What causes comets to develop tails as they approach the Sun?

What causes comets to develop tails as they approach the Sun?

• A. Comets tails form because the icy components sublimate near the Sun, creating a visible tail.
• B. Tails are formed by cosmic rays.
• C. Tail is formed by gravitational drag.
• D. Tail is produced by the comet's nucleus breaking apart.

Answer: (A)

When a comet gets close to the Sun, heat causes the icy components of its nucleus to sublimate—turn from solid directly into gas. This outgassing creates a cloudy envelope around the nucleus (the coma) and drags dust particles from the surface with it. The solar wind then pushes the ionized gas outward, forming a gas (ion) tail that points directly away from the Sun. At the same time, radiation pressure from sunlight pushes the dust particles, creating a broader dust tail that also trails away from the Sun. So the tails arise from sublimation driven by solar heating plus the forces of the solar wind and radiation, rather than from cosmic rays, gravitational drag, or simple breakup of the nucleus.

When a comet gets close to the Sun, heat causes the icy components of its nucleus to sublimate—turn from solid directly into gas. This outgassing creates a cloudy envelope around the nucleus (the coma) and drags dust particles from the surface with it. The solar wind then pushes the ionized gas outward, forming a gas (ion) tail that points directly away from the Sun. At the same time, radiation pressure from sunlight pushes the dust particles, creating a broader dust tail that also trails away from the Sun. So the tails arise from sublimation driven by solar heating plus the forces of the solar wind and radiation, rather than from cosmic rays, gravitational drag, or simple breakup of the nucleus.