NucleusA frozen core of ice and dust, often a few miles across.
ComaA cloud of gas and dust that forms as the ice warms.
Ion tailCharged gas; it always points straight away from the Sun.
Dust tailDust pushed off by sunlight along a broad, gently curving path.
JetsGas bursting out of the nucleus and carrying dust with it.
Around it 3
OrbitThe comet’s path around the Sun, a long stretched oval.
Solar windHigh-speed particles from the Sun that blow the coma’s gas back.
SunIts heat turns the comet’s ice to gas.
How this list was compiled: Every name checked on 2026-09-30 in two independent places, NASA and Wikipedia. (1) NASA Space Place, What Is a Comet?, https://spaceplace.nasa.gov/comets/en/ (nucleus, coma, jets of gas, dust tail, ion tail, orbits as long stretched ovals). (2) NASA Science, Comets: Facts, https://science.nasa.gov/solar-system/comets/facts/ (nucleus, coma, dust tail and ion or gas tail, the solar wind, jets of dust). (3) Wikipedia, Comet, https://en.wikipedia.org/wiki/Comet (nucleus, coma, tails, jets, solar wind, orbital characteristics). Licence: own work
The drawing: Drawn for this site on 2026-09-30 from plain geometry. Own original drawing; nothing is traced or copied. Licence: own work
How it works
Label the parts of a comet as it nears the Sun: a small nucleus, the cloud round it, the jets that feed the cloud and two tails, with the orbit the comet follows.
Read the full guide
Why a comet grows a head and tails
Far from the Sun a comet is only its nucleus, a frozen lump of ice and dust. Near the Sun the ice turns to gas, jets burst out, and gas and dust form the coma. Sunlight and the solar wind then sweep them back into tails.
Telling the two tails apart
The ion tail is narrow and points directly away from the Sun. The dust tail is broad and curves gently. Both point away from the Sun, whichever way the comet is traveling.
Questions and answers
What are the parts of a comet?
A nucleus of ice and dust, a coma of gas and dust around it, and two tails, one of dust and one of ions. Jets of gas burst from the nucleus when the Sun warms it.
Why does a comet have two tails?
Dust and gas leave the comet differently. Sunlight pushes the dust into a broad, curved tail, while the electrically charged gas is carried straight back by the solar wind.
Which way does a comet’s tail point?
Away from the Sun, whichever way the comet is moving. The ion tail points directly away; the dust tail points away at a slightly different angle.
How big is the nucleus of a comet?
Small. NASA says it is usually less than 10 miles (16 kilometers) across, about the size of a small town.