Astronomy Picture Of the Day (APOD)Ancient Cratered Plains on Ganymede
The largest moon in the Solar System shows regions that are ancient and battered. The high density of craters demonstrate that patches of Ganymede are indeed billions of years old. This photo is one of a series released by NASA two days ago from the Galileo spacecraft orbiting Jupiter.
Ganymede: A Really Groovy Moon
Ganymede's surface is a wrinkled mess. As large ice-sheets shift on the moon's surface, parts of the surface buckle causing high ridges, deep furrows, and parallel grooves. This photo, taken by the Galileo spacecraft currently orbiting Jupiter, was released yesterday. The large circular feature near the picture bottom is a large impact crater.
Galileo Photographs Ganymede
Ganymede's surface is slowly being pulled apart. This photo of Ganymede was released earlier today by the Galileo team at NASA. The Galileo Spacecraft arrived at Jupiter in December 1995. In late June...
M74: A Grand Design Spiral Galaxy
M74 is about the same size as our own Milky Way Galaxy. Like our Milky Way, M74 is classified a spiral galaxy. M74's sweeping lanes of stars and dust combined with its small nucleus make it a classic Grand Design Spiral. On the Hubble Sequence of Galaxies, M74 is listed as "Sc".
M33: The Triangulum Galaxy
The spiral galaxy M33 is a mid-sized member of our Local Group of galaxies. M33 is also called the Triangulum Galaxy for the constellation in which it resides. About four times smaller (in radius)...
Isaac Newton Explains the Solar System
Sir Isaac Newton changed the world. Born in 1643, Newton was only an above-average student. But he went home from Cambridge one summer in 1665, thought a lot about the physical nature of the world, and came back two years later with a revolutionary understanding of mathematics, gravitation, and optics.
Edmund Halley's Greatest Discoveries
Sir Edmond Halley was quite a discoverer. Born in 1656, he computed in 1705 that a bright comet was periodic and would make another appearance in 1758. The comet appeared as predicted and is now known as Comet Halley. Unfortunately, Halley died in 1742 and never saw his prediction come true.
The Mysterious Rings of Supernova 1987a
What's causing those odd rings in supernova 1987a? In 1987, the brightest supernova in recent history occurred in the Large Magellanic Clouds. At the center of the picture is an object central to the remains of the violent stellar explosion.
The Cat's Eye Nebula (Revisited)
Three thousand light years away, a dying star throws off shells of glowing gas. This image from the Hubble Space Telescope reveals "The Cat's Eye Nebula" to be one of the most complex planetary nebulae known.
Superbubbles in the LMC
Why is there a hole in the center of this nebula? A leading explanation is that it is caused by the stellar winds from the stars that live there. Stars - including the Sun - expel electrons, protons, and other charged ions in a steady stream - the stellar wind.