What does JFC mean in ASTRONOMY

Jupiter family comets are a group of short-period comets that have similar orbits that share common origins from the Kuiper belt. These comets have orbital periods of less than 20 years and often originate from the same region in the outer solar system. While some are highly active, others are dormant objects with low activity levels or no activity at all.

One of the most famous JFCs is comet Halley; discovered by Edmond Halley in 1705, it has an orbital period of around 76 years and returns to Earth's vicinity approximately every 75-76 years. Several pieces of the spacecraft Giotto flew past Halley in 1986, making it one of the most studied comets in history.

Most JFCs originate from two different regions; either near Neptune's orbit, which is known as the "Scattered Disk" region, or beyond Neptune's orbit, which is known as the "Kuiper Belt". The majority of these comets spend millions of years slowly migrating towards the inner part of our solar systems before they become visible to us.

The names given to JFCs typically come from their discoverers; typically astronomers who explore and observe this type of comet for further study. As such, many JFCs have been named after famous scientists such as Galileo Galilei or Johannes Kepler.

Generally speaking, Jupiters family comets have relatively short orbital periods ranging from 5 to 20 years. This means that after completing one full orbit around the sun they return much closer to Earth than longer-term comets like Hale-Bopp which can take thousands/millions of years for each complete orbit around our star.

Generally speaking, a typical JCF features a bright condensation nucleus - sometimes referred to as its “head” - surrounded by plasma tails caused by volatile gases sublimating off its surface due to heat from sunlight when close enough to perihelion(closest approach). Additionally these comets often sport multiple tails depending on their composition and range in size up to several kilometres across.

In general these types of comet are classified according to their spectrum/colour index – specifically those that measure higher than 0 on what’s called an “HZ” plot – which is derived from measurements taken using CCD cameras or spectrography observations over time in order to determine how much light is entering/absorbed by each object respectively.

Not necessarily; while most do display tail phenomena due primarily to gas sublimation during perihelion passage some may not always be active depending on their distance and angle relative to the Sun at any given time therefore extinguishing their associated tails altogether.