Activities

1. What materials compose a comet?
   
   
2. According to the International Astronomical Union (IAU), what are the three criteria necessary for an object in the solar system to be considered a planet?
   
   
3. What is a dwarf planet?

4. How is the Earth related to a meteoroid?  A meteor?  A meteorite?
   
   
5. Select an inner planet.  How is this planet similar to Earth?  How is it different?
   
   
6. Select an outer planet.  How is this planet similar to Earth?  How is it different?

7. Some people believe that one day the Earth will be uninhabitable.  If this happens, people will need a new place to live.  Which planet do you think would be the best place to relocate Earth’s population?  Write a newspaper article persuading them to move to the planet of your choice.  Support your argument using facts about your planet that will help persuade the citizens of Earth.  Make sure to list some similarities to Earth to help convince your readers!

Answer Key/Rubric

1. Comets are made of dust and ice.
   
   
2. The criteria necessary for a body to be considered a planet is:

• It must orbit the Sun.
• It must be a sphere.
• It has a clear orbital path around the Sun.

3. A dwarf planet is a small object in space that resembles a planet, but does not meet all of the criteria set by the IAU to be considered a planet.

4. Acceptable responses may include, but are not limited to:

• A meteoroid can be found outside of the Earth’s atmosphere.  It is still in space.
• A meteor is inside of the Earth’s atmosphere.  Once the meteor is in the Earth’s atmosphere, it begins to fall toward the Earth’s surface.
• A meteorite is on the Earth’s surface.  It was once a meteoroid and a meteor, but when it touches Earth’s surface, it becomes a meteorite.

5. Acceptable responses may include, but are not limited to:

Similarities:

• Mars and Earth are both inner planets.
• They both have rocky surfaces.
• Both planets have an atmosphere.
• Both have similar surface features (mountains, canyons, polar ice caps, volcanoes, valleys).
• Both planets have iron in the soil.

Differences:

• Mars is about half the size of Earth.
• Mars does not have liquid water on its surface.
• Mars does not have life.
• Most of the atmosphere on Mars is carbon dioxide.  There is also argon and nitrogen.
• Earth’s atmosphere is mostly nitrogen and oxygen.

6. Acceptable responses may include, but are not limited to:

Similarities:

• Earth and Neptune both orbit the Sun.
• Earth is an inner planet.
• Both planets have an atmosphere.
• Both planets have at least one moon.  Earth has one moon.  Neptune has 13 moons.

Differences:

• Neptune’s atmosphere is mostly hydrogen, helium, and methane.
• Earth’s atmosphere is mostly nitrogen and oxygen.
• Neptune has six rings.  Earth does not have rings.
• Neptune does not support life.
• Neptune is larger than Earth.
• Earth is closer to the Sun.
• Neptune is made of gas.
• Neptune is an outer planet.

7. Use the following rubric to grade the student's response.  Answers will vary.