How do astronomers discover star-forming fuel in early galaxies?

Astronomers use special tools to peek into early galaxies and find out what fuels new stars.

Imagine you're baking a cake for a big party, but your kitchen is in the middle of space, far away from Earth. You need to know what ingredients are inside that cake (like flour, sugar, or eggs) so you can figure out how it was made. Astronomers do something similar with galaxies: they look at light coming from them and use special tools to see what kind of gas is there, because gas is like the ingredient that helps make new stars.

Astronomers use a big, powerful telescope, which is like a super-detailed eye. This eye can see not just regular light but also infrared light, which is like the warm glow of a toaster, it tells them about the gas in galaxies.

When they study this infrared light, they find out if there’s lots of gas, especially a kind called molecular hydrogen. This gas is the main ingredient for making stars, just like sugar and eggs are ingredients for baking a cake.

So when astronomers see plenty of this gas, they know that early galaxies had enough fuel to make lots of new stars, just like you need enough ingredients to make a big, delicious cake!