New Worlds - Spectroscopy. Using special equipment like a spectrograph or a spectroscope, astronomers can split light from space into a spectrum and examine its spectral lines to infer what compounds are emitted or absorbed. ... It was by using spectroscopy that we discovered the first extrasolar planets.

What is a spectrometer used for in astronomy?

A spectrometer uses a prism or diffraction rating to spread out a incoming beam of light into its spectrum of different colors or wavelengths. The tool allows astronomers to determine the chemical composition of planets and stars, as well as to indicate the speed and direction of a star or galaxy.

How do astronomers use spectroscopes to study the stars?

"You take the light from a star, planet or galaxy and pass it through a spectroscope, which is a bit like a prism letting you split the light into its component colours. "It lets you see the chemicals being absorbed or emitted by the light source. From this you can work out all sorts of things," says Watson.