Understanding Celestial Bodies and Their Orbits

The question asks to identify the term used for celestial bodies that travel around the sun in orbits that are significantly stretched out, or highly elliptical.

Let's look at the characteristics of the given options:

• Comet: Comets are icy, rocky, and dusty bodies that orbit the sun. They are famous for their highly elliptical orbits, which often take them far out into the solar system (beyond Neptune, in regions like the Oort Cloud or Kuiper Belt) and then swing them back closer to the sun. As a comet approaches the sun, the ice vaporizes, creating a visible coma and often a tail.
• Meteor: A meteor is not a celestial body orbiting the sun. It is the streak of light we see when a piece of space debris (a meteoroid) enters the Earth's atmosphere and burns up due to friction. Meteoroids themselves orbit the sun, but the term "meteor" refers specifically to the atmospheric phenomenon.
• Asteroid: Asteroids are rocky or metallic bodies that orbit the sun. Most are found in the asteroid belt between Mars and Jupiter. While asteroid orbits can vary in shape, they are generally less elliptical than the orbits of comets.
• Planet: Planets are large celestial bodies that orbit the sun in relatively stable, nearly circular paths. Their orbits are generally close to being in the same plane (the ecliptic). Their orbits are much less elliptical than those of comets.

Analyzing the Characteristic: Highly Elliptical Orbit

The key phrase in the question is "highly elliptical orbit". Comparing the descriptions above:

• Planets have nearly circular orbits.
• Most asteroids have less elliptical orbits than comets.
• Meteors are atmospheric events, not bodies orbiting the sun in a specific path (though the parent meteoroid does orbit).
• Comets are well known for their extremely elongated, highly elliptical orbits.

Therefore, the term specifically used for celestial bodies that revolve around the sun in highly elliptical orbits is Comet.

Conclusion

Based on the orbital characteristics of different celestial bodies in our solar system, comets are the objects that are primarily defined by their highly elliptical orbits around the sun.

The term used for celestial bodies that revolve around the sun in highly elliptical orbit is Comet.