| 词条 | 1999 CW8 |
| 释义 |
| minorplanet = yes | name = {{mp|1999 CW|8}} | background = #FFC2E0 | image = Celestia 1999 CW8 orbit.png | image_size = 250 | caption = Screenshot of the orbit of {{mp|1999 CW|8}} in the program Celestia. | discovery_ref = | discovered = 12 February 1999 | discoverer = LINEAR | discovery_site = Lincoln Laboratory ETS | mpc_name = {{mp|1999 CW|8}} | alt_names = | pronounced = | named_after = | mp_category = NEO{{·}}Apollo | orbit_ref = | epoch = 4 September 2017 (JD 2458000.5) | uncertainty = 0 | observation_arc = 10.47 yr (3,823 days) | aphelion = 3.5762 AU | perihelion = 0.8956 AU | semimajor = 2.2359 AU | eccentricity = 0.5994 | period = 3.34 yr (1,221 days) | mean_anomaly = 176.81° | mean_motion = {{Deg2DMS|0.2948|sup=ms}} / day | inclination = 33.641° | asc_node = 317.03° | arg_peri = 262.07° | moid = 0.2323 AU{{·}}90.5 LD | mars_moid = 0.07356 AU [4] | satellites = | dimensions = {{nowrap|0.64 km {{small|(generic at 0.159)}}[5]}} | rotation = | albedo = | spectral_type = SMASS = B | abs_magnitude = 18.6 }}{{mp|1999 CW|8}} is a bright carbonaceous asteroid and sub-kilometer near-Earth object of the Apollo group, first observed on 12 February 1999, by astronomers of the Lincoln Near Earth Asteroid Research program at Lincoln Laboratory ETS in New Mexico, United States.[4] Description{{mp|1999 CW|8}} is a B-type asteroid, relatively rare in the asteroid belt but common in the inner Solar System. The asteroid never approaches Earth closer than 0.2 AU, but occasionally makes close approaches to Mars of 0.07 AU. It makes one such approach in 2073, at 0.067 AU, and another one in 2103, at 0.094 AU. Due to {{mp|1999 CW|8}}'s relatively high inclination, although it passes closer to the Sun than the Earth (0.9 AU), it never comes closer than 0.2 AU.Based on an absolute magnitude of 18.6, and an assumed albedo of 0.159 (derived from the B-type asteroid 2 Pallas), the asteroid can be estimated to have a mean-diameter of approximately 640 meters.[5] If it impacted the Earth would cause significant damage, but not as much as the Cretaceous–Paleogene extinction event progenitor, which brought about a mass extinction, as it is only 1/20 to 1/10 the size. However, it is unlikely to come close enough to Earth to impact it, or even become a risk of impact. {{clear|left}}See also
References1. ^1 2 {{cite web |title = 1999 CW8 |work = Minor Planet Center |url = http://www.minorplanetcenter.net/db_search/show_object?object_id=1999+CW8 |accessdate = 16 October 2017}} [1][2]2. ^1 2 {{cite web |title = Asteroid Size Estimator |publisher = CNEOS – NASA/JPL |url = https://cneos.jpl.nasa.gov/tools/ast_size_est.html |accessdate = 16 October 2017}} }} External links
4 : Apollo asteroids|Minor planet object articles (unnumbered)|B-type asteroids (SMASS)|Astronomical objects discovered in 1999 |
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