Module 1 - The Solar System

The Solar System to Scale

The solar system is very large, which makes it impractical to use kilometers as a unit of measurement for planetary distances.  But it is too small to use another familiar astronomical unit, the lightyear.  It takes the light from the sun only 8.3 minutes to get to Earth and only ~13 hrs to get to Pluto. As Earth-centric beings we have invented a unit of measurement that is referred to as the Astronomical unit (AU). It is defined as the mean Earth to Sun distance, or approximately 150 million kilometres. The distances in the planetary facts table are given in  AUs.  Distances for all inner planets vary between 0.387-1.52 AUs, while the outer planets have orbits starting at 5.2 AUs to 30.05 AUs  if you want to stop at Neptune, or 39.48 if you want to visit Pluto. The inner planets are clustered quite closely near the sun, while the outer planets are spaced far apart and quite far from the sun.  This makes static presentations of solar system dimensions difficult. As we have done in the graph below, the orbits of the inner planets must be displayed separately from those of the outer ones.

Fortunately there are a number of nice videos that illustrate the scale very well. We like this one:

Here is another one using drones.  (feel free to ignore the sales pitch in the middle)



 

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