Relativity: Right or wrong?

Einstein’s relativity replaced Newton’s gravity. Now observations of black holes might test the limits of Albert’s masterpiece.

Party with the Perseids

This meteor shower is the most famous, and in 2018 it will again be one of amateur astronomy’s great social events.

Voyage to the bottom of an alien sea

The next step in space exploration may be replacing rovers with underwater robots.

Observe deep-sky gems in Cygnus

Dazzling double stars, open clusters, nebulae, and even a galaxy will highlight your summer of viewing the night sky.

We test Sigma’s 20mm lens

This wide-angle lens will let you produce high-quality shots with just a camera and tripod.

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