Astronomy:From planets to the Universe

Our solar system

• The sun is a very ordinary star among thousands of millions of other stars in the Milky Way galaxy.

• It has a planetary system made up of planets, dwarf planets, moons, asteroids, comets and other material left over after its formation.

Lets start with our Solar System

Planets in our solar system:

• Mercury• Venus• Earth• Mars

• Jupiter• Saturn• Uranus• Neptune

Solar system

• What do you think is incorrect about this representation of the solar system?

• They are misleading as they do not show the relative sizes of our sun and the planets or the vast distances between them.

Task : Constructing a model.

• To appreciate the relative size of the sun and the planets we shall make a model.

• Using the items suggested on the chart, arrange them in the correct order and make labels for them.

Body Diameter Distance to scale from one object to next / m

Distance to scale of object to sun / m

Suggested object

Sun 240 10 - Basketball

Mercury 0.8 9 10 Pinhead

Venus 2 7 19 Peppercorn

Earth 2.1 13 26 Peppercorn

Mars 1.1 95 39 Pinhead

Jupiter 24 112 134 Grape

Saturn 20 249 246 Marble

Uranus 8 281 493 Dried pea

Neptune 7.8 244 774 Dried pea

• Now that we have represented the solar system, we must try and understand the scale .

• Calculate the approximate scale if:• If the earth is 12,724 km wide and in this

model it is 2.1 mm• The sun is 1,391,900 km in diameter whereas

the basketball is only 240 mm in diameter.

• The scale is approximately 1: 6,000,000.• This means that 1 m will represent about

6,000,000 km. ( every cm represents 60,000 km)

• To demonstrate this effectively we shall go outside and use a trundle wheel to space out the distances between the planets.