| Minorplanet: | yes |
| 2064 Thomsen | |
| Background: |
|
| Discovery Ref: |   |
| Discovered: | 8 September 1942 |
| Mpc Name: | (2064) Thomsen |
| Alt Names: | 1942 RQ1958 RO 1974 OK 1977 KAA913 QB |
| Named After: | Ivan Leslie Thomsen |
| Mp Category: | Mars-crosser  |
| Orbit Ref: |   |
| Epoch: | 4 September 2017 (JD 2458000.5) |
| Uncertainty: | 0 |
| Observation Arc: | 74.50 yr (27,211 days) |
| Perihelion: | 1.4600 AU |
| Semimajor: | 2.1783 AU |
| Eccentricity: | 0.3298 |
| Period: | 3.22 yr (1,174 days) |
| Mean Motion: | / day |
| Inclination: | 5.6946° |
| Asc Node: | 302.16° |
| Arg Peri: | 2.7479° |
| Moid: | 0.4446 AU |
| Mean Diameter: | 13.59 km km |
| Rotation: | h h h h |
| Albedo: | 0.0644 |
| Spectral Type: | SMASS SS  B–V = 0.887 U–B = 0.524 |
| Abs Magnitude: | 12.612.9313.10 |
2064 Thomsen (prov. designation:) is a stony asteroid and Mars-crosser on an eccentric orbit, that measures approximately 13abbr=offNaNabbr=off in diameter. The asteroid was discovered by Finnish astronomer Liisi Oterma at Turku Observatory, Finland, on 8 September 1942. It was named after New Zealand astronomer Ivan Leslie Thomsen
The S-type asteroid orbits the Sun in the inner main-belt at a distance of 1.5–2.9 AU once every 3 years and 3 months (1,174 days). Its orbit has an eccentricity of 0.33 and an inclination of 6° with respect to the ecliptic.
This minor planet was named in memory of New Zealand astronomer Ivan Leslie Thomsen (1910–1969), director of the Carter Observatory, Wellington, from 1945 until he was appointed director of the Mount John University Observatory only two months before his death. He was an enthusiastic coordinator of New Zealand's astronomy and his efforts eventually led to the minor-planet observing program with the Carter Observatory 41-cm reflector. It was the 1977 rediscovery at the Carter Observatory that allowed this minor planet to be numbered. The official was published by the Minor Planet Center on 1 August 1978 .
Four rotational lightcurves gave a well-defined rotation period of 4.233 hours with a brightness variation of 0.62–0.69 magnitude and an albedo of 0.055 and 0.16, as measured by the IRAS and Akari surveys, respectively.