Answer:
1. About a trillion comets are thought to be located far, far beyond Pluto in the Oort cloud.
2. The bright spherical part of a comet observed when it is close to the Sun is the coma .
3. A comet's plasma tail stretches directly away from the Sun.
4. A comet's nucleus is the frozen portion of a comet.
5. Particles ejected from a comet can cause a(n) meteor shower on Earth.
6. The Kuiper belt extends from about beyond the orbit of Neptune to about twice the distance of Neptune from the Sun.
Explanation:
1. Oort cloud is a theoretical cloud of icy objects in interstellar space. Its inner limit begins about 2000-5000 AU from sun outer limit (about 100000-200000 AU) defines the boundary of solar system.
Note: AU is the astronomical unit which is defined as the distance between the Sun and Earth.
2. Comets are described as “dirty snowballs” which is a mixture of frozen gases and dust. When this snowball gets closer to the Sun, gas evaporates, and a fuzzy haze of gas and dust emerges. This fuzzy tail is the coma.
3. Dust and gas in the coma interact with the sunlight and the solar wind. Charged particles in the coma are caught up in the magnetic field of sun and flow away from the sun.
4. Nucleus is the dirty snowball which consists of rock, dust and frozen gas.
5. Meteor shower is a celestial event with number of meteors can be observed. Meteors are meteoroids that enters earth’s atmosphere with extremely high speeds.
6. Kuiper belt is a region beyond Neptune including dwarf planets and icy objects.
