: To discover and take a close-up look at the characteristics and personality of each of the nine planets.
:. Size discrimination, number sequence review (with emphasis on ordinal numbers 1 through 10), classifying and categorization, spatial concept recognition (near-far, large-small . . . ) and directionality (left-right, front-back . . . ), measurement through estimated, non-standard units of measure; developing and enhancing language arts through journal writing, poetry and role play; becoming familiar with non-fiction literature; group/social interactive skill development.
* Note: Help your students conceptualize gases by relating to one with which they may be familiar. (Ask you children, for example, if they have ever seen a balloon inflated by a tank-like machine. The invisible substance that fills up the balloon, causing the balloon to float, is called helium. It is a very light gas—lighter than the air around us. Helium is one of the gases that surrounds many of the planets we will learn about.)
How many planets are there and what are planets?
In sequential order from our Sun, Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto constitute the nine planets. Planets can be grouped into two categories: Terrestrial-type or gas-giant planets. Earth, Mercury, Venus and Mars are terrestrial-types. These planets are for the most part rocky, hard, and small with little or no atmosphere (air and gases that surround the planet). They have land masses with hills, mountains, and valleys. One planet alone, Earth, has water—an essential life-giving substance.
Gas-giant planets are surrounded by thousands of miles of thick atmosphere. While they are enormous, they have low density. They rotate on their axes more quickly than terrestrial planets. Jupiter, Saturn, Uranus and Neptune are gas-giant planets. Pluto is an extremely low-mass planet, similar to a terrestrial planet.
Unlike our Sun, planets do not produce all or their own heat and light, but rather depend on the Sun to provide them. They differ in temperature based on their distance from the Sun. An invisible force called gravity keeps them in an elliptical orbit around the Sun, that is, they move around the Sun in an egg-like shaped path.
Planets move around the Sun in a fascinating way: Most spin or rotate on a tilted, invisible rod called an axis. While planets spin, they also orbit (revolve) around the Sun. A planet moves around the Sun faster when it is closer to the Sun, and slower when it is far away. It also rotates faster when it is less dense.
What are satellites?
Several planets have satellites, often referred to as Moons. The word “satellite” is tricky because it can have several meanings. Satellites created by scientist are machines that can be sent through space to learn more about our Solar System. When we, however, discuss satellites that belong to planets, we are describing their Moon(s).
Moons can have a powdery-rocky or icy surface, or a combination of both. They revolve around the planets, just like planets revolve around the Sun. Gravitational pull from a planet helps hold satellites in orbit.
What are the nine planets actually like?
(The use of NASA photos when presenting this information is preferred. See RESOURCE LISTING re: how to obtain complimentary space photos. In addition, the planet information that follows can be xeroxed, cut out and affixed to the back of obtained planet photos for quick-reference purposes.)
MERCURY, the nearest planet to the Sun, has a bumpy, cratered surface, similar to that of the Earth’s Moon. There appear to be a lot of cracks and cliffs on its surface. It has a core comprised mostly of iron and a mantle made of rocks much like Earth. Mercury revolves around the Sun the fastest of all the planets, but it rotates very slowly. Because of this the side of Mercury that faces the Sun is extremely hot. The side turned away from the Sun is extremely cold. Mercury has no satellite and no atmosphere to carry heat around the planet. No life has been found on Mercury. It takes 88 Earth days for Mercury to revolve around the Sun.
VENUS, the second planet from the Sun, rotates the slowest of all the planets. It is a little bit smaller than Earth, and it has no satellites, This planet is surrounded by poisonous, gaseous clouds and winds that blow from east to west. Its surface is filled with craters, enormous mountains, and some volcanoes that may still be active. Venus is extremely hot (the gases that surround Venus contribute to its extremely high temperature). The temperature on this planet is so intense, it can easily melt lead! Thus, no water nor living things have been found or can exist on Venus. It takes 225 Earth days for Venus to revolve around the Sun.
EARTH, the planet on which we live, is the third planet from the Sun. Our planet is the only one that has oceans, breathable atmosphere and all forms of life. Its surface is tilled with mountains, valleys, deserts, and plant-laidened stretches of land. If we were to travel way above the clouds and look down on our planet, we would see that the Earth is mostly covered with water. The rotation of the Earth on its axis gives us day and night. It takes 365 days for our planet to travel around the Sun: The revolution of the earth around the sun gives us our year and seasonal changes. Our planet has one satellite, a Moon called “The Moon”, covered by rocks, powdery seas, craters and mountains. It orbits the Earth in approximately 29 1/2 days. Our monthly calendar is based on that revolution.
MARS, known as the red planet because of its reddish color, is most similar to Earth of all the planets. The fourth planet from the Sun, Mars has deserts, enormous mountains, deep canyons and craters large and small. It has the largest volcano among all the planets. That’s where its similarity with Earth ends: Unlike our planet, there is no permanent water surface on Mars. Scientist believe there may have been in the past because of the frozen water and snow that appear on some portions of its surface. Because it is farther from the Sun than Earth, Mars’ temperature is much colder. No signs of life have been found on this planet. It takes 68 days for Mars to orbit our Sun.
JUPITER, the largest of the nine planets, is comprised mostly of hydrogen and helium gases. The surface we see from our telescopes is really a thick cloud layer. Scientist believe Jupiter’s surface is made up of gases, a small portion of liquid, and a rocky solid core. A thin ring with several satellites go around the planet. Jupiter’s atmosphere and pressure beneath the cloud layers causes this planet to be extremely hot. To date, sixteen Moons have been discovered to revolve around Jupiter. It takes 12 Earth years for this planet to orbit the Sun.
SATURN, the sixth planet from our Sun, is the most spectacular one. It is the second largest planet of the nine. Because of Saturn’s distance from the Sun, it is extremely cold. Saturn is surrounded by captivating rings made of small particles of ice and/or ice-covered rocks. To date, 17 Moons have been noted encircling this planet. It takes 29 Earth years for Saturn to revolve around the Sun.
URANUS is the third largest planet and the seventh from our Sun. It appears to be almost colorless, for it is slightly bluish green with a bland, smooth surface. It is surrounded by a gaseous (methane, helium and hydrogen) cloud. Like Jupiter and Saturn, it too has rings—eleven of them! When Uranus revolves around the Sun, it is tilted in such a way that its north and south poles point directly to our Sun. (In some instances, it’s north pole faces the Sun. Seasonal changes on this planet must be very different from those on Earth. We will learn why later on.) It takes Uranus 84 Earth years to travel around the Sun. This planet has 15 known satellites.
NEPTUNE is the fourth largest planet. Eighth from the Sun, it is much colder than Uranus and extremely colorful. Neptune is surrounded by a gaseous atmosphere, comprised mostly of hydrogen, helium and methane clouds. Strong wind gusts and gales occur on its surface. Its inner core is extremely hot. Neptune has several rings made of dust and small rocks and is to date is known to be encircled by eight satellites. Titan is its most well-known Moon. It takes 165 Earth years for Neptune to revolve around the Sun.
PLUTO, the ninth planet and farthest away from the Sun, is so distant that not much is known about it. Space scientists have, however, learned that Pluto is very small. (If we could stand on Pluto, our Sun would look like a very bright star.) It has one satellite, Charon. Both this planet and its Moon appear to be completely covered with ice and frozen (methane) gas. Pluto’s temperature is extremely cold (350 degrees below zero F). It takes Pluto 248 Earth years to travel around the Sun! Space researchers have also learned that, for now, something unusual is happening to the orbit of Pluto. Although this planet is furthest away from the Sun, its orbit during the 1990s has made it “trade places” with Neptune. For now, it is not the ninth, but the eighth planet. NASA scientists state this phenomena will continue through 1998.
Are there any more planets beyond Pluto?
Although not proven, scientist believe there may be a planet much farther out than Pluto. Perhaps you will become the scientist who makes this discovery!
Postcards from the Planets
by David Drew.
Related Creative Writing/Math/Art Activity
: Have your students pretend they have visited the planets. Based on prior visual presentations and discussion, have them describe shapes that can depict their spacecraft and celestial objects, each planets’ characteristics, the clothing they had to wear, life forms if any, and how they felt being on the planet. (See Appendices B and C)