The “Big Bang” was an enormous release of energy! “Big Bang” Theory the jolt of space, time, matter and energy that most astronomers think gave rise to the universe as we see it today. occurred about 13.7 billion years ago thought to have expanded from something the size of a spec of dust to the size of our solar system The “Big Bang” was an enormous release of energy!

BIG BANG THEORY - The Expanding Universe Big Bang According to the Big Bang Theory, the universe formed in an enormous explosion about 10 to 15 billion years ago. Evidence Moving galaxies: All galaxies are moving away from us and from one other. Theory Big Bang Cosmic background radiation: This glow comes from thermal energy left over from the big bang.

Retreating Galaxies - The Expanding Universe All distant galaxies are moving rapidly away from our galaxy and from each other.

Edwin Hubble In 1924 Edwin Hubble discovered that other galaxies exist, besides the Milky Way He observed that galaxies were moving away from each other Hubble Law – the farther away a galaxy is, the faster it is moving away from us; supports the Big Bang Theory Image taken from: http://apod.nasa.gov/apod/ap960217.html

Galaxy a large assemblage of millions to billions stars (and often gas and dust) Star - a large hot ball of gas which generates energy in its core by nuclear reactions held together by the gravity of all its member stars formed around 200 million years after the “Big Bang”

3 Types of Galaxies Elliptical shaped like eggs; have almost no dust or gas between stars; contain old stars Irregular faint galaxies without a definite shape; smaller than the other types of galaxies; contain fewer stars Spiral have arms of stars, gas , and dust that curve away from the center of the galaxy in a spiral pattern Ex. – Milky Way Images taken from: http://school.discoveryeducation.com/schooladventures/universe/galaxytour/toknow.html

Solar System the sun and all things orbiting around it, including the eight major planets, their satellites, and all the smaller pieces such as asteroids and comets formed around 4.6 billion years ago Image taken from: http://asm.arc.nasa.gov/Gallery/images/generic/LG_Capableofeverything.jpg

Planet derived from a Greek word that means “wanderer” a major object which orbits around a star in our solar system, there are eight such objects which are traditionally called “planets”

Meteoroid, Meteor, Meteorite Meteoroid – solid debris from space (asteroids) that are moving towards Earth Meteor A particle entering Earth’s atmosphere at a high speed often referred to as “shooting stars” or “falling stars” Meteorite – an object from outer space that passes through Earth’s atmosphere and reaches the surface Meteoroid (asteroid) Meteor Meteorite

Comet a small body of ice and dust (“dirty snowball”) that orbits the Sun contains a head (coma) followed by a tail(s) of gas and dust the tail always points away from the sun and can be millions of kilometers long. Image taken from: http://www.space.com/bestimg/index.php?guid=45b0fd31f065d&cat=bestcomet

Astronomical Unit (AU) unit of distance between the Earth and the Sun equal to about 150 million kilometers (93 million miles) light takes about eight minutes to cover this distance The Earth animation is not rotating in the correct direction; it should be rotating from west to east 150 million km (93 million mi.)

Light Year the distance that light travels in one year. (about 6 trillion miles) The Milky Way Galaxy is about 100,000 light years in diameter the speed at which light travels this distance is about 300,000 km/sec (186,000 mi/sec) The second closest star to the Earth is a little over four light years away. How far away (in miles) is the star?