As a comet leaves the inner Solar System, the ion tail points a. back along the orbit. b. forward along the orbit. c. toward the Sun. d. away from the Sun.

Solar wind is a stream of charged particles released from the upper atmosphere of the Sun, known as the corona. These particles include electrons and protons, which travel through space and impact various celestial objects.
When solar wind interacts with a comet, it has significant effects, particularly on the comet's ion tail. The charged particles in the solar wind collide with the ionized gas in the comet's tail, causing it to point directly away from the Sun. This happens regardless of the comet's movement or position in its orbit.
Understanding solar wind helps us grasp why a comet's ion tail behaves as it does. By pushing the ionized particles in the tail away, the solar wind ensures that the tail always points in the opposite direction from the Sun.

A comet typically has two distinct tails: a dust tail and an ion tail. Each tail is formed by different materials and processes.
The dust tail is made of small, solid particles that are released from the comet's nucleus as it warms up near the Sun. These particles reflect sunlight, and the tail follows the comet's orbit closely but with a slight curve.
The ion tail, on the other hand, is composed of ionized gas. This gas is formed when ultraviolet light from the Sun ionizes the gas molecules in the comet's coma. Because the ion tail is made of charged particles, it is influenced directly by the solar wind. As a result, it straightens out and points directly away from the Sun, creating a unique, often bluish, light due to the emission of specific wavelengths from the ionized gases.

Ionized gas in the context of a comet is a gas that has been electrically charged by losing or gaining electrons. This happens primarily due to the influence of ultraviolet sunlight. The gases in the comet's coma get ionized, turning into ions.
When these ionized gas molecules come into contact with the solar wind, they experience a force pushing them away from the Sun. This interaction explains why the comet's ion tail always points away from the Sun.
Ionized gases are crucial for understanding many astronomical phenomena, not just comets. They help explain various space weather effects and interactions between solar radiation and celestial bodies.
By observing and studying ionized gases, scientists gain insight into the physical conditions and processes that occur in space.