Christopher Crockett
A rainbow-like background, with concentric circles indicating movement. The red side is stretched out; the blue side is squished up.

What do redshifts tell astronomers?

A redshift reveals how an object is moving in space and enables astronomers to discover otherwise-invisible planets and the movements of galaxies, and to uncover the beginnings of our universe.

What are coronal mass ejections?

Coronal mass ejections – CMEs for short – are powerful eruptions near the surface of the sun that ripple through our solar system and can interfere with satellites and power grids on Earth.

A colorful, ring-shaped cloud in space.

What are white dwarf stars?

White dwarfs are dead stars. A single white dwarf contains roughly the mass of our sun in a volume no bigger than our planet. Our sun will become a white dwarf someday.

What is the electromagnetic spectrum?

The electromagnetic spectrum describes all the wavelengths of light, both seen and unseen.

What is the zodiac?

Maybe you associate the word ‘zodiac’ with astrology, but it has an honored place in astronomy, too. It’s defined by the annual path of the sun across our sky.

What is a parsec?

Why do professional astronomers speak of distances in the universe not in terms of light-years, but in terms of parsecs, a distance of 3.26 light-years? Explanation here.

What is retrograde motion?

Retrograde motion of Jupiter or Mars or Saturn in our sky is an illusion, caused by Earth’s passing these slower-moving outer worlds. But there’s a real retrograde motion, too.

Sun's path through the zodiac.

Ecliptic traces the sun’s path

The ecliptic is an imaginary line that marks the path of the sun. The signs of the Zodiac come from the constellations that lie along this line.

Gamma ray burst

What are gamma ray bursts?

Only the most powerful explosions in the universe.

What is a light-year?

Hint: A light-year is a unit of distance, not time.