| C/1927 X1 (Skjellerup-Maristany) | |
| Discoverer: | John Francis Skjellerup, Edmundo Maristany |
| Discovery Date: | December 6, 1927 |
| Designations: | Great Comet of 1927, 1927 IX, 1927 X1 |
| Epoch: | 1927-Dec-26 (JD 2425240.5)[1] |
| Semimajor: | 1101 AU |
| Perihelion: | 0.1761 AU |
| Aphelion: | 2202 AU |
| Eccentricity: | 0.9998 |
| Period: | ~36600 yr |
| Inclination: | 85.1° |
| Last P: | December 18, 1927 |
| Next P: | unknown |
Comet Skjellerup–Maristany, formally designated C/1927 X1, 1927 IX, and 1927k, was a long-period comet which became very bright in 1927. This great comet was observable to the naked eye for about 32 days.[2] It was independently discovered by amateur astronomers John Francis Skjellerup in Australia on 28 November 1927 and Edmundo Maristany in Argentina on 6 December 1927, and noted for its strong yellow appearance, caused by emission from sodium atoms.
Forward scattering of light on 15–16 December 1927 allowed the comet to be seen during daylight if the observer blocked the Sun.[3] C/1927 X1 passed only 1.4° from the Sun on 15 December 1927.[4]
Comet Skjellerup–Maristany has been more than 105AU from the Sun since 2010. It was mentioned in J. R. R. Tolkien's book Letters From Father Christmas.