The SN 1006 Supernova Remnant

Likely the brightest supernova in recorded human history, the SN 1006 supernova remnant is about 60 light years across. A supernova is caused by the death of a star in two different ways. A gravitational collapse will cause the star to end as a neutron star. In the case of SN 1006, the star acquired too much material from a neighboring star (a stellar companion), causing an uncontrollable nuclear reaction, completely destroying the star. This explosion was first seen in the year 1006 AD. Seeing that the SN 1006 supernova remnant is about 7,000 lightyears away from Earth, the thermonuclear destruction of the star occurred 7,000 years before it was seen in the night sky in the year 1006.

When Galaxies Collide

NGC 7331, the galaxy at the upper right of the picture, is one of the brightest galaxies in the universe. Nearly 50 million lightyears away, it is very similar in size and shape to our own galaxy. In the lower left, Stephan's Quintet is a cluster of five galaxies about 300 million lightyears away, four of which make up the first ever recorded collision of galaxies. The four colliding galaxies are involved in a cosmic dance that will eventually end with them merging into one large galaxy. You would think that many of the stars in these galaxies would collide also, but in fact, the distance between stars in any galaxy (which average between 5-10 lightyears) makes the chances of this happening nearly zero.

M31 Seen in Ultraviolet Wavelengths

The Andromeda Galaxy (a.k.a. M31) is the closest spiral galaxy to the Milky Way, about 2,500,000 lightyears away. Seen here in ultraviolet wavelengths, the bright blue sections of the galaxy are dominated mainly by very hot, young stars and very dense star clusters. M31 is the furthest stellar object visible in the night sky by the naked eye, visible on a moonless night with moderate light pollution. Although it appears nearly six times as wide as the full moon, only the bright central region of the galaxy is visible. In 2006, the Spitzer Space Telescope revealed that M31 contains more than one trillion stars. In comparison, the Milky Way Galaxy only contains between 200 billion to 400 billion stars.

NGC 3621

This is NGC 3621, a galaxy located far outside our "neighborhood" of galaxies, some 22,000,000 lightyears away. The blueish haze that surrounds the galaxy is the furthest outskirts of the galaxy in which millions of stars exist. To travel across NGC 3621 from end to end would take nearly 100,000 lightyears. The brighter stars in the picture that seem to be closer are stars located in our own Milky Way Galaxy, and the stars that seem further away (circled in red) are not stars at all - some are galaxies even more distant than NGC 3621.

Orion's Many Secrets

The constellation known as Orion holds much more than simply 3 stars in a straight line. The three bright blue stars pictured are the stars that make up Orion's Belt. Below the lowest star of Orion's Belt, Alnitak, is the Flame Nebula, which glows with excited hydrogen gas. To its immediate right is the Horsehead Nebula, a dark formation of dense dust in the familiar shape of a horse's head. The formations found in this picture are estimated to be between 1,500-1,600 lightyears away from Earth. It is estimated that it would take approximately 13 lightyears to travel the expanse of the Horsehead Nebula alone.

CoRoT Satellite Discovers Rocky Planet

CoRoT-7b, a newly discovered planet more than 500 light years away, is the closest physical match to Earth scientists have ever found. It's mass is nearly 5 times that of Earth's, and it's radius is estimated at about 1.7 Earths. However, CoRoT-7b is closer to its star than Mercury is to our sun, causing its year to last only 20 hours, and its surface temperature to be much too hot to support life. Astronomers will be observing CoRoT-7b further, hoping to find what composes the first rocky planet discovered outside our solar system.