Astronomy Picture of the Day

2012-11-06

Why is this moon shaped like a smooth egg? The robotic Cassini spacecraft completed the first flyby ever of Saturn's small moon Methone in May and discovered that the moon has no obvious craters. Craters, usually caused by impacts, have been seen ...

2012-11-05

Why does one half of Dione have more craters than the other? Start with the fact that Saturn's moon Dione has one side that always faces Saturn, and one side that always faces away. This is similar to Earth's Moon. This tidal locking means that ...

2012-11-04 Tim Thompson

Are those UFOs near that mountain? No -- they are multilayered lenticular clouds. Moist air forced to flow upward around mountain tops can create lenticular clouds. Water droplets condense from moist air cooled below the dew point, and clouds ...

2012-11-03 Stefano De Rosa

A Full Moonset can be a dramatic celestial sight, and Full Moons can have many names. Late October's Full Moon, the second Full Moon after the northern hemisphere autumnal equinox, has been traditionally called the Hunter's Moon. According to ...

2012-11-02

At the center of our Milky Way Galaxy, a mere 27,000 light-years away, lies a black hole with 4 million times the mass of the Sun. Fondly known as Sagittarius A* (pronounced A-star), the Milky Way's black hole is fortunately mild-mannered ...

2012-11-01 Rogelio Bernal Andreo

Double, double toil and trouble; Fire burn, and cauldron bubble -- maybe Macbeth should have consulted the Witch Head Nebula. The suggestively shaped reflection nebula is associated with the bright star Rigel in the constellation Orion. More ...

2012-10-31 Stephen Leshin

Described as a "dusty curtain" or "ghostly apparition", mysterious reflection nebula VdB 152 really is very faint. Far from your neighborhood on this Halloween Night, the cosmic phantom is nearly 1,400 light-years away. Also catalogued as Ced ...

2012-10-30 Descubre Foundation

Is this what will become of our Sun? Quite possibly. The bubble of expanding gas pictured above is the planetary nebula PK 164 +31.1, the remnants of the atmosphere of a Sun-like star expelled as its supply of fusion-able core hydrogen became ...

2012-10-29 Carlos Milovic

Oh what a tangled web a planetary nebula can weave. The Red Spider Planetary Nebula shows the complex structure that can result when a normal star ejects its outer gases and becomes a white dwarf star. Officially tagged NGC 6537, this two-lobed ...

2012-10-28

This moon is doomed. Mars, the red planet named for the Roman god of war, has two tiny moons, Phobos and Deimos, whose names are derived from the Greek for Fear and Panic. These martian moons may well be captured asteroids originating in the main ...