Comet Machholz, formally designated C/2004 Q2, is a long-period comet discovered by Donald Machholz on August 27, 2004. It reached naked eye brightness in January 2005. Unusual for such a relatively bright comet, its perihelion was farther from the Sun than the Earth's orbit.
Comet C/2006 M4 (SWAN) is a non-periodic comet discovered in late June 2006 by Robert D. Matson of Irvine, California and Michael Mattiazzo of Adelaide, South Australia in publicly available images of the Solar and Heliospheric Observatory (SOHO). These images were captured by the Solar Wind ANisotropies (SWAN) Lyman-alpha all-sky camera on board the SOHO. The comet was officially announced after a ground-based confirmation by Robert McNaught on July 12.
Comet McNaught, also known as the Great Comet of 2007 and given the designation C/2006 P1, is a non-periodic comet discovered on 7 August 2006 by British-Australian astronomer Robert H. McNaught using the Uppsala Southern Schmidt Telescope. It was the brightest comet in over 40 years, and was easily visible to the naked eye for observers in the Southern Hemisphere in January and February 2007.
Terry Lovejoy is an information technologist from Thornlands, Queensland, Australia, most widely known as an amateur astronomer. He has discovered six comets, including C/2011 W3 (Lovejoy), the first Kreutz Sungrazing comet discovered by ground-based observation in over 40 years. He is also known for popularizing procedures for modifying consumer-grade digital cameras so that they can be used for digital camera astrophotography.
C/2007 W1 (Boattini) is a long-period comet discovered on 20 November 2007, by Andrea Boattini at the Mt. Lemmon Survey. At the peak the comet had an apparent magnitude around 5.
Comet Lulin is a non-periodic comet. It was discovered by Ye Quanzhi and Lin Chi-Sheng from Lulin Observatory. It peaked in brightness and arrived at perigee for observers on Earth on February 24, 2009, at magnitude +5, and at 0.411 AU from Earth. The comet was near conjunction with Saturn on February 23, and outward-first headed towards its aphelion, against the present position of background stars, in the direction of Regulus in the constellation of Leo, as noted on February 26 and 27, 2009. It was expected to pass near Comet Cardinal on May 12, 2009. The comet became visible to the naked eye from dark-sky sites around February 7. It figured near the double star Zubenelgenubi on February 6, near Spica on February 15 and 16, near Gamma Virginis on February 19 and near the star cluster M44 on March 5 and 6. It also figured near the planetary nebula NGC 2392 on March 14, and near the double star Wasat around March 17. According to NASA, Comet Lulin's green color comes from a combination of gases that make up its local atmosphere, primarily diatomic carbon, which appears as a green glow when illuminated by sunlight in the vacuum of space. When SWIFT observed comet Lulin on 28 January 2009; the comet was shedding nearly 800 US gallons (3,000 l) of water each second. Comet Lulin was methanol-rich.
C/1992 J1 (Spacewatch) is a comet that was discovered 1 May 1992 by David Rabinowitz of the Spacewatch Project. This was the first comet to be discovered using an automated system.
C/1980 E1 is a non-periodic comet discovered by Edward L. G. Bowell on 11 February 1980 and which came closest to the Sun (perihelion) in March 1982. It is leaving the Solar System on a hyperbolic trajectory due to a close approach to Jupiter. In the 42 years since its discovery only two objects with higher eccentricities have been identified, 1I/ʻOumuamua (1.2) and 2I/Borisov (3.35).
C/2007 Q3 , is an Oort cloud comet that was discovered by Donna Burton in 2007 at Siding Spring Observatory in New South Wales, Australia. Siding Spring came within 1.2 astronomical units of Earth and 2.25 AU of the Sun on October 7, 2009. The comet was visible with binoculars until January 2010.
C/1999 F1 (Catalina) is one of the longest known long-period comets. It was discovered on March 23, 1999, by the Catalina Sky Survey. The current perihelion point is outside of the inner Solar System which helps reduce planetary perturbations to this outer Oort cloud object.
Comet Lovejoy, formally designated C/2011 W3 (Lovejoy), is a long-period comet and Kreutz sungrazer. It was discovered in November 2011 by Australian amateur astronomer Terry Lovejoy. The comet's perihelion took it through the Sun's corona on 16 December 2011, after which it emerged intact, though greatly impacted by the event.
Comet ISON, formally known as C/2012 S1, was a sungrazing comet from the Oort cloud which was discovered on 21 September 2012 by Vitaly Nevsky and Artyom Novichonok.
C/2012 F6 (Lemmon) is a long-period comet discovered in Leo on 23 March 2012, by A. R. Gibbs using the 1.5-m reflector at the Mt. Lemmon Survey, located at the summit of Mount Lemmon in the Santa Catalina Mountains north of Tucson, Arizona, USA. Initially, the object was considered to be of asteroidal nature before later observations confirmed its cometary appearance. Comet Lemmon has a highly eccentric orbit, bringing it as close to 0.73 AU from the sun at perihelion and as far as 973 AU from the sun at aphelion. This also leads to the comet's long-period nature with an orbital period of approximately 8,000 years based on epoch 2050. The comet last reached perihelion on 24 March 2013.
Comet C/2012 E2 (SWAN) was a Kreutz group sungrazing comet discovered by Vladimir Bezugly in publicly available images taken by the SWAN instrument on board the SOHO spacecraft. It is recognized for being the first Kreutz sungrazer observed in SWAN imagery.
C/2012 K1 (PanSTARRS) is a retrograde Oort cloud comet discovered at magnitude 19.7, 8.7 AU from the Sun on 17 May 2012 using the Pan-STARRS telescope located near the summit of Haleakalā, on the island of Maui in Hawaii (U.S.).
C/2013 R1 (Lovejoy) is a long-period comet discovered on 7 September 2013 by Terry Lovejoy using a 0.2-meter (8 in) Schmidt–Cassegrain telescope. It is the fourth comet discovered by Terry Lovejoy. C/2013 R1 crossed the celestial equator on 14 October 2013, becoming a better Northern Hemisphere object.
C/2014 Q2 (Lovejoy) is a long-period comet discovered on 17 August 2014 by Terry Lovejoy using a 0.2-meter (8 in) Schmidt–Cassegrain telescope. It was discovered at apparent magnitude 15 in the southern constellation of Puppis. It is the fifth comet discovered by Terry Lovejoy. Its blue-green glow is the result of organic molecules and water released by the comet fluorescing under the intense UV and optical light of the Sun as it passes through space.
C/2017 K2 (PanSTARRS) is an Oort cloud comet with an inbound hyperbolic orbit, discovered in May 2017 at a distance beyond the orbit of Saturn when it was 16 AU (2.4 billion km) from the Sun. Precovery images from 2013 were located by July. It had been in the constellation of Draco from July 2007 until August 2020. As of June 2022, the 3-sigma uncertainty in the current distance of the comet from the Sun is ±5000 km. The comet is record breaking because it is already becoming active at such a distance. Only Comet Hale–Bopp produced such a show from that distance with a similar nucleus. However, this comet will not be as visible as Hale–Bopp was in 1997 in part because it does not come nearly as close to the Sun. Astronomers had never seen an active inbound comet this far out, where sunlight is 1/225th its brightness as seen from Earth. Temperatures, correspondingly, are at -440 °F (-262 °C) in the Oort cloud. However, as it was approaching the Sun at a distance of 16 AU at discovery, a mix of ancient ices on the surface containing oxygen, nitrogen, carbon dioxide and carbon monoxide began to sublimate and shed the dust frozen into it. This material expands into a vast 130,000 km (81,000 mi) wide halo of dust, called a coma, enveloping the solid nucleus.
C/2021 A1 (Leonard) was a long period comet that was discovered by G. J. Leonard at the Mount Lemmon Observatory on 3 January 2021 when the comet was 5 AU (750 million km) from the Sun. It had a retrograde orbit. The nucleus was about 1 km (0.6 mi) across. It came within 4 million km (2.5 million mi) of Venus, the closest-known cometary approach to Venus.
C/2021 O3 (PanSTARRS) was an Oort cloud comet, discovered on 26 July 2021 by the Pan-STARRS sky survey. It came to perihelion on 21 April 2022 at 0.287 AU (42.9 million km). from the Sun.
