# Physics

## Exhibits

#### Scale Model of the Solar System

A scale model of the Solar system hangs in the CCIS West Atrium. The model depicts the location of the planets on September 23, 2008, the 100-year anniversary of the University of Alberta.

The plane of the solar system is vertical. Try to imagine the planets moving in orbits over and under the Sun.

The technical design of the installation was by Craig Heinke and Marc van der Sluys. The artist Michael Prettyman interpreted the design and built the model out of fibreglass and plexiglass. The installation was made possible through a generous donation by the Edmonton Centre of the Royal Astronomical Society of Canada.

There are 3 different length scales used in this installation. This page will explain the different scales used.

#### Scale 1: Distance Between the Planets

• The real distance between the Sun and the Earth is 1.5 x 108 km = 150,000,000 km = 150 million km. Astronomers call this distance the Astronomical Unit (AU).
• In this model the AU was shrunk down to 50 cm, or a scale of 1:300 billion.
• The locations of the planets and the Sun (centre to centre) are all done to this same scale.
• The closest star to the Sun is Proxima Centauri. If we used the same scale, this star would be 130 km away, which is pretty close to the distance between Edmonton and Red Deer. (Red Deer is actually 150 km away.)
• If we used the same scale to display the Sun and the Planets, the Sun would have a diameter of only 5 mm, Jupiter would be 0.5 mm, and Earth would be 0.05 mm. This would be an accurate, but boring model!

#### Scale 2: Sizes of the Planets

• The sizes of the planets had to be increased so that we could see them.
• The scale used for the sizes of the planets is 1:180 million.
• The real diameter of Jupiter is 1.4 x 105 km = 140 thousand km.
• In the scale model, Jupiter has a diameter of 76 cm.
• The sizes of the planets and their rings are all made to the same scale.

#### Scale 3: Size of the Sun

• The Sun is approximately 10 times larger than Jupiter. If we made the Sun to the same scale as the planets, it would be 8 m in diameter, and the orbits of the 4 inner planets and Jupiter would lie inside of the Sun!
• The size of the Sun had to be shrunk so that we could show the orbits of the inner planets around it.
• The scale used for the Sun is 1:6 billion
• The true diameter of the Sun is 1.4 x 106 km = 1.4 million km
• In the scale model, the Sun's diameter is 22 cm.