Post on 12-Jan-2016
Other objects in the Solar System
• Describe characteristics of the moon.• Describe asteroids• Describe meteors and meteorites.• Describe comets
KEY WORDSMoon LunarSatellites Comet Asteroid MeteoroidMeteorite Meteor
Io - only moon known to have active volcanoes
Europa – contains more ice and water than Earth and may contain life.
Moons
(Oct 2008)– 172 known natural moons orbiting planets in our Solar System.
Planet (2006) Known moonsMercury 0Venus 0Earth 1Mars 2
Jupiter 63Saturn 60Uranus 27Neptune 13
Pluto 3
Moon: Large natural object (rock/metals) that revolves around a planet – also called a satellites.
• Roman goddess of the moon was Luna.
• Most moons were discovered with telescopes.
• Probes (robot explorers) have investigated moons of Mars, Jupiter and Saturn.
• Studying moons helps us learn about the origin and evolution of the solar system.
Humans have visited its surface six times between 1969 and 1972.
• First visit - Soviet Luna 2 in 1959.
• 2nd brightest object in sky.
• No atmosphere• Surface filled with hills, valleys, and craters.
• ¼ diameter of Earth• Its gravity is responsible for the tides of the oceans.
Asteroids
Asteroids: Chunks of rock/metal that orbit the Sun but too small to be planets – minor planets.
• “Asteroid belt” in large gap from Mars - Jupiter.• Largest is only 1000 Km in diameter.• Asteroids are rich in minerals – future mining.
• Asteroid with orbits that cross paths with Earth are called Trojans.
• Could cross close enough to be pulled in by Earth’s gravity and collide with it.
Meteoroids
Meteoriods: lump of rock that is trapped by Earth’s gravity and pulled into the atmosphere.
As it falls, it rubs again molecules of air (friction) and becomes hot and breaks apart (vapourizes) so the air glows – burns up.
• Meteoroid that completely burns up - meteor.
• Streak of light produced across the sky called also known as a shooting star.
• The largest are probably asteroids.
Meteoroids that don’t completely burn up and strikes the Earth, it is called a meteorite.
• Large meteorites make craters. • Westhawk Lake is a crater.
Crater in Arizona formed by meteorite
Meteor shower Swarm of visible meteors when Earth passes through debris left behind by old comet.
Comets
Some comets have regular periods of revolution around the Sun.
• Halley’s comet: last seen in 1986 it has a period of 76 years.
Comets: chuck of ice/dust that orbit the Sun. • Made of the head (coma) and the tail.
• Approach the Sun - warmed by solar radiation.• Heated material becomes glowing gas that is
blown out by solar wind forming the tail – millions of km long.