Why do certain comets return at regular intervals?

Answer 1

All comets (there are over 3,500 known) have different time-scales for their appearances.

These depend on the length of their orbits - some comets have extremely large orbits which take them from being 'close' to the earth to almost going out of our solar system.

They appear because they come close enough to the Earth to be seen, and then they may take anything from a few years to hundreds of thousands of years beore they come back.

The best-known comet is Halley's Comet which has a period of between 75 and 76 years between appearances.

Answer 2

Comets that return at regular intervals are known as periodic comets. This occurs because their orbits take them close to the Sun, where they heat up, releasing gas and dust that form the characteristic coma and tail. The gravitational influence of planets and other celestial bodies can then adjust their trajectories and periodicity, leading to their predictable return.

Answer 3

Because comets have very elliptical orbits. They go way out in space and move very slowly the further out they go. When they come whipping around the sun they are going fast but then they are heading nearly straight out in space again. As they go out the sun's gravity keeps slowing them down trying to pull them back till they finally stop (the other end of the ellipse) and they fall back toward the Sun but they are so far out the suns gravity is week and they pick up speed slowly till they get close to the sun again and greatly speed up.

Its when they are near the sun that we can see them because they are close. When they are way out even telescopes can't see them.

Answer 4

I assume you mean comets.

Only a few come every 75 years, some come as often as every few years and some not for centuries.

It all depends on their orbit around the sun; the further out they go, the longer it takes them to return.

Answer 5

Comets reappear because they are in fixed orbits; once the orbital parameters are determined, it's relatively easy to calculate when any particular comet should be visible again.

Some comets are "hyperbolic"; they come into the solar system from outside, make a single pass by the Sun, and exit the system completely. And some comets either collide with a planet (as the Shoemaker-Levy 9 comet did when it broke apart and then crashed into Jupiter) or disintegrate and evaporate completely, leaving nothing but a meteor shower in its wake.

And some comets are in such long-period orbits that no one was around the see them the last time, and will not come again for millennia.

Answer 6

probably because all comets return i have posted a question myself and there is only one comet i dont now if is coming back but comet halley will always return unless we are lucly and it never comes back

Answer 7

They all appear when they get close enough to the Sun for us to see them illuminated by the Sun.

Some comets are periodic (they return on a regular basis) and their period of return is governed by their individual, specific orbit round the Sun. There are "short" and "long" period comets.

There are also single-apparition or non-periodic which come in from the Oort cloud on a random basis.

Answer 8

Comets travel in orbits like the planets around the sun. Comets "return" because they are reappearing at a certain point on their orbits which coincides with the earth's orbit.

Answer 9

How often a comet reappears depends on its orbital period. Comets can be either short-period or long-period, with the orbital periods ranging from a few years to millions of years.

Answer 10

because, just like earth they orbit the sun