| Date | Miss Distance | Speed |
|---|---|---|
| June 20, 1906 | 0.1470 AU (22.0 million km) | 6.0 km/s |
| May 25, 1943 | 0.0898 AU (13.4 million km) | 10.9 km/s |
| June 30, 1953 | 1.8025 AU (269.7 million km) | 6.2 km/s |
| May 4, 1955 | 0.3744 AU (56.0 million km) | 15.8 km/s |
| May 16, 1959 | 0.2265 AU (33.9 million km) | 11.1 km/s |
| June 8, 1963 | 0.1180 AU (17.7 million km) | 6.8 km/s |
| July 7, 1965 | 1.4420 AU (215.7 million km) | 4.9 km/s |
| July 8, 1967 | 0.1124 AU (16.8 million km) | 9.2 km/s |
| July 4, 1971 | 0.0925 AU (13.8 million km) | 8.4 km/s |
| August 27, 1971 | 0.0805 AU (12.0 million km) | 12.7 km/s |
| July 5, 1975 | 0.0988 AU (14.8 million km) | 8.6 km/s |
| July 3, 1977 | 1.2681 AU (189.7 million km) | 4.3 km/s |
| July 20, 1979 | 0.1548 AU (23.2 million km) | 11.9 km/s |
| July 6, 1983 | 0.0739 AU (11.1 million km) | 8.8 km/s |
| June 22, 1987 | 0.0715 AU (10.7 million km) | 7.6 km/s |
| June 18, 1989 | 1.1854 AU (177.3 million km) | 4.1 km/s |
| July 4, 1991 | 0.0575 AU (8.6 million km) | 8.7 km/s |
| May 27, 1995 | 0.1055 AU (15.8 million km) | 9.1 km/s |
| May 5, 1999 | 0.2443 AU (36.5 million km) | 14.3 km/s |
| May 23, 2001 | 1.1619 AU (173.8 million km) | 4.0 km/s |
| May 3, 2003 | 0.2576 AU (38.5 million km) | 15.0 km/s |
| April 17, 2013 | 1.1601 AU (173.6 million km) | 4.0 km/s |
| March 10, 2025 | 1.1607 AU (173.6 million km) | 4.0 km/s |
| January 30, 2037 | 1.1588 AU (173.4 million km) | 4.0 km/s |
| December 20, 2048 | 1.1546 AU (172.7 million km) | 4.1 km/s |
| November 5, 2060 | 1.1567 AU (173.0 million km) | 4.2 km/s |
| September 15, 2072 | 1.1690 AU (174.9 million km) | 4.3 km/s |
| August 22, 2082 | 0.4136 AU (61.9 million km) | 21.8 km/s |
| July 21, 2084 | 1.2082 AU (180.7 million km) | 4.5 km/s |
| August 1, 2086 | 0.0900 AU (13.5 million km) | 12.8 km/s |
| May 6, 2090 | 0.2136 AU (32.0 million km) | 15.3 km/s |
| May 16, 2096 | 1.3076 AU (195.6 million km) | 5.0 km/s |
| February 25, 2108 | 1.5699 AU (234.9 million km) | 6.2 km/s |
| August 14, 2121 | 0.1169 AU (17.5 million km) | 15.4 km/s |
| April 10, 2125 | 0.4858 AU (72.7 million km) | 25.9 km/s |
| August 21, 2144 | 0.1692 AU (25.3 million km) | 17.4 km/s |
| June 24, 2167 | 0.1160 AU (17.4 million km) | 11.4 km/s |
| May 25, 2190 | 0.1083 AU (16.2 million km) | 11.7 km/s |
6491 (1991 OA) is classified as a Potentially Hazardous Asteroid (PHA) because it is estimated to be larger than 140 meters and its orbit comes within 0.05 AU of Earth. NASA continuously monitors this object for any future impact risk. Current data does not indicate a confirmed impact event.
6491 (1991 OA) is classified as a potentially hazardous asteroid (PHA) by NASA. This means it is large enough and its orbit brings it close enough to Earth to warrant close monitoring. However, a PHA classification does not mean an impact is imminent.
The closest recorded Earth approach of 6491 (1991 OA) is 0.1470 AU (22.0 million km) on June 20, 1906, at a speed of approximately 6.0 km/s.
6491 (1991 OA) has an estimated diameter of 0.775 km (479โ1072 meters range). Its absolute magnitude (H) is 18.72, which NASA uses along with assumed albedo to estimate size.