- The outer planets are Jupiter, Saturn, Uranus, and Neptune.
- Located outside of the asteroid belt.
- These planets are much larger than the inner planets and are called gas giants as they are composed primarily of hydrogen and helium.
- No solid surface. The hydrogen and helium are in gas form in the atmosphere and below that in a liquid state.
- Each has many moons and rings.
I found a very nice flash piece on another website that shows the relative speed of these planets in orbit around the sun. Click here to view it.
The Kuiper Belt is a region in space beyond the orbits of the planets in our solar system, similar to the asteroid belt but 20 times wider, where there are many small bodies. With the advances in our telescopes, more objects have been found similar in composition to Pluto but larger. The question of what to classify them has arose. To help answer this, the International Astronomical Union (IAU) formalized the definition of a "planet" in 2006. To qualify as a planet, a body must meet three requirements:
- It needs to be in orbit around the Sun.
- It needs to have enough gravity to pull itself into a spherical shape.
- It needs to have cleared the neighborhood of its orbit.
Pluto fails to meet the third requirement. Any object not meeting the third requirement is called a dwarf planet. Pluto, Ceres, and Eris became the first three members of the dwarf planet classification, and many others are expected to follow.
I was a little sad at Pluto's demotion to a dwarf planet. However, I understand the need to be more precise. Our knowledge base changes as we learn more things about this world. After all, there was big upheaval over the Earth not being flat and not at the center of the universe and yet we managed to get over that eventually.
The lowest spot on dry land on the Earth is located along the shore of the Dead Sea. The shore is 1,385 feet below sea level. The deepest ocean depth is in the Mariana Trench in the western North Pacific Ocean. Its maximum depth is 35,798 feet (6.78 miles).
The tallest spot is Mount Everest located in Nepal. It is 29,029 feet (5.50 miles) above sea level. Height above sea level is the usual choice when determining elevation. There is another method. Due to its rotation, the Earth is slightly flattened at the poles and slightly bulging around the equator. So if you measure from the center of the Earth to the highest peak, then Mount Chimborazo in Ecuador is actually 1.3 miles taller than Everest, although it is only measured as 20,561 feet above sea level.
The highest recorded temperature was 136° F in Libya. The lowest recorded temperature was -129° F in Antarctica.
Driest place: Atacama Desert in Chile. Average rainfall is about one inch, but some places haven't had rain in human history. Due to the lack of moisture in the air, metal items never oxidize and meat can be left in the open air for an unlimited time. Now that's dry!
Wettest place: Mount Wai-’ale-’ale, Kauai, up to 512 inches in a year.