“We don’t know,” says Ed Churchwell, professor of astronomy. “We know it’s a very large number.”
It’s in the hundreds of billions, Churchwell says. In contrast, there are but 4 billion stars in our own galaxy, the Milky Way — and the number will keep growing for some time before we run out of galaxies to [...]

After 20 years, star explosion reveals more secrets. What gives in these giant bangs?

Bush proposes mission to moon and Mars, but how great are the scientific payoffs of this expensive, risky adventure? Would it be smarter – and cheaper – to send robots?

Hubble Space Telescope is fixed, will add to history of discovery. Get a gander of galaxies, quasars, gamma ray sources, and other greatest hits of the greatest spyglass.