Nina Amatulli, in the second grade at The American School in Japan, asks the scientists why Earth is the only place with life. Hear the response from Robert Hazen of the Carnegie Institution For Science.

As seen from the moon, the Earth waxes and wanes - just as the moon does as seen from our world.

John Mather talks about the James Webb Telescope. It should help answer many questions people want to know about the universe. Read more.

More than 70 percent of all energy in our universe is thought to be dark energy. But - though theoretical models say it should exist - astronomers have yet to detect dark energy. How astronomers are trying to solve one of the greatest scientific mysteries of our time.

Dense pools of dark matter are yanking on galaxies deep in space. Astronomer Catherine Heymans talks about mysterious force of dark matter.

In the far future, a giant cloud of hydrogen will collide with our Milky Way galaxy and help create thousands of new stars.

Astronomers have identified the telltale sign of a possible hypernova - a huge stellar explosion - in one of our galaxy's oldest stars.

Are we alone in the universe, or is there intelligent life out there? And if so, how would we find it? Read more about habitable zones on distant worlds.

A dwarf galaxy in the direction of the constellation Pegasus is being stripped of its gas, according to astronomers. A galaxy needs its gas to create new stars. So we might be seeing this galaxy near the end of its ability to form stars.

An astronomer has found four stars in a tight orbit that might help unlock secrets of how stars evolve. The system is BD -22°5866, and astronomers thought it was one star.