Page 199 - Science Course 3 (Book 2)

Mo13-L1a: What are the Planets of Our Solar System?

It is easier to express very large distances using The planet would move
astronomical units rather than kilometers. in a straight line without The planet move faster
the Sun’s gravitational here because is close to
pull. the Sun.
Average Distance of Planets from the Sun
Average Distance Average Distance
Planet
(kms) (AU)
Mercury 57,910,000 0.39

Venus 108,210,000 0.72

Earth 149,600,000 1.00

Mars 227,920,000 1.52

Jupiter 778,570,000 5.20

Saturn 1,433,530,000 9.58

Uranus 2,872,460,000 19.20 The planet move in a The gravitational pull
slower here because it is of the Sun is always
Neptune 4,495,060,000 30.05 further from the Sun. towards the Sun.

A planet’s orbit is an ellipse—a stretched-out circle.
Key Concept

What are the Planets of Our Solar System? Focus points, or foci, determine the shape of the
ellipse.
Def ne what an astronomical unit is and explain
why it is used. Key Concept

What are the Planets of Our Solar System?

Describe the shape of a planet’s orbit.

SUMMARY

What are the Planets of Our Solar System?

The solar system contains the Sun, the inner
planets, the outer planets, the dwarf planets,
asteroids, and comets.

An astronomical unit (AU) is a unit of distance
The time it takes an object to travel once around the equal to about 150 million km.
Sun is its period of revolution.
The speeds of the planets change as they
The time it takes an object to complete one rotation move around the Sun in elliptical orbits.
is its period of rotation.
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