When it comes to celestial visitors to our night skies, short-period comets are among those that astronomers look forward to the most.
Comets travel in huge elliptical orbits that take them in close to the Sun and then far out into the distant Solar System.
As they approach the Sun, the powerful energy of our host star heats these rocky ice balls, causing the release of dust and gas and producing a comet tail that can be seen with the naked eye from Earth or captured in astrophotos.
Short-period - or periodic comets - are comets which take less than 200 years to orbit the Sun, though some may only take a few years or decades.
They have much smaller orbits than long-period comets - whose orbits might last a million years.
Perhaps the most famous short period comet is Halley's Comet, which orbits the Sun every 75 years and can be seen with the naked eye.
An image of Halley’s Comet taken on 8 March 1986 by W. Liller from Easter Island. Credit: NASA/W. Liller - NSSDC's Photo Gallery (NASA)
More recently, Comet 67P/Churyumov-Gerasimenko has been thrust into the spotlight following the success of the European Space Agency's Rosetta mission.
While the terms 'short-period' and 'long-period' comets are still used, as is often the case in astronomy, these distinctions have become more refined the more astronomers have learned about comets and their place in the Solar System.
Nowadays, short-period comets are generally divided up into Jupiter-family comets and Halley-type comets.
Jupiter-family comets
Jupiter-family comets are short-period comets that complete an orbit of the Sun in less than 20 years.
Their orbits are mainly influenced by the gravitational pull of gas giant Jupiter. Jupiter-family comets are thought to orbit in the Kuiper belt.
Halley-type comets
As is perhaps obvious given their name, Halley-type comets are short-period comets that have a slightly longer orbit, more like their famous cometary namesake.
Halley-type comets have orbital periods between 20 and 200 years and they are thought to originate further out, in the Oort Cloud.
Comet Wirtanen is an example of a Jupiter-family comet, with an orbit of about 5 years. Credit: Peter Louer, Tenerife, 8 December 2018.
Below is a selection of images of short-period comets captured by comet-watchers and astrophotographers.
Many of the images in our gallery were captured by prolific comet-chaser José J. Chambó. To see more of José's work, visit his Astrobin page or follow him on Instagram.
Return of the Comet Encke by José J. Chambó by Mayhill, New Mexico. Equipment: Planewave 20" CDK 2280mm f/4.5, FLI-PL11002MComet 10P/Tempel into Milky Way by José J. Chambó by Benali, Valencia, Spain. Equipment: GSO 8" @ f/3.8 reflector, Canon EOS-100D.Short-period Comet Holmes by Dee Amos, Essex, UK. Equipment: 10"SCT, Canon EOS350dComet 24P/Schaumasse by José J. Chambó by Benali, Valencia, Spain. Equipment: GSO 8" @ f/3.8 reflector, Canon EOS-100D.Comet 41P/Tuttle-Giacobini-Kresak by José J. Chambó, Hoya Redona, Valencia, Spain. Equipment: GSO 8" @ f/3.8 reflector, Canon EOS-100D.Comet 41P Tuttle-Giacobini-Kresak passing M108 and M97 the Owl Nebula by Lee Phillips, Kent, UK. Equipment: Canon 1000D, Altair Starwave 102mm ED, 0.6 reducer.Comet 41P into the Dipper by José J. Chambó, Valencia, Spain. Equipment: GSO 8" f/3.8, Canon EOS-100DComet 41P near Earth by José J. Chambó, Valencia, Spain. Equipment: GSO 8" f/4.0, Atik 383L Comet 41P/Tuttle-Giacobini-Kresak by José J. Chambó, Valencia, Spain. Equipment: GSO 8" f/4.0, Atik 383L Short-period Comet 43P/Wolf-Harrington by José J. Chambó, Mayhill, New Mexico, USA. Equipment: Planewave 20" CDK 2280mm f/4.5, FLI-PL11002MComet 45P toward Perihelion by José J. Chambó, Benali, Valencia, Spain. Equipment: GSO 8" f/3.8, Canon EOS-100DShort-period Comet 45P: Twelfth Night's Comet by José J. Chambó, Benali, Valencia, Spain. Equipment: GSO 8" f/3.8, Canon EOS-100DComet 45P after Perihelion by Alessio Vaccaro, Sicily, Italy. Equipment: APO refractor 80/480mm, Canon EOS 60D, HEQ5, QHY5L-II, 60mm scope.Comet 45P Sails in the Dark by José J. Chambó, Mayhill, New Mexico. Equipment: Takahashi FSQ-106ED 530mm f/5, SBIG STL-11000MComet 66P/duToit and Silver Dollar Galaxy by José J. Chambó, Siding Spring, Australia. Equipment: Planewave 20" CDK f/4.4, FLI PL09000First Color Image of Comet 67P by José J. Chambó, Siding Spring, Australia. Equipment: Planewave 20" CDK f/4.4, FLI PL09000Comet 67P/Churyumov-Gerasimenko by José J. Chambó, Mayhill, New Mexico. Equipment: Planewave 20" CDK, FLI PL11002MComet 71P/Clark by José J. Chambó, Siding Spring, Australia. Equipment: Planewave 20" CDK, FLI PL11002MStrangers in the Night - Comet 103P passes by the Pacman Nebula by Nick Howes, Cherhill, Wilsthire, UK. Equipment: TMB105 F6.2, EQMOD/EQ Mosaic controlled EQ6 mount, Atik 4000 mono CCD, Astronomik CLS/HA/OIII and SII filtersComet 168P Hergenrother by Andrew Laing, Northamptonshire, UK. Equipment: SW200P, HEQ5, Canon 1000D, DMK21 guide, ST80Comet 174P/Echeclus in Outburst by Paula Sola La Serna & José J. Chambó Bris, Teide Observatory, Canary Islands, Spain. Equuipment: IAC-80 0.82m f/11.3, CamelotTwo Sibling Comets Approaching to Earth by José J. Chambó Bris, Siding Spring, NSW, Australia. Equipment: Takahashi FSQ ED 106mm. f/5.0, SBIG STL-11000MComet 252P and M14 on the Milky Way by José J. Chambó Bris, Mayhill, New Mexico, USA. Equipment: Takahashi FSQ ED 106mm. f/5.0, SBIG STL-11000MComet 252P/LINEAR (Apr.10,2016) by José J. Chambó Bris, Hoya Redonda, Valencia, Spain. Equipment: GSO 8" f/3.8, Canon EOS-100D