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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
Top 6 favorite EarthSky videos from 2025. Watch them here!
Here are our top 6 favorite EarthSky videos from 2025. What will we share in 2026? Visit YouTube.com/@EarthSky to find out!
December 23, 2025
What was the Christmas star? Science and mystery
What was the Christmas star? Some scientific explanations attempt to explain the Star of Bethlehem, including a planetary conjunction, comet or supernova.
December 21, 2025
December has the longest days (wherever you live)
The longest days accompany the winter solstice. In December, a day - a whole cycle of day and night - is about half a minute longer than the average 24 hours.
December 18, 2025
Forms of aurora: Arcs, curtains, coronas and more
Here are some of the forms of aurora that you might see. Some are more common, such as diffuse glows, while others are a sign of a big geomagnetic storm.
December 14, 2025
