Page 158 - General Knowledge

GENERAL KNOWLEDGE 2019

WORLD GEOGRAPHY

UNIVERSE

The Universe is all of space and time and their contents, including planets, stars, galaxies, and
all other forms of matterand energy. While the spatial size of the entire Universe is unknown, it
is possible to measure the size of the observable universe, which is currently estimated to be 93
billion light years in diameter. In various multiverse hypotheses, a universe is one of many
causally disconnected constituent parts of a larger multiverse, which itself comprises all of
space and time and its contents.

SOLAR SYSTEM

The System comprises the Sun and its eight planets, which are believed to have been
developed from the condensation of gases and other lesser bodies.

MAJOR COMPONENTS OF THE SOLAR SYSTEM

The Sun and the collection of all of its companions that travel through space together along with
it is known as the Solar System. There are a variety of objects in the Solar System.

 Planets: There are ten planets in the Solar System. Five of them are visible from Earth
without using a telescope. Historically, the Sun, Moon and the five visible planets were
used as the sources for the names for the seven days of the week.

 Satellites: Most of the planets have satellites. The satellite that revolves around the
Earth is called the Moon. Mars has two satellites. Even some asteroids have satellites.

 Asteriods: Asteriods are smaller than planets. They are located mainly in the asteroid
belt which which is found between the orbits of Mars and Jupiter.

 Comets: Comets are objects consisting of frozen molecules of gases and other solid
materials. The period of a comet refers to how long it takes the comet to revolve around
the Sun. Some comets have very, very long periods. Halley's Comet has a period of
about 76 years.

 Meteoroids: A meteoroid is an interplanetary particle in the Solar System. When a
meteoroid enters the Earth's atmosphere it heats up and evaporates producing a streak
of light called a meteor. Sometimes they come in groups called meteor showers. If a
meteor reaches the ground then it is called a meteorite. Some really large meteors have
impacted the Earth. One produced the Meteor Crater in Arizona.

 Dust: The inner Solar System contains a vast cloud of very small dust particles. On a
really clear night it can be seen as a glow in the west just at the end of twilight, provided
there are not too many street lights around.

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