Lava Lake Loki on Jupiter's moon Io, up close

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The LBT image of Loki Patera (orange) laid over a Voyager image of the volcanic depression. The emission (in orange color) appears spread out in the north-south direction due to the telescope point-spread function; it is mainly localized to the southern corners of the lake.

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 sulfur and sulfur 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 (about 27 feet) 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 (75-foot) 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. Their study is published in the Astronomical Journal.

"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."

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http://www.sciencedaily.com/releases/2015/05/150501162128.htm