Astronomy Picture Of The Day

How fast can a black hole spin? If any object made of regular matter spins too fast — it breaks apart. But a black hole might not be able to break apart — and its maximum spin rate is really unknown. Theorists usually model rapidly rotating black holes with the Kerr solution to Einstein’s General Theory of Relativity, […]

Like Earth’s moon, Saturn’s largest moon Titan is locked in synchronous rotation with its planet. This mosaic of images recorded by the Cassini spacecraft in May of 2012 shows its anti-Saturn side, the side always facing away from the ringed gas giant. The only moon in the solar system with a dense atmosphere, Titan is […]

The first to orbit inner planet Mercury, the MESSENGER spacecraft came to rest on this region of Mercury’s surface on April 30, 2015. Constructed from MESSENGER image and laser altimeter data, the projected scene looks north over the northeastern rim of the broad, lava filled Shakespeare basin. The large, 48 kilometer (30 mile) wide crater […]

Sometimes, the sky itself seems to smile. A few days ago, visible over much of the world, an unusual superposition of our Moon with the planets Venus and Saturn created just such an iconic facial expression. Specifically, a crescent Moon appeared to make a happy face on the night sky when paired with seemingly nearby planets. […]

This cosmic skyscape features glowing gas and dark dust clouds alongside the young stars of NGC 3572. A beautiful emission nebula and star cluster, it sails far southern skies within the nautical constellation Carina. Stars from NGC 3572 are toward top center in the telescopic frame that would measure about 100 light-years across at the […]

Where are Saturn’s ears? Galileo is credited, in 1610, as the first person to see Saturn’s rings. Testing out Lipperhey‘s recently co-invented telescope, Galileo did not know what they were and so called them “ears“.  The mystery deepened in 1612, when Saturn’s ears mysteriously disappeared. Today we know exactly what happened: from the perspective of the Earth, Saturn’s […]

What is creating the strange texture of IC 418? Dubbed the Spirograph Nebula for its resemblance to drawings from a cyclical drawing tool, planetary nebula IC 418 shows patterns that are not well understood. Perhaps they are related to chaotic winds from the variable central star, which changes brightness unpredictably in just a few hours.By contrast, […]

This stunning portrait of NGC 5335 was captured by the Hubble Space Telescope. Some 170,000 light-years across and over 200 million light-years away toward the constellation Virgo, the magnificent spiral galaxy is seen face-on in Hubble’s view. Within the galactic disk, loose streamers of star forming regions lie along the galaxy’s flocculent spiral arms. But […]

Main belt asteroid 52246 Donaldjohanson is about 8 kilometers long and 3.5 kilometers across. On April 20, this sharp close-up of the asteroid was captured at a distance of about 1100 kilometers by the Lucy spacecraft’s long range camera during its second asteroid encounter. Named after American paleoanthropologist Donald Johanson, discoverer of the Lucy hominid […]

Beautiful emission nebula NGC 6164 was created by a rare, hot, luminous O-type star, some 40 times as massive as the Sun. Seen at the center of the cosmic cloud, the star is a mere 3 to 4 million years old. In another three to four million years the massive star will end its life […]

This surprising sky has almost everything. First, slanting down from the upper left and far in the distance is the central band of our Milky Way Galaxy. More modestly, slanting down from the upper right and high in Earth’s atmosphere is a bright meteor. The dim band of light across the central diagonal is zodiacal light: sunlight reflected […]

What’s different about this Moon? It’s the terminators. In the featured image, you can’t directly see any terminator — the line that divides the light of day from the dark of night.  That’s because the featured image is a digital composite of many near-terminator lunar strips over a full Moon. Terminator regions show the longest and most prominent […]