How does ALMA work?

The electromagnetic spectrum

The Sun emits light. Sunlight appears white, but it consists of different colors, as can be seen in the rainbow. Every color has its own wavelength: red waves of lights are longer than violet waves of light. But there’s more than the visible colors of the rainbow. Scientists have discovered many forms of invisible light. For instance,...

How are ALMA images created?

ALMA measures millimeter waves from the sky. These millimeter waves are emitted by cold dust clouds in the Universe. The clouds are so cold that they don’t produce visible light. They’re completely dark. With a normal telescope, you can’t see them. But ALMA can detect their invisible radiation. But if millimeter waves are invisible for...

How are the antennas moved around?

The huge array of 66 ALMA antennas is located at the Chajnantor Plateau in the north of Chile, at 5,000 meters altitude. The site is known as the AOS – the Array Operations Site. Because of the high altitude, the air at the AOS is very thin. There’s not much oxygen to breathe. So it’s almost...

How are ALMA’s antennas connected?

Your eyes are connected to your brain through thick bundles of nerve cells. These optic nerves transfer the signals from your two retinas to your brain. Your brain processes the signals, and turns them into a nice three-dimensional view of your surroundings. Of course, it’s important that the signals from your left eye arrive at...

How does ALMA see ‘invisible light’?

Look around you. You see the text you are reading right now. You see the room where you’re sitting in. Outside the window, you may see the street where you live, and the Sun in the sky. Or, if it’s already dark, you may see the Moon and the stars. But how does this all...