What are Comets?

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

The path of a comet can be elliptical, parabolic or hyperbolic, and the vast majority of comets make periodic journeys.

When a comet passes through the Earth’s atmosphere, it breaks up into multiple fragments, causing a meteor shower.

structure of a comet

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


It is made up of ice and rocks. From here the remains of the cometary dust come out, which 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 tail

It is formed with 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 tail

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

Hydrogen envelope

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

Classification of comets

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

According to your 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: large kite. From 10 km to 50 km: giant kite. More than 50 km: Goliath.

According to your 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 comet. Less than 30 CY: young comet. Less than 70 CY: medium comet. Less than 100 CY: old comet. More than 100 CY: Methuselah comet.

According to your translation period

The translational movement is what the comet makes around the Sun. The periods of a comet can be:

Less than 20 years: short period comets. Between 20 and 200 years: intermediate period comets. 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.

Origin of comets

Comets have two possible origins: 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 group of comets and other celestial bodies that orbit around the Sun, near the planet Neptune. Short period comets are believed to come from there.

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