What type of celestial object becomes visible with a tail when it approaches the Sun?

A comet becomes visible with a tail when it approaches the Sun due to the interaction of its icy core with solar radiation and the solar wind. As the comet nears the Sun, the heat causes the ices within it to vaporize, releasing gas and dust particles. This process forms a glowing coma around the nucleus and often creates a tail that extends away from the Sun, which can be several million kilometers long. The gravitational and solar forces influence the tail, directing it away from the Sun regardless of the comet’s direction of travel.

In contrast, an asteroid, which is primarily rocky or metallic, generally does not exhibit a tail, as it lacks the volatile materials that would sublimate and form such a feature. Meteoroids, which are smaller rocky or metallic fragments, typically become meteors when they enter Earth's atmosphere, producing a brief flash of light due to friction, but they do not develop tails. Planets, being much larger celestial bodies, remain stable in their orbits and do not exhibit features like tails as comets do.