The planets are a wonderful example of how scientists
slowly accumulate new information and make new conclusions. With each new
space probe, much is learned about the planets. The discovery of more
satellites around a planet to changing atmosphere can be revised with new
information.. We really do not know all
there is about the planets. As your students grow, they should be accustomed
to the changing of planetary information.
There is more to learn about the planets than just
their position and name. The following paragraphs give detailed information
about each planet. You may wish to share some of these key characteristics
with students. Constantly repeating and questioning students, will help them
retain planetary information.
Mercury is the closest planet to the Sun. It
orbits the Sun quickly, once every 88 days. It rotates slowly, however, only
once every 59 days. Mercury is small, about 4850 kilometers (~3000 miles) in
diameter. Because Mercury is so close to the Sun, the side of its surface
that faces the Sun is very hot, ~700oK. The surface of Mercury is
gray to orange in color, and is covered with craters. Mercury is named for a
mythical god who ran very fast.
Venus, the second planet away from the Sun, is
Earthís closest neighbor. It is about the same size as the Earth, a little
over 12,000 kilometers (7300 miles) in diameter. Venus has a very thick
atmosphere, composed largely of sulphuric acid and CO2. We could
not breathe on Venus, because the atmosphere would be very toxic to humans.
This atmosphere gives Venus a brownish-yellow color. It also traps heat (the
greenhouse effect) making the surface of Venus the hottest in the Solar
System, about 750oK. Venus rotates very slowly, taking 243 days
to complete one turn. It is named for the Roman goddess of love.
Earth is a little more than 12,000 kilometers
in diameter. It differs from the other planets because it has liquid water
on its surface, maintains life, and has active plate movement. It rotates on
its axis every 24 hours (a day) and revolves around the Sun every 365 days
(a year). The Earth has one moon.
Mars is a little more than half the size of the
Earth, having a diameter of 6,790 kilometers. It takes Mars 687 days to
revolve once around the Sun. It rotates at about the same speed as the
Earth, taking 24.6 hours. Mars has a very thin atmosphere which is composed
largely of CO2. Its surface is very cold, and is covered with
craters, volcanoes, and large canyons. Mars is reddish in color. Mars has two
small moons. It is named for the Roman god of war.
Jupiter is the largest planet in the Solar
System, with a diameter of 142,980 kilometers, more than 11 times wider than
the Earth. Jupiter orbits the Sun once every 12 years. It rotates very fast,
in only 10 hours. Its surface is made up of gas (mostly hydrogen), so that
if you landed on the surface you would sink into it. Jupiter probably has a
core of metallic hydrogen and rock, although evidence for this is
theoretical. The outer gaseous part of Jupiter is broken into bands of
white, yellow, red, and brown clouds. Huge oval-shaped storms also occur on
the surface. Jupiter has 63 known satellites (as of 2004) including the four large Galilean moons
(Io, Europa, Callisto, and Ganymede) plus many more small ones some of which have not yet been named.
Jupiter is named for the Roman
supreme god of heaven.
Saturn is well known for its system of three
rings. It is a large planet: at 120,536 kilometers it is only a little
smaller than Jupiter. It revolves around the Sun in 12 years, and rotates a
little more than 10 hours. Like Jupiter, Saturn is composed of mostly gas, and has a core composed of rock and metallic hydrogen. The surface of
Saturn looks banded, and has a brown-yellow, butterscotch color. Saturnís
rings are probably composed of small particles of ice and rock. Saturn has
47 moons (2004). It is named for the Roman god of agriculture.
Uranus is 51,118 kilometers in diameter, about
4.4 times the size of the Earth. It revolves around the Sun slowly, taking
84 years to complete one orbit. It rotates in about 17 hours. It is covered
by a thick layer of gas, and has a fairly uniform blue-green color. Uranus
has 21 named moons and six unnamed ones and is surrounded by a system of nine
rings. It is named for another Roman god, the grandfather of Jupiter
Neptune is slightly smaller than Uranus, with a
diameter of 49,500 kilometers. It circles the Sun once every 165 years, and
rotates in 16 hours. Its atmosphere appears blue , and is marked by large
dark blue storm systems. It is surrounded by a system of five rings and at
least 13 moons. Neptune is named for the Roman god of the ocean.
Pluto is the most distant planet from the Sun.
It has an eccentric, oval-shaped orbit, which is tilted with respect to the
rest of the Solar System. Pluto revolves around the Sun in 248 years, and
rotates in a period of 6.4 days. Pluto is probably composed of rock. Its
surface and color are unknown. It has one large moon that is almost like a
twin with 2 smaller moons. Pluto is named for the
Roman god of outer darkness.
the students to memorize the names and positions of the planets. To make
this easier, teach them a mnemonic device. Creating a silly sentence
using the first letter of the planets that you are trying to remember is
very helpful to children. For example "MY VERY EARTHLY MOTHER JUST
SERVED US NEW PICKLES" helps students remember that the order of
the planets. The lab sheet has students make their own silly sentences.
- Discuss the different planets, and have your students develop a way of
distinguishing the planets from each other. Use the key characteristics
listed in the Background information. If you have pictures of the
planets, hang them around the room. Remember, you are just exposing the
students to the different planets and emphasizing the need to compare
and contrast their key characteristics.