MCQ Detailed View

Comets are small celestial bodies that orbit the Sun and are made primarily of ice, dust, and frozen gases. Because of their unique composition, comets are often described as “dirty snowballs.” This nickname was first used by astronomers to explain their structure: a mixture of frozen water and gases, combined with rocky and dusty material, forming a compact nucleus.

When a comet is far from the Sun, it appears as a small, icy body. However, as it approaches the Sun, heat causes the ice to vaporize, releasing gas and dust into space. This process forms a glowing coma (a cloud around the nucleus) and sometimes a spectacular tail that always points away from the Sun due to the pressure of solar wind and radiation.

Comets are considered to be some of the oldest and most primitive objects in the solar system. They are leftovers from the early days of planetary formation over 4.6 billion years ago. Most comets originate in distant regions such as the Kuiper Belt or the Oort Cloud, and their long elliptical orbits occasionally bring them close to the Sun and planets.

The nickname “dirty snowball” accurately reflects the fact that comets are not just pure ice balls. They contain significant amounts of dust, rock fragments, and organic compounds mixed with frozen water, carbon dioxide, methane, and ammonia. This combination gives them a dark, non-reflective surface despite being icy bodies.

Comets are important to study because they may have delivered water and organic molecules to early Earth, potentially playing a role in the development of life. Their composition provides scientists with valuable clues about the conditions in the early solar system.

The correct answer is Dirty snowballs, as this is the widely accepted term used by astronomers to describe the true makeup of comets.