The object was discovered by a team using the WISE space telescope under the NEOWISE program on March 27, 2020.
It was classified as a comet on March 31 and named after NEOWISE on April 1.
It has the systematic designation C/2020 F3, indicating a non-periodic comet which was the third discovered in the second half of March 2020.

Comet NEOWISE 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 through the planetary region increases the comet's orbital period from about 4400 years to about 6700 years.
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.

In early July, the comet could be seen in the morning sky just above the north-eastern horizon and below Capella.
Seen from Earth, the comet was less than 20 degrees from the Sun between June 11 and July 9, 2020.
By June 10, 2020, as the comet was being lost to the glare of the Sun, it was apparent magnitude 7, when it was 0.7 AU (100 million km; 65 million mi) away from Sun and 1.6 AU (240 million km; 150 million mi) away from Earth.
When the comet entered the field of view of the SOHO spacecraft's LASCO C3 instrument on June 22, 2020, the comet had brightened to about magnitude 3, when it was 0.4 AU (60 million km; 37 million mi) away from the Sun and 1.4 AU (210 million km; 130 million mi) away from Earth.

By early July, Comet NEOWISE had brightened to magnitude 1, far exceeding the brightness attained by previous comets, C/2020 F8 (SWAN), and C/2019 Y4 (ATLAS).
By July, it also had developed a second tail.
The first tail is blue and made of gas and ions stretching almost 70° from its nucleus.
There is also a red separation in the tail caused by high amounts of sodium which is nearly stretched 1°.
The second twin tail is a golden color and is made of dust stretched almost 50°, like the tail of Comet Hale–Bopp.
This combination resembles comet C/2011 L4 (PANSTARRS).
The comet is brighter than C/2011 L4 (PANSTARRS), but not as bright as Hale–Bopp was in 1997.
According to the British Astronomical Association, the comet brightened from a magnitude of about 8 at the beginning of June to −2 in early July.
This would make it brighter than Hale–Bopp.
However, as it was very near to the Sun, it was reported as 0 or +1 magnitude and remained that bright for only a few days.
After perihelion, the comet began to fade, dropping to magnitude 2.
Its nucleus activity subdued after mid-July, and its green coma was clearly visible after that.

On July 13, 2020, a sodium tail was confirmed by the Planetary Science Institute's Input/Output facility.
Sodium tails have only been observed in very bright comets such as Hale–Bopp and C/2012 S1 (ISON).

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 spectrographic emissions.
On 31 July 2020, strong detection of OH 18-cm emission was observed in radio spectroscopic studies at the Arecibo Observatory.
On August 14, 2020, the rotation period of the comet was reported to be "7.58 +/- 0.03 hr".

A number of authors have suggested considering the comet a great comet.
Others have argued that it lacked the brightness and visible tail to qualify.
The object was discovered by a team using the WISE space telescope under the NEOWISE program on March 27, 2020. It was classified as a comet on March 31 and named after NEOWISE on April 1. It has the systematic designation C/2020 F3, indicating a non-periodic comet which was the third discovered in the second half of March 2020.
Comet NEOWISE 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 through the planetary region increases the comet's orbital period from about 4400 years to about 6700 years. 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.
In early July, the comet could be seen in the morning sky just above the north-eastern horizon and below Capella. Seen from Earth, the comet was less than 20 degrees from the Sun between June 11 and July 9, 2020. By June 10, 2020, as the comet was being lost to the glare of the Sun, it was apparent magnitude 7, when it was 0.7 AU (100 million km; 65 million mi) away from Sun and 1.6 AU (240 million km; 150 million mi) away from Earth. When the comet entered the field of view of the SOHO spacecraft's LASCO C3 instrument on June 22, 2020, the comet had brightened to about magnitude 3, when it was 0.4 AU (60 million km; 37 million mi) away from the Sun and 1.4 AU (210 million km; 130 million mi) away from Earth. 
By early July, Comet NEOWISE had brightened to magnitude 1, far exceeding the brightness attained by previous comets, C/2020 F8 (SWAN), and C/2019 Y4 (ATLAS). By July, it also had developed a second tail. The first tail is blue and made of gas and ions stretching almost 70° from its nucleus. There is also a red separation in the tail caused by high amounts of sodium which is nearly stretched 1°. The second twin tail is a golden color and is made of dust stretched almost 50°, like the tail of Comet Hale–Bopp. This combination resembles comet C/2011 L4 (PANSTARRS). The comet is brighter than C/2011 L4 (PANSTARRS), but not as bright as Hale–Bopp was in 1997. According to the British Astronomical Association, the comet brightened from a magnitude of about 8 at the beginning of June to −2 in early July. This would make it brighter than Hale–Bopp. However, as it was very near to the Sun, it was reported as 0 or +1 magnitude and remained that bright for only a few days. After perihelion, the comet began to fade, dropping to magnitude 2. Its nucleus activity subdued after mid-July, and its green coma was clearly visible after that.
On July 13, 2020, a sodium tail was confirmed by the Planetary Science Institute's Input/Output facility. Sodium tails have only been observed in very bright comets such as Hale–Bopp and C/2012 S1 (ISON).
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 spectrographic emissions. On 31 July 2020, strong detection of OH 18-cm emission was observed in radio spectroscopic studies at the Arecibo Observatory. On August 14, 2020, the rotation period of the comet was reported to be "7.58 +/- 0.03 hr". 
A number of authors have suggested considering the comet a great comet. Others have argued that it lacked the brightness and visible tail to qualify.
C/2020 F3 (NEOWISE)