Our solar system lies right at the center of a relatively empty region in space.
This cavity has an extremely low particle density, at least ten times lower than the average density of the interstellar medium in our galaxy.
But at the same time, it contains a thin gruel of high-temperature X-ray-emitting plasma that can rage up to a million degrees.
This cavity is known as the local bubble and is home to our Sun and thousands of other neighboring stars.
But how did we discover this bubble?
How did it form in the first place?
And most importantly, when did the Sun enter it?
First of all, the shape of the local bubble isn't spherical, so referring to it as a bubble is a bit inaccurate.
Instead, it appears to have an hourglass shape that is narrowest in the galactic plane and widens above and below the plane.
Furthermore, the bubble seems open-ended and bursts into the galactic halo in the direction away from the galactic plane.
