Revised (2003) Standard 6.8
The Solar System

The student will investigate and understand the organization of the solar system and the relationships among the various bodies that comprise it. Key concepts include
a) the, sun, moon, Earth, other planets and their moons, meteors, asteroids, and comets;
b) relative size of and distance between planets;
c) the role of gravity;
d) revolution and rotation;
e) the mechanics of day and night and phases of the moon;
f) the unique properties of Earth as a planet;
g) the relationship of the Earth’s tilt and seasons;
h) the cause of tides; and
i) the history and technology of space exploration.
• The solar system consists of the sun, moon, Earth, other planets and their moons, meteors, asteroids, and comets. Each body has its own characteristics and features.

• The distance between planets and sizes of the planets varies greatly. The outer, “gas” planets are very large, and the four inner planets are comparatively small and rocky.

Observe the relative sizes of the planets.
Pluto is the smallest, Saturn and Jupiter the largest.
are like tiny planets. There are about 2000 of them orbiting around the sun, mostly on a path between Mars and Jupiter.
Meteors are chunks of matter orbiting the sun in orbits that cross the planets. When meteors occasionally hit the Earth's atmosphere, they vaporize and give off a streak of light.
Comets are balls of ice and rock circling the sun from regions beyond Pluto. Glowing clouds surround most comets, and tails of gas can often be seen trailing them as their orbits take them near the sun.
· The Earth is a geologically active planet with a surface that is constantly changing. Unlike the other four inner planets, it has large amounts of life-supporting water and an oxygen-rich atmosphere. The Earth’s protective atmosphere blocks out most of the sun’s damaging rays.

· The Earth is one of nine planets that revolve around the Sun and comprise the solar system. The Earth, third planet from the sun, is one of the four rocky inner planets. It is about 150 million kilometers from the sun.
Remember the order of the planets with the sentence: My Very Educated Mother Just Served Us Nine Pickles.
• Gravity is a force that keeps the planets in motion around the sun. Gravity acts everywhere in the universe.

• Planets revolve around the sun, and moons revolve around planets. A planet rotates upon an axis.
• As the Earth rotates, different sides of the Earth face toward or away from the sun, thus causing day and night, respectively.

Rotation or Revolution?

Rotation and Revolution: Planets revolve around the sun, and moons revolve around planets. A planet rotates upon an axis. The Earth completes one revolution (or orbit) around the sun every year (365 days). The Earth completes one rotation on its axis every 24 hours.

Day and Night
-As the Earth rotates, different sides of the Earth face toward or away from the sun causing day and night.
• The phases of the moon are caused by its position relative to the Earth and sun.

The Moon's Phases

· The moon revolves around the Earth every 27-28 days. The phases of the moon are caused by the moon's position relative to the Earth and the sun.  (we see only part of the sunlit side of the moon) The phases of the moon include the new, waxing crescent, first quarter, waxing gibbous, full, waning gibbous, last quarter, and waning crescent.


• The Earth is a rocky planet, extensively covered with large oceans of liquid water, and having frozen ice caps in its polar regions. The Earth has a protective atmosphere consisting predominantly of nitrogen and oxygen and has a magnetic field. The atmosphere and the magnetic field help shield the Earth’s surface from harmful solar radiation. Scientific evidence indicates that the Earth is about 4.5 billion years old.
• Seasons are caused by the tilt of the Earth on its axis, and thus, the angle at which sunlight strikes the surface of the Earth during its annual revolution around the sun.

Earth's Tilt and the Seasons

· Earth's tilt causes seasons:   The Earth is tilted on its axis as it revolves around the sun. The  hemisphere tilted toward the sun receives the sun's rays more directly and  therefore has warmer temperatures as well as  longer days (summer), while the half of the Earth tilted away has cooler temperatures and shorter days (winter).  It's important to realize that warmer summer temperatures occur because the Sun's rays are striking more directly, not because part of the Earth is closer to the Sun.


• Tides are the result of the gravitational pull of the moon and sun on the surface waters of the Earth.


-Tides are the result of the gravitational pull of the moon on the surface waters of the Earth.  The moon's gravity causes the oceans to bulge at the point nearest the moon, and also at the directly opposite point on the other side of the Earth.  The two bulges at opposite sides of the Earth is the reason why there are two high and two low tides every day. Twice a month, at the new moon and full moon, the tides are especially high because the sun is lined up with the moon and gravity from the sun pulls the oceans also. These are called "spring tides."  During first quarter and third quarter moons, the tides are low because the sun and moon are pulling in opposite directions and essentially canceling each other out. 

• The ideas of Ptolemy, Aristotle, Copernicus, and Galileo contributed to the development of our understanding of the solar system.
• With the development of new technology over the last half-century, our knowledge of the solar system has increased substantially.


• Our understanding of the solar system has changed from an Earth-centered model (Aristotle and Ptolemy) to the sun-centered model (Copernicus and Galileo).
• With the expansion of technology over the last half century, our knowledge of the solar system has increased substantially.
• SPUTNIK 1 - Modern space exploration began in 1957 with Soviet launch of this satellite
MERCURY PROGRAM - Sent the first Americans into space in 1961
• PROJECT APOLLO -  Landed 12 humans on the moon between 1969 and 1972.
• VOYAGER SPACE PROBES - Sent back pictures of Jupiter, Saturn, and Neptune. A space probe is a robot vehicle used to explore deep space.
• VIKING 1 AND 2 Landed on Mars in 1976 and sent back data about the planet's soil and atmosphere
• PIONEER PROBES - Used instruments to see through the thick clouds that cover Venus
• SPACE SHUTTLES - In use since 1981, the first reusable spacecraft
• HUBBLE SPACE TELESCOPE - Launched in 1990, it produces images five times as sharp as those from any telescope on Earth


In order to meet this standard, it is expected that students should be able to:

• describe the nine planets and their relative position from the sun.

• design and interpret a scale model of the solar system. (A scale model may be a physical representation of an object or concept. It can also be a mathematical representation that uses factors such as ratios, proportions, and percentages.)

• explain the role of gravity in the solar system.

• compare and contrast revolution and rotation and apply these terms to the relative movements of planets and moons their moons.

• model and describe how day and night and the phases of the moon occur.

• model and describe how the Earth’s axial tilt and its annual orbit around the sun cause the seasons.

• describe the unique characteristics of planet Earth.

• compare and contrast the ideas of Ptolemy, Aristotle, Copernicus, and Galileo related to the solar system.

• create and interpret a timeline highlighting the advancements in solar system exploration over the past half century. This should include information on the first modern rockets, artificial satellites, orbital missions, missions to the moon, Mars robotic explorers, and exploration of the outer planets.

• discuss the relationship between the gravitational pull of the moon and the cycle of tides.