What is 3753 Cruithne?
{{Infobox Planet | name = 3753 Cruithne | background = #dddddd | apsis = gee | symbol = | image = Orbits of Cruithne and Earth.gif | caption = Earth and Cruithne's orbit | periapsis = | apoapsis = | semimajor = | eccentricity = | period = | synodic_period = | avg_speed = 27.73[[Kilometres per second|km/s]] | inclination = 19.81[[Degree (angle)|°]] | asc_node = | arg_peri = | satellite_of = [[Earth]] | flattening = | equatorial_radius = | polar_radius = | mean_radius = | circumference = ~5km ([[equator]]ial) | surface_area = | volume = | mass = | density = 2g [[Gram per cubic centimetre|g/cm³]] | surface_grav = {{nowrap|1.622 [[Metre per second squared|m/s²]]}} {{nowrap|(0.165 4 [[G-force|g]])}} | escape_velocity = 2.38 k[[Metre per second|m/s]] | sidereal_day = 27.321&nbsp;582 [[Day|d]] ([[Synchronous rotation|synchronous]]) <!--Wieczorek et al. 2006--> | rot_velocity = 4.627 m/s | axial_tilt = 1.542&nbsp;4° (to [[ecliptic]])<br />6.687° (to [[Orbital plane (astronomy)|orbit plane]]) | albedo = 0.12 | magnitude = | angular_size = | temp_name1 = | min_temp_1 = | mean_temp_1 = | max_temp_1 = | temp_name2 = | min_temp_2 = | mean_temp_2 = | max_temp_2 = | atmosphere_ref = | surface_pressure = | adjectives = }} '''3753 Cruithne''' is an [[asteroid]]. == Discovery == 3753 Cruithne was discovered on October 10, 1986, by Duncan Waldron on the UK Schmidt Telescope at Siding Spring Observatory, Coonabarabran, [[Australia]]. The 1983 appearance is given to Giovanni de Sanctis and Richard M. West of the European Southern Observatory in [[Chile]]. It was not until 1997 that its unusual orbit was found by Paul Wiegert and Kimmo Innanen, working at York University in [[Toronto]], and Seppo Mikkola, working at the University of Turku in [[Finland]]. The asteroid is named after the Cruithne, a people of early medieval [[Ireland]]. == Measurements == 3753 Cruithne is about 5 [[kilometres]] (3.1&nbsp;mi) in diameter. From 1994 through 2015, 3753 Cruithne makes its annual closest approach to [[Earth]] e