Starship Asterisk*

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New data from NASA’s Cassini mission, combined with measurements from the two Voyager spacecraft and NASA’s Interstellar Boundary Explorer, or IBEX, suggests that our sun and planets are surrounded by a giant, rounded system of magnetic field from the sun — calling into question the alternate view of the solar magnetic fields trailing behind the sun in the shape of a long comet tail.

The sun releases a constant outflow of magnetic solar material — called the solar wind — that fills the inner solar system, reaching far past the orbit of Neptune. This solar wind creates a bubble, some 23 billion miles across, called the heliosphere. Our entire solar system, including the heliosphere, moves through interstellar space. The prevalent picture of the heliosphere was one of comet-shaped structure, with a rounded head and an extended tail. But new data covering an entire 11-year solar activity cycle show that may not be the case: the heliosphere may be rounded on both ends, making its shape almost spherical. ...

• Nature Astronomy 1:0115 (online 24 Apr 2017) DOI: 10.1038/s41550-017-0115