The Solar System

(Fourth and Fifth Grade Level)

There are nine planets in our solar system that orbit, or travel around, the sun.

The sun is the largest object in the solar system.  

The planets can be split into two groups, the inner planets (or terrestrial plants) and the outer planets.

Inner planets include:  

   Mercury  

 -Mercury is the closest plant to the sun.  It has gently rolling intercrator plains.  Mercury is the densest planet.  It's interior is dominated by a huge iron core.
 

Venus

-Venus was named for the Roman goddess of love and beauty.  The environment of Venusis very harsh, with the gaseous atmosphere, very  hot temperatures and crushing surface pressures.  Also, it has the slowest rotation of any planet.   

 Earth

-Earth is the only planet in the solar system with oceans of liquid water and breathable air.  It is also the only planet that supports as we know it.  Another feature that makes earth different is it's interior.  Erupting volcanoes and earthquakes remind us that the interior is hot and its surface plates are continuously shifting into new positions.

  Mars

-Mars is the planet most like earth.  It has mountains and valleys, polar ice caps and dry river beds. Mars also has seasons, an atmosphere with clouds, winds and dust storms, and a solid rocky surface.

Outer planets include:  

 Jupiter

-Jupiter is more massive than all the other planets in the solar system and is known as the "gas giant."  The pressure and temperature of Jupiter is so high that there is no clear boundary between solid and liquid.  The atmosphere of Jupiter is made up primarily of hydrogen and helium in about the same abundances found in the sun and other stars.

 Saturn

-Saturn is know for its rings, although all the gas giants are now known to possess rings.  Of all the planets in our solar system, Saturn is the least dense.  If there was an ocean large enough to hold the planet, it would float on water.  Saturn is ten times the diameter of earth.  Also, it is the second largest planet in our solar system.

  Uranus

-Uranus's axis, which on the planet Earth is connected bye the north and south poles, is tipped almost exactly on its side.  This rotation gives Uranus its unique 21 year long summer while the other side of the planet is having a 21 year long winter.

    Neptune

-Of the gas giant planets, Neptune is the fourth and outermost.  Its atmosphere is mostly hydrogen and helium, plus a good amount of methane that gives the planet its blue color because it absorbs red light.  The storms and winds in Neptune's atmosphere are the fastest in the solar system.

      Pluto

-The ninth and last planet from the sun is Pluto.  There are no pictures of the surface of Pluto yet because space craft has yet to visit there.  Unlike the gas giants of the outer solar system, Pluto is small and icy.

**We really don't know too much about Pluto yet.