When the next mission to Mars lifts off inApril, another robotic probe will be sent to learn more about conditions on aplanet where humans may one day live. One great reason that we send robots:They don't mind crummy weather. When we humans follow, to Mars or anywhere elsein the solar system, weather extremes like none we know await.

At Mars, Hurricane Andrewwould stick in the memory as a gentle breeze. The discovery of the South Poleback on Earth would be retold as Roald Amundsen's pleasant summer stroll.And the oppressive heat and biting sandstorms of the Mojave? Hang on to yourcosmic hats.

Because the wildest,wackiest and worst weather known does not occur on Earth. For truly tempestuoustemperatures, take a trip to roasting Venus or frigid Pluto. Want some wind?The giant planets will blow you away.

And before you say,"But Mars is the planet we're most likely to colonize," considertornadoes as tall as Mount Everest.

More than just a thrill

Why should we care aboutextraterrestrial weather? Besides eventual preservation of the species, oneobvious answer is that bad weather is exhilarating, especially when viewed fromjust far away enough to avoid death. And scientists have a couple of otherreasons that are slightly more, well, scientific.

For one, weather is amanifestation of the movement of matter and energy through a planet'satmosphere, said Jonathan Lunine, professor of planetary sciences at theUniversity of Arizona.

"As such,"explained Lunine, "understanding the types of weather and overall climatestates of the planets represents an essential insight into the energy and massbalance of planetary atmospheres, their interaction with the surface andevolution in the short and long term."

Meaning that if we canunderstand Jupiter's 300-year-old Great Red Spot, for example, we'll know moreabout the inner Jupiter that we can't see.

Want a reason that's alittle closer to home?

Studying the weather onother planets, where conditions sometimes endure for eternities, helpsscientists better understand Earth's weather.

"It's harder topredict a storm that's going to disappear in a week or two compared topredicting a storm that has been around for 300 years," said Andrew Ingersoll,a planetary science professor at Caltech.

Mystery winds

Jupiter is not even theworst place for wind. The giant planets don't have continents or oceans tointerfere with the flow of gas in the atmosphere. One result is tremendousgusts that exceed 900 miles per hour (400 meters per second) on Saturn andNeptune.

But these winds arepuzzling. The root cause of all wind is energy. On Earth, the Sun warms theplanet at different rates in different places. These temperature differencescreate pressure differences, and air moves from high pressure to low pressureto try to equalize the differences.

The giant planets alsogenerate a little energy of their own. Still, because it is so far from theSun, Jupiter gets about one-twentieth the amount of energy, compared to itssurface area, as Earth, according to Ingersoll. And Neptune has about one-twentieththe energy of Jupiter to work with.

"Yet there is aninverse relation between energy input and the speed of the winds,"Ingersoll said. "Neptune is the windiest planet, Jupiter is intermediate,and Earth has the weakest winds. This inverse relation is a mystery."

Jupiter's moon Io has athin, fluid atmosphere that is somewhat like Mars'. These atmospheres can turnmostly to ice at night or during the winter. The effect? Io's atmosphere is sothin that winds reach supersonic speeds as the gas expands into the vacuum onthe nightside, according to Ingersoll.

While Earth's weather mayseem tame compared to some of these crazy places, Ingersoll notes one importantfeature -- a scientific fact -- that forecasters still wrestle with every day:Our planet has the most unpredictable and inexplicable weather in the solarsystem.

Other news about weather in our solar system
Venus:No Lightning, But a Strange Green Glow
Jupiter:Cassini Snaps Earth-like Weather
Jupiter:Cassini Makes First Color Movie of Clouds
Titan:Earth-Like Weather and Methane Rain
The Sun: SpaceWeather