How Far Is Mercury From The Sun?
QUICK ANSWER
Mercury orbits an average of 36 million miles (57.9 million km) from the Sun, making it the closest planet in our solar system. Because Mercury's orbit is highly elliptical, its actual distance ranges from about 29 million miles at its closest point to 43 million miles at its farthest.
Mercury is the Sun's closest neighbor, but the distance isn't fixed. Its orbit is the most elliptical of any planet, which means the gap shrinks and stretches by about 14 million miles every 88 Earth days.
What is Mercury's average distance from the Sun?
Mercury's average distance from the Sun is about 36 million miles, or 57.9 million kilometers. Astronomers also describe this distance as 0.39 astronomical units (AU), where 1 AU is the average distance between Earth and the Sun (about 93 million miles). So Mercury sits at roughly 39 percent of Earth's distance from the Sun. That proximity is why Mercury orbits so quickly: the Sun's gravitational pull is much stronger this close, and the planet completes a full orbit every 88 Earth days.
Why does the distance change so much?
Mercury has the most eccentric (elongated) orbit of any planet in our solar system. According to NASA, Mercury's distance from the Sun ranges from 29 million miles at perihelion (its closest approach) to 43 million miles at aphelion (its farthest). That's a swing of about 14 million miles over the course of each orbit. Most other planets have orbits that are much closer to circular; Mercury's pulled-oval path is the outlier.
How does that compare to other planets?
Mercury sits at 0.39 AU, while Venus is at 0.72 AU, Earth at 1.0 AU, and Mars at 1.52 AU. That means Venus is nearly twice Mercury's distance from the Sun, and Earth is about two and a half times as far. The outer planets are dramatically farther out: Jupiter sits more than 13 times Mercury's distance, and Neptune is over 77 times farther. By solar system standards, Mercury is hugging the Sun.
How long does sunlight take to reach Mercury?
Sunlight takes about 3 minutes and 13 seconds to travel from the Sun to Mercury. That same light then takes about 5 more minutes to reach Earth, for a total of roughly 8 minutes 20 seconds from the Sun to us. The numbers shift slightly as Mercury moves through its eccentric orbit, but the rule of thumb holds: when you see the Sun, you're seeing light that left it about 8 minutes ago. Mercury sees that same light 5 minutes earlier.
Mercury's distance from the Sun is a moving target, swinging between 29 million miles at its closest and 43 million miles at its farthest. The 36-million-mile average gets used in most reference materials, but the real story of Mercury's orbit is in the stretch. That elongated path is one of the things that makes its environment so extreme.
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