C/1960 Y1 (Candy)

Lore & Background

The comet was first imaged unnoticed in three prediscovery images taken from the Sonneberg Observatory on 17 December 1960. Michael Philip Candy discovered it on 26 December while testing an eyepiece of his 5-inch (13 cm) comet seeker. At discovery, it was a magnitude 8.0 object about 3 degrees southeast of the star Kappa Cephei. Clear skies over the next two nights allowed Candy and G. E. Taylor to calculate its orbit and ephemeris immediately. Precovery ephemerides showed the comet should have been only 5 degrees from Comet Borrelly in October 1960.

The comet made its closest approach to Earth on the day of discovery, 26 December 1960, at a distance of 0.645 AU. It moved quickly southwards and faded as it approached perihelion. Observations from 13 January 1961 showed a very sharp nuclear condensation of magnitude 15.0. Throughout January, the comet produced no discernible tail, though photometric analysis indicated intense far-red emission activity. A faint tail about 15–20 arcminutes long was observed in January and February. The comet remained a 9th magnitude object through February and was last detected on 14 May 1961.

Reader's Guide

C/1960 Y1 holds a unique place in cometary astronomy as the first comet whose orbit was calculated by the same person who discovered it. An initial orbit based on a short observation arc of only 8 days suggested it was a Halley-type periodic comet with a 58-year period. The comet's very small minimum orbit intersection distance with Earth of 0.152 AU (22.7 million km) led JPL to classify it as a near-Earth comet, though orbital simulations by CNEOS do not show any close approaches to Earth. A revised orbit calculated by Brian G. Marsden, Zdenek Sekanina, and E. Everhart from positions obtained from 30 December 1960 to 14 May 1961 indicated an eccentricity of 0.9899, corresponding to an orbital period of 932 years inbound and 1,057 years outbound. This discrepancy between the initial and revised orbital calculations highlights the challenges of determining cometary orbits from limited data. The comet's retrograde orbit and its classification as a near-Earth object, despite simulations showing no future close approaches, add to its scientific interest.

Did You Know?

• Candy's Comet was first imaged unnoticed on 17 December 1960, nine days before its official discovery.
• It is the first comet to have its orbit calculated by its own discoverer.
• The comet's minimum orbit intersection distance with Earth is only 0.152 AU (22.7 million km).