Weather on Exoplanets

Cloudy for the morning, turning to clear with scorching heat in the afternoon."

While this might describe a typical late-summer day in many places on Earth, it may also apply to planets outside our solar system, according to a new study by an international team of astrophysicists from the University of Toronto, York University and Queen's University Belfast.

Using sensitive observations from the Kepler space telescope, the researchers have uncovered evidence of daily weather cycles on six extra-solar planets seen to exhibit different phases. Such phase variations occur as different portions of these planets reflect light from their stars, similar to the way our own moon cycles though different phases.

Among the findings are indications of cloudy mornings on four of them and hot, clear afternoons on two others.

"We determined the weather on these alien worlds by measuring changes as the planets circle their host stars, and identifying the day-night cycle," said Lisa Esteves, a PhD candidate in the Department of Astronomy & Astrophysics at the University of Toronto, and lead author of the study published today in The Astrophysical Journal.

"We traced each of them going through a cycle of phases in which different portions of the planet are illuminated by its star, from fully lit to completely dark," said Esteves.

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paper originally appeared here on The Dragon's Gaze as an arxiv pre print last summer.