Answer:
The sidebar tells us what Earth scientists are actually doing about the risk of an asteroid impact.
Explanation:
The main part of the page discusses how frequently the moon is hit by rocks; how most rocks are too small to make it past Earth's atmosphere; how the rocks that do make it all the way to Earth's surface are usually pretty small and don't hit anything important; how screwed we would be if a massive rock – like an asteroid – made it to Earth's surface.
The sidebar says that scientists are understandably worried enough about these asteroids – they "feel the danger is to great to ignore" – so they're keeping a lookout for asteroids that might be on a collision course with Earth.
