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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
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
Why are stars so bright on winter nights?
In December, January and February, we look away from the Milky Way's cloudy core toward the Orion spiral arm, with stars so bright they capture our attention.
December 26, 2025
