system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 how does scientist exactly describe or know a very, very far away planet with interesting properties like lava ocean and raining rocks?
gpt
For the most part they don’t know. Here is how they determine properties: first they look at the parent star. From the light, brightness, relative movement of the star, they can figure out the size, mass and composition go the star. They detect the planets mostly by measuring the light of the star. Every time the planet passes in front, scientists measure the dip in intensity. From that they can determine the mass and distance of the planet to the star. From the stars composition and the distance to the star, along with the mass of the planet, using models for the formation of star systems, they can make predictions, or educated guesses about the chemical make up of the planet, as well as surface temperature. Finally, hopefully we are able to do this soon, we will be able to see light shining through the atmosphere of the planet with a powerful enough telescope. This will give info on how thick the atmo is and what exactly is in it.