Hot Jupiters are one of the most exotic of all varieties of alien planets. Massive balls of gas and dust, they whip around their parent star, often closer than Mercury comes to the Sun. The weather on these strange globes is even more wild than you might expect, according to a new model of these giant worlds developed from observations of hot Jupiter HAT-P-2b.
Because these giant worlds travel so close to their home stars, they are locked by tidal forces, so that one side of the planet always faces toward its sun, much the same way that one side of the Moon is eternally turned toward the Earth. This constant, uneven heating of the planet is what helps to drive highly-energetic weather patterns. Winds generated on such worlds could reach thousands of miles per hour.
"We can see daytime [side] temperatures as high as [3,800 degrees Fahrenheit]," Nikole Lewis, of the Massachusetts Institute of Technology (MIT), said. "while the nightside drops below [1,700 degrees]." She explained that even the dark side of this giant world is ten times hotter than Jupiter.
The technique used to measure the temperature on these distant, massive worlds was made possible by the fact that, as seen from Earth, planets orbiting other stars exhibit phases, as do our Moon and Venus. The infrared brightness of the planets were examined in different phases as they orbited around their home suns. Using this data, the team was able to make a rudimentary map of the temperatures on HAT-P-2b at different latitudes.
Hot Jupiters orbit so close to their home suns that our views of these worlds, sometimes hundreds of light years away, are drowned out by light from the nearly star. Although this makes them easy to detect from their graviatational influence on their home star, it also makes it tough to see the planets with a telescope.
"Even to see the planet as a single pixel next to the star would be a huge accomplishment," Heather Knutson of Caltech said. Knutson created the world's first weather map of a hot Jupiter in 2007.
The Spitzer Space Telescope is the only observatory sensitive enough to take the measurements needed to create Lewis' alien weather map.
Computer models developed to model the weather on such giant, hot worlds suggest that storms on these alien worlds could grow to tremendous sizes. Using current models, if our own Jupiter were transported as close to our Sun as some hot Jupiters are to their home stars, the Great Red Spot would gain so much energy from heating that it would cover one-quarter of the face of the planet, and a twin to that structure in Jupiter's southern hemisphere might form in the north, as well, creating an effect like a giant pair of eyes in the sky.
