'Venus Zone' that may help search for Earth-like alien worlds is discovered

Exoplanet hunters have just made it easier to identify alien Venuses, in the hopes that doing so will lead to the discovery of more alien Earths. Researchers have delineated the “Venus Zone”, the range of distances from a host star where planets are likely to resemble Earth’s similarly sized sister world, which has been rendered un-livably hot due to a runaway greenhouse effect. The new study should help scientists get a better handle on how many of the rocky planets spotted by NASA’s prolific Kepler space telescope are truly Earth-like, team members said.

The Earth is Dr. Jekyll, and Venus is Mr. Hyde, and you can’t distinguish between the two based only on size. So the question then is, how do you define those differences, and how many ‘Venuses’ is Kepler actually finding?

Study lead author Stephen Kane, of San Francisco State University

The results could also lead to a better understanding of Earth’s history, said lead author Stephen Kane, of San Francisco State University. Kane and his team defined the Venus Zone based on solar flux—the amount of stellar energy that orbiting planets receive. The outer edge of the zone is the point at which a runaway greenhouse effect would take hold, with a planet’s temperature soaring thanks to heat-trapping gases in its atmosphere. The inner boundary, meanwhile, is the distance at which stellar radiation would completely strip away a planet’s air.

We believe the Earth and Venus had similar starts in terms of their atmospheric evolution. Something changed at one point, and the obvious difference between the two is proximity to the sun.

Stephen Kane

Science nasa