ElI5: how do they know what other planets are made off, how can the be so sure? Jupiter could be made of a completely unknown gas?
In: 96
When we want to know what things are made of, we perform tests. So if we want to know whether there’s too much CO2 in the air, we break out a CO2 detector, which has a way of checking for CO2. There are lots of ways to test, so we tend to use the easiest one we can. So while testing things on Earth, we can build a detector and drop it into the stuff we’re testing. But there are also ways to test from further away.
For example, we can test temperature by sticking a thermometer into the substance. We also have thermometers that work at a distance. We only use those if we need to, since they’re more difficult to use.
Likewise we can test for gases by putting a detector in a room, or scanning from a distance. We only use the distance scanners when we need to, and we can check that they work by doing controlled experiments and comparing them to in-the-room scanners. We then just build them bigger and point them at objects in space.
Latest Answers