Short Wave Did Earth’s Water Come From Space?
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Jan 5, 2026 
Join astrobiologist Michael Wong from Carnegie Science as he dives into the hot debate about the origins of water on Earth. Could it have always been here, or did it come from space? He discusses the role of asteroids and comets, explaining new evidence suggesting that carbonaceous asteroids delivered much of Earth's water. Wong also explores the possibility of water forming on Earth itself through chemical reactions and details exciting experiments proving this theory. Tune in for a fascinating look at our planet's watery beginnings!
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Earth Was Thought Born Bone Dry
- Planetary scientists long thought Earth formed too hot and dry to hold water during formation.
- That view made external delivery from icy bodies the leading explanation for Earth's water.
Snow Line Explains Early Water Distribution
- The protoplanetary disk had a temperature gradient with a snow line where water could condense as ice.
- Earth formed inside that snow line, so local building materials were expected to be dry.
Isotopes Point Toward Wet Asteroids
- Scientists compare deuterium-to-hydrogen (D/H) ratios to trace water sources.
- Carbonaceous chondrite asteroids match Earth's D/H better than many comets do.