The Solar System Exists Inside a Giant, Mysterious Void, And We Finally Know Why

The Solar System floats in the middle of a peculiarly empty region of space.

This region of low-density, high-temperature plasma, about 1,000 light-years across, is surrounded by a shell of cooler, denser neutral gas and dust. It's called the Local Bubble, and precisely how and why it came to exist, with the Solar System floating in the middle, has been a challenge to explain.

A team of astronomers led by the Harvard & Smithsonian Center for Astrophysics (CfA) has now mapped the Local Bubble with the highest precision yet – and found that the Local Bubble was likely carved out of the interstellar medium by a series of supernova explosions millions of years ago.

This is consistent with previous studies, with an additional sting in the tail: the still-expanding Local Bubble is responsible for regions of heightened star formation at its perimeter.

"This is really an origin story; for the first time we can explain how all nearby star formation began," says astronomer Catherine Zucker of the Space Telescope Science Institute, who conducted the research while at the CfA.

The Local Bubble was only discovered relatively recently, in the 1970s and 1980s, through a combination of optical, radio, and X-ray astronomy. Gradually, these surveys and observations revealed a huge region about 10 times less dense than the average interstellar medium in the Milky Way galaxy.

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