science: galaxies and beyond

GALAXIES AND BEYOND

WHAT ARE GALAXIES?

GalaxiesAre group of star clusters

held together by gravity.Could contain more than 200

billion stars.

MAIN GROUPS OF GALAXIES

1.Spiral Galaxy

Looks like a whirlpool

MAIN GROUPS OF GALAXIES2. Elliptical Galaxy

Shape is similar to a football

Has no spiral arms and little or no dust.

MAIN GROUPS OF GALAXIES3. Irregular Galaxy

Has no recognizable shape

May have been caused by collisions with other galaxies

STARBURST GALAXY

A galaxy that nearly collides with another can undergo a period of intense star formation.

MILKY WAY GALAXY

Our home galaxy

Is a spiral galaxy

To find the center of the galaxy:

1. Look in the center of the constellation Sagittarius, the archer.

What was the Big Bang?

SPECTRUM

• When light passes through water droplets, it separates into a band of colors.• This is because white light is a

combination of all the colors of the rainbow.

• Astronomers think the galaxies must have been closer to each other in the past.• At the beginning moment, the universe

was extremely tiny, hot, and dense.

• From this tiny beginning, the universe expand rapidly.

This expansion called the big bang, sent matter out in all directions.

BIG BANG THEORY• The universe is expanding, and its

temperature are decreasing.• Gravity has caused matter to collect

into clumps, forming stars and galaxies.

BIG BANG THEORY• Background radiation is radiation that

is left over from the beginning moments of the universe.

HOW DID OUR

SOLAR SYSTEM

FORM?

FORMATION OF THE SOLAR SYSTEM• Scientists believe that billions of years

after the big bang, dust and gas in a part of the Milky Way gathered into a nebula massive enough to rotate.

HOW ARE SOLAR SYSTEM FORMED

1. A rotating cloud of gas and dust begin to contract.

2.Protoplanets form, and they orbit a protostar, the Sun.

3.The solar system as it is today emerged.

EARTH• Scientists think that Earth is about 4.6

billion years old. Astronomers think that Earth and its atmosphere developed in a series of stages.

ANY

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