Final answer:
Astronomers are primarily interested in Earth-approaching asteroids for their proximity, allowing for easier study, and the vital aspect of planetary defense to track and potentially deflect hazardous asteroids.
Step-by-step explanation:
Today's astronomers are highly interested in the discovery of additional Earth-approaching asteroids (NEAs) for several key reasons.
First, since they come close to Earth, these NEAs are more accessible for study, which provides valuable information about their composition, structure, and origin. This knowledge is essential for future space missions or resource utilization.
Secondly, there is a practical and immediate need to track these objects to protect the planet. The possible impact of a sizable asteroid could have catastrophic effects on Earth, including climate disturbances and global crop failures.
Thus, programs like the NASA Spaceguard Survey have been set up to identify and track the majority of these potentially hazardous objects, with a success in identifying thousands of NEAs to date, increasing our capacity to potentially deflect a threatening asteroid.