Thursday, April 27, 2017
The bubble-like shape of the heliosphere observed by Voyager and Cassini - UNIVERSE
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.
A paper on these results was published in Nature Astronomy on April 24, 2017.
Read the paper:https://www.nature.com/articles/s41550-017-0115
Source & further reading:https://www.nasa.gov/feature/goddard/2017/nasa-s-cassini-voyager-missions-suggest-new-picture-of-sun-s-interaction-with-galaxy
The image on the left shows a compact model of the heliosphere, supported by this latest data, while the image on the right shows an alternate model with an extended tail. The main difference is the new model’s lack of a trailing, comet-like tail on one side of the heliosphere. This tail is shown in the old model in light blue.
Credits: Dialynas, et al. (left); NASA (right)