Sun leaves Earth wide open to cosmic rays

摘要

The sun provides ideal conditions for life to thrive, right? In fact, it periodically leaves Earth open to assaults from interstellar nasties in a way that most stars do not.rnThe sun protects us from cosmic rays and dust from beyond the solar system by enveloping us in the heliosphere - a bubble of solar wind that extends past Pluto. These cosmic rays would damage the ozone layer, and interstellar dust could dim sunlight and trigger an ice age. However, when the solar system passes through very dense gas and dust clouds, the heliosphere can shrink until its edge is inside Earth's orbit.