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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
Neptune at opposition on September 26, 2026
Neptune at opposition - when it's 180 degrees from the sun on the sky's dome - comes on September 26, 2026. You'll need optical aid to spot it.
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
Sky measurements: Degrees, arcminutes and arcseconds
What are sky measurements - or distances - in the night sky? Here's what it means for objects to be several degrees (or arcminutes or arcseconds) apart.
January 1, 2026
How often are there three eclipses in one month?
We last had three eclipses in one lunar month in 2020. It'll next happen in the year 2029. From 2000-2050, there are 3 eclipses in one lunar month 14 times.
January 1, 2026
Uranus at opposition on November 25, 2026
Don't miss Uranus at opposition on November 25, 2026. At this time, it's brightest for the year and visible to the eye under optimum observing conditions.
January 1, 2026
How to know your eclipse glasses are safe
Unscrupulous companies are printing ISO certification labels on fake eclipse glasses. Check here for reputable vendors from the American Astronomical Society.
January 1, 2026
New Year’s Star Sirius, the moon and Jupiter ring in 2026
Entertain your friends on New Year's Eve by showing them the New Year's Star, the soon-to-be full supermoon and Jupiter. Sirius is highest at midnight.
December 31, 2025
