Astronomy The Universe The universe is defined as

Astronomy

The Universe The universe is defined as everything that physically exists: the entirety of space and time, all forms of matter, energy and momentum.

How our Universe Formed • Theory of how the universe formed called the Big Bang Theory • Big Bang Theory – 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

The universe began billions of years ago as a tiny dot that exploded into today’s huge system of stars and planets.

Support for the Big Bang Theory https: //www. youtube. com/ watch? v=HY 2 R 2 d 6 AVPM • Red shifts • Cosmic background radiation – Radio signals coming from every direction in space. – Believed to be created by the big bang explosion.

1929 – Edwin Hubble found that the universe is expanding

Hubble’s Law: the more distant galaxies have greater red shifts, therefore they are moving away at faster speeds. https: //www. youtube. com/watch? v=y 5 t. KC 3 n. Ex 2 I

Hubble’s Law

Note: Our solar system is part of a bigger system called a galaxy. Our galaxy is part of a bigger system called the universe Milky Way Galaxy…spiral shaped!

The universe is made up of galaxies. Galaxies are held together by gravity. The galaxy that we are in is the Milky Way Galaxy. Types of Galaxies– spiral, barred, elliptical, irregular

Spiral - Milky Way Galaxy The Milky Way galaxy contains more than 100 BILLION stars

Barred – NGC 1300 Galaxy

Elliptical – NGC 1316 Galaxy

Irregular – Large Megallanic Cloud This is the CLOSEST galaxy to us

Solar System Solar systems - consist of at least one star and include all bodies that revolve around it in the stars gravitational pull.

Pluto Uranus Mercury Saturn Jupiter Mars Venus Earth Neptune

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

1. Solar System began as a giant ball of dust and gases (after the Big Bang) 2. Cloud flattened as it spun around, forming an accretion disk. ►Sun formed in the middle from all the heat in the middle of the disk 3. Cooling of the disk caused small shapes to form 4. These cool forms combined to make the 4 SOLID inner planets 5. The lighter material combined farther away, forming the 4 GASEOUS outer planets

End of Day 1

The Earth moves in 3 ways The Earth: 1. Rotates (Rotation) 2. Orbits 3. Revolves (Revolution)

The earth rotates on its axis • Rotates = spins. • The earth makes 1 full rotation every 24 hours.

The axis of the Earth is tilted at an angle of 23. 5 degrees. The axis always points towards the North Star.

We have day and night because of the Earth’s rotation.

The Earth also revolves around the sun in an elliptical orbit. The earth makes one full revolution around the sun every 365. 25 days = 1 year