Astronomy Archives

Stars at Night

When you look up into the sky on a moonless night, you see even more stars than you think. That’s because about 75 percent of the ‘stars’ you see are actually groups of two, three, or more stars orbiting around each other.

The Discovery of Helium

Helium was discovered in spectral analysis of the sun 14 years before anyone realized it also exists on the earth.

Liquid helium, public domain via Wikimedia Commons

Seeing Back Billions of Years

Scientists estimate that the universe is 15 billion years old. By looking far out into space, they can see the past in other places, because light takes time to reach us. An event that happened on the sun nine minutes ago will just be now visible to us. Astronomers have recently discovered a place so far away that it dates back to almost the beginning of the universe. What we see today happened 14 billion years ago.

Radio Waves and Snowflakes

In a 1980 television show, popular astronomer Carl Sagan said, “All of the radio waves from space ever studied equal less than the power of a single snowflake hitting the ground.”

That wasn’t quite true then, but it was close. Today, with many more radio telescopes and many more years of collecting astronomical radio waves, the total power of all the waves studied from space is still much less than the energy your body used while you read this post.