53 billion kilometers!
Comet Hale-Bopp, the Great Comet of 1997, travels around the Sun on a long, stretched orbit. At the farthest point of that orbit, it will be about 53 billion kilometers from the Sun, more than 350 times as far as Earth is. It will not get there until around the year 3200.
Hale-Bopp's orbit is an ellipse, but a very stretched one. Its closest point to the Sun, called perihelion, is inside Earth's orbit. The comet last passed it on April 1, 1997, about 0.91 astronomical units (au), or 137 million kilometers, from the Sun. One au is about 150 million kilometers, Earth's average distance from the Sun.
The farthest point, called aphelion, is about 390 times as far out as the closest. It is calculated from the comet's observed path, since the comet will not arrive there for about 1,200 years. Orbit calculations by NASA's Jet Propulsion Laboratory and the Minor Planet Center put it at 354–360 au, or 53–54 billion kilometers. The figures differ slightly with the method and the date each orbit was worked out for.
One trip around the whole orbit takes about 2,400 years. As of September 2026, the comet is about 51 au (7.6 billion kilometers) from the Sun and heading outward at about 5.4 kilometers per second.
Alan Hale in New Mexico and Thomas Bopp in Arizona each discovered the comet on July 23, 1995. It was then 7.15 au from the Sun, still almost two years from its closest approach. Its official name, C/1995 O1, records the year of discovery, and the "C" marks a long-period comet.
Hale-Bopp's nucleus, the solid body at its center, is about 60 kilometers (37 miles) across, which is large for a comet. Because of its size, the comet could be seen without a telescope for 18 months in 1996 and 1997.
On April 5, 1996, on its way in toward the Sun, Hale-Bopp passed about 0.77 au (115 million kilometers) from Jupiter. The giant planet's gravity changed the comet's orbit.
Before that encounter, the orbit took about 4,200 years and carried the comet out to about 520 au, or 78 billion kilometers. The encounter shrank the orbit, cutting the time for one trip to about 2,400 years.