Calling all scientists! How do you explain the concept of time to an 11-year-old?
NASA officials weigh in on the flurry of planetary science news from the past week.
Two astronauts answer your questions and discuss the many curiosities of living in space.
Bacteria locked under Antarctic lake ice may shed light on life's limits, and the possibility of life on other worlds.
The film tells the stories of a soldier addicted to painkillers, and a doctor with no time for her patients.
A new documentary explores how climate change is affecting the world's glaciers.