Name: ______Date: ______Period: _____
Astronomy Unit: Key Topics
______: most widely accepted theory for the origin of our universe.
• States that ______years ago, the universe was only a few millimeters across.
• According to this theory, the contents of the universe expanded explosively into existence about ______.
• After the big bang, the universe ______, and continues to ______, and cooled enough for atoms to form.
• ______pulled the atoms together into ______that eventually became ______, which comprise young ______.
Evidence of the Big Bang:
- ______
• This is called ______, named after Edwin Hubble who discovered this phenomenon in ______. This supports the expansion of the universe and suggests that it was once compacted.
- ______
• In ______, Radioastronomers Arno Penzias and Robert Wilson discovered ______, which supports the Big Bang.
- The abundance of ______found in the universe is thought to support the Big Bang.
______provides the basis for many new discoveries related to space and the universe.
• Visual, radio, and x-ray ______collect info from across the entire electromagnetic spectrum.
• ______are used to manage data and complicated computations.
• ______send back data and materials from remote parts of the solar system.
• ______provide subatomic particle energies that simulate conditions in the stars and in the early history of the universe before stars formed.
A ______is a group of ______of individual stars, star systems, star clusters, dust and gas bound together by ______. There are billions of galaxies in the universe, and they are classified by ______and ______. They vary in size from a few thousand to a hundred thousand ______across.
3 Types of Galaxies:
- ______: round or oval in shape; some of the largest galaxies are elliptical galaxies. They are thought to be the most common type of galaxy in the nearby universe.
- ______: disc shaped galaxy that has a bulge in the middle; have spiral arms; makes up more than 50% of galaxies
- ______: cannot be classified as elliptical or spiral; makes up about 3% of galaxies.
Our solar system is part of the ______, which is a ______galaxy.
• It has more than ______and a diameter of more than ______light years.
• At the ______is a bulge of stars from which are spiral arms of ______.
______states that galaxies which are farther away have a greater ______, so the ______at which a galaxy is moving away is proportional to its ______from the Earth.
• The ______is a phenomenon due to ______shifting, so the shift of light from a galaxy to the ______end of the spectrum indicates that the galaxy is moving farther away.
• This is evidence for the Big Bang Theory because it tells us that the universe is still ______.
Stars
• Early in the formation of the universe, stars coalesced out of clouds of ______and clumped together by ______attraction into galaxies.
• When heated to a sufficiently high temperature by gravitational attraction, stars begin ______, which converts ______and fuse lighter elements into heavier ones.
• All of the elements, except for ______and ______, originated from the nuclear fusion reactions of stars.
• Stars are classified by:
• ______: from hottest to coldest:
• O (blue), B (blue), A (blue), F (blue to white), G (white to yellow), K (orange to red), M (red)
• ______
• ______: amount of energy released from the star; measured in Watts
• ______
• A star’s mass determines the star’s place on the ______and how long it will stay there.
• Patterns of stellar evolution are based on the ______of the star.
• Stars begin to ______as the core energy dissipates.
• ______outside the core cause ______of the star, eventually leading to the collapse of the star.
• A ______diagram is used to estimate the ______of stars and predict how stars will ______.
• Most stars fall on the ______of the H-R diagram, a diagonal band running from the bright hot stars on the upper ______to the dim cool stars on the lower ______.