7th Grade Science: The Solar System

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7th Grade Science The Solar System

• Section 1 An Overview of The Solar System
• Section 2 The 9 Planets of The Solar System

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Whats in Our Solar System?

• Our Solar System consists of a central star (the
  Sun), the nine planets orbiting the sun, moons,
  asteroids, comets, meteors, interplanetary gas,
  dust, and all the space in between them.
• The nine planets of the Solar System are named
  for Greek and Roman Gods and Goddesses.

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The Sun

• The Suns age is about 5 billion years.
• Its energy comes from nuclear fusion (where
  hydrogen is converted to helium) within its core.
  This energy is released from the Sun in the form
  of heat and light.
• Stars are the only solar bodies that generate
  their own light. Very bright planets, such as
  Venus and our moon, appear bright because they
  are reflecting sunlight. Remember Stars
  produce light. Planets reflect light.
• Our sun is classified as a yellow main sequence
  star. A stars temperature determines its
  color. The coldest stars are red. The hottest
  stars are blue.

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Geocentric vs. Heliocentric Theory

• Geocentric Theory (or Ptolemaic Theory
  pronounced Tole-ah-may-ic) is an ancient view
  of the universe based primarily on religion,
  philosophy, and mathematical ideals.
• Heliocentric Theory (or Copernican Theory) is a
  revised view of the universe based on the studies
  of Nicholas Copernicus, who was a mathematician
  in the 1500s.

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Geocentric Theory Basic Beliefs

1. The cosmos (or universe)
2. Is geocentric has the earth as its center with
   the sun and other planets revolving around the
   earth
3. Is geostatic the earth itself does not move
4. Celestial bodies move in uniform, circular motion
   around a central point.
5. Celestial bodies are composed of a fifth element
   the quintessence.
6. The cosmos is finite, which means that it does
   not go on forever.

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Heliocentric Theory Basic Beliefs

1. The earth rotates daily on its axis.
2. The earth and the planets revolve around the sun
   (a heliocentric model).
3. The earths orientation is fixed in space because
   of the conical axial motion of the earth.

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The 9 Planets of the Solar System

• Planets are categorized according to composition
  and size. There are two main categories of
  planets
• small rocky planets (Mercury, Venus, Earth, Mars,
  and Pluto)
• gas giants (Jupiter, Saturn, Uranus, and Neptune)

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The Relative Size of the Planets in the Solar
System
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Characteristics of Small Rocky Planets

• They are made up mostly of rock and metal.
• They are very heavy.
• They move slowly in space.
• They have no rings and few moons (if any).
• They have a diameter of less than 13,000 km

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Mercury

• Mercury has a revolution period of 88 days. A
  revolution period is the time it takes for a
  planet to complete one full orbit around the sun.
  This is also called a year.
• Mercury has extreme temperature fluctuations,
  ranging from 800?F (daytime) to -270?F
  (nighttime).
• Even though it is the closest planet to the sun,
  recent radar info suggests there is ICE on
  Mercury! Scientists believe the ice is protected
  from the suns heat by crater shadows. It is
  covered with meteorite impacts and barely has a
  trace of an atmosphere.

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Venus

• Venus is the brightest object in the sky after
  the sun and moon because its atmosphere reflects
  sunlight so well. People often mistake it for a
  star.
• The atmosphere of Venus has a large amount of
  carbon dioxide gas. Carbon dioxide traps heat in
  Venuss atmosphere, causing the surface
  temperatures to increase greatly. We call this
  effect the Greenhouse Effect. Venuss Greenhouse
  Effect is so strong that its maximum surface
  temperature may reach 900?F.
• Venus has no moons. It has thick yellowish
  clouds composed of sulfuric acid driven by fast
  winds. Its surface is dry and dusty with
  craters, mountains, and volcanoes.

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Earth

• Earth is the only planet known to support living
  organisms.
• Earths surface is composed of 71 water.
• Water is necessary for life on Earth.
• The oceans help maintain Earths stable
  temperatures.
• Water is a primary cause of Earths surface
  weathering.
• Earth has a distinct atmosphere.
• It helps screen harmful radiation from the sun.
• It prevents meteorites from reaching Earths
  surface.
• It traps heat to help maintain Earths stable
  temperatures.
• Earth has one moon.

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Earths Moon

• It takes the same amount of time for the moon to
  rotate once on its axis as it does for it to
  orbit the earth (27.3 days). Thus, the same side
  of the moon always faces us.
• The moons surface is covered in dust and rocky
  debris from meteor impacts. It has no water or
  atmosphere. The dark areas of the moon are
  called maria (Maria is a Latin word meaning
  seas). Maria are large craters which have been
  filled by solidified lava.
• The moon reflects light from the sun onto the
  earths surface. Sometimes the moon may appear
  reddish-brown in color as the sunlight is
  deflected through dust in the earths atmosphere.
• The moons gravitational effects on the earth are
  most apparent in the coming and going of the
  tides

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Mars

• Mars has permanent ice caps at its poles. The
  ice caps are composed mostly of frozen carbon
  dioxide (what we call dry ice).
• Mars has the largest volcano in our solar system
  Olympus Mons. Olympus Mons is approximately 24
  km high (15 miles).
• Atmospheric dust makes Marss sky pink in color.
• Mars has two moons Phobos and Deimos

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Pluto

• Pluto is the only planet not visited by
  spacecraft. We are not sure of its composition.
  Based on current data, scientists believe it is a
  small, rocky planet.
• Pluto seems to lie on its side its equator
  points straight up, and one of its poles points
  directly at the sun.
• Pluto has only one moon (Charon). Plutos moon
  is half the size of Pluto itself, which is
  unusually large for a moon. Because they are so
  close in size, sometimes Pluto and its moon are
  considered to be a double planet system.
• Pluto was located and named in 1930.

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Characteristics of Gas Giants

• They are made up mostly of gases (primarily
  hydrogen helium).
• They are very light for their size.
• They move quickly in space.
• They have rings and many moons.
• They have a diameter of less than 48,000 km

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Jupiter

• Jupiter is the largest and most massive planet
  its diameter is 11 times bigger than that of the
  Earths. Overall, Jupiter is about 318 times the
  size of Earth. Jupiter is composed almost
  entirely of hydrogen and helium.
• Because Jupiter rotates so quickly, its clouds
  form belts (low-lying, relatively warm cloud
  layers) and zones (bright, high-altitude, cooler
  cloud layers) that encircle the planet.
• Jupiters characteristic Great Red Spot is an
  enormous storm, consisting of a spiraling column
  of clouds big enough to contain three Earths.
  The clouds are colder than the surrounding areas,
  and so the Great Red Spot sits about five miles
  above the upper cloud layer.
• Jupiter has 16 known moons.

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Saturn

• Saturn, like Jupiter, is composed almost entirely
  of hydrogen and helium. Saturn is the least
  dense of all the planets. In fact, Saturns
  density is less than that of water.
• Saturn has many rings composed primarily of ice
  with some ice-coated rocky particles. Saturns
  rings are very wide (they extend outward to about
  260,000 miles from the surface) but very thin
  (less than 1 mile thick).
• Saturn has 18 known moons, some of which orbit
  inside the rings!

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Uranus

• Uranus is tilted on its axis at 98?. Because of
  its strongly tilted axis of rotation, Uranus
  essentially spins on its side as it orbits the
  sun.
• Uranus is blue in color due to methane gas in its
  atmosphere.
• Uranus has 11 dark rings surrounding it. These
  rings contain some of the darkest matter in our
  solar system.
• Uranus has 15 known moons, and scientists suspect
  more lurk within its rings.

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Neptune

• Neptune has the fastest winds on the solar
  system up to 2000 km/hr.
• Neptune is also blue in color due to methane gas
  in its atmosphere.
• Neptune has a Great Dark Spot in its atmosphere.
  The Great Dark Spot is a huge storm the size of
  Earth.