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Discovered by William Henry Finlay
Discovery date September 26, 1886
1886 S1; 1886 VII;
1886e; 1893 K1;
1893 III; 1893a;
1906 V; 1906d;
1919 II; 1919d;
1926 V; 1926d;
1953 VII; 1953i;
1960 VIII; 1960d;
1967 IX; 1967g;
1974 X; 1974d;
1981 XII; 1981e;
1988 IX; 1988f
Orbital characteristics A
Epoch 2014-Dec-09
(JD 2457000.5)
Aphelion 6.019 AU
Perihelion 0.976 AU
Semi-major axis 3.488 AU
Eccentricity 0.7202
Orbital period 6.51 a
Inclination 6.799°
Earth MOID 0.009 AU (1,300,000 km)[3]
Jupiter MOID 0.16 AU (24,000,000 km)[3]
Dimensions 1.8 km (uncertain)[4]
Last perihelion December 27, 2014[1][2]
June 22, 2008
Next perihelion July 13, 2021[1]
Perihelion distance
at different epochs
Epoch Perihelion
1866 1.0
1906 0.96
1919 1.0
1981 1.1
2008 0.97
2021 0.99

Comet Finlay is a periodic comet in the solar system discovered by William Henry Finlay (Royal Observatory, Cape of Good Hope, South Africa) on September 26, 1886. It came to perihelion (closest approach to the Sun) on December 27, 2014,[2] at around apparent magnitude 10.[5]

When the first parabolic orbit calculations were made in 1886, there was a similarity between this orbit and that of Francesco de Vico's lost periodic comet of 1844 (54P/de Vico-Swift-NEAT). Lewis Boss (Dudley Observatory, Schenectady, United States) noted large discrepancies between the orbits and after further observations concluded that de Vico's comet could not be the same as Finlay's.[6]

The 1899 apparition was missed, in 1910 a close pass with Jupiter increased the orbital period, in 1919 the path was off predictions and a new comet discovered by Sasaki (Kyoto Observatory, Japan) on October 25, 1919, was discovered to be Finlay's.

The magnitude of the comet declined after 1926, and it was not until 1953 that it has been observed on every return.

During the 2015 perihelion passage the comet outburst on 16 December 2014 from magnitude 11 to magnitude 9 becoming bright enough to be seen in common binoculars with a 50 mm objective lens.[7] On December 23, 2014, 15P and Mars were only 1/6 of a degree apart in the sky after sunset.[7] But by December 23, 2014, the comet had dimmed considerably since the outburst. On 16 January 2015, the comet outburst to magnitude 8.[8]

The comet currently has an Earth-MOID of 0.01 AU (1,500,000 km; 930,000 mi).[3] On October 25, 2060, the comet will pass roughly 0.04 AU (6,000,000 km; 3,700,000 mi) from the Earth.[3]


  1. ^ a b c "15P/Finlay Orbit". Minor Planet Center. Retrieved 2014-06-21.
  2. ^ a b Syuichi Nakano (2011-11-05). "15P/Finlay (NK 2161)". OAA Computing and Minor Planet Sections. Retrieved 2012-02-18.
  3. ^ a b c d "JPL Close-Approach Data: 15P/Finlay" (last observation: 2015-04-20). Retrieved 2014-11-01.
  4. ^ Comet II (2004) pg 242
  5. ^ Seiichi Yoshida (2010-07-31). "15P/Finlay (2014)". Seiichi Yoshida's Comet Catalog. Retrieved 2012-02-22.
  6. ^ Kronk, Gary W. "15P/Finlay". Cometography. Retrieved 2007-01-31.
  7. ^ a b Bob King. "Comet Finlay in Bright Outburst, Visible in Small Telescopes". Universe Today. Retrieved 2014-12-20.
  8. ^ Michael Mattiazzo. "24324Re: [comets-ml] Re: Possible another outburst of 15P/Finlay?". Yahoo: comet-ml. Retrieved 2015-01-17.

External links

  • Orbital simulation from JPL (Java) / Horizons Ephemeris
  • Elements and Ephemeris for 15P/FinlayMinor Planet Center
  • 15P at Kronk's Cometography
  • 15P at Kazuo Kinoshita's Comets
  • 15P at Seiichi Yoshida's Comet Catalog
  • 15P at CometBase database
  • 2014 June 22 recovery at apmag 20 (comets-ml)
  • 15P/Finlay on 18 Dec 2014 (200mm lens F5.6 / Rob Kaufman of Australia)
  • Animation of 15P/Finlay by FRAM (0.3-m f/10 reflector + CCD, MPC I47), 17th and 18th Dec 2014 (Martin Masek)
Numbered comets
15P/Finlay Next
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