The order of the planets is something most of us learn in school: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and (until 2006) Pluto.
So they would forgive you for thinking that as Earthlings, our nearest planetary neighbor is Venus. And somehow, you would be right: at its closest point, Venus is closer to Earth than any other planet in the Solar System. Similarly, its orbit is closer to our orbit than any other. However, in another sense, you are wrong. At least that’s the point of an article in Physics Today.
To identify our nearest neighbor, NASA-affiliated engineers, the Los Alamos National Observatory, and the U.S. Army Engineers Research Development Center built a computer simulation to calculate the average proximity of the Earth to its three nearest planets (Mars, Venus and Mercury) over a period of 10,000 years. Due to the way the planets align during their respective orbits, the model shows that the Earth spends more time closer to Mercury than Venus or Mars.
“In other words, Mercury is closer to Earth, on average, than Venus because it orbits closer to the Sun,” the authors explain.
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In fact, it is not just the Earth. Additional calculations suggest that the seven planets in the Solar System (minus Mercury) pass most of their orbit closer to the “winged messenger” than any other planet. Sounds impossible? That’s how they worked.
The results are based on a technique called the dot-circle method (PCM), essentially a mathematical equation that takes the orbits of two planets as circular, concentric, and coplanar, and calculates the average distance between two planets as they orbit the sun.
“From the PCM, we noticed that the distance between two bodies in orbit is minimal when the inner orbit is minimal,” the authors explain.
“This observation results in what we call the turbulent corollary (named after an episode of the cartoon Rick and Morty): for two bodies with approximately coplanar, concentric circular orbits, the average distance between the two bodies decreases. as the radius of the inner orbit decreases “.
“From this corollary, and from the table, it is clear that Mercury (average orbital radius of 0.39 AU), not Venus (average radius of 0.72 AU), is the closest planet to Earth on average. “. (AU are astronomical units, the distance between the Earth and the Sun.)
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To test their hypothesis, they built a computer simulation that tracked the positions of the four planets over a period of 10,000 years and calculated the average distance between them. The results of this simulation differ from traditional calculations (determined by subtracting the average radius of the inner orbit from the average radius of the outer orbit) by a staggering 300 percent. However, it differed from PCM calculations by a relatively insignificant 1 percent.
He found that the average distance between Earth and Venus was 1,136 astronomical units (0.28 according to the “ancient method”). In comparison, the average distance between Earth and Mercury was 1,039 astronomical units (0.61 according to the “ancient method”).
The hypothesis has yet to be presented in a peer-reviewed article and will no doubt be thoroughly cross-examined by experts in the field, but the authors have already pointed out some possible uses for their newly designed PCM equation. .
“With the correct assumptions, the PCM could be used to get a quick estimate of the average distance between any set of orbiting bodies,” the authors write.
“It may be useful to quickly estimate satellite communication relays, for which the signal strength decreases with the square of the distance. In any case, at least now we know that Venus is not our nearest neighbor, and that Mercury belongs to everyone. “
[H/T: Physics Today]
This article was originally published in March 2017