Here's why:
* The Sun's Gravity: Comets are primarily composed of ice and dust. They reside in the outer solar system, far beyond the orbit of Neptune, in regions like the Kuiper Belt and the Oort Cloud. The Sun's gravity, though weaker at these distances, still exerts a pull on comets.
* Elliptical Orbits: When a comet gets nudged by a gravitational disturbance (like a passing star or a giant planet), it can be thrown into a highly elliptical orbit around the Sun. This orbit brings the comet closer to the Sun during part of its journey, causing it to become visible from Earth.
* Periodicity: The time it takes for a comet to complete one orbit around the Sun is called its period. The longer the comet's orbit, the longer its period. Comets with shorter periods, like Halley's Comet (approximately 75 years), return to the inner solar system more frequently than comets with longer periods.
Let me know if you'd like to know more about comets or their orbits!
