| 词条 | 2018 CF2 |
| 释义 |
| minorplanet = yes | name = {{mp|2018 CF|2}} | background = #FFC2E0 | image = 2018_CF2-orbit2018.png | image_size = 260 | caption = The orbit before and after its 2018-flyby | discovery_ref = [1] | discoverer = MLS | discovery_site = Mount Lemmon Obs. | discovered = 7 February 2018 | mpc_name = {{mp|2018 CF|2}} | alt_names = | pronounced = | named_after = | mp_category = NEO{{·}}Apollo [1] | orbit_ref = | epoch = 23 March 2018 (JD 2458200.5) | uncertainty = 7 | observation_arc = 2 days | aphelion = 2.7662 AU | perihelion = 0.9089 AU | semimajor = 1.8375 AU | eccentricity = 0.5054 | period = 2.49 yr (910 days) | mean_anomaly = 29.432° | mean_motion = {{Deg2DMS|0.3957|sup=ms}} / day | inclination = 16.284° | asc_node = 137.68° | arg_peri = 320.19° | moid = {{Convert|0.00077|AU|LD|abbr=on}} | mean_diameter = {{val|4|-|15|u=m}}[5] {{val|7|u=m}} {{small|(est. at 0.20)}}[6] {{val|14|u=m}} {{small|(est. at 0.057)}}[6] | rotation = | albedo = | spectral_type = | abs_magnitude = 28.036 }} {{mp|2018 CF|2}} is a micro-asteroid and near-Earth object of the Apollo group on an eccentric orbit with has an estimated {{convert|4|-|15|m|ft|sigfig=1|sp=us}}. It was first observed on 7 February 2018, by astronomers of the Mount Lemmon Survey at Mount Lemmon Observatory, Arizona, United States.[1] The discovery occurred the day after its sub-lunar passage as it approached the Earth from a sunward direction, and this flyby altered the asteroid's orbit slightly. Orbit and classification{{mp|2018 CF|2}} belongs to the Apollo asteroids, the largest group of near-Earth objects with nearly 10 thousand known members, which cross the orbit of Earth.Based on a high uncertainty, it orbits the Sun at a distance of 0.91–2.77 AU once every 2 years and 6 months (910 days; semi-major axis of 1.84 AU). Its orbit has an eccentricity of 0.51 and an inclination of 16° with respect to the ecliptic. With an aphelion of 2.77 AU, it is also a Mars-crosser, as it crosses the orbit of the Red Planet at 1.666 AU. The body's observation arc begins at Mount Lemmon with its first observation on 7 February 2018.[1] 2018 flybyOn 6 February 2018, 18:45 UTC, the day before its first observation, it had a flyby with the Earth at a nominal distance of 0.25 lunar distances (LD).[5] Its next close approach to Earth is projected to occur on 23 January 2023, at {{convert|0.111|AU|LD|abbr=on}}. After the 2018-passage, the body's minimum orbital intersection distance with Earth increased to {{convert |0.00077 |AU |LD|abbr=on |lk=off |sigfig=2 |order=flip}}. {{multiple image|direction = horizontal |align = left |width1 = 380 |width2 = 200 |image1 = 2018 CF2-skyview.png |image2 = 2018 CF2-flyby.png |footer = 2018 flyby: Path in sky with daily motion south to north (left). View of path across earth-moon system, moving from south to north (right). }}{{clear|left}} Physical characteristicsThe Minor Planet Center estimates a diameter of {{convert|4|-|15|m|ft|sigfig=1|sp=us}}.[5] Based on a generic magnitude-to-diameter conversion using an absolute magnitude of 28.036, the body measures between 7 and 14 meters in diameter for an assumed albedo of 0.057 and 0.20, which represent typical values for carbonaceous and stony asteroids, respectively.[6] As of 2018, no rotational lightcurve of {{mp|2018 CF|2}} has been obtained from photometric observations. The body's rotation period, pole and shape remain unknown. Numbering and namingThis minor planet has not yet been numbered.[1] See also
References1. ^1 2 3 4 5 {{cite web |title = 2018 CF2 |work = Minor Planet Center |url = https://www.minorplanetcenter.net/db_search/show_object?object_id=2018+CF2 |accessdate = 22 February 2018}} [1][2][3]2. ^1 2 3 {{cite web |title = Asteroid Size Estimator |publisher = CNEOS NASA/JPL |url = https://cneos.jpl.nasa.gov/tools/ast_size_est.html |accessdate = 22 February 2018}} 3. ^1 2 3 {{cite web |title = 2018 CF2 |author = Minor Planet Center |publisher = Twitter |url = https://twitter.com/MinorPlanetCtr/status/962433652205477888 |accessdate = 22 February 2018}} }} External links{{Commons category|2018 CF2}}
5 : Apollo asteroids|Minor planet object articles (unnumbered)|Discoveries by MLS|Near-Earth objects in 2018|Astronomical objects discovered in 2018 |
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