Heliocodex

Learn / Outward from here

Planets round other stars

On the scale of light: from 4.2 light years. 5 lessons, in the order to read them.

  1. Start herePlanets round other starsMore than 6,000 planets are now known round other stars. Almost none has been seen directly. Here is how they are found.First look · How it works
  2. TRAPPIST-1Seven planets the size of the Earth circle one small red star, all of them closer in than Mercury is to the Sun.First look · How it works
  3. The kinds of planet out thereMore than 6,000 planets are known round other stars, and most are nothing like ours. The commonest kind found so far is one the Solar System does not have.First look · How it works
  4. How planets are foundFour ways of finding a planet round another star: the star's wobble, its dimming, a direct picture, and a flicker of bent light. Each finds a different kind.First look · How it works
  5. The habitable zoneThe band round a star where a planet could keep liquid water on its surface. It is a useful first guide, and our own Solar System shows how much it leaves out.First look · How it works

Outline Still to be written here

  1. Hot JupitersGiant planets closer to their star than Mercury is to ours.
  2. Reading the air of another worldHow starlight passing through a planet’s air shows what it is made of.