• What is a harvest moon?
  The harvest moon is the full moon nearest the autumnal equinox (when ...

• Why does the sea have tides?
  The Moon's gravity draws the oceans into an oval around the Earth, ...

• What is moonlight?
  The Moon is by far the brightest thing in the night sky. But it has ...

• What is a lunar eclipse?
  As the Moon goes round the Earth, sometimes it passes right into ...

• How long is a day?
  A day is the time Earth takes to turn once. The stars come back to ...

• Why does the Earth spin?
  The Earth spins because it is falling around the Sun. As the Earth ...

• How old is the Earth?
  The Earth is about 4.6 billion years old. The oldest rock is about ...

• What is the Earth made of?
  The Earth has a core of iron and nickel, and a rocky crust made ...

• How big is the Earth?
  Satellite measurements show it is 24,870 miles (40,024 km) around the ...

• What shape is the Earth?
  The Earth is not quite a perfect sphere. Because it spins faster at ...