C/1957 P1
Comet Mrkos August 25.19 by Palomar.jpg
Comet Mrkos on August 25, 1957
Discovered byAntonín Mrkos
Discovery dateJuly 29, 1957
Comet Mrkos, 1957 P1
Orbital characteristics
Epoch2436040.5 (July 21, 1957)
Aphelion1,117 AU
Perihelion0.355 AU[1]
Semi-major axis559 AU
Last perihelionAugust 1, 1957

Comet Mrkos, formally known as C/1957 P1 (old style 1957d), was a non-periodic comet discovered in 1957 by Antonín Mrkos. It was one of two bright comets that had their perihelion in 1957, the other being Comet Arend–Roland. Its peak magnitude was estimated to be around 1[2] and it has been characterised as a great comet.[3]


The comet was discovered by Czech astronomer Antonin Mrkos by naked eye at the observatory on Lomnický štít, Czechoslovakia. He announced its discovery on August 2, 1957, but by that point it had already been discovered independently by others, with a report of observation from Japan dated July 29. However, the comet became known as comet Mrkos, as Mrkos' telegram was the first to arrive at the IAU. The comet was then near perihelion and its apparent magnitude was estimated to be around 2.[4] By August 4 it had brightened to magnitude 1.[5]

At the time of discovery the comet was near perihelion and located near Pollux in the constellation Gemini. It then moved north of the sun and was visible both in the evening and morning sky.[6] The comet gradually moved away from the sun and became a conspicuous object visible after sunset. The tail of the comet was estimated to be more than 5 degrees long. The comet had two tails, one that at the start was brighter and curved, and a straight one with knots that became brighter at the end of August and showed rapid changes in appearance.[4][5] From 10 August to 15 August the tail of the comet appeared striated.[7] The comet moved from the southern part of Ursa Major to Coma Berenices, while fading slowly. In September it crossed into Virgo as a third-magnitude object;[6] it remained visible to the naked eye until the end of September.[4]

By the end of October 1957, the comet had moved close to the sun again and wasn't observable. It was recovered at the end of January 1958 and was last observed July 9, 1958, when it was photographed as a diffuse 19th-magnitude object.[4]

Observation of the comet revealed the presence of sodium[8] and cyanide[9] in its spectrum in the predicted values.


  1. ^ "JPL Small-Body Database Browser: C/1957 P1 (Mrkos)" (1958-07-09 last obs). Jet Propulsion Laboratory. Retrieved 2011-03-13.
  2. ^ "Brightest comets in the last two-thirds century". www.icq.eps.harvard.edu. November 17, 2013.
  3. ^ Richter, N. (January 1960). "II Cometary physics and the comets Arend-Roland and Mrkos". Vistas in Astronomy. 3 (1): 132–137. Bibcode:1960VA......3..132R. doi:10.1016/0083-6656(60)90013-1.
  4. ^ a b c d Porter, J.G. (January 1960). "I Arend-Roland (1956h) and Mrkos (1957d)". Vistas in Astronomy. 3 (1): 128–132. Bibcode:1960VA......3..128P. doi:10.1016/0083-6656(60)90012-X.
  5. ^ a b "Comet Mrkos, 1957d". Journal of the Royal Astronomical Society of Canada. 51: 323. December 1957. Bibcode:1957JRASC..51..323.. ISSN 0035-872X.
  6. ^ a b Bortle, John E. (1998). "THE BRIGHT-COMET CHRONICLES". www.icq.eps.harvard.edu. Retrieved 22 April 2020.
  7. ^ McClure, Alan; Liller, William (August 1958). "Rayed Structure in the Tail of Comet Mrkos, 1957 D". Publications of the Astronomical Society of the Pacific. 70 (415): 404. Bibcode:1958PASP...70..404M. doi:10.1086/127247.
  8. ^ Vainu Bappu, M. K.; Sinvhal, S. D. (1 February 1960). "Polarization Measures of Comet Arend-Roland (1956h) and Comet Mrkos (1957d)". Monthly Notices of the Royal Astronomical Society. 120 (2): 152–162. Bibcode:1960MNRAS.120..152V. doi:10.1093/mnras/120.2.152.
  9. ^ Ferron, Ignacio R. (November 1977). "On the CN (0, 0) spectrum of Comet Mrkos 1957d". Astrophysics and Space Science. 52 (1): 11–16. Bibcode:1977Ap&SS..52...11F. doi:10.1007/BF00647154.