Topic Indicators

Página 1

Stars, Solar Systems, Nebulae and Galaxies

1. Describe

the major components of the universe including: stars, solar systems, nebulae,

star clusters, galaxies and galaxy clusters.

Stars

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luminous

ball of gas (made mostly of hydrogen and helium)

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held

together by its own gravity

Nuclear fusion

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reactions

in the core supports the star against gravity and produce photons and heat +

some other heavier elements

-

fusion

happens when lighter elements are forced to become heavier elements.

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tremendous

amounts of energy are created, causing the star to heat up and shine.

Solar System

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Solar

system is our galaxy

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Made

up of moons, comets, asteroids, minor planets and dust and gas.

-

Everything

in the solar system orbits around the sun. The larger an object, the more

gravity it has

-

While

the sun has the strongest gravitational pull, other objects have their own

gravitational pull as well e.g

Sun and

earth. The sun has the stronger gravitational pull because it has a larger

mass, but the earth still had its own mass. While the sun is attracting the

earth, the earth is trying to pull away. That is why the earth is not sucked

into the sun, but it is also not flying away. Therefore, it is stuck in a

constant orbit.

Nebulae

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Nebula

is a cloud of dust, hydrogen, helium and other ionized gases

-

Some

examples are of Nebulae are galaxies and star clusters (globular clusters and open

clusters)

Star Clusters

A group of stars that share a common

origin and are gravitationally bound for some length of time. Open clusters

have stars that are younger than globular clusters.

Galaxies

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huge

collections of stars, dust and gas

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usually

contain several million to over a trillion stars and can range in size from a

few thousand to several hundred thousand light-years across.

-

galaxies,

like stars, are found alone, in pairs, or in larger groups called clusters.

Galaxy Clusters

Página 2

Hierarchy of the Universe