Origins
Most comets come from the Oort Cloud or from the Kuiper Belt. Comets from the Oort Cloud are called long-period comets and are less predictable, while those from the Kuiper Belt are called short-period comets.
Comets
Comets are theorized to have formed 4.6 billion years ago, when the solar dust in our solar system first began cooling and condensing.
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Anatomy of a Comet
Comets are “dirty snowballs” composed of frozen rocks, gases, and dust. Click on each part of the comet to learn more.
A. Nucleus
+The nucleus of the comet is its solid core consisting of frozen water, carbon monoxide, carbon dioxide, and many other oranic and inorganic molecules. It is usually around 10 kilometers (6miles) in diameter or less.
B. Coma
+As the comet gets closer to the sun, the ice on its surface sublimes into a body of gas around the nucleus. These clouds are often 1,000 times larger than the nucleus.
C. Ion Trail
+Charged solar particles from the sun covert some of the sublimed gases into ions, forming an ion trail. They can measure over 100 million kilometers long, and usually in a straight line.
D. Dust Trail
+Dust particles on the comet's surface are blown off by solar winds, forming a dust trail. They can measure up to 10 million kilometers, and usually curve off in shape.
E. Hydrogen Envelope
+Dust particles on the comet's surface are blown off by solar winds, forming a dust trail. They can measure up to 10 million kilometers, and usually curve off in shape.
How Many?
There are currently a known 3,883 comets.
Of those, about 160 comets are near-Earth objects (NEOs). The orbital paths of NEOs bring them closer in proximity to Earth's orbital, which can impact our planet and help advance our astronomy research.
Famous Comets
Scroll along to see some of the most notable comets in history.
Hally's Comet
First recorded in ancient civilizations as early as 1066, Halley is predictably visible to the naked eye about every 75 years.
Shoemaker-Levy 9
Most famous for its collision to planet Jupiter in 1994, it ripped itself apart into at least 21 visible fragments on impact.
Hale-Bopp
At a magnitude of -1, this comet was one of the brightest (and maybe most watched)comets to reach the inner solar system in recorded history.
When Will the Next Sighting Be?
Though it is a bit too soon to tell, some expect comet Tsuchinshan-ATLAS to be "the next Hale-Bopp." Discovered in February 2023, it will come close to the Sun and Earth in September to October of 2024, and has the potential to be a bright naked eye comet.
