Enrique Garcia works with a very big computer. He wears an oxygen tank on his back. He needs it because the air is thin. The computer is in Chile, high in the mountains, 5,100 metres above the sea. It is the highest computer of this kind in the world. The fans must push a lot of air, because the computer gets too hot.
The place is called Chajnantor. It is flat, high and very dry. In some parts, only 3 millimetres of rain falls in a year. This is good for astronomers. Astronomers study the sky. Water in the air is bad for their work. The air here has very little water.
Here people built ALMA. ALMA has 66 antennas, like big dishes. Twenty countries worked together. The work took ten years. It cost more than one billion dollars.
Iván López works at ALMA. He takes care of the safety of the people. He said that about 250 people work there, and about 50 of them do not get enough oxygen. The cars go up in less than one hour. The workers stay eight days up in the mountains. Then they go down and rest for six days.
In 2017, eight telescopes in the world worked together. They worked like one very big telescope. ALMA helped a lot.
On 10 April 2019, the scientists showed a photo. It was the first photo of a black hole. The black hole is in the galaxy Messier 87. It is very far away.
In the photo you see a ring of hot gas. In the middle you see a dark spot. You cannot see the black hole, because it has no light.