Though scientists have yet to find alien life on distant
exoplanets, much about those planets certainly seems alien — especially the
weather.
Now researchers have developed a model that can explain some
of the bizarre weather patterns seen on other
worlds.
Many of the roughly 300
extrasolar planets discovered so far are called "hot
Jupiters" because they are large gas giants like our own Jupiter.
Often, these planets orbit much closer to their stars than Jupiter does to the
sun, so their daylight temperatures can reach 3,000
degrees Fahrenheit (1,600 degrees Celsius) — much hotter than any planet
in our solar system.
While many extrasolar planets are
too far away to detect anything at all about their weather, for a few planets
scientists have been able to infer temperature changes from the varying
brightness of the planet as it rotates relative to the Earth.
On one such planet, called HD
189733b, Spitzer Space Telescope observations showed the night-side temperature
exceeds 1,300 Fahrenheit, which is much warmer than scientists expected.
Because many exoplanets orbit so
close in to their stars, scientists think they are often "tidally
locked," or trapped in position with one side permanently facing the
star's light and the other side in perpetual nighttime. Somehow, heat gets
transported from the daytime to the nighttime side of the planets, though how
this happens has not been understood.
Now a new model created by Adam
Showman of the University of Arizona and his team finally explains the
processes creating the exotic weather patterns seen on exoplanets.
"Our model I think is
the most realistic in the sense that it includes not only the weather processes
in the atmosphere but couples them to how heat is absorbed and lost,"
Showman told SPACE.com. "We created a pretty good representation
that matches the observations."
The researchers found that
fast-moving jet streams could carry warm air from the sunny side to the dark
side of a planet. To account for the temperatures measured on planets such as
HD 189733b, these streams would have to be speeding along at 7,000 mph (11,000
kph).
"You're talking about winds
fast enough to carry you in a hot air balloon from San Francisco to New York in
25 minutes," Showman said.
While jet streams occur on planets
in our solar system, including Jupiter and Earth, the streams are generally
smaller and slower-moving than what's not being suggested for exoplanets.
"The basic chemical and physical processes are similar,
but all the details are different," Showman said. "These planets are
so close to their stars, so their temperatures are much higher and winds speeds
are much higher. These types of jet streams are something that doesn't exist in
our solar system."
While the strange weather patterns
on some exoplanets would certainly be fascinating to see up close, they
wouldn't be very hospitable
to life like us.
"Hot Jupiters are pretty
crazy places," Showman said. "Expect supersonic winds and
dayside temperatures hot enough to melt lead and rocks. Only problem is, if you
tried to visit, you'd be fried to a crisp before you could enjoy the
view."
advertisement
