2018 CB
{{Use dmy dates|date=February 2018}}
{{Infobox planet
| minorplanet = yes
| name = 2018 CB
| background = #FFC2E0
| image = 2018_CB orbits.png
| image_scale =
| caption = Highly elliptical orbit of {{mp|2018 CB}}, crossing those of both Mars and Earth. Positions shown for 1 January 2018, before flyby.
| discoverer = CSS
| discovery_site = Mount Lemmon Obs.
| discovered = 4 February 2018
{{small|(first observed only)}}
| mpc_name = 2018 CB
| alt_names =
| pronounced =
| named_after =
| mp_category = NEO{{·}}Apollo
{{nowrap|Earth- and Mars crosser}}
| epoch = 23 March 2018 (JD 2458200.5)
| uncertainty = 2
| observation_arc = 5 days
| aphelion = 1.8589 AU
| perihelion = 0.9582 AU
| semimajor = 1.4085 AU
| eccentricity = 0.3197
| period = 1.67 yr (611 days)
| mean_anomaly = 10.249°
| mean_motion = {{Deg2DMS|0.5896|sup=ms}} / day
| inclination = 5.3027°
| asc_node = 320.79°
| arg_peri = 208.11°
| moid = 0.0004 AU (0.2 LD)
| mean_diameter = 7 m {{small|(assumed)}}
20 m {{small|(upper limit)}}
| albedo = >0.18
~1 {{small|(assumed)}}
| spectral_type =
}}
{{mp|2018 CB}} is a very bright micro-asteroid, classified as a near-Earth object of the Apollo group, less than {{convert|20|m|ft|sp=us}} in diameter. It was first observed by astronomers of the Catalina Sky Survey at Mount Lemmon Observatory, Arizona, on 4 February 2018, during its sub-lunar close encounter with Earth.
2018 flyby
On 9 February 2018, the asteroid passed about {{convert|64500|km|mi|abbr=on}} from Earth, traveling {{convert|10|mi/s|km/s}} relative to Earth and briefly reaching apparent magnitude 13.{{cite web|last1=Bob King|title=Asteroids 2018 CB And CC Graze Earth This Week — Watch It Online|url=http://astrobob.areavoices.com/2018/02/05/asteroids-2018-cb-and-cc-graze-earth-this-week-watch-it-online/|website=Astro Bob|date=Feb 5, 2018}} It was observed by the Goldstone Observatory, which constrained its size to no more than 20 meters.{{cite web|last1=Benner|first1=Lance|title=2018 CB Astrometry - Minor Planet Mailing List|url=https://groups.yahoo.com/neo/groups/mpml/conversations/messages/33880|website=groups.yahoo.com|accessdate=9 February 2018}}
During the flyby its period was changed from 1.48 years to 1.67 years.
= Flyby gallery =
File:2018CB skypath.png|Its path across the sky on February 9 was north to south (30 minute positions shown)
File:2018CB earthflyby.png|Seen from space, it passes just outside geosynchronous orbit
File:2018 CB Northolt Branch Observatory Feb7 video.gif|20 minute timelapse, taken two days before closest approach. The asteroid can be seen near the center of the image, moving towards the lower left. Brightness is inverted (stars appear dark, the sky background appears light).{{cite web|last1=Wells|first1=G.|last2=Bamberger|first2=D.|title=Very close approacher 2018 CB (Video)|url=https://www.facebook.com/NBObservatories/videos/1850341625000700/|website=Northolt Branch Observatories, Facebook|date=8 February 2018|accessdate=11 February 2018}}
File:2018 CB Northolt Branch Observatory Feb7 stack.png|2018 CB on February 7. The image is corrected for the asteroid's motion, so stars appear trailed.{{cite web|last1=Wells|first1=G.|last2=Bamberger|first2=D.|title=Very close approacher 2018 CB|url=https://www.facebook.com/NBObservatories/posts/1849910691710460/|website=Northolt Branch Observatories, Facebook|date=8 February 2018|accessdate=11 February 2018}}
Other flybys
{{mp|2018 CB}}'s orbit is in Earth's neighborhood, so it frequently makes other close approaches to Earth like the 2018 one, although not usually as close. In 1953 (65 years or 44 orbits earlier), it passed {{convert|0.00650|AU|km mi|abbr=on}} from Earth, and in 2090 it will pass between {{convert|0.00475|AU|km mi|abbr=on}} and {{convert|0.00798|AU|km mi|abbr=on}} from Earth.
It also may have passed similarly near Earth in 1914, but the uncertainty in the 1953 approach makes it difficult to determine.
Physical characteristics
{{mp|2018 CB}} appears unusually bright for its size, suggesting it is made of brighter materials than the average asteroid.
See also
References
{{reflist|refs=
|type = 2018-02-09 last obs.
|title = JPL Small-Body Database Browser: (2018 CB)
|url = https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=3798991;cad=1
|publisher = Jet Propulsion Laboratory
|accessdate = 15 February 2018}}
|title = 2018 CB
|work = Minor Planet Center
|url = https://www.minorplanetcenter.net/db_search/show_object?object_id=2018+CB
|accessdate = 15 February 2018}}
}}
External links
{{Commons category}}
- Minor Planet Circulars of 2018 CB:
- [https://minorplanetcenter.net/mpec/K18/K18C12.html MPEC (C12)], 4 February 2018
- [https://minorplanetcenter.net/mpec/K18/K18C25.html MPEC (C25)], 6 February 2018
- [https://minorplanetcenter.net/mpec/K18/K18C44.html MPEC (C44)], 8 February 2018
- [https://minorplanetcenter.net/mpec/K18/K18C47.html MPEC (C44)], 9 February 2018
- {{cite web|last1=Bob King|title=Asteroids 2018 CB And CC Graze Earth This Week — Watch It Online|url=http://astrobob.areavoices.com/2018/02/05/asteroids-2018-cb-and-cc-graze-earth-this-week-watch-it-online/|website=Astro Bob|date=5 February 2018}}
- [http://earthsky.org/space/asteroids-feb-2018-cb-and-2018-cc-online-viewing Watch online as 2 asteroids sweep close this week] (2018 CB and 2018 CC), EarthSky, 5 February 2018
- {{NeoDys|2018CB}}
- {{JPL small body|id=3798991}}
{{2018 in space}}
{{Small Solar System bodies}}
{{Authority control}}
{{DEFAULTSORT:2018 CB}}
Category:Minor planet object articles (unnumbered)
Category:Discoveries by the Catalina Sky Survey