*Question*:How do we work out the trajectory of an NEO?

By making observations of the object at several points in time, we can calculate its speed and trajectory.

The trajectory of an NEO will change over time because of the gravitational attraction of the planets and other objects in the Solar system.

So to get a precise trajectory we need to observe how the object changes position over time in order to calculate its mass.

Once the current position, direction of travel, speed and mass of an object are known, scientists can accurately determine its future trajectory.