NASA’s Juno spacecraft not too long ago noticed a glassy-smooth lava lake amid the volcanic hellscape of Jupiter’s moon Io.
When Juno’s orbit swooped previous Io final December, its cameras captured a mirrorlike reflection from a small patch of the moon’s floor. The unusually shiny landmark seems to be a lava lake, lined with a skinny crust of {smooth}, gleaming volcanic rock. The rock was in all probability one thing like obsidian, a pure glass that varieties from cooling magma right here on Earth. Generally known as Loki Patera, the lava lake stretches 127 miles lengthy and is dotted with rocky islands, and its edges glow with warmth from the molten magma simply beneath the floor.
Loki Patera isn’t the primary lava lake scientists have noticed on Io; earlier spacecraft, together with Galileo (RIP) have additionally despatched house pictures of comparable options, however Juno’s pics are the clearest and most detailed. Primarily based on Juno’s knowledge, NASA created this animation of what a flight over Loki Patera would possibly seem like.
That is an artist’s illustration, based mostly on the pictures from Juno; Juno captured loads of element, however not fairly this a lot.
On Io, lava lakes like Loki Patera in all probability type when the bottom over a magma reservoir sinks or collapses. Earth has related options referred to as calderas, which type when a volcano erupts and its high collapses inward as a result of there’s much less magma beneath to assist it. Io’s paterae (the plural of patera) are just like calderas on Earth and Mars, however they’re additionally completely different in ways in which recommend they could type a bit of in another way. A 2001 examine, which used knowledge from Galileo, recommended that tectonic actions could pull items of Io’s crust aside, leaving gaps that collapse and type paterae.
As soon as a patera like Loki varieties, lava often floods its flooring – and infrequently spreads nicely past the sides of the patera. The lava pours in from underground magma chambers just like the one planetary scientists say in all probability lies beneath Loki Patera. Galileo captured a picture of a patera on Io, with magma gushing in from fissures on the base of its rocky partitions, again in 2000.
NASA’s Galileo spacecraft captured this picture of lava seeping right into a patera on Io; it’s the one outlined in pink on the far left of the picture.
Radebaugh et al. 2024
The floor of Loki Patera is uncovered to the toxic environment of Io, so it slowly cools into a tough, skinny crust of volcanic glass, which displays daylight so brightly in Juno’s pictures. Islands of rock — rock with a better melting level than the magma beneath the patera — dot the center of the lava lake. Glowing sizzling magma traces their shores and the lake’s edges, peeking by cracks that type on the edges of the glassy crust.
Image a frozen lake right here on Earth: {smooth} ice on the floor and liquid water beneath. Now think about that it’s all lava as an alternative of water, and that’s Loki Patera.
However in contrast to ice, rock will get heavier, not lighter, when it cools and solidifies. Finally, the crust will probably be too heavy to drift on high of the liquid, molten rock beneath, and it’ll sink into the magma. This occurs each Earth yr or two, leaving the effervescent molten floor of the lava lake uncovered, which spacecraft like Juno can see as a result of the molten rock radiates about ten instances extra warmth than the cooled, glassy crust.
