Mercury: The Surprising Closest Planet to All Others
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Chapter 1: The Misconception of Closest Planets
When asked which planet is nearest to Earth, most people instinctively say Venus. While this is a common response, it is, in fact, incorrect. Many sources, including NASA, assert that Venus is our nearest neighbor in space. However, a recent article in Physics Today presents a more precise method for determining the proximity of planets. Surprisingly, this method reveals that Mercury is actually the closest planet to Earth—and to every other planet in the solar system.
This revelation stems from a common misunderstanding about the arrangement of planets. Although Venus orbits between Earth and Mercury, the distance from Earth to the sun is 1 astronomical unit (AU), with Venus sitting at 0.72 AU from the sun. You might think that this places Venus just 0.28 AU away from Earth, but this is only true for brief moments during its orbit. For the majority of the time, Venus is significantly farther away.
Chapter 2: Understanding Planetary Distances
The study in question employs a model that tracks the positions of all planets over a span of 10,000 Earth years. It assumes that planetary orbits are nearly circular and that they all move within the same orbital plane. This assumption holds true enough for the new distance rankings to be reliable. The researchers refer to this distance measurement method as the point-circle method (PCM), which calculates the average distance between two planets by considering all points along their orbits.
Mercury's orbit remains relatively close to the sun, while Venus can drift much farther from Earth during its journey. Although Venus can approach Earth at times, it can also be as distant as 1.72 AU. According to the PCM analysis, Mercury is closer to Earth nearly 50% of the time, with Mars and Venus sharing the remaining proximity.
Section 2.1: The Closest Relationships Among Planets
The findings extend beyond Earth and Venus—this principle applies to all planets in the solar system. For instance, even though Neptune is approximately 30 AU from the sun, it is, on average, closer to Mercury than Uranus, which orbits at 19 AU. Earth and Venus, like Neptune and Uranus, often find themselves on opposite sides of the solar system, despite their orbits eventually bringing them near each other.
Section 2.2: The Case of Dwarf Planets
As for dwarf planets like Pluto, while they don't qualify as traditional planets, there may be similar patterns. However, Pluto's orbit is distinct and crosses Neptune's path, making it incompatible with the PCM model.
Now read:
- FarFarOut: The Most Distant Object in the Solar System
- The Possibility of 50 Billion Rogue Planets in Our Galaxy
- NASA's Discovery of a Mercury Dust Ring and Implications for Hidden Asteroids Near Venus
Originally published at www.extremetech.com on March 18, 2019.