Alpha Centauri, the closest star system to Earth, is home to three stars, one of which is so tantalizingly similar to our sun that many experts speculate that its solar system might contain habitable planets. But Alpha Centauri is about 4.3 light-years, or 25 trillion miles, from Earth. It would take a spacecraft over 25,000 years—more than 300 lifetimes of an astronomer—to reach it. When astronomers want to investigate Alpha Centauri, other nearby star systems, or even more remote objects like galaxies, they cannot rely on space missions. Instead, they resort to the primary scientific method of their discipline, a light analysis technique called spectroscopy. In this interactive, learn the basics of spectroscopy and use the technique to reveal the composition of four different cosmic objects.
To launch the interactive, click on the image at left.—Lexi Krock
