Chapter 15 – Stars, Galaxies and the Universe

Chapter 15 – Stars, Galaxies and the Universe Section 5 – History of the Universe Standards 2.g – Students know the role of gravity in forming and maintaining the shapes of planets, stars and the solar system 4.a – Students know galaxies are clusters of billions of stars and may have different shapes

Big Bang Theory Big Bang Theory – initial explosion that resulted in the formation and expansion of the universe Theory explained Big Bang Theory states that the universe formed in an explosion about 10 to 15 billion years ago – Universe has been growing ever since the big bang

Moving Galaxies Scientists can tell if galaxies are moving toward or away from earth based on a light spectrum of that galaxy Hubble’s Law – states that the farther away a galaxy is, the faster it is moving away from us

Expanding Universe – Balloon Example Each little piece on the balloon is like a galaxy and as the balloon grows (universe expands) the galaxies move apart

Speeding Galaxies Use the graph to answer the questions about moving clusters of galaxies.

Speeding Galaxies Reading Graphs: How far away is the Bootes cluster? How fast is it moving? About 2.5 billion light-years About 39,000 km/sec

Speeding Galaxies Drawing Conclusions: How are the distance and speed of a galaxy related? The greater the distance from Earth, the greater the speed of the galaxy.

Speeding Galaxies Predicting: Predict the speed of a galaxy that is 5 billion light-years from Earth Its speed would be about 80,000 km/s

Formation of the Solar System About 5 billion years ago, a giant cloud of gas and dust, or nebula, collapsed to form the solar system

Formation of the Solar System The nebula shrank to form a spinning disk and as gravity pulled some of the gas into the center of the disk, the gas became hot and dense enough for nuclear fusion to begin and created the sun

Solar Nebula video Solar Nebula – a large cloud of gas and dust that formed our solar system Gravity pulled the nebula together, it shrank and spun faster Elsewhere in the disk, gas and dust formed solid spheres smaller than the sun and the planets were created

The Future of the Universe New observations lead many astronomers to conclude that the universe will likely expand forever. Expanding Universe – Infinite Universe (The crunch – alternative theory) (The big rip – alternative theory)

Mysterious Stuff Dark Matter (video) – matter that does not give off electromagnetic radiation (possibly 90% of all matter in the universe) Dark Energy (video) – mysterious force that appears to be causing the expansion of the universe to accelerate