Did You Know?
Halley's Comet, appearing about every 76 years, is arguably the most famous comet. It is the only naked-eye comet that can appear twice in a human lifetime.
The comet's perihelion (nearest point to the sun) is 0.5 AU at a velocity of 55 km/sec; its aphelion (farthest point to the sun) is 35 AU at a velocity of 1 km/sec. Hence, it has an orbital eccentricity of 0.967.
It is one of the darkest, or least reflective, objects in the solar system. It has an albedo of 0.03, which means that it reflects only 3% of the light that falls on it.
The last time it was here was in 1986, and it is projected to return in 2061.
