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Lesson 4a
CELESTIAL OBJECTS IN SPACE
Comets
 chunks of frozen gases,
rock & dust that orbit the
sun
 tail is formed when the
comet comes close to the
Sun
Comet Shoemaker-Levy 9 hit Jupiter in 1994.
Asteroids
 Irregular shaped rocky
objects
 many orbit around the Sun
and this is called an asteroid
belt
Meteors & Meteorites
 A meteoroid is a clump of rock or metal which is
pulled towards Earth by gravity
 In Earth’s atmosphere it heats up, begins to glow
and becomes a meteor
 If the object is not vaporized before it contacts the
Earth’s surface it is called a meteorite
meteoroid
meteor
meteor shower
What’s the difference?
Asteroid:
-Small; inactive
- made of rock, carbon or metal
- Orbits the sun
Comet:
- small; sometimes active object
- made of dirt, gas and ice
Meteoroid:
- small particle from an asteroid or comet
- orbits the sun
- A meteoroid that burns up in the Earth's
atmosphere - a shooting star.
- A meteoroid that survives its passage
through the Earth's atmosphere and impacts
the Earth's surface.
Meteor:
Meteorite:
Moons/Satellites
 Large natural objects which revolve
around a planet
 many planets have more than one
moon
 Earth’s moon has no atmosphere and
has hills/valleys/craters
 after the invention of the telescope
Galileo saw 4 moons of Jupiter
 Moons can come in a variety of size
and with a variety of surfaces
Stars
 A STAR is a luminous ball of plasma that is held
together by gravity.
 What is the nearest star to Earth?
 What is the nearest star to the Sun?
Binary Solar System
Stars
 Polaris
 pole star for the Northern Hemisphere
 390 light years from Earth
 part of a binary star system
 Sirius
 the brightest star in the sky (70 times more
luminous than the sun)
 8.6 light years from the Earth
 Betelgeuse
 one of the brightest stars in the sky
 supergiant
 1,000 times bigger than the Sun but cooler than
the Sun
Outside our Solar System
 Voyager I, Pioneer 10 & 11
and Voyager 2 built to
explore outside our solar
system
 Took 20 years to leave solar
system
 will reach the nearest star in
50 000 years
video
 Bill Nye- Comets and Meteors