When a rare planetary alignment opened up the outer Solar System, Voyager 1 was sent forth. It observed the gas giants Jupiter and Saturn and their moons. At nearly 4 billion miles from the Sun, the probe turned and took one last picture of home before continuing its journey to the stars.

If you think being an astronaut is a glamorous occupation, Mary Roach's book “Packing for Mars” will bring you down to Earth. Playing in free-fall looks like fun, but without gravity, eating, hygiene and dealing with waste are not fun. Here's the lowdown. Still want to go to Mars?

How big is the Universe? And how small? This website takes you from yoctometers - unbelievably small - to yottameters – just as unbelievably big. Navigate up or down from the human scale, with drawings and diagrams that make sense of the numbers. A great tour for everyone.

Everybody had known for a long time that the Moon was bone dry. In the nineties probes found some evidence of water. After a big announcement of water on the Moon, it went back again to being described as dry. What's the story in the 21st century?

Take a quick tour of the Solar System, the star system where we live. It's our neighborhood of the Milky Way. Find out what lies between the Sun and the edge of the Oort Cloud.

Four moons circling Jupiter. It was a sensation when Galileo discovered them in the early 17th century - and they're still sensational! One is bigger than a planet. Another seethes with volcanic activity and has mountains taller than Everest. And which one has ocean that could harbor life?