Atlantis shuttle returns to Earth

Extra second to keep UK on time
A "leap second" will be added onto official clocks at midnight to account for the Earth's slowing spin on its axis.

Grim details of Columbia disaster
Columbia's crew knew they had no control of the doomed orbiter, says a report by Nasa into the 2003 disaster.

Enceladus has 'spreading surface'
Pictures of Saturn's moon Enceladus suggest its surface splits and spreads apart - just like the ocean floor on Earth.

Moon sails close to Earth
The Moon is set to pass closer to the Earth on Friday evening than at any other time during the past 15 years.

UK weighs into Earth-check system
The British government commits substantial investment into the world's biggest environmental monitoring programme.