The story of how water first arrived on Earth

A 4.6 billion-year-old meteorite that crashed into a driveway in England last year contained some of the most compelling evidence to date that Earth’s water originally came from asteroids, per a new study published yesterday in Science Advances.

☄️ Let’s start at the beginning: When a giant fireball lit up the night sky over the small village of Winchcombe in late February 2021, it left piles of dark stones and powder scattered across gardens, driveways, and local fields.

And just like every alien movie ever, scientists and astronomers quickly issued an appeal to collect as many fragments of the meteorite as possible before they could degrade. Fortunately local residents answered the call, working with authorities to gather over a pound’s worth of fresh extraterrestrial material for analysis.

🔬 So, what did they find?... Up to 11% of the meteorite’s weight was made up of water – and the molecules in that water are a near-perfect match for those on Earth. More specifically, the ratio of different types of hydrogen atoms (aka isotopes) in the water are practically identical.

• The study lends credence to the leading theory that water first arrived on Earth via icy meteoroids from the outer regions of the solar system billions of years ago.