The Launch Pad Monday, 9/20/10 Identify

 We will have a test this Friday.

Assignment Currently Open Pages Date of Notes on Website Date IssuedDate Due

Current Events in Earth/Space Jupiter is approaching Earth for the closest encounter between the two planets in more than a decade. The night of closest approach is Sept st. This is also called "the night of opposition" because Jupiter will be opposite the sun, rising at sunset and soaring overhead at midnight. Among all denizens of the midnight sky, only the Moon itself will be brighter. Earth-Jupiter encounters happen every 13 months when the Earth laps Jupiter in their race around the sun. But because Earth and Jupiter do not orbit the sun in perfect circles, they are not always the same distance apart when Earth passes by. On Sept. 20th, Jupiter will be as much as 75 million km closer than previous encounters and will not be this close again until 2022.

 Asteroids Most asteroids lie between the orbits of Mars and Jupiter. They are small bodies – the largest is Ceres, which is about 620 miles in diameter. Some asteroids have very eccentric orbits Many of the recent impacts on the Moon and Earth were collisions with asteroids They usually have irregular shapes and their origin is uncertain. We have landed a spacecraft on the asteroid Eros.

Figure 22.25

Eros Courtesy: NASA/JPL-Caltech Eros

Dr. Frank Summers Space Telescope Science Institute March 28, 2008

This impact crater in Winslow, Arizona, is one of about 200 on Earth. At 50,000 years old, it’s also one of the newest. The crater is 1.1 km (.7 mi) in diameter and 150 m (495 ft) deep. The meteorite that made it weighed 100,000 tons. Most meteorites that hit the ground are too small to leave a crater, but anything larger than a house explodes just before or during impact and leaves a crater that is much larger than itself. Photo © Charles and Josette Lenars/CORBIS

 Comets Comets are often described as large, dirty snowballs. Composition of comets ▪ Frozen gases ▪ Rocky and metallic materials The frozen gases vaporize when near the Sun ▪ This produces a glowing head called the coma. ▪ Some comets may develop a tail that points away from Sun due to radiation pressure and the solar wind

Comets

Figure 22.27

 Comets The origin of comets is not well known because they form at great distances from the Sun. The most famous short- period comet is Halley’s comet, with a 76-year orbital period and potato- shaped nucleus (16 km by 8 km.) Halley’s Comet

 Meteoroids Called meteors when they enter Earth’s atmosphere A meteor shower occurs when Earth encounters a swarm of meteoroids associated with a comet’s path Meteoroids are referred to as meteorites when they are found on Earth

 Meteoroids Meteoroids are referred to as meteorites when they are found on Earth ▪ Types of meteorites classified by their composition Irons  Mostly iron  5%–20% nickel Stony  Silicate minerals with  Inclusions of other minerals

 Meteoroids Meteoroids are referred to as meteorites when they are found on Earth ▪ Types of meteorites classified by their composition Stony - irons – mixtures Carbonaceous chondrites  Rare  Composition – simple amino acids and other organic material  May give an idea as to the composition of Earth’s core  Give an idea as to the age of the solar system

 Dwarf planets are a new class of planet. They orbit the Sun. They are not the only objects to occupy their area of space. The former planet Pluto is the prototype of this new category. Many dwarf planets are located in the Kuiper belt, a band of icy objects found beyond the orbit of Neptune.

 Pluto Pluto is not visible to the unaided eye. Discovered in 1930 Now classified as a dwarf planet Pluto’s moon Charon was discovered in Pluto’s average temperature is -210ºC