Talk:2011 ES4

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City Killer

"City Killer" is a very dramatic term, suggesting an event that would kill everyone in the affected area. Since the Chelyabinsk meteor didn't kill anyone, it seems misleading. If "city killer" intends to refer to a particular class of asteroid on a known scale, please reference it. In fact if this is a standard class it would be very handy to have a wiki page about the scale and the various classes of asteroid in it. Rafflesgluft (talk) 13:50, 5 September 2020 (UTC)[reply]

Need to check for decent references, but as I recall city-killer asteroids are generically defined as around 35 meters in diameter which is near the midpoint for size estimates of 2011 ES4. I want to say Don Yeomans used the term after Chelyabinsk in 2013? But we can always waterdown the wording. A generic asteroid 30 meters in diameter will airburst around 20km with 1MT of energy remaining. Larger and/or slower asteroids can penetrate deeper. Twice the diameter will have 8 times the mass. Assuming a more common impact velocity of 18 km/s, infrastructure damage starts getting ugly around diameters of 35+ meters. -- Kheider (talk) 14:05, 5 September 2020 (UTC)[reply]

P1154IU

https://www.projectpluto.com/neocp2/mpecs/P1154IU.htm -- Kheider (talk) 06:23, 6 September 2020 (UTC)[reply]

Great news that this has been recovered, and thanks for updating the page so quickly to keep it current. Given that there is now known to be no risk of an impact in 2055, is it worth stating this up front at the start of the section (currently the section leads with the old out-of-date information)? Perhaps hiving off the paragraph about the possible impact into a sub-section, and explaining the history in there would read better (i.e. that until the 2020 observations refined the orbit determination, the possibility of an impact had been considered)? It is interesting historical information, but probably needs separating out? 90.196.81.200 (talk) 14:38, 7 September 2020 (UTC)[reply]