- Slides: 30
Comets, Asteroids, Meteoroids and Meteorites Chapter 21 Section 5 Pages 668 -673
Comets A comet is a small body of ice, rock and cosmic dust loosely packed together. Scientists refer to them as dirty snowballs.
Comet’s Orbit Comets orbit the Sun in highly elliptical orbits. Their velocity increases greatly when they are near the Sun and slows down at the far reaches of the orbit. Since the comet is light only when it is near the Sun (and is it vaporizing), comets are dark (virtually invisible) throughout most of their orbit. The solar wind pushes the tail away from the Sun.
Parts of a Comet When they are near the Sun and active, comets have several distinct parts: Nucleus: relatively solid and stable, center of the comet mostly ice and gas with a small amount of dust and other solids; Coma: dense cloud of water, carbon dioxide and other neutral gases, surrounds the nucleus. Hydrogen cloud: Dust tail: up to 10 million km long composed of smoke-sized dust particles driven off the nucleus by escaping gases; this is the most prominent part of a comet to the unaided eye; Ion tail:
Comets Facts A comets ion tail always points away from the sun. Solar winds blow the ion tail away from the sun. Scientists believe that comets come from the Oort Cloud, a region that surrounds the solar system. Comets can also come from the Kuiper Belt which exists outside of Neptune’s orbit.
Halley’s Comet Halley's returns to the inner Solar System have been observed and recorded by astronomers since at least 240 BCE. Clear records of the comet's appearances were made by Chinese, Babylonian, and medieval European chroniclers, but were not recognized as reappearances of the same object at the time. The comet's periodicity was first determined in 1705 by English astronomer Edmond Halley, after whom it is now named. Halley's Comet last appeared in the inner Solar System in 1986 and will next appear in mid-2061. 
The comet's tail gets bigger as it gets closer to the sun and then decreases as it moves away from the sun.
Stardust In the early 1990 s, NASA established a program called Discovery to competitively select proposals for low-cost solar system exploration missions with highly focused science goals. Stardust, the fourth Discovery mission, sent a spacecraft to fly through the cloud of dust that surrounds the nucleus of a comet. For the first time ever, the mission brought cometary material back to Earth. Stardust was the first U. S. mission dedicated solely to a comet and was the first to return extraterrestrial material from outside the orbit of the moon. Stardust's main objective was to capture a sample from a well-preserved comet called Wild-2 (pronounced "Vilt-2"). Launched February 7, 1999, from Cape Canaveral, Florida, on a Delta II rocket, Stardust collected interstellar dust as it flew through the solar system in spring 2000. On January 15, 2001, the spacecraft executed a flyby of Earth. In summer and fall 2002, the spacecraft again collected interstellar dust.
Shoemaker-Levy Comet In 1994, over twenty fragments of comet Shoemaker-Levy 9 collided with the planet Jupiter. The comet, discovered the previous year by astronomers Carolyn and Eugene Shoemaker and David Levy, was observed by astronomers at hundreds of observatories around the world as it crashed into Jupiter's southern hemisphere.
Video Link to NEO’s (Near Earth Objects) http: //neo. jpl. nasa. gov/neo/ VIDEOS- COMETS http: //videos. howstuffworks. com/science/cometvideos-playlist. htm#video-28784 Dates to come: http: //cosmiclog. nbcnews. com/_news/2012/12/2 8/16217532 -the-comet-of-the-century-and-othernight-sky-highlights-for-2013? lite
Asteroids are small rocky bodies that revolve around the sun. They range in size from a few meters to more than 900 kilometers in diameter. Asteroids have irregular shapes, but some are spherical, or round. Most asteroids orbit the sun in asteroid belt. The asteroid belt orbits between Mars and Jupiter. Asteroids are thought to be left over from the formation of the solar system.
Ceres: was an asteroid, now a dwarf planet Observations of 1 Ceres, the largest known asteroid, have revealed that the object may be a "mini planet, " and may contain large amounts of pure water and ice beneath its surface
Meteoroids, Meteors and Meteorites Meteoroids are small rocky bodies that travel through space. A meteor is a bright streak that results from a meteoroid burning up in Earth’s atmosphere, what we call shooting stars. A meteorite is a meteoroid that reaches the Earth’s surface without burning up.
Three Types of Meteorites Stony- Rocky material Metallic- Iron and Nickel Stony Metallic- Rocky material, iron and nickel
Stony Meteorites Rocky material
Metallic Meteorite iron and nickel
Stony-Iron Meteorite rocky material, iron and nickel
Russian Meteorite https: //www. youtube. com/watch? feature=player_detailpage &v=dpm. Xy. Jrs 7 i. U Feb. 15, 2013: A meteorite contrail is seen over Chelyabinsk. A meteor streaked across the sky of Russia’s Ural Mountains on Friday morning, causing sharp explosions and reportedly injuring around 1, 000 people, including many hurt by broken glass.
Meteorite Crater-Winslow, Arizona This crater was formed approximately 50, 000 years ago when an iron mass, estimated to be about 80 feet in diameter and weighing over 60, 000 tons entered the Earth's atmosphere over the American Southwest. The resulting formation is about 4, 000 feet (1, 200 meters) wide and 570 feet (175 meters) deep.
A fragment of the meteorite that created Meteorite Crater. Metallic Meteorite
Meteors hitting the moon https: //www. youtube. com/watch? v=L 8 d. XIx Zz. BMk Comet ISON meteor shower https: //www. youtube. com/watch? v=llpx 30 Yzdy. Q
Questions for page 36 1. 2. 3. What is a meteoroid that enters Earth’s atmosphere? What is another name for a “dirty snowball”? What is the gas cloud that the surrounds the nucleus of a comet? 4. What are the largest rocks in space called? The orbit the sun between an outer planet and an inner planet? 5. What would cause a crater on the surface of Earth? 6. What do we call a meteor that reaches Earth’s surface? 7. What two planets border the asteroid belt? 8. A comet’s tale always points away from the sun? 9. What are small rocky bodies that move through space? 10. Where do comets come from?
DEFINE DON’T JUST COPY THE WORDS!!!!! MAKE SURE YOU ARE LABELING THE PARTS CORRECTLY!!!!!! THINK!!!!!