It is estimated to be at least 1000 light years in size,[clarification needed] and is defined by its neutral-hydrogen density of about 0.05 atoms/cm3, or approximately one tenth of the average for the ISM in the Milky Way (0.5 atoms/cm3), and one sixth that of the Local Interstellar Cloud (0.3 atoms/cm3).

[dubious – discuss][4] The exceptionally sparse gas of the Local Bubble is the result of supernovae that exploded within the past ten to twenty million years.

[8] The Solar System has been traveling through the region currently occupied by the Local Bubble for the last five to ten million years.

[9] Its current location lies in the Local Interstellar Cloud (LIC), a minor region of denser material within the Bubble.

The Loop I Bubble was cleared, heated and maintained by supernovae and stellar winds in the Scorpius–Centaurus association, some 500 light years from the Sun.

[13] In 2020, the shape of the dusty envelope surrounding the Local Bubble was retrieved and modeled from 3D maps of the dust density obtained from stellar extinction data.

[14] In January 2022, a paper in the journal Nature found that observations and modelling had determined that the action of the expanding surface of the bubble had collected gas and debris and was responsible for the formation of all young, nearby stars.

[18] The isotope most commonly associated with supernovae on Earth is Iron-60 from deep sea sediments,[19] Antarctic snow,[20] and lunar soil.