Solar System Orbital Data
Notes and Explanations:
Our solar system is located in a spiral galaxy known as the Milky Way, and our Sun is just one of about 400-billion stars in the galaxy. All the stars in this galaxy, including the Sun, orbit around the center of the Milky Way. Our Sun is about 28,000 light years from the center (which is known as the Galactic Center and is likely a massive black hole), and moving at a speed of around 250 kilometers per second it takes 220-million years to complete one orbit. (Note that an aircraft which traveled at 250 kilometers per second would take less than 20 seconds to fly from New York to Los Angeles.)
A number of bodies are affected by the gravitational pull of our Sun and thus orbit it while the Sun is already orbiting the Galactic Center; collectively, these bodies form the solar system. So far, there are nine named planets in the solar system -- Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. Numerous comets, asteroids, and meteoroids also orbit our Sun, while most of the planets have one or more Moons orbiting the particular planet. Note that all solar system orbits are retrograde, i.e. they orbit in anti-clockwise direction.
Solar system distances are very large indeed. The Sun itself has a diameter of about 863,700 miles, while Earth is about 93-million miles from the Sun, and Pluto is a whopping 3.67-billion miles away from the Sun (on average). To enable you to understand these vast distances, let us pretend that we build a scale model of the Sun somewhere in the center of the Europe, say in Berlin. Now, the Sun is huge, so let us make this model Sun in Berlin 278 meters (about 912 feet) in diameter. This is what we would have to do with the nine planets:
Mercury would be 975mm (38.4 inches) in diameter, and would be located about 11.5km (7.2 miles) away.
Venus would be about 2.42m (7.94 feet) in diameter, and would be located about 21.6km (13.4 miles) away, perhaps on the west side of Potsdam.
Earth would be 2.55m (8.4 feet) in diameter, and would be located about 30km (18.6 miles) away, located maybe more than halfway to Frankfurt.
Mars would be about 1.35m (4.43 feet) in diameter, and would be located about 45km (28 miles) away, now almost in the Frankfurt suburbs.
Jupiter would be 28.6m (94 feet) in diameter, and would be located about 156km (97 miles) away; the southern suburbs of Rostock would be a good location.
Saturn would be 24.1m (79 feet) in diameter, and would be located 286km (178 miles) away in the eastern part of Bremen.
Uranus would be 10.2m (33.5 feet) in diameter, and would be located 574km (357 miles) away, possibly on the east side of Warsaw.
Neptune would be about 9.89m (32.5 feet) in diameter, and would be located 900km (560 miles) away; Minsk or the west side of Paris would be good placement positions.
Pluto would be just 455mm (18 inches) in diameter, and would be located nearly 1200km (750 miles) away; St. Petersburg or Dublin are possible sites to display this model.
Earth, Mars and Earth's Moon, in correct proportion
Because distances are so immense, to make things easier astronomers have devised a special measurement called an astronomical unit (AU), which is defined as being the average distance of the Earth from the Sun, or 149,597,870.691 km (about 92.95-million miles). Jupiter is thus said to be 5.2 AU's from the Sun, while Neptune is just over 30 AU's out -- which is certainly simpler than saying, for example, that Neptune is 4,487,936,121 kilometers from the Sun.
The Sun, by the way, is not very big as stars go. By way of example, the orange-colored Betelgeuse, which can be seen in the constellation of Orion, is about 500 times bigger -- which means that if we were to construct a scale model of Betelgeuse centered where our Berlin Sun model is, Betelgeuse would have to be 139km in diameter. In this case, Mercury, Venus, Earth and Mars would all be contained within Betelgeuse, and Jupiter would be only a few kilometers away.
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© Sandra Rout, 2008
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