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How far is a light-year? Plus, distances in space
How can we comprehend the distances to the stars and other galaxies? Here's a way to understand a light-year in terms miles and kilometers.
January 1, 2026
What’s a Blood Moon? All you need to know
By this definition, Blood Moon is a member of a special kind of lunar tetrad : four total lunar eclipses in a row. Now it's used for any total lunar eclipse.
January 1, 2026
Earthshine is a lovely glow on the unlit portion of the moon
Earthshine - the dim glow on the darkened portion of a crescent moon - is light from Earth cast on the night side of the moon. Watch for it around the new moon.
January 1, 2026
Radiant point of meteor showers: All you need to know
Meteors enter Earth's atmosphere on parallel paths. So, you'll see meteors appear to come from a single point in the sky: the radiant point!
January 1, 2026
Why is there no eclipse every full and new moon?
If the moon orbited Earth on the same plane that Earth circles the sun, we'd have an eclipse at every full and new moon. Here's why we don't.
January 1, 2026
Greatest elongation, superior and inferior conjunction
When Mercury and Venus are as far from the sun as they get from our earthly point of view, they are at greatest elongation. It is the best time to observe them.
January 1, 2026
The moon illusion makes the moon look huge!
When you see a large-looking moon low in the sky, does the moon look bigger to you? That's the moon illusion that makes the moon look so big.
January 1, 2026
What is stellar magnitude?
The brightest stars to the eye are 1st magnitude, and dimmest stars to the eye are 6th magnitude. How does stellar magnitude work in astronomy?
January 1, 2026
What is the zodiac? Why is it important in astronomy?
Maybe you associate the word zodiac with astrology. But it has an honored place in astronomy, too. It's defined by the path of the sun across our sky.
January 1, 2026
What’s a supermoon? Here are the supermoons in 2026
What's a supermoon? In 2026, we will have three full supermoons and five new supermoons. The first full supermoon is in January.
January 1, 2026
