# List of asteroid close approaches to Earth in 2011

Below is the list of asteroid close approaches to Earth in 2011.

## Timeline of close approaches less than one lunar distance from Earth in 2011

A list of known near-Earth asteroid close approaches less than 1 lunar distance (384,400 km or 0.00257 AU) from Earth in 2011, based on the close approach database of the Center for Near-Earth Object Studies (CNEOS).
The CNEOS database of close approaches lists some close approaches a full orbit or more before the discovery of the object, derived by orbit calculation. The list below only includes close approaches that are evidenced by observations, thus the pre-discovery close approaches would only be included if the object was found by precovery, but there was no such close approach in 2011.
This list and the relevant databases do not consider impacts as close approaches, thus this list does not include any of the objects that collided with Earth's atmosphere in 2011, none of which were discovered in advance, but were observed visually or recorded by sensors designed to detect detonation of nuclear devices.
Rows highlighted red indicate objects which were not discovered until after closest approach
Rows highlighted yellow indicate objects discovered less than 24 hours before closest approach
Rows highlighted green indicate objects discovered more than one week before closest approach
Rows highlighted turquoise indicate objects discovered more than 7 weeks before closest approach
Rows highlighted blue indicate objects discovered more than one year before closest approach (i.e. objects successfully cataloged on a previous orbit, rather than being detected during final approach)
| Date of closest approach | Date discovered | Object | Nominal geocentric distance (AU) | Size (m) (approximate) | (H) | Closer approach to Moon | Refs |
| 2011-01-11 | 2011-01-13 | 2011 AM$_{37}$ | 0.00086 AU (129,000 km; 80,000 mi) | 2.8–6.2 | 29.9 | | data · 2011 AM$_{37}$ |
| 2011-01-17 | 2011-01-14 | 2011 AN$_{52}$ | 0.00213 AU (319,000 km; 198,000 mi) | 5.1–11 | 28.6 | Yes | data · 2011 AN$_{52}$ |
| 2011-01-20 | 2011-01-24 | 2011 BY$_{10}$ | 0.00238 AU (356,000 km; 221,000 mi) | 10–23 | 27.1 | Yes | data · 2011 BY$_{10}$ |
| 2011-01-25 | 2011-01-26 | 2011 BW$_{11}$ | 0.00086 AU (129,000 km; 80,000 mi) | 5.8–13 | 28.3 | | data · 2011 BW$_{11}$ |
| 2011-01-31 | 2011-02-05 | 2011 CA$_4$ | 0.00165 AU (247,000 km; 153,000 mi) | 10–23 | 27.1 | | data · 2011 CA$_4$ |
| 2011-02-04 | 2011-02-04 | 2011 CQ1 | 0.000079 AU (11,800 km; 7,300 mi) | 1–2.3 | 32.1 | | data · 2011 CQ$_1$ |
| 2011-02-06 | 2011-02-07 | 2011 CF$_{22}$ | 0.00027 AU (40,000 km; 25,000 mi) | 1.8–4 | 30.9 | | data · 2011 CF$_{22}$ |
| 2011-02-09 | 2011-02-07 | 2011 CA$_7$ | 0.00069 AU (103,000 km; 64,000 mi) | 2.3–5.2 | 30.3 | | data · 2011 CA$_7$ |
| 2011-02-23 | 2011-02-27 | 2011 DU$_9$ | 0.00192 AU (287,000 km; 178,000 mi) | 12–27 | 26.7 | | data · 2011 DU$_9$ |
| 2011-03-03 | 2011-03-04 | 2011 EN$_{11}$ | 0.00166 AU (248,000 km; 154,000 mi) | 7–16 | 27.9 | | data · 2011 EN$_{11}$ |
| 2011-03-07 | 2011-03-05 | 2011 EY$_{11}$ | 0.000876 AU (131,000 km; 81,400 mi) | 5.3–12 | 28.5 | | data · 2011 EY$_{11}$ |
| 2011-03-08 | 2011-03-10 | 2011 EM$_{40}$ | 0.00162 AU (242,000 km; 151,000 mi) | 6.7–15 | 28.0 | | data · 2011 EM$_{40}$ |
| 2011-03-16 | 2011-03-15 | 2011 EB$_{74}$ | 0.00219 AU (328,000 km; 204,000 mi) | 11–25 | 26.9 | | data · 2011 EB$_{74}$ |
| 2011-04-06 | 2011-04-04 | 2011 GW$_9$ | 0.00133 AU (199,000 km; 124,000 mi) | 6.4–14 | 28.1 | | data · 2011 GW$_9$ |
| 2011-04-06 | 2011-04-04 | 2011 GP$_{28}$ | 0.00064 AU (96,000 km; 59,000 mi) | 3.5–7.8 | 29.4 | | data · 2011 GP$_{28}$ |
| 2011-05-05 | 2011-05-08 | 2011 JV$_{10}$ | 0.00232 AU (347,000 km; 216,000 mi) | 3.1–6.8 | 29.7 | Yes | data · 2011 JV$_{10}$ |
| 2011-06-02 | 2009-01-16 | 2009 BD | 0.00232 AU (347,000 km; 216,000 mi) | 6.4–14 | 28.1 | | data · 2009 BD |
| 2011-06-27 | 2011-06-22 | 2011 MD | 0.000125 AU (18,700 km; 11,600 mi) | 6.7–15 | 28.0 | | data · 2011 MD |
| 2011-07-24 | 2011-08-06 | 2011 PU$_1$ | 0.00224 AU (335,000 km; 208,000 mi) | 20–45 | 25.6 | Yes | data · 2011 PU$_1$ |
| 2011-07-28 | 2011-07-31 | 2011 OD$_{18}$ | 0.00115 AU (172,000 km; 107,000 mi) | 13–30 | 26.5 | | data · 2011 OD$_{18}$ |
| 2011-09-27 | 2011-09-23 | 2011 SE$_{58}$ | 0.00159 AU (238,000 km; 148,000 mi) | 7.3–16 | 27.8 | | data · 2011 SE$_{58}$ |
| 2011-09-28 | 2011-10-01 | 2011 TO | 0.00086 AU (129,000 km; 80,000 mi) | 13–29 | 26.6 | | data · 2011 TO |
| 2011-09-30 | 2011-09-29 | 2011 SM$_{173}$ | 0.00194 AU (290,000 km; 180,000 mi) | 7.3–16 | 27.8 | | data · 2011 SM$_{173}$ |
| 2011-10-12 | 2011-10-17 | 2011 UT | 0.00152 AU (227,000 km; 141,000 mi) | 18–41 | 25.8 | Yes | data · 2011 UT |
| 2011-10-17 | 2009-10-15 | 2009 TM$_8$ | 0.00226 AU (338,000 km; 210,000 mi) | 5.6–12 | 28.4 | Yes | data · 2009 TM$_8$ |
| 2011-10-26 | 2011-10-27 | 2011 UL$_{169}$ | 0.00177 AU (265,000 km; 165,000 mi) | 5.9–13 | 28.3 | | data · 2011 UL$_{169}$ |
| 2011-10-28 | 2011-10-30 | 2011 UX$_{255}$ | 0.00093 AU (139,000 km; 86,000 mi) | 8.8–20 | 27.4 | | data · 2011 UX$_{255}$ |
| 2011-11-08 | 2005-12-28 | (308635) 2005 YU55 | 0.00217 AU (325,000 km; 202,000 mi) | 360 | 21.9 | Yes | data · 2005 YU$_{55}$ |
| 2011-12-03 | 2011-12-08 | 2011 XC2 | 0.00232 AU (347,000 km; 216,000 mi) | 61–140 | 23.2 | Yes | data · 2011 XC$_2$ |
| 2011-12-28 | 2011-12-29 | 2011 YC$_{40}$ | 0.00071 AU (106,000 km; 66,000 mi) | 3.1–7 | 29.6 | | data · 2011 YC$_{40}$ |
| 2011-12-29 | 2012-01-01 | 2012 AQ | 0.00180 AU (269,000 km; 167,000 mi) | 1.9–4.3 | 30.7 | | data · 2012 AQ |
| 2011-12-30 | 2011-12-31 | 2011 YC$_{63}$ | 0.00161 AU (241,000 km; 150,000 mi) | 4.2–9.4 | 29.0 | | data · 2011 YC$_{63}$ |

### Warning times by size

This sub-section visualises the warning times of the close approaches listed in the above table, depending on the size of the asteroid. The sizes of the charts show the relative sizes of the asteroids to scale. For comparison, the approximate size of a person is also shown. This is based the absolute magnitude of each asteroid, an approximate measure of size based on brightness.
Absolute magnitude H ≥ 30 (smallest)
(size of a person for comparison)
Absolute magnitude 30 > H ≥ 29
Absolute magnitude 29 > H ≥ 28
Absolute magnitude 27-28
Absolute magnitude 27 > H ≥ 26
Absolute magnitude 26 > H ≥ 25
Absolute magnitude 25 > H (largest)
* After closest approach: 1 (50.0%)
* < 24 hours before: 0 (0.0%)
* up to 7 days before: 0 (0.0%)
* > one week before: 0 (0.0%)
* > 7 weeks before: 0 (0.0%)
* > one year before: 1 (50.0%)