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What makes a red rainbow?

Red rainbows happen when the sun is on the horizon. They’re created in much the same process that causes a sunset or sunrise to look red.

Video teaser: Noctilucent cloud season

Noctilucent clouds – aka night-shining clouds – can be seen at high latitudes in summer, typically beginning for northern latitudes in late May. French photographer Adrien Mauduit in Denmark assembled his best 2016 photos into a wondrous video.

Why did Tsavo lions eat people?

In 1898, a pair of lions ate 135 people at a railroad camp in Kenya. Scientists have analyzed microscopic wear on the lions’ teeth to find out why.

Earth clouds from space

New from NASA, a short video tour of unusual and beautiful clouds observed from space.

What’s the birthstone for May?

Happy birthday May babies! Your birthstone, the emerald, is a type of beryl colored green by chromium. Perfect emeralds are among the rarest of gemstones.

Why birds smash into windows

Up to 1 billion birds die each year in the U.S. due to collisions with windows. Why do birds slam into windows, and what can you do to prevent it?

Why cats can’t resist (even a phony) box

Twitter has been blowing up with posts on cats’ attraction to taped squares on the ground. An animal behavior expert explains what draws Fluffy to the #CatSquare.

Happy World Penguin Day

Antarctica has 12 million penguins and 5 penguin species, according to a new report released today. But at least 2 penguin species have recently and significantly declined.

Favorite photos for Earth Day 2017

Here’s a collection of lovely, gorgeous, and wonderful photos from the EarthSky community in celebration of our favorite planet. Thank you all!

What is a glory?

People traveling in airplanes often see glories. The sun has to be behind your head. You’ll see the plane’s shadow cast on a cloud, surrounded by a halo of light.