1. February 25, 2016 WHAT TO DO… The timer is set for 10 minutes: NO T-CAP TODAY… instead SILENT worktime 1.Take out your solar system drawing and make sure you have included the following: Planets and the sun colored Used appropriate distances and sizes Included the AU of each planet Included one fact about each planet and the sun 2.If you finish the drawing, turn it in. 3.Take out your notes from the past week and make flashcards to study with.

2. TN Standard: Analyze information about the major components of the Universe.

3. CHAPTER 9.5 SMALL BODIES IN THE SOLAR SYSTEM Comets, Asteroids, Meteors…Oh my!

4. THINK ABOUT IT… You are traveling in a spacecraft to explore the edge of our solar system. You see several small bodies, as well as the planets and their satellites, moving through space….. What are those small bodies? ( pics are the hints)

5. COMETS, ASTEROIDS, AND METEOROIDS ! COMET - a small body of ice, rock and cosmic dust loosely packed together. Nicknamed “ dirty snowballs ” because of their composition Nothing much has happened to comets since the birth of the solar system 4.6 billion years ago Since each comet is a sample of the early solar system, scientists want to learn more about them to help piece together the history of our solar system. They are…

6. COMET TAILS When a comet passes close enough to the sun, solar radiation heats the ice so that the comet gives off gas and dust in the form of a long tail. Sometimes comets have two tails - 1. Ion – made up of electrically charged particles called ions 2. Dust – guess what it is made up of? The nucleus is the solid center of a comet – ranges in size from less than ½ kilometer to more than 100 kilometers in diameter.

8. COMET ORBITS The orbits of all bodies that move around the sun are ellipses. Ellipses are circles that are somewhat stretched out of shape, elongated. Orbits of planets are close to perfect circles. A comet’s ION tail always points away from the sun. Why? …Because it is blown away from the sun by solar wind, which is also made of ions. The DUST tail tends to follow the comet’s orbit around the sun but does NOT always point away from the sun. When a comet is close to the sun, the tail can extend millions of kilometers through space.

9. COMET ORIGINS – WHERE DO THEY COME FROM? Scientists think they come from the Oort (AWRT) cloud, a spherical region that surrounds the solar system. (Named after the astronomer, Jan Oort, who proposed the idea that billions of comets surround the solar system) When the gravity of a passing planet or star disturbs part of this cloud, comets can be pulled toward the sun. They can also exist in the Kuiper Belt (KIE-per), which is the region outside the orbit of Neptune.

10. Oort Cloud Kuiper Belt

11. FAMOUS COMETS 1. Halley’s Comet – Last seen from Earth in 1986. Named after English astronomer, Edmund Halley. He realized that the comet sightings had taken place every 76 years. 2. Hale-Bopp – On July 23, 1995, two amateur astronomers saw a new comet heading toward the sun. It was larger than most and was the brightest comet to be visible from Earth in 20 years. It was it the brightest in the spring of 1997. Question – Given that Halley’s orbits every 76 years, when will it next be seen by Earth? How old will you be then?

12. ASTEROIDS ASTEROIDS are small, rocky bodies that revolve around the sun. Size – few meters to 900 kilometers Shape – irregular, but larger ones are spherical Origin – thought to be left-over material from the formation of the universe Orbit – most orbit the sun in the Asteroid Belt Asteroid Belt – wide region between the orbits of Mars and Jupiter.

14. METEOROIDS METEOROID - a relatively small, rocky body that revolves around the sun. Most meteoroids are probably pieces from asteroids.

15. METEORS – A. K. A. SHOOTING STARS METEOR - a bright streak of light caused by a meteoroid or comet dust burning up in the Earth’s atmosphere. Many meteors are dust-pebble sized rocks. You can see meteors on most nights IF you are away from the city lights. METEOR SHOWERS – large numbers of meteors seen at certain times of the year. They happen when Earth passes through the dusty debris that comets leave behind.

16. METEORITES METEORITE - a meteoroid that enters Earth’s atmosphere and strikes the ground. It falls so fast that its surface melts. As it burns up, it gives off enormous amount of light & thermal energy

17. TYPES OF METEORITES 3 Major Types OF Meteorites: 1. Stony – rocky material 2. Metallic – iron and nickel 3. Stony-iron – rocky material, iron, & nickel Origins - probably from carbon-rich asteroids. Scientists use them to study the early solar system.

18. THE ROLE OF IMPACTS IN THE SOLAR SYSTEM An impact happens when an object in space collides with another direct object. These collisions result in impact craters, visible on many moons and planets. Planets and moons that do not have atmospheres have a lot more impact craters than planets and moons with atmospheres. WHY does our moon have so many more visible craters than seen on the surface of Earth?

19. THE EARTH AND CRATERS Earth’s moon has many more impact craters than Earth because the moon has no atmosphere to slow objects down. Fewer objects strike Earth because our atmosphere acts as a shield. Smaller objects burn up before reaching Earth’s surface. Most craters left on Earth are no longer visible because of: 1. weathering 2. erosion 3. tectonic activity

20. FUTURE IMPACTS ON EARTH Scientists estimate that impacts that are powerful enough to cause a natural disaster happen once every few thousand years. An impact large enough to cause a global catastrophe is estimated to happen once every few hundred thousand years on average. Can you give an example of a catastrophic change on the Earth?...hint

21. THE TORINO SCALE THE TORINO SCALE is a system that allows scientists to rate the hazard level of an object moving toward Earth. Scientists observe the object, rate danger 0-10, color coded: 0 / white, 1 / green = rarely strikes Earth 2, 3, 4 / yellow = higher chance objects will hit Earth 5, 6, 7 / orange = objects highly likely to hit Earth 8, 9, 10 / red = objects will definitely hit Earth, ….level 10 will cause a global disaster

22. PUTTING IT TOGETHER Illustrate and color the SMALL BODIES and their characteristics including the following information: COMET – with both types of tails illustrated and labeled ASTEROID - shown as part of the Asteroid Belt between Mars & Jupiter METEOROID – shown as a smaller piece of an asteroid METEOR – shown as entering the Earth’s atmosphere METEORITE – shown as striking Earth’s surface