Space shuttle Endeavour begins a kind of farewell tour this week. The shuttle will set off on a cross-country trip to its retirement home, flying from Florida to Los Angeles on the back of a modified jumbo jet.
Along the way, the spaceship will stop off in Houston, home of NASA's Mission Control and, weather permitting, fly over NASA centers and various landmarks in cities that include San Francisco and Sacramento.
U.S. astronaut Sunita Williams is now in command of the International Space Station, after receiving control of the facility this weekend. Three departing astronauts whose capsule left the station early Monday landed safely three and a half hours later.
For NPR's Newscast, Peter van Dyk filed this report from Moscow:
Here's an old, old, question, but this time with a surprise twist. The question is — and I bet you asked it when you were 8 years old and sitting on a beach: Which are there more of — grains of sand on the Earth or stars in the sky?
Obviously, grains and stars can't be counted, not literally. But you can guestimate.