Saturn’s largest moon, Titan, looks more like Venus and Mars than astronomers ever suspected—at least when it comes to suffering a severe strike from the solar wind.
NASA’s Cassini spacecraft made a flyby of Titan in December 2013 that offered a unique opportunity for scientists, in newly reported observations. For the first time, scientists caught a close glimpse of the large moon when it was outside Saturn’s protective magnetic field.
The solar wind, basically fast-flowing charged particles, continually blasts out from the sun and past the entire solar system.
Earth’s magnetic field shields the atmosphere from being stripped away by the solar wind. By studying the solar wind’s impacts on worlds lacking a global magnetic field, like Venus, Mars, and now Titan, scientists learn about their atmospheres and how their chemistry changes under solar assault.
Titan spends about 95 percent of its time around Saturn, within the planet’s strong, protective magnetosphere. So Cassini mission planners were excited to observe the moon exposed and naked in the solar wind during the 2013 flyby. The visit allowed them to see the shock wave produced around Titan as the fast-flowing solar particles slammed directly into the moon’s unprotected atmosphere.
“We observed that Titan interacts with the solar wind very much like Mars, if you moved it to the distance of Saturn,” said Cesar Bertucci of the Institute of Astronomy and Space Physics in Buenos Aires, who led the research with colleagues from the Cassini mission.
Despite the complicated chemistry of thick methane-rich skies, Titan’s atmosphere seems to have responded to the solar wind in essentially the same way as the red planet, which has a much thinner atmosphere than Earth or Saturn's big moon.
“We thought Titan in this state would look different,” Bertucci said. “We certainly were surprised.”
Now researchers believe these new findings suggest that regardless of where unmagnetized planets lie in the solar system, they all interact with the solar wind in the same way.
See for Yourself
Backyard sky-watchers can glimpse both Saturn and Titan through even the smallest telescope. Look for the stately lord of the rings in the southern sky just before dawn.
Saturn is the yellow-tinged bright object standing above the orange-hued star Antares, which is the lead member of the constellation Scorpius, the Scorpion. At the tip of one of the claws of the mythical arachnid is Saturn.
While the ringed planet itself is easily viewed with unaided eyes, to resolve its majestic rings and its retinue of moons, a small telescope is needed.
Shining at ninth magnitude, Titan is the second largest moon in the entire solar system and the only one to possess a thick atmosphere. Not surprisingly, it is the brightest and easiest of the 62 moons, and counting, of Saturn to spot.