Transcript The Solar System 1. Earth-centered model

Ch 23 - The Solar System
Early Greeks
600BC – 150AD
1. Earth-centered model – the planets,
sun, and stars were imbedded in
spheres that rotated around Earth.
2. Sun-centered model – the moon
revolves around Earth, but all planets
and objects in the solar system
revolve around the sun.
Nicholas Copernicus
1543
3. The sun contains 99.86% of the
mass in the solar system.
4. The solar system formed when a
large cloud of gas and dust began to
contract and spin. Gravity pulled
matter inward. Densely packed
matter in the center grew hot and
formed the sun. Cooler matter
clumped together in the outer disk
and formed the planets.
Formed about 4.6 to 5 billion years
ago.
5. Our sun became a protostar when
the core reached about 10 million °C
and nuclear fusion began.
6. Nuclear fusion – atoms of low mass
(H) combine to form heavier elements
(He, C, O, etc.).
Genesis – to collect
solar wind particles.
7. Inner Planets
1. Mercury
2. Venus
3. Earth
4. Mars
Also known as: Rocky or Terrestrial
planets
8. Outer Planets
1. Jupiter
2. Saturn
3. Uranus
4. Neptune
5. Pluto ??? NOT!
Also known as: Gas or Jovian planets
9. Orbits of
planets are
elliptical.
Johannes Kepler
1600’s
P2 = R3
R = average distance to
sun in astronomical
units (AU)
Earth = 1 AU from Sun
a. Mercury d. Mars
g. Uranus
b. Venus
e. Jupiter
h. Neptune
c. Earth
f. Saturn
23.5 Other Objects in Space
1. Comet – a “dirty snowball” that
orbits the sun.
Halley’s Comet – orbits every 76
years.
2. Comets are composed of dust
and rock particles mixed with frozen
water, methane, and ammonia.
3. Oort Cloud - an immense
spherical cloud of icy comets.
Located: beyond Pluto to about 30
trillion km.
4. Meteoroid – small pieces of rock
moving through space.
Meteor – meteoroid that enters
Earth’s atmosphere.
Meteorite – meteor that strikes
Earth.
Commonly called “shooting stars”.
Peekskill meteorite
October 9, 1992.
The meteorite was
found crashed into
the trunk of a parked
car.
6. Asteroid – remnants of a former
planet.
Asteroid belt lies between Mars
and Jupiter.
Ida and Dactyl
Asteroid belt - gravitational pull from
Jupiter's huge mass prevented
protoplanetary bodies from growing
larger than about 1,000 km (620
miles),
The largest asteroid that has been
found is the asteroid belt is as big as
Texas. It has been given the name
Ceres (590miles in diameter). An
asteroid is a chunk of rock in space.
It is what was leftover when the Sun
and planets formed.
7. Kuiper Belt - a disk-shaped
region past containing many
small icy bodies (comets)
Located: past the orbit of Neptune
30 to 50 AU from the Sun