Icy nucleus orbiting a glowing sun. The thin blue
curves along
the comet's orbital path. Camera drifts automatically — no interaction required.
A comet nucleus is often called a "dirty snowball": a loosely bound mixture of water
ice, frozen gases (CO2, CO, methane), dust and rocky grains left over from the solar
system's formation. As the nucleus nears the sun, solar heat sublimates the ices directly
from solid to gas, releasing dust and forming the glowing coma and two distinct tails.
The
ion tail is made of charged gas molecules swept up by the solar wind's magnetic
field, so it always points directly away from the sun regardless of the comet's direction
of travel. The heavier, neutrally-charged
dust tail is pushed more gently by
sunlight's radiation pressure and lags behind the comet's orbital path, producing its
characteristic curved shape.
- Nucleus size: typically 1–20 km across (Halley's nucleus: ~15 km)
- Composition: water ice, frozen CO2/CO, dust and rocky grains ("dirty snowball")
- Tail length: can reach tens of millions of km, briefly over 100 million km for Hale-Bopp
- Ion tail: bluish, straight, always points directly away from the sun
- Dust tail: yellow-white, broad and curved, follows the orbital path
- Coma (gas/dust envelope) can grow larger than the planet Jupiter
- Famous comets: Halley (76-yr period), Hale-Bopp, Hyakutake, NEOWISE
- Comet nuclei are among the darkest objects in the solar system (~4% albedo)