How do scientists calculate the mass, radius, and age of a star or planet?

Question

Hi everyone! I’ve always been fascinated by how scientists figure out the mass, radius, and age of stars and planets, especially when they’re so far away. Can someone explain in simple terms how they do this? What tools and methods do they use to gather and interpret this information? Thanks in advance for satisfying my curiosity!

In: Planetary Science

Answer 1

Imagine you’re trying to learn about a toy that’s far away on a shelf you can’t reach. You have to use clever tricks to figure out its size, weight, and how old it is without touching it. Scientists do something similar with stars and planets.

Mass

To figure out the mass (or weight) of a star or planet, scientists use something called gravity. Just like you can feel the pull when you hold a heavy toy, stars and planets pull on each other. By watching how they move around each other, scientists can figure out their mass. For example, if a planet orbits a star, the speed and path of the orbit tell scientists how heavy the star is.

Radius

The radius (or size) is like measuring how big around a toy is. Scientists often use the light from the star or planet. For stars, they look at how much light it gives off and sometimes how it dims when a planet passes in front of it (like a tiny shadow). This helps them figure out how big the star or planet is.

Age

To find out how old a star or planet is, scientists look at their “ingredients.” Imagine looking at a toy and seeing if it’s made of new or old materials. Stars and planets change over time, and by looking at the types of elements (like hydrogen and helium) and how they shine, scientists can tell if they are young or old. For planets, they might also look at the surfaces to see if they have lots of craters (old) or are smooth (new).

Tools and Methods

– Telescopes: Big cameras that look far into space.
– Spectroscopy: A tool that breaks light into a rainbow to see what elements are there.
– Computer models: Programs that simulate how stars and planets should behave.

So, just like you use clues to figure out things about a toy on a high shelf, scientists use light, movement, and materials to learn about stars and planets far away.