Giant telescope spots lava lake on Jupiter's moon

Astronomers have captured the first detailed observations of a lava lake on Io, one of Jupiter's moons, by using the Large Binocular Telescope.

Io, the innermost of the four moons of Jupiter discovered by Galileo Galilei in 1610 and only slightly bigger than our own moon, is the most geologically active body in our solar system.

Hundreds of volcanic areas dot its surface, which is mostly covered with sulphur and sulphur dioxide.

The largest of these volcanic features, named Loki after the Norse god often associated with fire and chaos, is a volcanic depression called patera in which the denser lava crust solidifying on top of a lava lake episodically sinks in the lake, yielding a raise in the thermal emission that has been regularly observed from Earth.

Loki, only 124 miles in diameter and at least 373 million miles from Earth, was, up until recently, too small to be looked at in detail from any ground-based optical/infrared telescope.

With its two mirrors, each 8.4 meters across, set on the same mount 20 feet apart, the Large Binocular Telescope, or LBT, produces images at the same level of detail that a telescope with a single, 22.8-meter mirror would achieve by combining the light through interferometry.

Thanks to the Large Binocular Telescope Interferometer, or LBTI, an international team of researchers was able to look at Loki Patera, revealing details as never before seen from Earth.

"We combine the light from two very large mirrors coherently so that they become a single, extremely large mirror," said Al Conrad, the lead of the study and a scientist at the Large Binocular Telescope Observatory, or LBTO.

"In this way, for the first time we can measure the brightness coming from different regions within the lake," Conrad added.

"While we have seen bright emissions - always one unresolved spot - 'pop up' at different locations in Loki Patera over the years, these exquisite images from the LBTI show for the first time in ground-based images that emissions arise simultaneously from different sites in Loki Patera," said Imke de Pater, a professor at the University of California, Berkeley.
"This strongly suggests that the horseshoe-shaped feature is most likely an active overturning lava lake, as hypothesised in the past," said de Pater.
The study was published in the Astronomical Journal.