The newly discovered near-Earth asteroid 1994 XM1 made the closest approach to the Earth of any object discovered outside the earth's atmosphere---some 105,000 km (60 000 miles) on the morning of Dec. 9 over Russia. The measured magnitude was H of about 28.4, so using S & C type albedoes, the diameter is 6-13 meters. The best guess on size for press purposes is probably 10 m or 30 feet or the size of a house.
MPEC 1994-X05 contains the orbital elements:
M.P.E.C. 1994-X05 Issued 1994 Dec. 9, 18:37 UT
The Minor Planet Electronic Circulars contain information on unusual minor planets and routine data on comets. They are published on behalf of Commission 20 of the International Astronomical Union by the Minor Planet Center, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Observer details: Steward Observatory, Kitt Peak. Observer J. V. Scotti. 0.9-m Spacewatch telescope.
Orbital elements: 1994 XM1; Epoch 1994 Nov. 24.0 TT = JDT 2449680.5
|n||0.34599227|| Peri.||41.99321|| -0.48384464||-0.86993443|
|a||2.0095175|| Node||77.14890|| +0.77463496|| -0.47646150|
|e||0.5539642||Incl.|| 5.61769||+0.40722848|| -0.12727346|