The icy moon Europa squirts water like a squishy bath toy when it’s kneaded by Jupiter’s gravity — and the Hubble Space Telescope caught it in the act.
The data captured by Hubble depict two huge geysers of water vapor spewing out of the moon, probably from cracks near its south pole. At 124 miles high, the geysers were tall enough to reach from Los Angeles to San Diego.
The discovery, described Thursday in the journal Science, shows that Europa is still geophysically active and could hold an environment friendly to life.
“It’s exciting,” said Lorenz Roth, a planetary scientist at the Southwest Research Institute in San Antonio and one of the lead authors of the study, which was presented at a meeting of the American Geophysical Union in San Francisco.
Europa isn’t the only squirty moon in our solar system: Saturn’s moon Enceladus has been caught spraying water from its south pole out of four parallel fractures, a formation dubbed “tiger stripes.”
These plumes are the result of tidal forces. Just as our moon’s gravity squeezes and stretches the Earth a bit, causing the oceans to rise and fall, Saturn’s massive gravitational pull squeezes and stretches Enceladus. That causes cracks on its icy surface to open and allows water to escape.
Scientists have long wondered whether Jupiter was doing something similar to Europa. After all, that moon’s surface is only about 65 million years old, making it less than 2 percent as old as the solar system.
Scientists figured that some geophysical processes must be going on that are constantly renewing the surface. But over several decades, researchers repeatedly failed to catch the moon in action, said Robert Pappalardo, a planetary scientist at NASA’s Jet Propulsion Laboratory who was not involved in the study.
Even Hubble had trouble seeing such plumes until shuttle astronauts fixed one of its cameras in 2009.
To catch Europa in the act, Roth and his colleagues also knew they had to get the timing just right. Enceladus releases water when it’s just about as far from Saturn as it can get. So they made sure to point Hubble toward Europa when it was most distant from Jupiter, in December 2012.
