COMETS small body of ice rock and cosmic
COMETS • small body of ice, rock, and cosmic dust • “dirty snowballs” • tail visible when comet gets close enough to the sun (points away from sun due to solar winds) --tail can be millions of miles long • gets smaller with every trip (melts)
…WEBSITE ANIMATION… • http: //www. classzone. com/books/earth_sc ience/terc/content/visualizations/es 2706/e s 2706 page 01. cfm? chapter_no=visualizati on (comet passage)
YOU CAN SEE A COMET FOR WEEKS (OR MONTHS)! …UNLIKE A METEOR
ASTEROIDS • dense, rocky bodies that orbit the sun (over 100, 000 known)—smaller than a planet • most are irregularly shaped (not round) • size: few meters to 900 km • most found in the asteroid belt (between Mars and Jupiter)
CERES LARGEST KNOWN ASTEROID (785 KM LONG)—NOW CONSIDERED TO BE A DWARF PLANET
METEOROIDS • Meteoroid= small pieces of comets or asteroids in space • Meteor= burning up in atmosphere (inaccurate “falling/shooting star”) • Meteorite= hits the ground (MAY make a crater) to say
WOW!!! • Meteor shower over Russia, Feb 15, 2013 • http: //www. youtube. com/watch? v=d. Bvot. Wf. R 3 j 4
WHICH ONE IS THIS? WHAT CAUSED THIS? • meteorite
DID YOU KNOW? ? • The mass of the earth increases every year because of the 3, 000 TONS of meteorite debris that hits the surface from space! • Approximately every 50 -60 years, somebody is struck by a meteor; last time was in 1954 • The odds of you being hit is a billion to one (no human has ever been killed by a meteor strike).
THINK ABOUT IT…. • If we were to send a manned mission to Mars, how could we avoid getting damaged by the asteroid belt? • The asteroid belt is between Mars and Jupiter. • If you lived on the moon, about how many meteors would you see on the moon in an earth year? • None—no atmosphere
• Which of the following is a characteristic of comets? • A. Comets are composed of rocky material, iron, and nickel. • B. Comets follow a circular orbit around the sun. • C. Comets give off gas and dust when heated by the sun. • D. Comets are rich in iron.
• Which of the following is a wide region of small, rocky bodies that is located between the orbits of Mars and Jupiter? • A. the Kuiper belt • B. the Oort cloud • C. the asteroid belt • D. the rings of Saturn
• When it approaches the sun, which object produces a shimmering tail that lasts at least a few days? • a comet • In which direction does a comet’s tail always face? • away from the sun
• Where are most asteroids found? • in orbit between Mars and Jupiter • What is the sequence that describes a space rock that falls to Earth’s surface? • meteoroid, meteorite
• Which one of the following objects in our solar system would travel the greatest distance during one revolution around the sun? • A. a terrestrial planet • B. an asteroid • C. a gas giant • D. a comet
- Slides: 17