The black hole at the center of the Milky Way, called Sag A*, is much less active than those at the center of other galaxies. A new study points to a simple answer: heat.
Floating mountains? Glowing plants? They're in 'Avatar,' and they're not beyond the realm of scientific possibility.
By gauging the subtle differences in light given off by a planet 1,000 light-years away, it shows that it's up to the job.
A study shows it stifles galaxy growth as it helps expand the universe.
Remnants from the explosions of stars in the 16th and 17th centuries are seen today.
The first spacecraft to peer down on the sun, it helped scientists in a vital task to predict solar weather.