Astronomy Picture Of the Day (APOD)Dione's Lagrange Moon Helene
Saturn's moon Helene is very unusual in that it circles Saturn near the orbit of a bigger moon: Dione. Helene is situated in what is called a "Lagrange point" of Dione - a place of stability created by Dione's gravity.
Saturn's Moon Dione
Dione, one of Saturn's larger moons, is remarkable for its bright surface streaks. These streaks run across some of Dione's many craters, which indicate that the process which created the streaks occurred later than the process which created the craters.
Apollo 12 Visits Surveyor 3
Apollo 12 was the second mission to land humans on the Moon. The landing site was picked to be near the location of Surveyor 3, a robot spacecraft that had landed on the moon three years earlier. Pictured above, Apollo 12 astronauts Conrad and Bean retrieve parts from the Surveyor.
Apollo 12's Lunar Module Descends
A few months after Apollo 11's historic Moon landing, Apollo 12 with commander Charles Conrad Jr., Command Module pilot Richard Gordan, and Lunar Module pilot Alan Bean returned for more geographic and scientific exploration.
Dark Bok Globules in IC 2944
The dark spots in the above picture are not photographic defects but an unusual type of interstellar cloud known as a Bok globule. Bok globules, named after astronomer Bart Bok who studied them extensively, are small dark clouds made of gas and dust that are typically condensing to form a star or stars.
CG4: A Ruptured Cometary Globule
The odd looking "creature" to the right of center in the above photo is a gas cloud known as a cometary globule. This globule, however, has ruptured. Cometary globules are typically characterized by dusty heads and elongated tails.
The Sun Spews X-rays
Our Sun is really very hot. The Sun's outer atmosphere is so hot that it emits much light in the X-ray band, which was unexpected. X-rays are usually emitted from objects having a temperature in the millions of degrees, not the mere thousands of degrees of the Sun's surface.
Deimos: Small Martian Moon
Mars has two tiny moons, Phobos and Deimos. Pictured above is Deimos, the smallest moon of Mars. In fact, Deimos is the smallest known moon in the Solar System measuring only 9 miles across.
Phobos: Doomed Moon of Mars
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...
Central Galactic Star Bursts
The pictured core of the galaxy NGC 253 shows an exceptionally high rate of star formation. In the center are some of the densest knots of stars ever found, surrounded by glowing gas and dust lanes. Galaxies where such high star formation rates are seen are called "starburst" galaxies.