• What does an alien look like?
  At the moment, the only aliens we are likely to encounter are very, ...

• Are there any other planets like Earth?
  There is no other planet like Earth anywhere in the solar system. ...

• What are particles?
  Particles are the tiny concentrations of energy from which all matter ...

• How were atoms made?
  Atoms of hydrogen and helium were made in the early days of the ...

• How was iron made?
  Iron was forged in the heart of supergiant stars near the end of ...

• What was the first element?
  The first element to form was hydrogen, which has the simplest and ...

• What’s the smallest particle?
  The smallest particle inside the nucleus is the quark. It is less ...

• What is antimatter?
  Antimatter is the mirror image of ordinary matter. If matter and ...

• What is a spiral galaxy?
  A spiral galaxy is a galaxy that has spiralling arms of stars like a ...

• How many galaxies are there?
  With the largest telescopes and most sensitive detectors, we could ...