1. The European Renaissance
Modern Astronomers
The European Renaissance
Crater Tycho (lower) Crater Copernicus (upper) Sea of Tranquility (right, bluish)

2. Nicolaus Copernicus 1473-1543 Developed another heliocentric model
Maintained perfect circular motion
Was able to prove the planetary positions.
He pretty much just copied Aristarchus and Ptolemy!!
Identified reason for varying brightness of planets.
Stars did not move in his model.

3. Tycho Brahe
Designed his own instruments – sextants, quadrants, celestial spheres- to use in observatories before the telescope.
Believed the Sun revolved around the Earth, but other planets revolved around the Sun…
Passed his observations to Johannes Kepler in
Sphere of stars moved in his model; stars were stationary

4. Johannes Kepler 1571-1630 Worked with Brahe
Tried to match data w/perfect circular orbits
Was able to match Brahe’s accuracy w/ Kepler’s Laws of Planetary Motion
The orbit of every planet is an ellipse with the Sun at one of the two foci.
A line joining a planet and the Sun sweeps out equal areas during equal intervals of time.
The square of the orbital period is proportional to the cube of the planet's distance from the Sun. (P² α a³)
Kepler's 3rd law - if you know the period of a planet's orbit (P = how long it takes the planet to go around the Sun), then you can determine that planet's distance from the Sun (a = the semimajor axis of the planet's orbit).

5. Galileo Galilei 1564-1642 Developed concept of inertia (Newton)
Developed 1st Theory of Relativity (Einstein)
Best known for designing refracting telescope
Sunspots
Mountains and craters on Moon
Phases of Venus
Rings of Saturn
Jupiter’s moons – Galilean satellites

6. Isaac Newton 1642-1727 Most known for the Laws of Motion
Invented calculus
Discovered the light spectrum of the Sun
Developed a reflecting telescope
Was the first to scientifically explain tides
Tides are periodic rises and falls of large bodies of water. Tides are caused by the gravitational interaction between the Earth and the Moon. The gravitational attraction of the moon causes the oceans to bulge out in the direction of the moon. Another bulge occurs on the opposite side, since the Earth is also being pulled toward the sun (and away from the water on the far side). Since the earth is rotating while this is happening, two tides occur each day.

7. Maria Mitchell
First person to discover a comet through a telescope in 1847
First woman Professor of Astronomy in USA at Vassar College in 1865
Photographed stars
Studied sunspots
Studied surfaces of Jupiter and Saturn
Helped found the American Association for the Advancement of Women.
Miss Mitchell’s Comet

8. Albert Einstein 1879-1955 Known for his Theory of Relativity E=mc²
Developed Einstein-Rosen Bridge aka wormholes (space-time short cut between a black hole and white hole)
Because the speed of light is a very large number (300,000,000 m/s) and is multiplied by itself, this equation points out how a small amount of matter can release a huge amount of energy, as in a nuclear reaction.

9. Henrietta Swan Leavitt 1868-1921
Worked at Harvard College Observatory in for $.30/hour.
First described the relationship between the period and the brightness (luminosity) of cepheid variable stars.
Could determine distances of stars up to 10 million light years!
Hertzsprung could plot the distance of stars
Shapely measured the size of the Milky Way
Hubble could determine the age of the universe.
Polaris is a cepheid variable. She discovered over 1200 in her lifetime in Large Magellanic Cloud.
Size increases, brightness decreases…and reverse.

10. Edwin Hubble 1889-1953 Showed that other galaxies exist
Detected that the universe is expanding
Cepheid variables in nebulae
Hubble’s Constant, H₀, shows the rate at which the universe is expanding
Uses distance of a galaxy and how fast it’s moving away from us
Can estimate size and age of universe.
Diameter of the universe is about 93 billion light years. Red shift shows that celestial bodies are moving away from us, blue shift shows they’re moving toward us.

11. Your name here! What is left to discover?
What problems can be solved by your unique idea or invention?
Maybe you just want to meet an alien…