• How big is Pluto?
  Pluto is very small, which is why it was so hard to spot. It is five ...

• What is a meteorite?
  Meteorites are lumps of rock from space big enough to penetrate the ...

• What’s strange about Uranus?
  Unlike any of the other planets, Uranus does not spin on a slight ...

• What’s an asteroid?
  Asteroids are the thousands of rocky lumps that circle round the Sun ...

• Why is Neptune green?
  Neptune is greeny blue because its surface is completely covered in ...

• How long is a year on Neptune?
  Neptune is so far from the Sun-2.8 billion miles (4.6 billion km) at ...

• Who found Neptune?
  Two mathematicians, John Couch Adams in England and Urbain le Verrier ...

• Why do some stars throb?
  The light from variable stars flares up and down. "Cepheid" are big ...

• How are stars born?
  Stars are born when clumps of gas in space are drawn together by ...

• How many stars are there?
  It is hard to know how many stars there are in the universe, for the ...