How Far Is Pluto From The Sun?

QUICK ANSWER

Pluto's distance from the Sun varies dramatically. At its closest (perihelion), Pluto is about 2.7 billion miles from the Sun. At its farthest (aphelion), it's about 4.6 billion miles away. The orbit is so elliptical that Pluto was actually closer to the Sun than Neptune from 1979 to 1999.

Pluto has one of the most eccentric orbits of any major body in our solar system. Its distance from the Sun varies by nearly 2 billion miles between closest and farthest approaches, which is unusual enough that for a 20-year stretch in the late 20th century, Pluto was actually closer to the Sun than Neptune.

How far is Pluto from the Sun on average?

About 3.7 billion miles on average. According to NASA, Pluto orbits the Sun at an average distance of 3.7 billion miles (5.9 billion km), or roughly 39.5 astronomical units (AU). For reference, 1 AU is Earth's distance from the Sun, about 93 million miles. Pluto sits in the Kuiper Belt, a vast region of icy bodies beyond Neptune's orbit. The average distance is much less useful for Pluto than for most planets because Pluto's orbit is so elliptical.

How much does Pluto's distance change?

Dramatically. Pluto's orbit has an eccentricity of about 0.249, the highest of any major body in the solar system other than some asteroids and comets. At perihelion (closest approach to the Sun), Pluto is about 2.7 billion miles from the Sun. At aphelion (farthest), it's about 4.6 billion miles. The 1.9 billion mile variation is huge: at perihelion, sunlight is about three times more intense than at aphelion, enough to noticeably affect Pluto's surface temperatures and atmospheric activity.

Was Pluto really closer to the Sun than Neptune?

Yes, from February 1979 to February 1999. During those 20 years, Pluto's elliptical orbit brought it inside Neptune's nearly circular orbit, making Neptune the most distant planet from the Sun. The two bodies never collided or even came close to each other, because their orbits are tilted relative to each other and the gravitational resonance between them keeps them separated. Pluto won't return to the inner part of its orbit until around the year 2227, far beyond any human lifetime.

How long does it take to reach Pluto?

About a decade with current technology. NASA's New Horizons spacecraft, the only mission ever to visit Pluto, launched in January 2006 and reached Pluto on July 14, 2015, a journey of just over 9 years. New Horizons traveled at speeds exceeding 35,000 mph, making it one of the fastest spacecraft ever launched. Even at that speed, Pluto was so far away that radio signals from the spacecraft took about 4.5 hours to reach Earth during the flyby. Returning samples from Pluto would take much longer.

Pluto's distance from the Sun varies dramatically because of its eccentric orbit, ranging from 2.7 billion miles at closest to 4.6 billion at farthest. For 20 years in the late 20th century, Pluto was actually closer to the Sun than Neptune. The variation affects Pluto's climate and atmosphere, with the planet being warmest and most active near perihelion. New Horizons remains the only spacecraft to have visited.

How Far Is Pluto From The Sun?