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CometsComets are celestial objects composed of frozen gases, rock, and dust. They are characterized by two tails as they orbit near the sun, whose radiation and solar wind vaporize and push gas and dust away from the comet. Comets serve as frozen archives of early solar system chemistry, and some models suggest they played a crucial role in bringing water to Earth during its formation. Most comets come from two regions of leftover material from the formation of the sun and planets: the Kuiper Belt—a disc of material beyond Neptune, approximately 20 times wider than the asteroid belt—and the Oort Cloud—a spherical shell of icy objects orbiting between 5,000 and 100,000 times the Earth-sun distance. Minor gravitational disruptions can bring comets in these regions toward the inner solar system on highly elliptical orbits. Those originating from the Kuiper Belt can have orbits that repeat with periods of less than 200 years, while those from the Oort Cloud may have periods of about a million years. Comets are named after the person, observatory, or mission that discovered them following a coded naming system developed by the International Astronomical Union.Explore Comets
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Find which comets are currently visible in the night skyIncorporating sightings reported in the Comet Observation database and information from NASA's Jet Propulsion Laboratory, this list provides a finder chart, star map, tracker, simulated orbit, and key properties for each comet, all viewable based on a user's input position on Earth. The Sky LiveExplore a guide to observing cometsBinoculars or telescopes can be used to see vivid tails, glowing comas, and brief bursts of brightness from these celestial objects. For photography, a DSLR or mirrorless camera with a wide-aperture lens, long exposure settings, and accessories such as tripods and star trackers is recommended. Space.comDark comets appear to be rocky asteroids but move like cometsCometary orbits are known to exhibit accelerations independent of gravity that result from forces related to the release of gases. Dark comets exhibit this behavior but lack visible clouds of frozen material that have turned into a gas—the coma the comets display—indicating minor quantities of escaping subsurface ice. University of MichiganView a gallery of notable cometsThe collection features 1973's Kohoutek, which had been dubbed the "comet of the century," 1965's Ikeya-Seki—one of the brightest comets of the millennium—and 2002's NEAT, a comet that survived a coronal mass ejection as it passed near the sun. Astronomy.comThe ancient Greeks and Romans viewed comets and meteors as divine omensBoth considered the appearance of a comet or its fragments as a precursor to significant events, such as the birth of a notable figure or the death of a ruler. One observed in 44 BCE was believed to be a sign of the deification of Julius Caesar after his assassination. The ConversationShooting stars, or meteors, are fragments of asteroids and comets that burn up as they enter Earth's atmosphere, creating streaks in the sky called meteor showers. NASAThe Oort Cloud is a shell of icy objects surrounding the solar system, from which many comets originateProposed in 1950 by Jan Oort, the theoretical structure is believed to be the origin of comets with periods of more than 200 years. Leftover planetary building blocks from the early solar system formed the Oort Cloud after being flung out by the gravity of planets like Jupiter. Space.comThere may be over one trillion comets in the Kuiper BeltNamed after Gerard Kuiper, who theorized the existence of a band of icy objects beyond Neptune in 1951, direct evidence for its existence did not arrive until 1992, when the first trans-Neptunian object, besides Pluto and its moon Charon, was observed. Comets with periods of less than 200 years originate from this belt. NASAComets can be categorized based on their orbital periodShort-period comets orbit around the sun once every 200 years or less and are made up of Jupiter-family (less than 20 years) and Halley-type (between 20 and 200 years) comet subgroups. Long-period comets have orbits greater than 200 years, while exocomets originate in solar systems outside our own. ESAThe names of comets can change based on subsequent observationsThe International Astronomical Union's coded naming system uses the first letter to indicate a comet's category, which can change over time. "D" represents comets that have been lost or broken up, while "A" applies to former comets that are now asteroids or dwarf planets. ESAHypotheses on the origins of Earth's water, from comets and asteroids to magma oceansBefore Earth's atmosphere formed, any liquid water would have boiled off, preventing the accumulation of water early on to create today's oceans. Planetary scientists continue to debate whether this water was delivered later from comet or asteroid collisions or via reactions between iron oxide in Earth's molten surface and hydrogen gas from the planetary nebula. Short WaveComets serve as time capsules of the early solar systemThe frozen objects preserve the molecular composition of the solar system's formation, dating back about 4.6 billion years. Spectral analysis of the gases they release when heated upon approaching the sun in eccentric orbits reveals this composition and helps assess solar system formation models. In Our Time: ScienceThe composition of comets earned them the nickname 'dirty snowballs'The icy relics of the solar system are composed of rock, gravel, dust, and frozen molecules, such as carbon dioxide, carbon monoxide, methane, ammonia, and water. Once close to the sun, these compounds sublimate into gases, creating a fuzzy cloud that earned the comets another nickname in history: hairy stars. CrashCourseNASA monitors potentially hazardous asteroids and cometsEstablished in 2016, the Planetary Defense Coordination Office characterizes and tracks asteroids and comets passing within 30 million miles of Earth. Over 40,000 near-Earth asteroids have been discovered, although estimates suggest that about 14,000 more such objects remain to be found. NASA ScienceExplore an interactive solar system with 3D visualizations of meteor showers—streams of dust-like debris left behind from comets or asteroids that burn up in Earth's atmosphere.Every year, Earth travels through a series of meteor showers—the Perseids in August, the Lyrids in April—and a fraction of them light up the sky as they hit the atmosphere. Explore each group of meteors with this fascinating, year-round interactive. Ian WebsterExplore the known asteroids, comets, and spacecraft involved in asteroid studies within our solar system with 'Eyes on Asteroids,' a 3D visualization from NASA.Explore the 3D world of asteroids, comets, and NEOs. Learn about past and future missions, tracking and predicting orbits, and close approaches to Earth. NASAWhere radon comes from and why it may be the most dangerous source of radioactivityReleased from underground bedrock before passing through soil, this radioactive gas is produced from the decay of uranium, thorium, and radium and accounts for about half of all human exposure to radiation. It is the leading cause of lung cancer among nonsmokers and can build up in enclosed spaces such as buildings without proper ventilation to dilute the gas. International Atomic Energy AgencyAmerican local government comes in five distinct formsCounties, municipalities, townships, special districts, and school districts are each created for a different purpose, operating under different rules, and answerable to the state in different ways. Special districts, the least known of the group, are created for specific purposes, such as transit or fire protection. National League of CitiesMalaria comes from the Italian term 'mal'aria,' meaning 'bad air'The term refers to marshy areas associated with the disease. An estimated 94% of malaria cases—215 million—occur in Africa. National Library of MedicineMold growth in space raises the hypothesis of life being brought to EarthPanspermia suggests that life could be carried throughout the cosmos by asteroids, comets, and other objects, but it requires organisms that can withstand the extreme cold of space travel, stellar radiation, lack of water, and intense heat of planetary impacts. The discovery of mold on the International Space Station and experiments showing it can withstand radiation in outer space-like conditions increase the plausibility of the hypothesis. StarTalkA year before Elvis appeared on 'Ed Sullivan,' Bill Haley brought rock 'n' roll to the programAlthough Elvis Presley's 1956 appearance on the popular TV show is viewed as a key moment in the rise of rock 'n' roll, the music appeared on the program a year earlier, on August 5, 1955, when Bill Haley and His Comets performed their hit "Rock Around the Clock." The Ed Sullivan Show'Graffiti' comes from the Italian for 'a scribbling'The word was first used in 1851 to describe the ancient inscriptions on Pompeii's walls. "Graffiti" is the plural form of "graffito," which means "a scribbling." EtymonlineThe word peptide comes from GreekOriginating from the Greek term "peptos," which means digestible, peptide as a word refers to two or more amino acids. (Some users may encounter a paywall.) Springer NatureThe word 'restaurant' comes from the Latin for 'restore'Many believe the word came into use thanks to Boulanger, an 18th-century Parisian soup vendor. According to legend, his shop claimed it served "bouillons restaurants," or "restorative broths." Merriam-WebsterThe word 'Peloton' comes from the word for the main group of riders in a cycling raceThe word itself is French for "ball," but became the inspiration for the word "platoon" in the 17th century to describe a group of soldiers. Now, it's a common cycling term and the main focal point in cycling races. Merriam-WebsterThe word ‘coupon’ comes from a French word meaning ‘to cut’The history of coupons starts in the US with the Coca-Cola coupon that was mailed to consumers, offering them a chance to come try the soda for free in a nearby pharmacy. A coupon created by cereal company Post is one of the earliest widely cited follow-ups—it offered a penny off a box of Grape Nuts in 1909. CNBCHalley's comet is named after the astronomer who predicted its next appearanceEdmund Halley realized that historical accounts of a celestial object passing in the night sky in 1531 and 1607 referred to the same object he observed in 1682. By applying Newtonian mechanics to his observational data, he calculated its orbit and accurately predicted its return in 1758. Penn MuseumDeep Impact was the first mission to probe beneath a comet's surfaceThe NASA mission sent a probe to deliberately crash into comet Tempel 1, producing an explosion equivalent to 4.7 tons of TNT. The payload included a compact disk with more than 625,000 names of people who participated in the "Send Your Name to a Comet!" campaign. NASAA comet's tails point away from the sun, rather than trailing its motionThe ion tail, composed of gases ionized by solar radiation and pushed by the solar wind, points away from the sun. In contrast, the dust tail is pushed away by radiative pressure and curves away from the comet's motion. As the comet approaches the sun, both tails get longer. Swinburne University of TechnologyVisualize the anatomy of a cometThe solid nucleus holds the frozen molecules, which are heated into a gaseous state once the comet is within three times Earth's distance from the sun. The surrounding coma, from which comets get their name, is a spherical cloud that can grow larger than Jupiter, from which tails develop. ESAThe word 'hoax' comes from the phrase 'hocus-pocus'The famous phrase "hocus-pocus" combines liturgical Latin and gibberish. It's a silly series of words often said during magic tricks. The phrase naturally evolved into "hoax" over time and became a standard English word around the year 1800. NPRSee how CES comes to life with a massive setup across Las VegasThis behind-the-scenes video shows crews assembling the sprawling CES show—filling more than 2.5 million square feet of exhibition space with booths, lights, and tech from around the world ahead of the event’s opening. CESOne man in Arizona works to defend Earth from catastrophic space rocksDavid Rankin, an observer and operations engineer at the NASA-funded Catalina Sky Survey, spends his days scanning for solar system objects that could collide with our planet. The job requires employees to work long shifts to help prevent asteroids from destroying our planet. Smithsonian MagazineThe name ‘tardigrades’ comes from the Latin word for ‘slow walkers’Before being renamed for their movements, German pastor Johann August Ephraim Goeze called them Kleiner Wasserbär—little water bears—in the first published observations of the creatures in 1773. He noted their voracious appetite made them seem like bears under a microscope. The Public Domain ReviewThe word 'influenza' comes from a 15th-century Italian belief in the starsIn Renaissance Italy, epidemics were thought to result from the influence of natural disasters or celestial bodies. The illness was named "influenza", meaning “influence” in Italian. Merriam-WebsterA diamond's color comes from impurities, defects, and unique formation processesWhile most diamonds are transparent and sparkly, the presence of nitrogen and boron during formation can make them yellow, orange, or blue. Radiation can produce green diamonds, and structural deformities can introduce red hues. Live ScienceThe standing ovation comes from an ancient Roman military traditionOvation is derived from the Latin for “I rejoice” and was a ceremonial salute to military generals who'd been victorious in battle. Mental FlossScientists determine the smells of objects in outer spaceUsing spectrographic techniques, scientists determine the chemical composition of planetary atmospheres, comets, and other objects in space. Combining these chemicals in labs on Earth has revealed locations in space that smell like nail polish remover, rotten fish, and urine. BBCThe word 'mortgage' comes from medieval French, meaning 'death contract.'The word "mortgage" comes from medieval French, meaning "death contract"—but the modern American mortgage has a more recent and complicated history. This explainer looks at how mortgages evolved from exclusive agreements for the wealthy into a key part of homeownership today, including the impacts of New Deal policies, redlining, and the Fair Housing Act. 1440View galleries of images taken by the Hubble Space TelescopeWith more than 1.7 million observations made since 1990, the Hubble Space Telescope has captured images of space missions, planets, stellar nurseries, interstellar comets, star clusters, galaxies, and more. This search tool allows users to sort and filter across these celestial objects to explore over 35 years of Hubble's astrophotography. NASA ScienceThe word 'Earth' comes from the German root word for 'ground'In English, "Earth" means the planet and the land, but many languages identify each with distinct words. Earth is often given a maternal name or one that identifies it as the land of the living. The Decolonial Atlas'Tattoo' comes from a Polynesian word that means 'to strike'“Tatatau” roughly translates to “strike,” a reference to the ancient process, which involved tapping ink into the skin with sharpened objects, like the bronze implements used circa 1450 BCE in Egypt, below. Smithsonian MagazineA real-time 3D-explorer of the solar systemNASA's Eyes on the Solar System allows you to track all kinds of objects in space in real time, from observatories like the James Webb Telescope to all manner of comets and asteroids. Zoom in and out, read up on space missions, and see the solar system from a totally new angle with this incredible interactive site. Jump in here. NASARead about the dangerous comet behind the Perseids meteor showerEvery summer, Earth passes through the debris trail of the Swift-Tuttle comet, producing the spectacle of the Perseids meteor shower. The phenomenon is a glorious opportunity for amateur stargazers, but astronomers have long noted the comet's orbit... Big ThinkStellar photos from around the world of the 2020 PerseidsThe annual Perseids meteor shower occurs in the Northern Hemisphere's summer, peaking usually around mid-August. The phenomenon is caused by the Earth's passing through a comet's debris trail of ice and dust, providing a weekslong spectacle for... CBS NewsAtlantis and the apocalypse: the world of fringe archaeologyA Netflix series called "Ancient Apocalypse" claims that a thriving civilization was wiped out during the ice age by comets and floods, but left humanity with science and technology. Experts call this “pseudo-archaeology.” This hour-long podcast... CBCThe Oort cloud, our solar system's theoretical icy shellRecurring comets lead astronomers to believe they originate from an extremely distant, icy shell encapsulating the solar system. They call it the "Oort cloud," and this giant swarm of icy objects is as fascinating as it is is massive. Home of comets and a tremendous number of planetesimals, this NASA site introduces you to the Oort. NASAVisualizing where happiness comes fromResearchers asked 10,000 participants to list 10 things that recently made them happy. One author broke down the responses into subject-verb-object categories, isolating the people and events that made responders satisfied. The result highlights how simple things like having dinner or watching a movie made someone happy. Dive in and look for some ideas or tips on feeling happy today with this fascinating visualization. FlowingDataWhat is the Kuiper Belt?The Kuiper Belt is a collection of extraterrestrial objects that might've been a planet if it hadn't been for Neptune. Still, the belt is a fascinating collection of dwarf planets, rocks, ice, and comets. Extending beyond Neptune's orbit, the Kuiper Belt provides an endless selection of interesting objects and anomalies for astronomers to explore. NASAA map of every object in our solar systemThe infographic from 2020 illustrates the complexity of our solar system, mapping over 18,000 objects including asteroids, comets, planets, and moons. Created by biologist Eleanor Lutz using data from NASA, it shows the non-linear distribution of objects due to the sun's gravitational pull. Objects nearer to the sun are more numerous, forming tighter orbits, while those farther out are fewer and more widely spaced. Visual Capitalist