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Space
Today's Image
Mercury’s sodium tail is now appearing in special filters
On December 3, 2025, Steven Bellavia imaged Mercury's sodium tail flowing away from the sun. See the image here and read more about Mercury's tail.
December 4, 2025
Sun
Sun news: Unexpectedly strong geomagnetic storm last night
Sun news December 4: A CME from Monday's X1.9 flare and fast solar wind triggered a stronger-than-expected geomagnetic storm last night, reaching G3 levels.
Astronomy Essentials
Space
The moon illusion makes the moon look huge!
It's the full Cold Moon tonight and it's a supermoon. You might see a large-looking moon low in the sky. It's the moon illusion that makes the moon look so big.
December 4, 2025
Earth
Expect high tides, following today’s close full supermoon
The sun and moon, among other things, affect the height of the tides. Expect higher-than-usual tides for a few days following tonight's full supermoon.
December 4, 2025
Astronomy Essentials
Tonight
Visible planets and night sky guide for December
Visible planets and night sky guide. Tonight, look for the full supermoon Cold Moon near Jupiter and Orion. And see a video about December's night sky.
December 4, 2025
Space
Did we just see dark matter? Scientists express skepticism
A bold new study claims to have made the 1st ever direct detection of dark matter, but scientists are expressing skepticism.
December 3, 2025
Tonight
December full moon is the Cold Moon and a supermoon
The 2025 December full moon will occur on December 4. It's also a supermoon, the last supermoon of 2025. It will look very bright. Don't miss it!
December 3, 2025
Human World
Most dogs still have a little wolf in them
Scientists found that many dog breeds have some wolf DNA added after wolves were 1st domesticated into dogs about 20,000 years ago.
December 3, 2025
Space
EarthSky’s lunar calendar: How to use this great gift!
Follow the moon! Here’s why you need an EarthSky lunar calendar, the top tips for using it and where you can order one.
December 3, 2025
Brightest Stars
Orange Aldebaran is Taurus the Bull’s fiery eye
Aldebaran is an enormous star that marks one of the eyes of Taurus the Bull. If placed where our sun is, its surface would pass the orbit of Mercury.
December 3, 2025
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