Study of Space by the Electromagnetic Spectrum

How do astronomers study stars, galaxies, and the vast expanse of space? They use electromagnetic waves to determine what’s out there.

Electromagnetic radiation, transmitted as waves of varying wavelengths, forms the electromagnetic spectrum.

It includes different types of energy waves, like radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays.

Astronomers study the universe by examining the energy waves that reach us from space.

Visible light, the part we see, reveals the colors of stars and galaxies.

But telescopes tuned to other wavelengths uncover invisible details—like stars emitting infrared radiation, high-energy X-rays from exploding stars, or radio waves coming from faint and distant objects like solar flares.

Light travels incredibly fast at 300,000,000 meters per second, but even at this speed, it takes 8 minutes for sunlight to reach Earth.

Astronomers measure cosmic distances in light-years, the distance light travels in one year.

For example, the Whirlpool Galaxy is 23 million light-years away, meaning we see it as it was 23 million years ago.