Ans: Comets originate in outer solar system and are formed of cosmic snowballs of frozen gases, rock and dust that orbit the sun. When a comet’s orbit bring it close to the sun ,it heat up and spewn dust and gases into a giant glowing head larger than most planets.
Q. Dark matter
Ans: Roughly 80% of the mass of the universe is made up of material that scientist cannot directly observe. This is called dark matter. Dark matter is completely invisible to light and other forms of electromagnetic radiation, making dark matter impossible to detect.
Q. Dark energy
Ans: Dark energy is a hypothetical term used for a kind of energy that exerts a negative, repulsive pressure, behaving like the opposite of gravity. Like dark matter dark energy is not directly observed, but rather inferred from observations of gravitational interactions between astronomical objects.
Q. Fundamental particle
Ans: All fundamental particle can be divided into one of two categories, fermions and bosons. Particles that make up matter called fermions eg electrons, protons, leptons, quarks. Particles that carry force are called Boson. Eg Photons, 4He atoms, gluons, W bosonetc.
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