1. Galaxies and Stars
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

2. Galaxies Galaxies are made up of gas, dust, and billions of stars
Galaxies have different shapes
Elliptical
Spherical or flattened disks
Spiral
A nucleus of bright stars and 2 or more spiral arms
Irregular
No definite shape
Shapes of Galaxies can change over time as a result of collisions with other galaxies and evolution of galaxies themselves

3. The Sun and the Milky Way
The Sun is a star in the Milky Way galaxy
Milky Way is a spiral galaxy
The Sun is located approximately 2/3 of the way from the center of the Milky Way

4. Galileo Galilei Born on February 15, 1564 in Pisa, Italy
“Father of Modern Science”
Modernized physics and astronomy
Discovered all objects fall at the same rate
Created a hydrostatic balance for measuring tiny objects
Supported the Heliocentric Theory
Developed a telescope of his own, used it to observe the moon’s surface features, Venus revolved around the Sun, and Jupiter’s moons revolved around Jupiter not the Earth providing evidence against the Geocentric Theory

5. Tycho Brahe Born December 14, 1546 Danish astronomer and alchemist
Precise and comprehensive astronomical and planetary observations which influenced future discoveries (Planetary Laws of Motion)
Did not use a telescope for his astronomical observations
Discovered the variation of the Moon’s longitude for the lunar theory

6. Johannes Kepler Born December, 27, 1571
From the Holy Roman Empire (modern day Germany)
1596, a math teacher
Worked with Tycho Brahe and seceded him upon Brahe’s death
Founded the 3 Laws of Planetary Motion
Using Brahe’s data, Kepler discovered that the orbit of Mars was an ellipse
Defended the Heliocentric Theory

7. 3 Laws of Planetary Motion
The Orbits of the Planets are Ellipses, with the Sun at one focus of the ellipse
The line joining the planet to the Sun sweeps out equal areas in equal times as the planet travels around the ellipse
The Ratio of the squares of the revolutionary periods for 2 planets is equal to the ratio of the cubes of their semimajor axes

8. Light Light travels 9.46 x 1012 Km (5.88 x 1012 miles) in a year
Light from the Sun travels 8 minutes before reaching us
Light from the Andromeda galaxy (closest galaxy to the Milky Way) was emitted 2.5 million years ago (before the first humans)
The further away a light is, the older the light is when we see it.

9. Parallax Method astronomers use to determine how far away stars are
Stars seem to shift in position when viewed from Earth because of Earth’s revolution around the Sun
Parallax shift
Astronomers use the diameter of Earth’s orbit to determine the parallax angle across the sky

10. Expanding Universe
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

11. The Universe The Universe is composed of matter and energy
All of the matter in the universe now was in the universe when it formed

12. Evidence Evidence to Support Scientist Claims
Looking for the oldest star
Nebula (gas and dust) exist in space and are remnants from the formation of the universe
Stars undergo a life cycle, amount of hydrogen gas in the star changes therefore affecting the brightness and color of the star

13. 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 which shifts the light toward the red end of the spectrum (red-shift). More distances or faint a galaxy, the more rapidly it is moving away from Earth