Astronomy. How our Universe Formed Big Bang Theory – that states how the universe formed from a massive expansion approximately 14 bya Big Bang Theory.

Astronomy

How our Universe Formed

•Big Bang Theory – that states how the universe formed from a massive expansion approximately 14 bya

The Universe is expanding and the visible edge is about 13.7 billion light years away

Note: Our solar system is part of a bigger system called a galaxy and our galaxy (Milky Way) is part of a bigger system called the universe

Milky Way Galaxy…spiral shaped!

So, how did our Solar System form?

•The Nebular Theory – explains that solar system was formed from a rotating disk of dust and gas

•Formed ~4.6 bya

Kepler’s Laws

•Earth orbits the Sun following Kepler’s 3 laws of planetary motion

1. The path of each planet around the Sun is an ellipse

2. Equal areas are covered in equal times

3. The length of time it takes a planet to orbit the Sun is proportional to its distance from the Sun

Kepler (1571-1630) came up

with these scientific laws and they are still used in Astronomy

today!

1st Law: Law of Ellipses

The path of the planets around the sun are elliptical in shape with the center of the sun being located at one focus

The shape of the ellipse is determined by the location of the two focus points!

2nd Law: Law of Equal Areas

This law states that an imaginary line from the sun to a planet sweeps out equal areas in equal time intervals

3rd Law: The Law of Periods

The Sun•Our Sun and all other stars produce their energy by a process called nuclear fusion

•Fusion is when hydrogen atoms collide to make a Helium atom; this releases lots of energy

Sun consumes 600 million tons

of H each second!

What is the Difference between Fusion and Fission?

•Fission is the opposite idea…instead of building bigger atoms, you are breaking atoms apart

Nuclear Power Plants like McGuire Nuclear Station in Huntersville do this with Uranium

Energy Produced by

the Sun

•Most of what astronomers know about our universe is from studying the light emitted from distant sources

Electromagnetic Spectrum• Visible light is just a small portion of the

energy emitted by stars…what else is there?

• Gamma rays are produced by violent nuclear explosions in space and are absorbed by our atmosphere…good thing, they are deadly to human cells!

• X- rays are also absorbed by Earth’s atmosphere, so NASA has to put x-ray telescopes into space

• UV rays are mostly blocked by the ozone layer, but some can get through and cause sunburns!

• Infrared rays cause the heat we feel from sunlight• Microwaves easily move through atmosphere and are used in with

satellites and GPS• Radio waves are used with huge telescopes to learn about the

structure, composition, and motion of objects in space

Let’s Draw the Electromagnetic Spectrum