Unit 3 “The Solar System” 6th Grade Space Science Key Concepts

Key Concept Scientists use models to demonstrate ideas, explain observations, and make predictions.

Key Concept Telescopes allow astronomers to observe distant objects in space that might otherwise not be seen. Scientific explanations are based on evidence gathered from observations and investigations.

Key Concept Planets orbit stars. Moons orbit planets.

Key Concept The solar system is centered around the Sun – the only star in the Solar System. (Heliocentric Model) Many diverse objects make up the Solar System.

Key Concept Scientists categorize objects in the Solar System by characteristics, such as: shape, and appearance, what they orbit, how large they are, and how far away their orbits are from the Sun.

Key Concept Not every Solar System object can be easily categorized. Solar system objects have a wide variety of characteristics.

Key Concept In general, the farther away a planet is from the Sun, the colder its temperature.

Key Concept The inner planets (Mercury, Venus, Earth, and Mars) are smaller in size than the outer planets. The composition of the inner planets is mostly rocky.

The Inner Planets

Key Concept The composition of the outer planets (Jupiter, Saturn, Uranus, and Neptune) is mostly gaseous. With the exception of Mercury, all the planets have atmospheres.

The Outer Planets

Key Concept The Solar System is mostly empty space and is very large compared to the objects within it. The Solar System formed from gas and dust, which gravity drew together into a whirling stream.

Key Concept Planets closer to the Sun have smaller orbits and move more quickly than planets farther from the Sun. Objects in the Solar System are in regular and predictable motion. As seen from Earth, the positions of the planets and the Sun are always changing.

Test Hint… If you know the order of the planets and whether they are an inner or an outer planet, then it can help you remember if their: Temperature is warmer or colder than Earth. Size is larger or smaller than Earth. What it is made of – mostly gas or mostly rock. Has an atmosphere or has NO atmosphere.

The Solar System