Bell Work: What is the center of the Universe? Unit 8 Earth in Space Bell Work: What is the center of the Universe?

The Origins of the Universe: David Christian – “The History of our world in 18’”

Timeline of the Universe Phase 1: Began ~14 billion years ago Lasted > 300 million years Major events: Big Bang and Universe expands Elements, stars & galaxies form

Began ~5 billion years ago Ended ~1000 years ago Major events: Phase 2: Began ~5 billion years ago Ended ~1000 years ago Major events: Our solar system forms inside Milky Way Galaxy Plants, animals, humans appear Origins of our solar system

Phase 3: Began ~1000 AD Continues today Major events: Discovery of gravity, relativity, telescopes, and the expanding universe

Phase 4: Scientists have projected ~100 trillion years into the future Possible Events: If universe keeps expanding it will eventually whither away and eventually only black holes will remain

Earth’s Relationship with other systems in space Our Solar System Earth Is part of Is part of The Milky Way Galaxy The Universe Is part of

How big is the Universe?

The Planets in our Solar System:

Many solar systems in our galaxy

There are ~100 billion galaxies in the Universe

Bell Work How much time elapsed between the “Big Bang”, when the Universe formed, and the formation of our solar system? What events occurred during this time?

Earth’s Motion in Space Nicholas Copernicus (1543): Heliocentric model of the solar system (sun at the center) Earth and other objects revolved around Sun in a circle Earth rotated on its axis Earth was tilted on its axis

Kepler’s 1st Law Johannes Kepler (1610): Three laws of planetary revolution Kepler’s 1st Law The orbit of a planet about a star is an ellipse with the star at one focus.

Kepler’s 2nd Law A line joining a planet and the Sun sweeps out equal areas in equal time.

Kepler’s 3rd Law The square of the orbital period of a planet is proportional to the cube of the semi-major axis of its orbit: P2 proportional to R3

Revolution Movement of one object around another object Earth’s revolution around the sun: ~365 days

Rotation (R) Earth’s movement on its axis 24 hrs per rotation

Precession (P) Conical sweep of Earth’s rotation on its axis Caused by Gravitational pull of sun & moons Cycles every 26,000 years

Nutation (N) A wobble in Earth’s rotation Caused by gravity from Sun & Moon Cycles every 41,000 years

Barycenter The center of mass between 2 bodies orbiting in space. The center depends on the mass of the 2 objects.

Oblate Spheroid A sphere that is squashed at its poles and swollen at the equator. Earth has an oblate spheroid shape.