Comet NEOWISE (C/2020 F3)
Object Type: Comet
Scope Images 1-4 : Nikon DSLR 600mm Lens
Scope Images 5-7 : 80mm APO
Exposures Range from 20 seconds to 18 minutes
C/2020 F3 (NEOWISE) or Comet NEOWISE is a long period comet with a near-parabolic orbit discovered on March 27, 2020, by astronomers during the NEOWISE mission of the Wide-field Infrared Survey Explorer (WISE) space telescope. At that time, it was an 18th-magnitude object, located 2 AU (300 million km; 190 million mi) away from the Sun and 1.7 AU (250 million km; 160 million mi) away from Earth.
By July 2020, it was bright enough to be visible to the naked eye. It is one of the brightest comets in the northern hemisphere since Comet Hale–Bopp in 1997. Under dark skies, it can be seen with the naked eye and might remain visible to the naked eye throughout most of July 2020. As of July 23, the comet was about magnitude 3.5, but binoculars are required near urban areas to locate the comet.
For observers in the northern hemisphere, the comet can be seen on the northwestern horizon, below the Big Dipper. North of the 45th parallel north, the comet was visible all night from July 13–22 because it was circumpolar. After July 23, it sets in the morning. On July 17, Comet NEOWISE entered the constellation of Ursa Major, below the asterism of the Big Dipper (the Plough).
From the infrared signature, the diameter of the comet nucleus is estimated to be approximately 5 km (3 mi). The nucleus is similar in size to Comet Hyakutake and many short-period comets such as 2P/Encke, 7P/Pons-Winnecke, 8P/Tuttle, 14P/Wolf, and 19P/Borrelly. By July 5, NASA's Parker Solar Probe had captured an image of the comet, from which astronomers also estimated the diameter of the comet nucleus at approximately 5 km (3 mi). Later in July 2020, other observations were also reported, including those related to coma morphology and sodium emissions.
Comet NEOWISE retrograde orbit crossed the plane of the ecliptic, to which it is inclined at approximately 129 degrees, in late June 2020. It made its closest approach to the Sun (perihelion) on July 3, 2020, at a distance of 0.29 AU (43 million km; 27 million mi). This passage increases the comet's orbital period from about 4400 years to about 6700 years. On July 18 the comet peaked at a northern declination of +48 and was circumpolar down to latitude 42N. Its closest approach to Earth occurred on July 23, 2020, 01:09 UT, at a distance of 0.69 AU (103 million km; 64 million mi) while located in the constellation of Ursa Major.