(66063) 1998 RO1

 is a stony near-Earth object of the Aten group on a highly-eccentric orbit. The synchronous binary system measures approximately 800 m in diameter. It was discovered by astronomers of the Lincoln Near-Earth Asteroid Research at the Lincoln Laboratory's Experimental Test Site near Socorro, New Mexico, on 14 September 1998.

Its minor-planet moon, provisionally designated, was discovered in September 2003. It has an orbital period of 14.53 hours and measures approximately 48% of its primary, or 380 meters. It is one of seven known Aten binaries as of 2017.

Interaction with Earth
's orbit is very eccentric, with an aphelion beyond the orbit of Mars and a perihelion inside the orbit of Mercury. It has an orbital period of 360.29 days (0.99 years) and makes close approaches to Earth. But makes closer approaches to other inner planets, especially Mars. Its closest approach to a planet between 1950–2200 was to Mars, as it passed 0.00898 AU from Mars on 18 March 1964, and will pass 0.0054 AU from Mars on 12 October 2065.

Moon


has one moon,. This moon was discovered from lightcurve observations going from 13 to 28 September 2013, and was confirmed by radar observations from the Arecibo Observatory one year later. It is in a very close orbit to, with a semi-major axis of 800 m and an eccentricity of 0.06, giving it a periapsis of 752 m and an apoapsis of 848 m. takes 14.54 hours to complete one orbit around.

From the surface of, would have an apparent diameter of roughly 41°. For comparison, the Sun appears to be 0.5° from Earth. The secondary orbits its primary in a manner very similar to the adjunct image, where the red cross is the center of mass.

Numbering and naming
This minor planet was numbered by the Minor Planet Center on 10 September 2003. As of 2018, it has not been named.