Question

Comets revolve around the Sun:
A. in a highly elliptical orbit
B. along a circular orbit
C. in an elliptical orbit
D. varying orbit depending on the comet

Answer 1

- Hint: Bodies in space revolve around a larger body under the force of gravity in an elliptical path (orbit). When the ratio of the major axis to the minor axis of the ellipse is very large, we say that the path of the revolving body is highly elliptical. Comets are situated at a very far distance from the sun.

Complete step-by-step solution -
Let us first understand what a comet is. A comet is made up of ice, gases, dust and chunks of rock mixed together. A comet looks like a dirty snowball.
A comet is initially located at a place far away from the sun or any other star such that the heat does not reach it. That is why it is an icy rock.
Just like a ball thrown upwards from the surface of the earth, is attracted back towards the earth, any body in the space revolves around a larger body under the influence of the gravitational force. These bodies revolve in an elliptical path called the orbit of the body.
In our solar system, the sun is the largest body and all other celestial bodies revolve around it in an elliptical orbit. The sun is situated at one of the foci of the ellipse.
When the ratio of the major axis to the minor axis of the ellipse is very large, we say that the path of the revolving body is highly elliptical. When this ratio is equal to one, the path of the body will be a circle. This ratio depends on where the body was initially. If the body was too far, the ratio is very large.
Similarly, a comet is also attracted by the force of gravity exerted by the sun. However, the comet is situated at a very far distance from the sun that it takes an elliptical path such that the ratio of the major axis to the minor axis is very large. Therefore, the path of the comet is highly elliptical.

Note: When we talk about the distance between the comet and the sun, it is beyond our imagination. It is not the distance that we deal with in our daily lives. The closest distance of the Halley’s comet from the sun is 89 million kilometres. When a body revolves in an elliptical orbit, it does not have a constant speed. Its speed increases when it comes closer to the sun and when it moves away from the sun, it becomes slower.