The building blocks of life as we know it require chemical reactions involving phosphorus. But phosphorus is scarce on Earth. Where did enough of it come from to fuel life's start? Carbonate-rich lakes, like Mono Lake in California, might hold a clue.

The Earth might be crawling with undiscovered alien creatures whose biochemistry is very different from life as we know it. An astrobiologist explains.

According to independent analyses by both NASA and NOAA, Earth's global surface temperatures in 2019 ranked 2nd-warmest since 1880.

According to the UK's Met Office, each decade from the 1980s has been successively warmer than all the decades that came before. 2019 concludes the warmest ‘cardinal’ decade (those spanning years ending 0-9) in records that stretch back to the mid-19th century.

Betelgeuse has dimmed recently, prompting some to wonder if it's about to explode. An explosion might trigger a gravitational wave burst. Betelgeuse is still there. The nearby gravitational wave burst probably means nothing for this star. Still ... 

It's difficult to see objects whose orbits are within that of Venus, because those objects always stay near the sun in our sky. Now, though, astronomers have spotted one!

The scientists call them "xenobots." They are tiny living robots assembled from the cells of frogs. Their creators promise advances from drug delivery to toxic waste clean-up.

A new NASA video combines visible, infrared and X-ray views of the famous Crab Nebula, a star that exploded into view in our sky 1,000 years ago.

NOAA reports that 2019 was the 5th consecutive year in which the United States experienced 10 or more $1 billion weather and climate disasters, including fires, hurricanes and flooding.

This image is part of a wider system of depressions that spiral outward from the very center of Mars' north pole. Seen in context, you can see rippling troughs that curve and bend and slice outwards from the pole counterclockwise.