Download Universe, Galaxies, Solar System

Universe, Galaxies, Solar System
Universe
 Many scientists believe the Universe formed about 13.8 billion years
ago. It is thought that the Universe started as a single point of
extremely dense mass about the size of a dime, and when the energy
could not be contained anymore, it expanded into the Universe we
know today.
 The name of the theory that explains how the Universe formed is called
the big bang theory.
 Everything is in the Universe, and there is nothing larger than the
Universe.
 Evidence includes Hubbles Law and Cosmic Background Radiation
Galaxies
• A galaxy is a large group of stars, gas, planets, rock, and dust held
together by gravity.
• There are billions of stars in galaxies, and billions of galaxies in the
universe.
• Just like stars are grouped together in galaxies, galaxies are grouped
together in clusters.
What is a Cluster?
• A cluster is a group of similar items in a given area.
• The cluster our galaxy belongs to is called the Local Group
Types of Galaxies - There are three main types of galaxies:
• Spiral Galaxies
• Elliptical Galaxies
• Irregular galaxies
Spiral Galaxy
• Named for the spiral arms that are prominent (like a pinwheel). The arms
are made of stars and dust.
• Spiral Galaxies have a central bulge, a disk, a halo, and some may
have a “bar” of stars passing through the center. These types of
galaxies are called barred spirals.
• Spiral galaxies are huge, and contain large amounts of gas and dust.
• Spiral galaxies have both young and old stars.
• Spiral galaxies have new stars because the large amounts of gas and dust
provide what is needed to create new stars.
• Our galaxy—the Milky Way—is a barred spiral galaxy
• The Milky Way is 100,000 Light Years across.
• A light year is the distance light travels in a year. Light years are units
to measure things that are very, very far away like stars or galaxies.
o The Milky Way is located in the local group cluster near the
constellations Sagittarius and Scorpius.
Elliptical Galaxy
• Also very large galaxies – some can be the size of several Milky Way
galaxies combined!
• Elliptical galaxies are named for their usual ellipse shape – some can be
round, but most are shaped like a football.
• Elliptical are the most common type of galaxy in our universe
• These galaxies have small amounts of dust and gas.
• Elliptical galaxies are made up of mostly older stars.
Irregular galaxies
• While these are still large, they are usually smaller than the other 2 types
of galaxies.
• Irregular galaxies don’t have a specific shape. This is why they are called
irregular.
• While these are still large, they are usually smaller than the other 2 types
of galaxies.
Our Solar System
•
The solar system formed from part of a contracting nebula of gas,
ice, and dust.
• What is a nebula?
• A nebula is a large cloud of gas and dust that contracts under
gravitational forces and breaks apart into smaller pieces, each of which
will collapse and form a star and planets.
• Our Solar System was thought to have formed 4.6 billion years ago.
• The nebula started to spin and contract; possibly because a nearby star
exploded setting this into action.
• As it contracted, the density grew immensely. It heated to extreme
temperatures and our Sun was born. Soon after, the planets started to
form as well.
• Our Solar System is located approximately 30,000 Light Years from the
center of the Milky Way Galaxy.
• Our Solar System is specifically located on the Orion arm of the Milky
Way
Our solar system is made up of the Sun, planets, and other objects that orbit the
Sun such as comets, meteors, and asteroids.
Our planet Earth is in the Solar System, our Solar System is in the Milky Way
Galaxy, our galaxy is in the Local Group Cluster, and galaxy clusters are in the
Universe.