Spectroscopy

Electromagnetic radiation

Atoms of each element emit or absorb radiation at different wavelengths. As you know, there is a spectrum called the electromagnetic spectrum. Electromagnetic radiation is energy that travels in waves. Everything emits radiation, such as light or X-rays! They all differ in wavelengths and how they interact with matter, because of this there is no one telescope that can detect them all (e.g. James Webb Space Telescope that detects infrared light)

Spectroscopy

Spectroscopy means studying the light emitted or absorbed by things. It all started when a memorial person named Issac Newton shined a light into a prism separating colors(Spectrum, e.g. rainbow) all around! We use a special kind of instrument called a spectrograph to study stars and nebulas(giant clouds of dust, some being puked out by dying stars((supernovas)).

Picture: Cat paw nebula!

Using spectrographs we can work out what it's made of. It can tell us its temperature, distance, direction, speed, and certainly almost everything! As the light interacts with the medium like a cloud or a nebula it will absorb certain wavelengths making a pattern on the absorption spectrum(as in the picture), the radiation admitted by an object is kind of like a fingerprint of the elements and compounds that make up that cloud or a nebula. (e.g. Hydrogen)

How do they work?

How they work is when light from an object enters a spectrograph, it enters a very tiny slit that helps cut off the light of other objects. When the light is alone, it bounces off grating(diffraction grating) that splits the light into different wavelengths then focusing them on a detector that records them.