SSC
"Cosmic snowballs" of frozen gases, rock and dust that orbit the Sun and develop glowing tails near it are called:
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Answer: Option A — Comets
Detailed Solution
Comets are icy bodies, often described as "dirty snowballs" or "cosmic snowballs", made of frozen gases (such as water, carbon dioxide, ammonia and methane), rock and dust. They orbit the Sun, usually in long, elongated orbits.
Structure of a comet:
- Nucleus: the solid, icy core, usually a few kilometres across.
- Coma: a fuzzy cloud of gas and dust that forms around the nucleus when the comet comes close to the Sun and its ice begins to turn into gas.
- Tails: comets usually develop two tails, a dust tail and an ion (gas) tail.
Why comet tails point away from the Sun:
- The tails are pushed by the pressure of sunlight and by the solar wind, a stream of charged particles from the Sun.
- So, a comet's tail always points away from the Sun, whether the comet is moving towards or away from it.
- The tail can stretch for millions of kilometres.
Where comets come from:
- Short-period comets, which take less than 200 years to orbit the Sun, come mainly from a belt of icy objects beyond the outer planets.
- Long-period comets come from the Oort Cloud, a vast, spherical shell of icy bodies thought to surround the solar system at a great distance, up to about 1 light-year from the Sun.
Famous comets:
- Comet Hale-Bopp, which was visible to the naked eye for about 18 months in 1996 and 1997.
- Comet Shoemaker-Levy 9, which broke apart and crashed into Jupiter in 1994.
- Comet Tsuchinshan-ATLAS, which was visible in 2024.
Missions to comets:
- The European Space Agency's Rosetta mission orbited Comet 67P/Churyumov-Gerasimenko, and its lander Philae became the first to land on a comet nucleus in 2014.
- NASA's Deep Impact mission struck Comet Tempel 1 in 2005.
Why not the other options?
- ✗Asteroids are rocky or metallic bodies that generally do not develop tails.
- ✗Meteorites are pieces of rock from space that survive their fall and reach the Earth's surface.
- ✗Satellites are bodies that orbit planets.
Quick tip
Remember: Comet = icy "dirty snowball" with a nucleus, coma and tails; tails always point away from the Sun.
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Universe & Solar System — Preparation
This question tests your understanding of Universe & Solar System, a key topic in the General Knowledge section. The detailed solution above uses a step-by-step approach to show the reasoning, and where available, a shortcut that helps you solve similar questions in under 90 seconds during the actual exam.
This topic covers the universe, galaxies and stars, the solar system and its planets, dwarf planets, moons, asteroids, comets and meteors, and the Earth's motions, including rotation, revolution, seasons, latitudes, longitudes and time zones. Common questions ask about the largest and smallest planets (Jupiter and Mercury), the hottest planet (Venus), the 'Red Planet' (Mars), and planets with the most moons. Other frequent questions cover solstices and equinoxes, the International Date Line, and Indian Standard Time, which is based on the 82.5 degree E meridian. Practise the universe and solar system questions below, written in the style of the general awareness sections of exams such as SSC, banking, railways, CUET GAT, MAH CET and CLAT. Each question comes with a detailed explanation that adds related facts, so every question helps you revise more than one point.