No. They form in the outer solar system where it is cold enough.
In the outer realms of the solar system.
I scientifically believe that comets are closer to the outer part of the solar system.
When they reach the inner solar system.
Occasionally they enter the realm of the inner solar system and become visible .five kilometers is a typical size -- but some are much larger.
Comets originate from the Oort cloud, a spherical shell of icy bodies at the outer edges of our solar system. These comets can be perturbed and sent into the inner solar system where they become visible as they approach the Sun.
The comets that orbit the sun in elongated ellipses are thrown into the inner Solar System and the Sun by gravitational changes of the Kuipler Belt planets from the Oort Cloud, consisting of debris left of from a solar nebula.
All the comets that have been seen in history were in the solar system and most still are.
Comets are made up of remnants from the early solar system, so their age is generally around the same as our solar system, approximately 4.6 billion years old. While some comets may contain even older material from beyond our solar system, as a whole, comets are not older than our solar system.
the Oort Cloud, which is a spherical shell of icy objects located at the outermost reaches of the solar system. These comets are believed to originate from the early days of the solar system and occasionally get gravitationally nudged towards the inner solar system.
Comets can be found throughout the solar system, but they typically originate from the Kuiper Belt and Oort Cloud, which are located beyond the orbit of Neptune. While comets can pass through the inner solar system and be visible near Venus and Mercury, they do not originate primarily from that region.
Large planetesimals from the outer solar system when they are on a trajectory that leads them to the inner solar system. This keeps large enough asteroids and comets from coming into the inner solar system. This was made very aparent during the comet that crashed into Jupiter in the 90's.
Comets contain various types of ice (water and also other frozen liquids or gases) which sublime to vapor when the comet approaches the inner solar system.