Atom & Cosmos

When Jupiter aligns with Mars’ moon, plus a salty Saturnian moon and an eye-catching comet in this week’s news

Salty geysers on Enceladus
A spectacular plume spewing from Saturn’s moon Enceladus turns out to be full of salt. Chemistry instruments aboard the Cassini spacecraft analyzed the plume and found it to contain as much as 99 percent salt-rich ice particles. The finding suggests that the plume comes from a reservoir of salty liquid water, a team led by Frank Postberg of the University of Heidelberg in Germany reports online June 22 in Nature. —Alexandra Witze

Jupiter gets behind Phobos
A spacecraft orbiting Mars recently observed an unusual alignment of Jupiter and the Martian moon Phobos. By determining the exact moment when Jupiter passed behind the moon, as seen by the European Space Agency’s Mars Express probe, planetary scientists should be able to improve the precision with which they know Phobos’ orbital position. Mars Express observed the alignment on June 1, recording 104 images over 68 seconds. The European Space Agency released images and videos of the event on June 17. —Ron Cowen 

New comet could be a beauty
A newly discovered comet could be a naked-eye spectacle from Earth early in 2013, astronomers announced June 16. First spotted by the Pan-STARRS 1 telescope in Hawaii on the night of June 5–6, the body was confirmed to be a comet by University of Hawaii astronomers the next night. Preliminary calculations show that in February or March of 2013 the comet will come about as close to the sun as Mercury does. At that time the icy body, dubbed C/2011 L4 (PANSTARRS), is expected to be visible without a telescope, low in the western sky after sunset. Scientists caution, however, that predicting a comet’s brightness when it nears the sun is notoriously difficult. —Ron Cowen

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