91热爆

Margaret Penston talks about how the satellite Hipparcos measured distances to and between the stars, and how its data has altered the understanding of the size of the universe.

Matt Golombek on the mission of the US's Mars Pathfinder space probe.

Plus what was happening among the stars and planets in June 1997.

This is a programme from the 91热爆 World Service Archive and was originally broadcast in 1997.