A%20Quick%20Survey%20of%20the%20Solar%20System

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A Quick Survey of the Solar System
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Size and Distance
If we model the Earth as a 12-inch globe, then
the Solar System to scale would look like
12 inches
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The Sun and the Planets to Scale

• The Sun would be larger than a BIG house.
• Jupiter would be over 11 ft. across.
• Pluto would be only 2 in. across.

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And the distances can be compared to New York
State
PLUTO
comets
ERIS
SUN
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At the center of it all THE SUN!
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The planets can be divided into two groups
The Earth-like or the terrestrial planets, which
include Mercury, Venus, Earth, and Mars.
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The Terrestrial Planets

• Are small in size (less than 8000 miles across).
• Are composed mostly of solid rock.
• Have thin atmospheres compared to the giant
  planets.
• Are relatively close to the Sun.

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The second group of planets are gas giants called
the Jovian planets after Jupiter.
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THE JOVIAN PLANETS

• Are very large compared to the terrestrial
  planets.
• Are composed mostly of dense gases or ices.
• They include Jupiter, Saturn, Uranus, and
  Neptune.
• All these planets have rings.

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Mercury
Animation

• Mercury is the closest planet to the sun, only
  0.39 AU away.
• It revolves around the Sun in just 88 days.
• It looks a lot like the Moon (cratered).
• Temperatures range from very hot to very cold.

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VENUS

• Venus has an atmosphere with thick clouds.
• Venus is almost the same size as Earth.
• Heat trapped by the atmosphere makes Venus a very
  hot world!

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A Venus Transit Across the Sun
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EARTH

• Earth is the largest terrestrial planet.
• It is the only planet with significant amounts of
  oxygen in the atmosphere and water in the liquid
  state.
• The Earth is a very active planet, tectonically.

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Mars

• The reddish color is caused by iron oxide (rust).
• Mars has about the same rotation rate as Earth.
• Mars has ice caps and seasons.
• The largest known volcano in the Solar System is
  found on Mars.

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Jupiter

• Jupiter is larger than all the other planets
  combined.
• The Great Red Spot is a huge storm on Jupiters
  surface.
• One day on Jupiter is only 10 hours, causing the
  planet to have a oval shape.
• The four largest moons of Jupiter are named for
  Galileo.

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The Galilean Satellites Io, Europa, Ganymede,
and Callisto
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Saturn

• The rings of Saturn are made of billions of small
  particles.
• Saturn has a very low density. It could float in
  water, if you could find a sea big enough.
• Some of the moons of Saturn have conditions that
  might allow living organisms.

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Uranus

• Uranus was the first planet discovered using a
  telescope in 1787.
• It was the second planet found to have rings.
• It is one of the ice planets along with
  Neptune.
• Uranus is tilted on its side, so it has extreme
  seasons.

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NEPTUNE

• Neptune is over 30 times farther from the Sun
  than Earth.
• It was discovered when Uranus orbit was slightly
  off predictions.
• Unlike its twin, Neptune is not tilted much.

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Pluto

• Pluto is smaller than the Moon.
• It has the most elliptical and tilted orbit of
  all previously known planets.
• Its origin is a major debate among astronomers.
  It was demoted to the category of dwarf planet in
  August 2006.
• Its companion is called Charon.
• Charon s status is still unclear according to
  the IAU.

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Eris - a Dwarf Planet

• In the summer of 2005 a tenth planet was
  identified with an orbit averaging 68 A.U. from
  the Sun.
• Its orbit is very eccentric and inclined.
• The International Astronomical Union has decided
  that Eris is the largest known dwarf planet.

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Makemake

• Another dwarf planet was discovered in 2005.
• This past year it was named Makemake in honor
  of a Polynesian god.
• It has a highly eccentric and tilted orbit,
  averaging around 45 AU from the Sun.

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Sedna - Way, Way, Out!
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Pluto is Dissed!

• In the mid-1990s the Hayden Planetarium in NYC
  was renovated.
• Their new exhibit left out Pluto, which set off a
  major media storm.
• This led to a reclassification of solar system
  objects (and a lot of angry elementary teachers).

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What then is a planet?

• In a very controversial vote on Aug. 24, 2006,
  the IAU stated that there are only eight
  classical planets.
• Pluto, Makemake, Eris, and Ceres are considered
  to be dwarf planets.
• There are probably many more dwarf planets
  waiting to be discovered.

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The Official Definition

• The IAU therefore resolves that planets and
  other bodies in our Solar System be defined into
  three distinct categories in the following way
• (1) A planet is a celestial body that (a) is in
  orbit around the Sun, (b) has sufficient mass for
  its self-gravity to overcome rigid body forces so
  that it assumes a hydrostatic equilibrium (nearly
  round) shape, and (c) has cleared the
  neighborhood around its orbit.
• In plain language, if it's round and it orbits
  the Sun, and it doesnt cross another orbit then
  it's a planet.

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The Dwarf Planets

• The IAU also defined a new category of bodies
  revolving around the sun, the dwarf planets.
• They are similar to classical planets, except
  they have not cleared the neighborhood around
  its orbit.
• Then in 2008, a subcategory was createdplutoids,
  dwarf planets beyond Neptune.

Ceres - dwarf planet, but not a plutoid
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Small Solar System Bodies

• Small Solar System Bodies are too small and
  irregular in shape to be true planets.
• SSSBs include natural satellites, asteroids,
  meteoroids, and comets.
• Satellites (or moons) revolve around planets as
  they revolve around the Sun.
• Some of the satellites of Mars, Jupiter and
  Saturn are probably captured asteroids.

Deimos and Phobos
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The Asteroids

• Asteroids are mini-planets found mostly between
  Mars and Jupiter.
• The rock fragments never managed to coalesce, so
  they have irregular shapes (i.e. they are NOT
  planets).
• Their orbits are often highly eccentric and
  inclined.

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The Asteroid Belt
Mars
Jupiter
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The Dawn Mission to the Asteroid Belt
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Meteoroids

• Meteoroids are small rocky fragments, probably
  left over from the formation of the Solar System.
• When they enter the earths atmosphere, they
  start to burn, creating meteor showers. If it
  reaches the ground, it is called a meteorite.

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Fireball
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Comets

• Comets are balls of rock and ice, usually no more
  than a few miles across.
• Their orbits are very elliptical, taking them way
  past the orbit of Pluto.
• When they approach the Sun, a tail of gases
  forms, always pointing away from the Sun.
• Sometimes the heat of the sun causes the comet to
  begin to disintegrate, such as Comet West.

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Orbit of a typical comet
Comet orbit P 100,000 yrs.
Earth
Pluto
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Many comets come from a distance region of the
Solar System called the Oort Cloud.
1 light-year
Plutos orbit
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These minor objects can enter the Earths
atmosphere, usually doing little damage.
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In rare instances, they can produce impact
craters.
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Origin of the Solar System
Around 5 billion years ago, a huge cloud of gas
(left over from an ancient supernova) began to
shrink and rotate.
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Most of the matter fell to center, producing the
Sun.
The outer rings became the planets. Those near
the sun lost most of their gases (terrestrial
planets).
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Those farther out kept their thick atmospheres
and icy cores
Jovian Planets
One of Jupiters moons
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The Goldilocks Solar System
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The Solar System appears to be stable, but there
is still much violent uncertainty.
Olympus Mons
Io
Shoemaker Levy
Enceladus
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Target Zero EARTH

• There seems to be a major collision with
  asteroids or comets every 25 million years.
• One major impact hit the Yucatan Peninsula and
  might have caused the extinction of the
  dinosaurs.
• In 1908 an asteroid exploded above Tunguska,
  Siberia.
• Is it only a matter of time before Armageddon II?

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A Near Miss in Feb. 2009
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2009 - Jupiter Gets Slammed Again!
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Quick Quiz

• What are the differences between the terrestrial
  and Jovian planets?
• What is meant by a dwarf planet?
• Name an usual property for each planet.
• What are the three Small Solar System Bodies in
  the Solar System?
• What seems to be the origin of the Solar System?