# Astronomy college course/Scale model of the solar system

See also http://www.openstreetmap.org/#map=17/40.54669/-84.50864 and http://www.openstreetmap.org/#map=19/40.54580/-84.50816 are open source files that are permitted on w:Wikimedia commons (with proper attribution).

Wikipedia has claimed that "if the Sun–Neptune distance is scaled to the length of a football pitch of about 100 metres, then the Sun is about 3 cm in diameter (roughly two-thirds the diameter of a golf ball) at one goal line with the gas giants all smaller than about 3 mm and Neptune found at the opposite goal line. Earth's diameter along with the other terrestrial planets would be smaller than a flea (0.3 mm) at this scale."

1. Is this true? Use an excel spreadsheet to verify this. The advantage of the spreadsheet is that if properly constructed, we can adjust the scaling and design our own scale model suitable for our own local environment.
2. Make a table of the diameters and orbital radii of all the planets (excluding Neptune). Include the Earth-Moon distance. Define a dimensionless scaling parameter that can be adjusted in order to make a custom designed scale model. This dimensionless number is the ratio of any distance divided by the corresponding distance on the miniaturized scale model. The meter is a convenient system of units for both astronomical and scaled lengths.
3. Use either local measurement or an internet program such as Google maps to find a distance that scales the actual Sun-Neptune distance to that of a local community such as the size of your town, campus, or building.
4. Construct the scale model. Simplest is to draw the objects on a piece of paper. You will need a strong magnifying glass and millimeter ruler to draw the terrestrial planets. Also easy is to find a ball to serve as the Sun and make the planets out of modeling clay. An alternative to actual construction is to design and estimate the construction costs of larger scale model for your local community. Then try to convince a person or organization to sponsor the construction of this model.

### Copy and paste

There is no need to look up information and copy it into Excel. If you click the word you will see a list that can be copied and pasted directly into Excel.

click to see planei names

Planet

Mercury

Venus

Earth

Mars

Jupiter

Saturn

Uranus

Neptune
click to see distances from the Sun

DistancefromSun(km)

57910000

108200000

149600000

227940000

778330000

1424600000

2873550000

4501000000
click to see diameters

Diameter(km)

4800

12100

12750

6800

142800

120660

51800

49500

The diameter of the Sun (km) has been reported as: 1392000[1] and 1391400[2]. The confusion being that it is a gas, and that the upper layer is so tenuous that it could be called a "hot vacuum" -- where it ends is a matter of choice.

## 2016 Spring Lake effort

### Phy1600 Astronomy

Goal: Set up scale model of solar system using Excel and this building. 10 Billion to one scale. How many AU is this building on that scale? We estimated the length of the building to be about 160 meters.

1 AU = 1.5E11 meters. Divide 1E10 (10 billion) to get 15 meters.

### Phy2400 General Physics

Prepare a document that explains the size of the transit of Venus shown in the image of the Sun. It looks like a dark shadow, but it is actually Venus as seen against the Sun in the background.

1. Measure the size of Venus and the size of its projection in the PDF file
2. Calculate the ratio of the angular sizes using geometrical arguments (similar triangles).
3. Prepare a one sheet explanation. Leave a one inch margin all around so we can post it on Commons. Put your real name, class and date in the margins. Either write "This document is donated to the Public Domain" inside the document, or post it yourself under your username. This lab will be graded. You may work in groups of one to five, all things being equal, the solitary efforts will receive better grades.

Tuesday's lab: Measurements taken with a ruler using the pdf paper copies: Measrements in mm. The magnified diameter of Venus was by five

 Venus Projection Ratio 0.75 3.75 x 1.2 5 x 1 4.5 x 1 3.5 x 1.4 5.1 x 1.4 4 x 1.2 3 m 1.4 4.8 m 1.2 3.5 m 1.2 3.5 m 1.2 6 m