Question

When does a comet have its longest tail and largest coma?

(a) When it is moving most slowly.
(b) When it makes its closest approach to the Earth.
(c) When it crosses the ecliptic plane.
(d) When it is at its farthest point from the Sun in its elliptical orbit.
(e) When it is at its nearest point to the Sun in its elliptical orbit.

Answer 1

A comet's tail and coma are most extensive and pronounced at its nearest point to the Sun, or perihelion, due to faster travel and increased solar radiation.

Step-by-step explanation:

A comet has its longest tail and largest coma when it is at its nearest point to the Sun in its elliptical orbit, which is known as the perihelion. Comets have highly eccentric orbits, meaning they are greatly elongated with one of the foci being the Sun. According to Kepler's second law, comets travel much faster when they are near the Sun compared to their speed when they are far away from it. As comets approach the perihelion, they accelerate due to the Sun's gravitational pull, causing the release of more gas and dust, which is then pushed away by the solar wind and pressure of sunlight, creating an extensive and more pronounced tail and coma.