1. Newton
17th century calculated that Sirius (one of the brightest stars was 1 million times further away than the sun (1 million AU)
Compared brightness of Sirius to brightness of Saturn
Actual distance to Sirius = 550,000 AU

2. Measuring with Triangulation and Parallax
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Measuring with Triangulation and Parallax
Triangulation
Method of measuring distance indirectly
Done by creating an imaginary triangle between an observer and an object who’s distance needs to be discovered

3. Triangulation A) Create a baseline
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Triangulation
A) Create a baseline
In this case line A to C
B) Measure angles from the two points on the baseline
In this case Angle A and Angle C
C) Make a scale drawing of the triangle using a protractor and a ruler

4. Greeks
Used triangulation 2000 years ago to calculate the distance between the Earth and Moon
Baseline was 300 km
Also knew they would have to take into account the curvature of the Earth.

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Parallax
Is the apparent shift in position of a nearby object when it is viewed from two different points.
Eg: Point finger close one eye then the other eye.
Using Earths orbit
Sightings are taken 6 months apart
If a star is close enough it will appear to move relative to more distant stars