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A Milestone in Predicting Solar Flares

By Dave Reneke

A milestone in predicting solar flares, and the discovery of a global ocean on Saturn’s moon Enceladus.

Solar flares are massive explosions in the Sun’s atmosphere. A single “monster” solar flare could cause up to $2 trillion worth of damage on Earth, including the loss of satellites and electricity grids. It also poses potential dangers to human life and health.

However, a new technique published in Nature Physics (tinyurl.com/oykoy8b) will allow changes in the Sun’s magnetic fields, which drive the initiation of solar flares, to be monitored up to ten times faster than previous methods, allowing for greater advanced warning of potentially devastating space storms.

The research team members, who span universities in Europe, the Asia-Pacific and the USA, harnessed data from both NASA’s premier space-based telescope, the Solar Dynamics Observatory, and the ROSA (Rapid Oscillations in the Solar Atmosphere) multi-camera system at the National Solar Observatory in New Mexico.

“Our new techniques demonstrate a novel way of probing the Sun’s outermost magnetic fields, providing scientists worldwide with a new approach to examine, and ultimately understand, the precursors responsible for destructive space weather,” said Dr David Jess of Queen’s University Belfast.

Prof Damian Christian of California State University added that understanding the behaviour of our Sun’s magnetic fields provides us with crucial information surrounding the immense energy it possesses.

The new technique will help facilitate future research, including the continual measurement of magnetic fields in the outer regions of the Sun’s atmosphere, which is one of the key goals of the new $300 million Daniel K. Inouye Solar Telescope. This will be the largest solar telescope in the world when construction is finished in 2019 on the Pacific island of Maui.

Saturn’s Moon Enceladus Hosts a Global Ocean

Every square inch of Saturn’s small moon Enceladus overlies a potentially habitable ocean. Observations of Enceladus’ slight wobble as it orbits Saturn can only be explained if the outer crust floats freely from the inner core, according to scientists studying images taken by NASA’s Cassini spacecraft. This means there is a globe-spanning ocean beneath Enceladus’ icy surface.

Enceladus has been a prime location for studying the potential for life in the solar system since 2006, when Cassini found a fine spray of water vapour, icy particles and simple organic molecules erupting from fractures near Enceladus’ south pole.

Measurements of the saltiness of geyser particles in 2009 proved that they must emanate from a liquid reservoir, and a 2014 analysis of Enceladus’ gravitational pull on the Cassini spacecraft demonstrated that the liquid reservoir is at least a regional sea underlying the entire south pole region.

The new results, derived using an independent line of evidence based on Cassini’s images, prove that the regional sea is a widening of a global ocean.

“The global nature of the ocean likely tells us that it has been there for a long time, and is being maintained by robust global effects,” said Matthew Tiscareno, a Cassini participating scientist at the SETI Institute.

Enceladus has a tiny wobble as it orbits Saturn. The icy moon is not perfectly spherical, and because it goes slightly faster and slower during different parts of its orbit, Saturn pulls and pushes the small moon back and forth as it rotates.

Tiscareno developed a series of dynamic models of this wobble, and another group then tested each model against hundreds of Cassini images of Enceladus’ surface at different times and from different angles.

“If the surface and core were rigidly connected, the core would provide so much dead weight that the wobble would be far smaller than we observe it to be,” said Tiscareno. “This proves that there must be a global layer of liquid separating the surface from the core,” he said.

The geysers deliver samples from this ocean to the surface regularly, which makes Enceladus a prime candidate in the search for life beyond Earth. Enceladus joins only Jupiter’s moon Europa in having an extraterrestrial ocean that is known to communicate with its surface.

David Reneke is an astronomy lecturer and teacher, a feature writer for major Australian newspapers and magazines, and a science correspondent for ABC and commercial radio. Subscribe to David’s free Astro-Space newsletter at www.davidreneke.com