Scientists studied Earth-sized planets that have very little surface water. They say dry, desert-like worlds are unlikely places for life even if they orbit in the habitable zone. There are billions of planets beyond the solar system and more than 6,000 confirmed exoplanets.
The team explains that a geologic carbon cycle needs rainfall and moving rocks to remove carbon dioxide from the air. If there is too little water, carbon dioxide builds up, the planet warms, and remaining water can evaporate. The researchers used computer models and simulations to study these drier conditions and compared their ideas to Venus.
Difficult words
- habitable zone — area around a star that can support life
- exoplanet — planet outside our solar systemexoplanets
- carbon cycle — natural process that moves carbon between air and rocksgeologic carbon cycle
- rainfall — water that falls from clouds to ground
- evaporate — change from liquid water to gas
- simulation — computer model that copies real eventssimulations
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Discussion questions
- Do you think water is necessary for life? Why?
- Would you prefer to live on a planet with lots of water or a dry planet? Explain.
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