The Earth is not the only planet whose atmosphere experiences seasonal weather changes. Optical observations of planets in our outer solar solar system, (Jupiter and Saturn, for example) ...

Most stars form in clusters, sometimes with ten thousand or more stars packed into a volume smaller than a few light-years in radius. (By way of comparison, the nearest star to the sun is...

Over the past two decades astronomers have come to realize that many galaxies are fabulously luminous -- some are more than a thousand times brighter than our Milky Way. Yet the most powe...

Here on earth we are aware of ultraviolet (UV) radiation in space because of the dangers it poses to our health; the atmosphere is our shield against its damaging effects. Most astronomi...

Many of our most profound mysteries -- for example, the nature of black holes, the birth of planets, and even the origin of life -- have stories that are intricately interwoven with the s...

There are currently 228 known planets around stars other than our sun, and all of them were discovered in one of only three kinds of observations: the periodic wobble of the "color" of th...

Cambridge, MA The leading method of finding planets orbiting distant stars spots mostly Jupiter-sized worlds. Technology limitations make it difficult to detect smaller planets. But that...

Ten billion years ago or so, at least according to the current picture, the youthful universe began to produce an abundance of new stars. The very first stars appeared in the young cosmo...

Black holes are often the sources of powerful emission despite their reputation for being implacable sinks for matter and energy. A black hole can be ringed by a disk of matter, and when...

Seyfert galaxies are quite similar to normal galaxies like our own Milky Way except in one critical respect: their nuclei are fantastically bright -- in some instances as luminous as 100...