The summer might get scorching here on Earth, but we're better off here than on some alien planets where the days are cloudy, overcast in the morning and blazing hot in the afternoons.
A team of international astronomers including York University scientist Ray Jayawardhana have uncovered evidence of daily weather cycles on six extra-solar planets using sensitive observations from the Kepler space telescope.
"Despite the discovery of thousands of extra-solar planets, what these far-off worlds look like is still shrouded in mystery," said lead author Lisa Esteves, a graduate student at the University of Toronto, according to a press release.
In their paper entitled "Changing Phases of Alien Worlds: Probing Atmospheres of Kepler Planets with High-Precision Photometry" published in the Astrophysical Journal, the team analyzed all 14 Kepler planets known to exhibit phase variations, and found indications of cloudy mornings on four and hot, clear afternoons on two others.
Most of the worlds examined in the study were very hot and large, with temperatures greater than 1,600 degrees Celsius and sizes comparable to Jupiter. These conditions are far from hospitable to life, but excellent for phase measurements, the authors note.
"We are getting to know these exotic alien planets as dynamic, three-dimensional worlds through remote sensing across vast distances. Someday soon we hope to provide similar weather reports for worlds not much bigger than the Earth," Jayawardhana said, according to the press release.
For the study, the researchers determined weather on these alien worlds by measuring phase changes as the planets circle their host stars. Similar to the Moon in the solar system, an exoplanet going through a cycle of phases can be traced, from fully lit to completely dark, when different portions of the planet are illuminated by its star.
"The detection of the light from these far-away planets, some of which took thousands of years to reach us, is in itself remarkable," said co-author Ernst de Mooij of Queen's University Belfast, U.K., according to the press release "But when we consider that phase cycle variations can be up to 100,000 times fainter than the host star, these detections become truly astonishing."
The Kepler space telescope was the ideal instrument for the study of exoplanet phase variations, according to the researchers. The telescope's very precise measurements and the vast amount of data it collected over its initial four-year mission allowed astronomers to beat the noise and measure the tiny signals from these distant worlds.
Reference:
"Changing Phases of Alien Worlds: Probing Atmospheres of Kepler Planets with High-Precision Photometry," Lisa J. Esteves, Ernst J. W. De Mooij & Ray Jayawardhana, 2015, Astrophysical Journal [https://apj.aas.org, preprint: https://arxiv.org/abs/1407.2245].
