MEPX
Chapter 6 of 12All chapters
  1. 1The scale of things
  2. 2The Sun
  3. 3The rocky planets
  4. 4The giant planets
  5. 5Moons
  6. 6Asteroids and comets
  7. 7Gravity and orbits
  8. 8Light and distance
  9. 9Stars and their lives
  10. 10Galaxies
  11. 11The expanding universe
  12. 12Observing for yourself

Chapter 6 of 12

Asteroids and comets

The leftovers.

Rock and ice

Asteroids are rocky remnants, most of them between Mars and Jupiter. Comets are ice and dust from further out, growing a tail only when the Sun heats them.

  • A meteor is the streak of light, a meteorite is the piece that lands.
  • The tail always points away from the Sun, not backwards along the path.

Dwarf planets

Pluto was reclassified in 2006 because it has not cleared its orbital neighbourhood. It sits in the Kuiper belt alongside Eris, Makemake and Haumea.