Solar system's heliosphere may be croissant-shaped - study

These findings could have major implications on the search for habitable planets outside the solar system.

Bright nebula gas cloud in deep outer space (photo credit: INGIMAGE)
Bright nebula gas cloud in deep outer space
(photo credit: INGIMAGE)
Scientists predicted the new shape of our solar system  – and it's in the shape of a delicious breakfast treat.
The solar system in which Earth is located has the general shape of a deflated croissant, according to a study led by Merav Opher, an Israeli-born astronomy professor at Boston University. The study was published in Nature Astronomy in March and featured on the journal’s cover for July, providing an alternative to previously predicted models.
Every plant in the solar system is encased in a magnetic bubble, carved out in space by a solar wind constantly flowing out from the Sun. Outside the bubble is an ionized gas magnetic field that fills the space between stellar systems in our galaxy, according to NASA. This field both serves as a shield protecting our solar system, in addition to helping scientists make projections for finding other potential habitable planets.
Until now, scientists have predicted the shape of this bubble, called a heliosphere, as a comet shape, with a rounded leading edge called the nose and a long tail trailing behind. The new prediction lacks this tail, leading scientists to predict that the shape is similar to a certain French pastry.
This new predictive model has significant implications for astronomers, particularly regarding the search for habitable planets in space. This is due to the role the heliosphere plays, with it being an essential component in protecting planets – and, by extension, life – from damaging cosmic rays.
The shape of the solar system's heliosphere is what makes this protection so effective, and could potentially be one of the deciding factors on whether life can thrive. As such, finding similarly shaped heliospheres could be the key to finding new habitable worlds.
It is still unclear how the solar system's heliosphere is shaped, but an upcoming NASA mission could help find answers to these mysteries.
Slated for 2024, the Intersteller Mapping and Acceleration Probe, or IMAP, will map particles streaming from the heliosphere boundaries back to Earth, which will shed new light on the heliosphere's nature, interstellar space and how cosmic rays make their way into the solar system.
For this project, Opher's DRIVE Science Center, which was instrumental in making this new prediction, seeks to create a testable heliosphere model in time for the launch, which could provide a baseline to compare with IMAP's data.
Opher's predictive model was made using data from previous NASA missions. In particular, her work focused heavily on the solar wind particles streaming out from the Sun, which are much hotter than other solar wind particles.
“There are two fluids mixed together. You have one component that is very cold and one component that is much hotter: the pick-up ions,” Opher explained.
“If you have some cold fluid and hot fluid, and you put them in space, they won’t mix – they will evolve mostly separately. What we did was separate these two components of the solar wind and model the resulting 3D shape of the heliosphere.”
She added that, “because the pick-up ions dominate the thermodynamics, everything is very spherical. But because they leave the system very quickly beyond the termination shock, the whole heliosphere deflates,” resulting in the croissant-shape.