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• 1 media/01 The Solar System PIA10231.jpg 2016-04-05T10:08:09+00:00 Orbits, Rotation and Temperature 10 image_header 2019-12-29T14:53:08+00:00 All planets orbit the Sun in the same sense:
  
  Each planet rotates and the axis and sense of rotation of these planets is very similar.  With the exception of Venus, Uranus and Pluto, the rotation axes of the planets are approximately parallel to the rotation axis of the sun and the sense of rotation is the same as illustrated in this image.
  
  As you might expect, planetary temperature decreases with increasing distance from the Sun.  The farther from the Sun the planet, the colder it is.  The big exception to that rule is Venus as illustrated in the graphic below (For comparison, the temperature to melt lead is 327.5˚C). We'll discuss that later. The temperatures in the graphic below of the gas and ice giants (Jupiter, Saturn, Uranus, and Neptune) are taken from a level in the atmosphere equal in pressure to sea level on Earth.
  There are also lots of objects besides planets in the solar system, as we'll see next.
• 1 2016-04-05T10:08:06+00:00 The Solar System to Scale 3 image_header 2016-07-12T12:14:48+00:00 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)