Astronomy Picture of the Day

🌌Spin up of a Supermassive Black Hole 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, which predicts several amazing and unu ...

🌌Titan: Moon over Saturn 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 only solar system world besides Earth known to h ...

🌌Young Star Cluster NGC 346 The most massive young star cluster in the Small Magellanic Cloud is NGC 346, embedded in our small satellite galaxy's largest star forming region some 210,000 light-years distant. Of course the massive stars of NGC 346 are short lived, but very energetic. Their winds and radiation sculpt the edges of the region's dusty molecular cloud triggering star-formation within ...

🌌MESSENGER's Last Day on Mercury 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 Janacek is near the upp ...

© Daniel Korona

🌌A Happy Sky over Bufa Hill in Mexico 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. Pictured is the scene as it appe ...

© Natan Fontes

🌌Saturn's Rings Appear to Disappear 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 ...

© Francis Bozon & Cecil Navick (AstroA. R. O.)