This passage is mainly about how astronomers discover asteroids.

asteroids striking Earth.

how scientists think dinosaurs died.

1997 XF11.

This passage is mainly about asteroids striking Earth.

Explanation:

The presented passage is mostly focusing on asteroids striking Earth. It is something that has been happening since Earth has formed, and it will happen in the future as well. The vast majority of the asteroids don't really have any impact on Earth, but some have an impact that is devastating and long-lasting.

In the earlier stages of Earth, many more asteroids were falling on the surface, and the main reason for that has been the lack of atmosphere or a very thin atmosphere. As the atmosphere started to take shape and became similar to what is nowadays, the asteroid impacts decreased significantly because the atmosphere was managing to burn them and break them apart. This is not possible with all asteroids though, as some are so big and fall under an angle where the atmosphere doesn't really have any impact on them so when they fall on the surface they are able to cause sudden climatic changes, mass devastation, and mass extinction of species. Such an asteroid will be in a direction to hit Earth in the future for sure, the question remains will humans with their technology be able to prevent an impact or not.