Observing the Solar System Chapter 14.1 [p. 538]

1. Observing the Solar SystemChapter 14.1 [p. 538]

2. Early Ideas of the Solar System • The Greeks thought that they were inside a rotating dome they called the celestial sphere. • The Greeks also thought that the universe was perfect and unchangeable. • Earth is stationary; the Greeks thought we are in a geocentric system: • The Earth is at the center of the revolving planets.

3. Early Ideas Cont. • In 140 A.D. Ptolemy • theorized that the planets moved on little circles that move on bigger circles, this explained why the planets moved at different speeds. • Ptolemy’s geocentricmodel of the planets was widely held for nearly 1,500 years after his death

4. Early Ideas Cont. 1500’s: Nicolaus Copernicus • 1543, Copernicus came up with a theory that would revolutionize the science of astronomy … “The Copernican Revolution” • In a heliocentric system the sun is at the center and the planets revolve around the sun.

5. Early Ideas Cont. • 1600s: Galileo • Galileo was the1st scientist to use a telescope to look at objects in the sky. • Galileo made 2 discoveries that supported the heliocentric theory: • Venus goes through phases similar to Earth’s moon. These phases could not be explained if Earth was the center of the system. • Jupiter’s moons revolved around Jupiter. Therefore not everything in the sky revolved around Earth.

6. Early Ideas Cont. • Late 1500s - 1600s • Tycho Brahe • Observed the positions of the planets for 20 yrs. • Johannes Kepler • Kepler analyzed Brahe’s data to determine the shape of the orbits. • He discovered the orbits are elliptical in shape.

7. Kepler’s Three Laws • First Law: Planets move in ellipses, not circles

8. Kepler’s Three Laws • Second Law: A planet moves faster when closer to the sun, slower when away

9. Kepler’s Three Laws • Third Law: Planets closer to the sun move faster than planet’s farther from the sun

10. Early Ideas Cont. • 1665:Newton: • Newton stated that two factors keep the planets in orbit: • Inertia and gravity • Gravity: attracts all objects toward each other • The strength of gravity depends on the mass of the objects and the distance between them. • Inertia: The tendency of a moving object to continue in a straight line or a stationary object to remain in place • The more mass and object has, the more inertia it has.

11. Components of our Solar System • Planets • Stars • Comets • Asteroids • Satellites • Space Trash • Dark Matter • Particles (Dust) • Electromagnetic radiation (Photons)

12. Planets • There are 8 planets: • Mercury • Venus • Earth • Mars • Jupiter • Saturn • Uranus (YOOR uh nus) • Neptune • Pluto Terrestrial Planets Gas Giants

13. Astronomical Unit • 1 AU (astronomical unit) = the Earth’s average distance from the sun (about 150 million kilometers or about 93 million miles)

14. How We Look Into Space! • We can see far into space with the help of telescopes, satellites and spectroscopes. • There are many types of telescopes, most of which collect and focus electromagnetic radiation, including visible light.

15. Telescopes • Visible Light Telescopes: • Reflecting Telescope: • 1668 Isaac Newton built this type of telescope. • Used a mirror instead of an objective lens. • Focuses a large amount of light onto a small area. • Refracting Telescope: • 1609 Galileo used this type of telescope to look into space. • Uses a convex lens to gather large amount of light and focus in onto a small area.

16. Telescopes Cont. • Radio Telescopes: • Used to detect radio waves from objects in space. • Have curved surfaces, up to 305m in diameter • Surfaces concentrate faint radio waves from space onto small antennas like those on radios. • The larger the telescope is, the more radio waves it can collect.

17. Telescopes • Infrared Telescopes: • Detect longer wavelengths than visible light • A building that contains 1 or more telescopes is called an observatory.

18. Telescopes • 1897: Yerkes Telescope • 1m in diameter • Largest refracting telescope ever built • The lens is so large, it can collect more light than any other refracting telescope • 1931: Karl Jansky • Accidentally discovered radio astronomy • Tried to figure out what static was interfering with radio communications. The static was coming from objects in space!

19. Telescopes • 1963: Arecibo radio telescope • Built in a natural bowl in the ground • It is 305m in diameter • Located in Puerto Rico • 1980: The Very Large Array • 27 radio telescopes in New Mexico • They can be moved close together or far apart • They are linked together, so they can be used individually or as one giant telescope 25km in diameter.

20. Telescopes • 1996: Keck Telescopes • 2 of the largest reflecting telescopes • Located in Hawaii • Each telescope is made of 36 smaller mirrors joined together to make one 10m curved mirror.

21. Satellites • Most UV radiation, X-rays, & gamma rays are blocked by the Earth’s atmosphere. • In order to detect these wavelengths, astronomers have placed telescopes on satellites and launched them into space.

22. Satellites • 1990: Hubble Space Telescope • HAPPY BIRTHDAY HUBBLE!!!!!!! • Launched April 24, 1990 • Can see objects in space more clearly than any other telescope. Large Ant Nebula

23. Homework • Read Section One of Chapter 14 • Do the questions at the end of the section, page 544 1a,b,c,d; 2a,b,c; 3a,b,c