Paul Sutter writes:

In our neighborhood of the Milky Way, we see a region surrounding the solar system that is far less dense than average. But that space, that cavity, is a very irregular, elongated shape. What little material is left inside of this cavity is insanely hot, as it has a temperature of around a million Kelvin.

What’s going on?

We call this region surrounding the solar system the Local Bubble, which is a bit unimaginative, but it gets the job done. This bubble is carved out of the interstellar medium and is about 1,000 light years wide and has a density about one tenth the average density of the Milky Way.

At the edge of the Bubble is a shell of gas with slightly higher density than the surroundings. And in that shell there are a bunch of young hot star-forming regions. Based on the sun’s current position, our velocity, the size of the Bubble, and our location in the Bubble, we know that we were not born here. We entered one end of the Local Bubble somewhere between five and ten million years ago, and we will continue traveling through the Bubble for tens of millions of years to come.

What could have the energy to create this enormous cavity, this giant bubble? [Continue reading…]