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EarthSky

Why fireflies light up

A firefly’s familiar glow is caused by chemical reaction. Explanation here, plus many wonderful firefly photos.

See the constellation Scutum the Shield

Scutum has only has 4 stars that make up the constellation outline, but it’s noticeable in a dark sky because a rich region of the Milky Way is behind it.

How to see a green flash

It’s said that once you’ve seen a green flash, you’ll never go wrong in matters of the heart. Here’s all you need to know … plus great pics!

Top tips for binocular stargazing

Whether you’re a beginning stargazer or a veteran of thousands of starry nights, binoculars can be your best friend.

Today in science: 1st Telstar launch

Telstar was the 1st satellite to relay television signals between Europe and North America. It launched on this date … and helped change the world.  

What’s the July birthstone?

Are you a July baby? Your birthstone, the ruby, is among the most highly prized of gemstones.

Find the Crown of the Scorpion

Here’s another cool asterism, or noticeable pattern of stars. The Scorpion’s Crown consists of just 3 stars.

Tunguska explosion

We celebrate Asteroid Day on June 30 because it’s the anniversary of a 1908 explosion over Siberia that killed reindeer and flattened trees.

NASA’s plans for August 21 eclipse

Not traveling to the centerline of the eclipse? Expect NASA images via 11 spacecraft, at least 3 aircraft, more than 50 high-altitude balloons, and the International Space Station.

How to see a full circle rainbow

It’s possible to see the whole circle of a rainbow – but sky conditions have to be just right. Plus you have to be up high!