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Editors of EarthSky

January birthstone: The colorful garnet

Garnets, the beautiful January birthstone, are often thought to be red gemstones. But they also come in yellow, green, orange, brown and black.

Why no retrograde motion for Mars in 2026?

Mars won't have any retrograde - or westward - motion in 2026. What is retrograde motion? An explanation, and bizarre examples on other worlds, here.

How to translate UTC to your local time zone

The Earth has about 24 time zones. Because these differ widely, science uses Universal Time, or UTC. Learn how to translate UTC to your local time zone.

Yarkovsky effect: Pushing asteroids with sunlight

The Yarkovsky effect is a minuscule push on a small body in space, imparted by nothing more than sunlight. It can change the direction of asteroids.

Best stargazing of 2026: Top events not to miss

Here's the best stargazing of 2026! Read about the top celestial events not to miss in the coming year, and mark them on your calendar.

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.
Astronomy Essentials

Saturn at opposition – brightest for 2026 – on October 4

Don't miss Saturn at opposition on and around the night of October 4, 2026. That's when our planet Earth passes between the sun and Saturn.

Dwarf planet Ceres discovered 225 years ago today

Dwarf planet Ceres was discovered by Giuseppe Piazzi on January 1, 1801. That was 225 years ago. It was 1st considered an asteroid.

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.

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.