What is Comet

A comet is a solid celestial body covered by organic material at rest, such as water, methane, ammonia or dry ice, which sublimates before solar energy, that is, they go from the solid to the gaseous state, without going through the liquid state.

The word comet comes from the Latin comēta, which means “hair”, alluding to the characteristic wake or tail that is generated in this celestial body when it approaches the Sun.

The path of a comet can be elliptical, parabolic, or hyperbolic, and the vast majority of comets travel periodically.

When a comet passes through the Earth’s atmosphere, it breaks down into multiple fragments, causing a shower of stars.

Origin of comets

Comets have two possible sources: the Oort cloud and the Kuiper belt.

Oort Cloud

It is a spherical formation that contains asteroids and comets inside. It is a hypothetical cloud, since it has not yet been seen, and it is believed to be located at the limits of the Solar System. Long-period comets are suspected to come from this cloud.

Kuiper Belt

It is a set of comets and other celestial bodies that orbit the Sun, near the planet Neptune. Short period comets are believed to come from there.

Structure of a comet

A comet is made up of five parts: nucleus, coma, ion tail, dust tail, and hydrogen envelope.


It is made up of ice and rocks. From here come the remnants of cometary dust that will later become part of the tail. It is the brightest part of the comet.


It is the cloud of dust and gas that covers the core.

Ionic glue

It is formed with the ions that are expelled from the nucleus. Its extension can reach several kilometers and although it is present in all comets, it is not always visible.

Powder glue

It is generated at the time of sublimation, when solar energy releases the dust found in the core.

Hydrogen sheath

When the comet absorbs ultraviolet light, it releases hydrogen, creating a kind of layer or envelope around it.

Comet classification

Comets are classified according to their size, their cometary age, and the periodicity with which they complete their orbit.

According to its size

  • From 0 to 1.5 km: dwarf kite.
  • From 1.5 to 3 km: small kite.
  • From 3 to 6 km: medium kite.
  • From 6 to 10 km: big kite.
  • From 10 km to 50 km: giant kite.
  • More than 50 km: Goliath.

According to his cometary age

The age of a comet is measured based on the orbits it has made around the Sun and is expressed in CY ( cometary years )

  • Less than 5 CY: baby kite.
  • Less than 30 CY: young kite.
  • Less than 70 CY: medium kite.
  • Less than 100 CY: old kite.
  • More than 100 CY: Comet Methuselah.

According to your translation period

The translational movement is the one made by the comet around the Sun. The periods of a comet can be:

  • Less than 20 years: short period kites.
  • Between 20 and 200 years: comets of intermediate period.
  • Between 200 and 1,000,000 years: long-period comets

There are comets that only pass once and then disappear forever, which is why they are called non-periodic. They are characterized by having parabolic or hyperbolic orbits. For their part, periodic comets have elliptical orbits.


by Abdullah Sam
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