1. Shapes, composition and motion of stars and galaxies
8.E.4A.1 Obtain and communicate information to model the position of the Sun in the universe, the shapes and composition of galaxies, and the measurement unit needed to identify star and galaxy locations.
8.E.4A.2 Construct and analyze scientific arguments to support claims that the universe began with a period of extreme and rapid expansion using evidence from the composition of stars and gases and the motion of galaxies in the universe.

2. The universe is composed of matter and energy
The universe is composed of matter and energy. All of the matter in the universe now, was in the universe when it formed. Scientists are able to estimate the age of the universe in 2 ways.

3. Scientists are able to estimate the age of the universe
#1 - By looking for the oldest stars.
Nebula (gas and dust) exist in space and are remnants from the formation of the universe.
Stars undergo a life cycle based on the composition of the gases within them. As stars age the amount of hydrogen in the star changes, which changes the color and brightness of the star.
Scientists are able to estimate the age of the universe

4. Eagle Nebula

5. Scientists are able to estimate the age of the universe
#2 - By measuring the rate of expansion of the universe.
Astronomers determined the galaxy is expanding based on the color of light emitted from galaxies and stars.
As the universe expands and galaxies move apart the wavelength of light emitted from those galaxies is stretched. This shifts the light toward the red end of the spectrum and is called “red-shift”. The more distant or faint a galaxy is, the more rapidly it is moving away from Earth.
As the galaxy moves away “red-shift” occurs. If it is moving toward Earth the shift is toward the blue end of the spectrum.
Scientists are able to estimate the age of the universe

6. Our place in space
The Sun is a star in the Milky Way galaxy located in a spiral arm about two- thirds of the way from the center of the galaxy.

7. Galaxies are made up of gas, dust and billions of stars and have different shapes
Elliptical – spherical or flattened disks.
Spiral – a nucleus of bright stars and two or more spiral arms
Irregular – no definite shape
Galaxy types

8. Distances in space are so great that conventional numbers are too large to work with.
Andromeda the closest galaxy to us is 14,920,000,000,000,000,000 miles away. (quintillion)
Astronomers use a unit called a light year.
A light year is equal to the distance that light is able to travel in one year.
(299,792,458 m/s x 60 x 60 x 24 x 365) = 9,454,254,955,000,000 m/year or 9,454,254,955,000 km/year
Distance

9. A light year is too large for use within our solar system so astronomers use a unit called an astronomical unit.
Astronomical Unit (AU) is based on the average distance between the earth and the Sun (93,000,000 miles)
The distance between Earth and Jupiter is AU rather than saying 365,000,000 miles.