Did you ever try to count the stars in the sky? It’s almost impossible – there’s just too many of them! On a clear, dark night, you can see thousands of stars. Too much to count. Sometimes, you can also see the Milky Way as a faint band of light that stretches across the sky.
Everyone likes the stars and the Milky Way. They’re just so beautiful! For thousands of years, people have gazed at the night sky trying to understand what they were looking at. But they still haven’t succeeded. Your eyes are just not good enough to study the stars in much detail.
Then, in 1608, Hans Lipperhey in the Netherlands invented the telescope. A telescope is an instrument that magnifies everything you’re looking at. If you look at the planet Saturn with your own eyes, there’s not much to see. Saturn just looks like a bright star. But if you look at Saturn with a telescope, you can see clouds, and rings, and moons.
Telescopes also collect more light than your eyes can. Therefore, they can reveal fainter stars. The Italian astronomer Galileo Galilei built his own telescopes, some 400 years ago. He discovered that the faint light of the Milky Way is actually the light of millions of stars.
Thanks to telescopes, astronomers could study the stars in much more detail. They discovered that every star is in fact a sun like our own Sun. In other words: our Sun is just one of the countless stars in the Universe! It’s so hot and bright because it’s close to us. All the other stars are much further away.
A place where big telescopes study the Universe is called an observatory. Observatories are usually built on high mountaintops, where the nights are dark and the air is clean.
ALMA is the largest observatory in the world. And also the highest. ALMA has 66 telescopes. Together, they study the birth of galaxies, stars and planets.
The telescopes of ALMA are not big tubes, like telescopes in a movie or a comic book. They are large radio antennas, most of them 12 meters across. They are so big they wouldn’t fit in your living room!
So is ALMA a telescope? No, it’s much more. It’s a huge astronomical observatory, consisting of 66 telescopes – 66 antennas. Lipperhey and Galileo would have been jealous!