If a comet's ion tail is pointing perpendicular to its direction of travel, the comet is
A) moving closer to the Sun.
B) close to or at perihelion.
C) close to or at aphelion.
D) moving away from the Sun.
E) A comet's tail never points perpendicular to its motion.

Question

Quizplus · Accepted Answer

A comet's ion tail always points directly away from the Sun due to the solar wind. When it is perpendicular to the comet's direction of travel, this indicates the comet is moving in a direction that is tangential to its orbit around the Sun, which typically happens close to or at perihelion (the point in its orbit closest to the Sun).

If a Comet's Ion Tail Is Pointing Perpendicular to Its