Final answer:
None of the near-Earth objects like Aten asteroids, short period comets, long period comets, Apollo asteroids, or Amor asteroids have been identified as on a collision course with Earth. Continuous monitoring and planetary defense research are essential for early detection of potential impactors to protect our planet.
Step-by-step explanation:
The question pertains to which type of Near-Earth Objects (NEOs)—specifically, asteroids and comets—pose no threat of collision with Earth. Currently, none of the objects in the categories mentioned (Aten asteroids, short period comets, long period comets, Apollo asteroids, Amor asteroids) have been found to be on a collision course with Earth.
Scientists continuously track these celestial bodies to ensure any potential impactor is discovered well in advance, allowing for possible defense measures.
It is important to note that planetary defense is a vital area of scientific research. Comets, particularly long period comets, have highly eccentric orbits, spend most of their time far from the Sun, and originate from distant regions like the Oort Cloud or the Kuiper Belt, which makes their trajectories somewhat more unpredictable compared to asteroids.
Asteroids, namely Aten, Apollo, and Amor asteroids, have orbits that can potentially cross Earth's path, but as of now, no known asteroids from these groups are predicted to collide with Earth. The efforts in tracking asteroids and implementing planetary defense strategies are crucial to mitigate the risk of future impacts.