near the center of the telescopic frame that spans over 1 degree. Toward the top is the dense, dark marking on the sky cataloged as Barnard 209.

Photo by Long Xin

NASA Astronomy Picture of the Day:

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.

Photo by Dave Doctor

NASA Astronomy Picture of the Day:

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.

Photo by Stéphane Vetter (Nuits sacrées)

NASA Astronomy Picture of the Day:

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

Photo by Alessandra Masi

NASA Astronomy Picture of the Day:

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

NASA Astronomy Picture of the Day:

Have you ever seen a rocket launch -- from space? A close inspection of the featured time-lapse video will reveal a rocket rising to Earth orbit as seen from the International Space Station (ISS). The Russian Soyuz-FG rocket was launched in November 2018 from the Baikonur Cosmodrome in Kazakhstan, carrying a Progress MS-10 (also 71P) module to bring needed supplies to the ISS. Highlights in the 90-second video (condensing about 15-minutes) include city lights and clouds visible on the Earth on the lower left, blue and gold bands of atmospheric airglow running diagonally across the center, and distant stars on the upper right that set behind the Earth. A lower stage can be seen falling back to Earth as the robotic supply ship fires its thrusters and begins to close on the ISS, a space laboratory that celebrated its 25th anniversary in 2023. Astronauts who live aboard the Earth-orbiting ISS conduct, among more practical duties, numerous science experiments that expand human knowledge and enable future commercial industry in low Earth orbit.

NASA Astronomy Picture of the Day:

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.

Photo by Barden Ridge Observatory