C/2016 R2 (PanSTARRS)

C/2016 R2 (PanSTARRS) is a comet, discovered using the Pan-STARRS telescopes on September 7, 2016. The comet attracted attention from many astronomers as it approached its closest point to the Sun in May 2018.^[5] It has been observed to have a very complex tail, which has been suggested to be due to a fast rotation period of the nucleus.

C/2016 R2 (PanSTARRS)

Comet PanSTARRS photographed from the Mount Lemmon Observatory on 16 January 2018
Discovery[1]
Discovered by	Pan-STARRS
Discovery site	Haleakalā Observatory
Discovery date	30 August 2016
Designations
Alternative designations	CK16R020
Orbital characteristics[2]
Epoch	29 May 2018 (JD 2458267.5)
Observation arc	1,762 days (4.82 years)
Number of observations	4,319
Aphelion	~1,410 AU
Perihelion	2.602 AU
Semi-major axis	~705 AU
Eccentricity	0.99631
Orbital period	~18,700 years
Inclination	58.224°
Longitude of ascending node	80.569°
Argument of periapsis	33.192°
Mean anomaly	0.001°
Last perihelion	9 May 2018
TJupiter	1.060
Earth MOID	1.720 AU
Jupiter MOID	2.117 AU
Physical characteristics[3][4]
Mean diameter	~38.0 km (23.6 mi)
Comet total magnitude (M1)	7.3
Comet nuclear magnitude (M2)	11.2
Apparent magnitude	9.8 (2018 apparition)

The comet orbits the Sun on a 20,000 year orbit, which takes it out about 740 AU.^[6] It was found to differ from typical comets, and was found to be rich in carbon monoxide (CO) but depleted in hydrogen cyanide (HCN), resulting in a blue coma.^[6][7] The blue color is thought to come from the rich amounts of carbon monoxide being ionized.^[8] The comet was also noted to be rich in nitrogen.^[9]

The comet was observed by a submillimeter wavelength telescope in the late 2010s.^[6]

The comet made its closest approach to the Sun in May 2018, and its blue, teal, and dust tail were noted as an astronomical target.^[8] Blue comets are a less common type of comet.^[9]

Gallery

• 
  Comet C/2016 R2 (PanSTARRS) taken by SPECULOOS project.^[10]

See also

• 2I/Borisov
• C/1908 R1 (Morehouse)
• C/1961 R1 (Humason)