Watching the Sun Rip into Planets' Atmospheres
Extreme Space Weather
Oct. 3, 2011 --
With hurricanes, floods, massive thunderstorms, heat waves and wildfires, we might be inclined to believe that the weather on Earth is sometimes less than hospitable to the life that inhabits it. But compared to other planets, stars and other bodies in the cosmos, the weather on Earth is downright mild. In this slide show, explore what conditions are like elsewhere in the universe. By the time you're done reading this slide show, you'll know exactly what to say the next time you hear someone whining about the weather: "Quit complaining. At least we don't live on HD 209458b."
Credit: Paul A. Kempton
The Sauna Planet "It's not the heat; it's the humidity" is a common expression on especially muggy days in the heat of the summer. But on exoplanet GJ 1214b, we guarantee you won't notice the difference. Located about 40 light-years from our planet, this super-Earth waterworld is believed to possess an atmosphere of dense steam. The exoplanet is between two and 10 times larger than Earth and located approximately 70 times closer to its parent star. Essentially, this planet is one giant sauna, turned up to temperatures in excess of 1,000 degrees Fahrenheit (537 degrees Celsius).
Mars Storms Hurricanes are the largest storms on Earth. With powerful wind gusts and heavy rains, the storms can take a devastating toll on millions at a time. But in terms of size, they can't compare to the dust storms that can roll across Mars and affect the entire planet. In fact, some storms are so large that amateur astronomers can occasionally view them using ground based telescopes. During dust storms, wind gusts can reach up to 300 miles per hour, far stronger than any storm ever recorded on Earth.
Supersonic Planet If you're a windsurfing enthusiast, HD189733b may be just the right place for you. That is, at least it would be if it weren't 60 light-years away and orbiting its parent star so closely. Classified as a hot Jupiter, this gas giant hosts wind speeds that exceed the speed of sound. And since, as Adam Showman of the University of Arizona Lunar and Planetary Laboratory explains, the speed of sound of HD189733b is 10 times faster than it is on Earth, that's a pretty significant accomplishment. To put a number on it, the winds can reach speeds of around 6,700 miles (10,870 kilometers) per hour. That should help to cool down any potential visitors, since the temperature on the surface of the planet facing the sun can reach 1,700 degrees Fahrenheit (926 degrees Celsius).
Tidally Locked World Located some 150 light-years from Earth, HD 209458b is a hot Jupiter with one major convenience: You never have to bother to set your watch. The planet is in a tidally locked orbit with its parent star, meaning one side is always facing the sun and the other side is stuck in perpetual night. Because of this disparity, the planet also has strong winds similar to those of HD189733b. However, wind speeds on this planet only reach 4,500 miles per hour, making it a better option for a thrill-seeking windsurfer who might still be holding out hope of keeping a hair or two in place.
Credit: Jon Lomberg/Univ. of Toronto
Forget Jupiter The swirling storm at the center of Jupiter's Great Red Spot might get all the attention in our solar system. But that storm is a tiny tyke compared to the one on this brown drawf. Affectionately called "2MASS J21392676+0220226," this brown dwarf is located approximately 47 light-years away.
Solar Storms Unlike the weather mentioned in every other entry on this slide show, storms on the sun can have a significant impact on life on Earth. As storm activity increases in frequency as the sun approaches its solar maximum in its 11-year cycle, solar flares and coronal mass ejections can threaten the functionality of satellite systems, affecting computer, navigation and telecommunications networks on Earth, as well as potentially disrupt power grids. Unfortunately, an umbrella won't do us much good in the event of a massive solar storm as the sun blasts plasma particles at Earth at speeds of hundreds of miles per hour. But that doesn't mean there's reason to panic, either. (Not yet, anyway.)
Credit: ESA/V. Beckmann (NASA-GSFC)
Honorable Mention: Black Holes If you're chasing massive storms in space, nothing quite rivals the strength and intensity of the tidal forces created by a hungry black hole. When black holes tear into stars, they pull in gasses from that star at such high speeds as to create bright gamma-ray bursts that are detectable from Earth. Anything that comes near a black hole is stretched out, then ripped apart and smashed together again with other matter at velocities approaching the speed of light. If there's one storm you absolutely don't want to get caught in this year, it's one created by drifting too close to a black hole.
More stories by Talal Al-Khatib.
Every second, the sun is emitting a wind of countless billions of charged particles, sending them screaming outwards, traveling at hundreds of kilometers per second. Watching what happens when this solar wind slams into planetary atmospheres is the mission of SPRINT-A, the first space telescope dedicated to observing the planets.
Constructed by JAXA, the Japanese Aerospace eXploration Agency, SPRINT-A (full name, the Spectroscopic Planet Observatory for Recognition of Interaction of Atmosphere) is due to be launched later this year. From its vantage point in an elliptical orbit around Earth (not unlike the orbit occupied by the Chandra X-ray Observatory), it’ll turn it’s gaze towards our neighboring planets.
Seeing with ultraviolet eyes, SPRINT-A’s main objective will be to watch for high energy interactions in the upper atmospheres of the planets. Taking both images and spectra in the Extreme Ultraviolet (EUV) wavelength range, it should afford us our best view yet of the solar wind crashing into our neighboring worlds.
We already know that the solar wind gradually erodes the atmospheres of every planet in our solar system — even Earth, hidden under its protective magnetic field, isn’t safe from the assault.
But of the rocky inner planets in our solar system, Earth was the lucky one. Many planetary scientists believe that Mars, Earth, and Venus began life as very similar worlds. Certainly, they condensed from the same cloud of dusty, planet forming material, so they must have originally had similar compositions. Needless to say, they didn’t all turn out the same way.
In no uncertain terms, the atmosphere of Venus is doomed. With charged solar wind particles grinding away at its atmosphere and no internally generated magnetic field to protect it, Venus is steadily losing billions of particles of its atmosphere into space every second.
Mars has no internally generated magnetic field either, and most of its atmosphere has already been lost to space. With so little atmosphere left to keep it warm, Mars is a cold, dry little planet.
Determining exactly how the atmospheres of these planets escaped into space is a rather important goal, especially if we want to ensure that Earth doesn’t one day share the same fate. It may also shed some light on the early days of the solar system, when the sun was much more active and the constant barrage of solar wind was even stronger than it is now!
SPRINT-A’s second goal lies a bit further out. Around our solar system’s largest planet lies the most volcanically active object we know of. Where the planets I mentioned before don’t have much of a magnetic field to speak of, Jupiter has a field strong enough to more than make up for them. And deep within that magnetic field lies Io, Jupiter’s ill tempered, sulfurous moon.
Exactly how Io interacts with its surrounding environment is also a topic in need of more research. Jupiter is a harsh planet to get close to, and Io, close as it is, gets constantly squeezed and warped by the giant planet’s gravity. As the tortured little moon orbits Jupiter, complaining perpetually through endless volcanic eruptions, it leaves a trail of sulfur ions in its wake.
As these sulfur ions leave Io, they collide with some of the harshest radiation belts in the solar system, trapped by Jupiter’s magnetic field. These collisions are actually remarkably similar to those that happen when the solar wind hits the atmosphere of a planet.
Precisely what SPRINT-A discovers remains to be seen, but it’s scheduled to launch on Aug. 22. As it leaves the atmosphere, it’ll also be sitting atop a launch vehicle adorned with messages sent to JAXA by 5812 people (of whom 5360 sent messages in Japanese), printed as part of the craft’s decoration.
Image: Collage Showing SPRINT-A in orbit, together with images of Mars and Jupiter. Credits: JAXA/NASA