Download File the solar system

The Solar
System
Models of the Solar System
• Important people in astronomy
• Aristotle (384-322 BC)- promoted
an Earth-centered, or geocentric,
model of our solar system.
Everything revolved around the
Earth? WRONG!
• Copernicus- a Polish astonomer,
challenged geocentric belief and
proposed a heliocentric, or Suncentered, model of the solar system in
which the planets were in orbit around
the Sun
• Galileo Galilei- confirmed Copernicus’
beliefs by observing the planets
through his newly invented telescope
• Tycho Brahe- a Danish
astronomer, devoted his life to
making detailed observations of
the positions of the stars and
planets
• Kepler- assistant to Brahe,
developed three laws that
explained most aspects of
planetary motion
Kepler’s Three Laws
• I. Law of Ellipses- Each planet orbits
the Sun in a path called an ellipse
• II. Law of Equal Areas- Describes the
speed at which the different planets
travel at different points in their orbits.
– Example: The Earth travels fastest when
closest to the Sun
• III. Law of Periods- Describes
the relationship between the
average distance of a planet
from the Sun and the orbit
period of a planet
• Orbit period- time required for
a planet to make one revolution
around the Sun
The Inner Planets
• The four planets closest to
the Sun are called the inner
planets, or the terrestrial
planets
• They are called the terrestrial
planets because they are
similar to Earth
• These planets consist of mostly
solid rock with a metal core
• They do not have rings
• They number of moons of these
planets vary from 0-2
• The inner planets also impact
craters on their surface
Mercury
• Planet closest to the Sun
• Shorter orbit period rthan any other
planet- 88 days
• Named by Romans, after Mercurius, a
swift messenger of the gods
• One rotation of Mercury = 59 Earth
days
• Mercury has no moons
• In 1974 and 1975 Mariner 10
(NASA spacecraft) visited
Mercury
• Mercury was once volcanic
• Temperature: during the
day427*C and during the night –
137*C
• Weak magnetic field
Venus
• Second planet from the Sun
• Orbit period of Venus is 225 days
• One rotation of Venus = 243 Earth
days
• The direction of rotation is opposite
that of other planets
• Meaning that the Sun rises in the west
and sets in the east
• Has no moons
• Venus is often called the Earth’s
twin due to being about the same
size and having the same mass and
density
• Much hotter than the Earth because
of closeness to the Sun and thick
atmosphere that provides insulating
effect
• Average surface temperature is
approximately 453*C
• Atmospheric pressure is about 100
times that of Earth. What does that
mean?
• May have had oceans and volcanic
activity at one time
• Clouds on Venus are composed of
sulfuric acid
• In the 1970’s, the Soviet
Union sent six Venera probes
to Venus
• Between 1990-94, the
Magellan (NASA spacecraft)
orbiter produced radar
images of most of the
Venusian surface
Earth
• Orbit period is 365.24 days
• Completes one rotation in about 23
hours and 56 minutes
• Is the fifth largest planet in our solar
system
• Has one moon
• At this point in the solar system’s
history, the Earth is like no other
planet. What does this mean?
• Life on Earth is possible because of it’s
distance from the Sun, meaning the
temperature is warm enough for water
to exist as liquid while Venus and
Mercury are too hot to retain liquid
water
• Water on other planets- (Mars
and outer planets) do not have
liquid water due to the coldness
of these planets and water exists
on these planets in the form of
ice
• Liquid water is the key to life
existing on Earth
Mars
• Fourth planet from the Sun
• Orbit period is 687 days
• One rotation = 24 hours and 37
minutes
• Length of day on Mars and Earth are
very close
• Also has seasons much like the Earth
due to tilt of it’s axis
• Has 2 moons
• Geologically active planet
• Volcanoes on Mars are the largest in
the solar system
• Example: Olympus Mons, which is 3
times higher than Mt. Everest and it’s
base is about the size of Nebraska
• Deep canyons cover the surface: the
largest is Valles Marineris, which is as
long as the United States
• Atmospheric temperature and pressure
are presently to low for water to exist
in liquid form
• Viking I and Viking II (NASA
spacecraft) found evidence of erosion
by water on the surface of Mars; from
this astronomers can infer that Mars
once had a warmer and wetter climate
• The little water that is left on Mars is
frozen in polar ice caps and possibly
beneath the surface
• Mars Pathfinder (NASA spacecraft)
took wonderful pictures of Mars and
studied the surface extensively
• You will see humans walk on Mars in
your lifetime
• To reach other planets is the only way
to ensure human existence in the future
The Outer Planets
• The outer planets are composed
of the five planets farthest from
the Sun and are called the
Jovian planets
• Although Jovian planets are far
larger than the terrestrial planets
(except Pluto) they are far less
dense than terrestrial planets
Jupiter
•
•
•
•
First of the outer planets
Fifth planet from the Sun
Largest planet in the solar system
It’s mass is twice that of the other 8
planets combined
• Orbit period is almost 12 years
• Rotation is faster than any other planet
at 9 hours and 50 minutes
• Has at least 16 moons
• One ring made up of millions of
particles
• Seems to have a liquid metallic core
surrounded by lighter elements
• Temperature in the interior of Jupiter
can rise as high as 30,000*C
• Intense pressure has changed most of
the interior of the planet into a sea of
liquid hydrogen
• Has an enormous magnetic field
• Jupiter is mostly made up of gases
• 92% of the planet is made up of
hydrogen and helium
• No evidence for possibility of life on
Jupiter
• Extensive atmosphere
• The Great Red Spot is a giant
rotating storm, somewhat like a
hurricane on Earth
• Galileo (NASA spacecraft) reached
Jupiter in 1995 and dropped an
entry probe into it’s atmosphere
and observed wind speeds of 600
km/hour
Io
Ganymede
Callisto
Europa
Saturn
• The sixth planet from the Sun
• A half a billion kilometers farther from
the Sun than Jupiter
• Second largest planet in the solar
system
• Average temperature is –176*C
• Has 22 moons
• Has several rings
• Orbit period is 29.5 years
• Rotates on it’s axis every 10
hours and 40 minutes
• Small rocky core with interior
of liquid metallic hydrogen
• Dense atmosphere composed
of hydrogen and helium gas
• Much less dense than Jupiter
(least dense in the solar
system)
• Very complex system of
rings
Uranus
• The seventh planet from the Sun
• Third largest planet in the solar system
• Discovered in 1781, first to be
discovered since ancient times
• Great difficulty seeing since it is nearly
3 billion kilometers from the Sun.
• Has 15 moons
•
•
•
•
Has 11 small rings
Orbit period is 84 years
Rotates once every 17 hours
Voyager 2 (NASA spacecraft) in 1986
discovered exact rotation rate of
Uranus
• Atmosphere contains methane (gives
greenish color)
• Atmosphere is mainly made up of the
gases hydrogen and helium
Neptune
•
•
•
•
•
•
The eighth planet from the Sun
Similar to Uranus in size and mass
Orbit period is 165 years
Rotates around every 16 hours
Has 8 moons
Possibly 4 rings
• Named after Neptune, the Roman
god of the sea
• 4.5 billion kilometers from the Sun
• Voyager (NASA spacecraft)
indicated from it’s voyage that
Neptune’s atmosphere is made up
largely of hydrogen, helium, and
methane
• Very active weather system
• Solar system’s strongest winds,
exceeding 1000 km/hour
• Average temperature is –225*C
• An Earth-sized storm noted
named The Great Dark Spot
Asteroids, Comets, and
Meteoroids
Asteroids
• Largest of smaller bodies in the
solar system are called asteroids
• Fragments of rock that orbit the
Sun
• Astronomers have observed more
than 50,000 asteroids
• Millions may exist in the solar
system
• Most have elliptical orbits
• Largest known asteroid is Ceres, is
about 1000 km. In diameter
• Most asteroids exist in an area
between Mars and Jupiter known
as the asteroid belt
Comets
• Orbit the Sun in long ellipses
• A comet is a body of rock, dust,
methane, ammonia, and ice
• The nucleus of a comet are usually
made up of rocks, metals, and ice and
are usualy between 1 to 100 km in
diameter
• A spherical cloud of gas and dust,a
coma, surrounds the nucleus
• Bright appearance of a comet is due to
sunlight reflecting off the coma
• Nucleus and coma combine to form the
head of a comet
• Most spectacular part of a comet is it’s
tail
• Tail is made up of gas and dust that
streams out of the head
• Formed by solar winds pushing gas
and dust away from the head of a
comet
• Tail always points away fro the Sun
• Oort Cloud- a spherical cloud of dust
and ice that contains the nuclei of as
many as a trillion comets
• This cloud surrounds our solar system
• Long-period comets- have orbit
periods of several thousand or
several million years
• Short-period comets- have
orbit periods of up to 100 years
Meteoroids
• Smaller bits of rock or metal that
move throughout the solar system
• Most are less than 1 mm in
diameter
• Most are small pieces of matter
that come detached from comets
• Larger meteoroids are more than 1
cm in diameter and are produced
by collisions between asteroids.
• When a meteoroid enters the
Earth’s atmosphere it is called a
meteor.
• Most burn up when entering the
atmosphere and never reach the
Earth’s surface
• Meteor shower- when a large number
of small meteoroids enter the Earth’s
atmosphere in a short period of time
• Astronomers estimate that about one
million kilograms of matter from
meteors falls to the Earth each day
• If a meteor actually reaches the Earth’s
surface it is called a meteorite
• Can possibly leave large craters: one
of the best known is Meteor Crater in
Arizona, struck the Earth about 20,000
years ago
• The meteor as it entered the Earth’s
atmosphere was 50 meters in diameter
weighed approximately 500,00 tons
• Crater is 1.3 km in diameter and 180
meters deep
3 types of meteorites
• 1. Stony meteorites- look very similar
to Earth rocks
• 2. Iron meteorites- have a distinctive
metallic appearance
• 3. Stony-Iron meteorites- contain both
iron and stone and are very rare
Various
The End
• A 923 Production