We think of the Sun as a fixed, yellow ball. Few of us imagine it as a thermonuclear engine. To understand how bright a star … Read More

If we put Sirius at same distance as us (ten parsecs), then it would of been over twenty times as bright than our own sun. … Read More

If you look out at a dark hillside, you may see lots of stars twinkling, but your eyes will not reveal there true nature. Each … Read More

Distance modulus allows you to figure out the distance to some distant bright thing in the night sky. It’s a way of working around astronomy’s … Read More

The best immediate measurement is parallax. On a clear night, go outside. Look up into the sky. The stars appears unchanging and ancient. But it’s … Read More

The parsec is a measure of distance. It’s not a measure of speed. In fact, you might have seen people quote that they’re going at … Read More

Astronomical units are a special type of unit. The International Astronomical Union has defined it exactly as 149,597,870,700 meters, and that number doesn’t change. This … Read More

Send a text from your phone to another person on Earth: instant. Send that text to a person in orbit aboard International Space Station: virtually … Read More

But wait! A light-year isn’t a measurement of time. It’s a unit of distance. Specificly, it’s the distance traveled by light in one Julian year. … Read More

Some people just seem to have intense magnetism for one another. And it’s not just about chemistry. There is an older pattern in the night … Read More