Skip Navigation: Avoid going through Home page links and jump straight to content
spacer spacer spacer
spacer spacer spacer
spacer
NASA Logo    + View the NASA Portal  
Near Earth Object Program
spacer
spacer spacer spacer
spacer
NEO Basics Search Programs Discovery Statistics Accessible NEAs News Frequently Asked Questions
spacer
spacer spacer spacer
spacer
Orbit Diagrams Orbit Elements Close Approaches Impact Risk Images Related LInks
spacer
spacer spacer spacer
spacer

NEO Discovery Statistics

NEAR-EARTH ASTEROID DISCOVERY STATISTICS

Some entries in the following charts and tables are dependent upon a diameter that is roughly inferred from the object’s estimated absolute magnitude (H) and its assumed reflectivity, or albedo. The absolute magnitude (H) of a near-Earth asteroid (NEA) is a measure of the object's brightness one astronomical unit from the sun and Earth and at zero phase angle (i.e., the angle between the sun and Earth, as seen from the NEA, is zero). The absolute magnitude (H) for a particular NEA is computed from the observed apparent magnitudes of the object at various times when the phase angles and the distances from the sun and Earth are known. An effective diameter is the diameter of a hypothetical spherical NEA that would provide the same apparent brightness as the observed NEA, whose actual shape is unknown.

Since most NEAs do not have a known reflectivity, or albedo, this albedo must be estimated before the H values, representing intrinsic brightness, can be converted to an approximate diameter. Pravec et al (2012) determined that, for their sample of 583 main-belt asteroids and NEAs, the mean albedos and their standard deviations are 0.057 (±0.013) for the Tholen/Bus/DeMeo C/G/B/F/P/D types and 0.197 (±0.051) for the S/A/L types. Since the albedos for NEAs are most likely to be either approximately 6% for asteroids of the C-type and associated taxonomic classes or 20% for asteroids of the more populous S-type and associated taxonomic classes, we have used an approximate mean value of 14% albedo and an H value of 17.75 to represent a one kilometer spherical NEA. Since the determined H values are uncertain, and likely biased by a few tenths (see Pravec et al., 2012, Icarus) and the single 14% albedo is only a rough mean representing a bimodal albedo distribution, the estimated numbers of one kilometer and larger sized objects in the tables below are very rough. However, these statistics are useful for monitoring the annual NEA discovery progress.

Using near-infrared data provided by the WISE spacecraft in 2010 and early 2011, Mainzer et al (2011) were able to determine diameters and albedos for 250 NEAs with a minimum uncertainty of 10% and 20% respectively. Hence they were able to determine the albedo distribution of these objects with known diameters and this distribution was then used to compute diameters for previously known NEOs with known H values but unknown diameters or albedos. They provided an estimate of 981 (±19) NEAs as the total population of NEAs one kilometer and larger. At the time of their analysis (Spring 2011), they also estimated that 911 (±17) of these large NEAs had already been discovered. While this latter estimate is both higher and more accurate than the estimated numbers given for Spring 2011 in the following tables, this statistical technique cannot be easily employed for day-to-day estimates of the population of NEAs one kilometer and larger. In the following tables, we will continue to use the simpler method described in the previous paragraph.

Mainzer, A. et al. (2011). NEOWISE observations of near-Earth objects: Preliminary Results. Astrophysical Journal. 743:156.
Pravec, P., A.W. Harris, P. Kusnirak, A. Galad, K. Hornoch (2012). Absolute magnitudes of asteroids and a revision of asteroid albedo estimates from WISE thermal observations. Icarus (submitted 6/2012).
Stuart, J.S. (2003). Observational constraints on the number, albedos, sizes and impact hazards of the near-Earth asteroids. Ph.D. thesis, MIT.

All Asteroids

Table: Number of Near-Earth Asteroid Discoveries at Half-Year Intervals: All Asteroids

Table 1. NEAs Discovered by Site

Half Year
Intervals
LINEAR
(704)
NEAT
(566,608,644)
Spacewatch
(691,291)
LONEOS
(699)
Catalina
(703,E12,G96)
Pan-STARRS
(F51)
NEOWISE
(C51)
OtherCumulative
Total
 1995 (1)001400004334
 1995 (2)001200002348
 1996 (1)151800004376
 1996 (2)051000002393
 1997 (1)321000004412
 1997 (2)149400007446
 1998 (1)4491911007527
 1998 (2)9221562005649
 1999 (1)75012611001754
 1999 (2)8707719003877
 2000 (1)10821421130041039
 2000 (2)15014121700081240
 2001 (1)942872200021393
 2001 (2)18364152000041679
 2002 (1)15856161410061930
 2002 (2)130896700052167
 2003 (1)10230233300092364
 2003 (2)13338332170082604
 2004 (1)167194114250062876
 2004 (2)13772925600063140
 2005 (1)778292211500103401
 2005 (2)5930541919300103766
 2006 (1)44445131950034070
 2006 (2)52175461990054403
 2007 (1)3842072010034676
 2007 (2)7402552660075053
 2008 (1)7404312810055457
 2008 (2)66043028000115857
 2009 (1)51032026000186218
 2009 (2)58031031500176639
 2010 (1)29021025708797042
 2010 (2)7502203451837147553
 2011 (1)410170331683128025
 2011 (2)2901502531040238449
 2012 (1)260130352120078967
 2012 (2)2901302771310269443
 2013 (1)301302881500189915
 2013 (2)0012031520812910480
 2014 (1)0080332242165011128
 2014 (2)*003031170112111364
* Incomplete half-year (based on discovery data through 2014-Sep-16 06:05 local)

Large Asteroids

Table: Number of Near-Earth Asteroid Discoveries at Half-Year Intervals: Large Asteroids

Table 2. Large NEAs Discovered by Site

Half Year
Intervals
LINEAR
(704)
NEAT
(566,608,644)
Spacewatch
(691,291)
LONEOS
(699)
Catalina
(703,E12,G96)
Pan-STARRS
(F51)
NEOWISE
(C51)
OtherCumulative
Total
 1995 (1)00300002178
 1995 (2)00400001183
 1996 (1)02200000187
 1996 (2)02000000189
 1997 (1)01300001194
 1997 (2)23100002202
 1998 (1)74210002218
 1998 (2)242130003251
 1999 (1)160244000277
 1999 (2)230112002306
 2000 (1)322114001347
 2000 (2)382350004399
 2001 (1)238040000434
 2001 (2)225040001466
 2002 (1)304230001506
 2002 (2)1910010001537
 2003 (1)143160002563
 2003 (2)175142001593
 2004 (1)165123001621
 2004 (2)910112000644
 2005 (1)100219001667
 2005 (2)645010001693
 2006 (1)30219000708
 2006 (2)102012000723
 2007 (1)20309001738
 2007 (2)50107000751
 2008 (1)20109000763
 2008 (2)30105000772
 2009 (1)10009000782
 2009 (2)60006002796
 2010 (1)00004030803
 2010 (2)10001030808
 2011 (1)20005100816
 2011 (2)00106300826
 2012 (1)00009100836
 2012 (2)10005200844
 2013 (1)00004000848
 2013 (2)00003201854
 2014 (1)00002420862
 2014 (2)*00000100863
* Incomplete half-year (based on discovery data through 2014-Sep-16 06:05 local)
NOTE: In the year 2010, the "Other" site category was exclusively WISE.
A separate table of WISE discoveries is
available.

Data compiled by Alan Chamberlin.

NUMBER OF NEOS
With over 90% of the near-Earth objects larger than one kilometer already discovered, the NEO Program is now focusing on finding 90% of the NEO population larger than 140 meters. A separate table containing WISE discoveries for NEAs and comets is available.

The chart below shows the cumulative total known near-Earth asteroids versus time. The blue area shows all near-Earth asteroids while the red area shows only large near-Earth asteroids (those with diameters roughly one kilometer and larger).
Table: Number of Known Near-Earth Asteroids Over Time
(click on the chart above for a larger version)

The chart below shows the total known near-Earth asteroids per size bin. Diameters are estimated using an assumed average albedo for NEAs. The first size bin represents NEAs smaller than 30m in diameter. The second represents NEAs with diameters from 30m to 100m, and so on.
Known Near-Earth Asteroids by Size Bin
Data shown in the chart above represent known NEAs as of the date shown in the bottom-right corner of the chart.

The table below shows the total number of NEOs known at selected dates. The most recent date at the top of the table is generally not the date the table was updated, but rather the discovery date of the most recently discovered NEO. Numbers for large asteroids (PHA-KM and NEA-KM) are rough estimates (see introductory note above). This table is updated daily using discovery data published by the Minor Planet Center.

----------------------------------------------------------------------------
   Date      NEC  Atira  Aten Apollo  Amor  PHA-KM  PHA  NEA-KM  NEA    NEO
----------  ----  ----- ----- ------ -----  ------ ----  ------ -----  -----
2014-09-14    94     14   862   6136  4352     155 1500     863 11364  11458
2014-09-01    94     14   860   6122  4341     155 1500     863 11337  11431
2014-08-01    94     14   855   6069  4269     155 1491     862 11207  11301
2014-07-01    94     14   853   6026  4235     155 1481     862 11128  11222
2014-06-01    94     14   844   5989  4177     154 1473     858 11024  11118
2014-05-01    94     14   837   5930  4131     154 1461     856 10912  11006
2014-04-01    94     14   826   5853  4069     154 1454     855 10762  10856
2014-03-01    94     13   819   5797  4042     154 1449     855 10671  10765
2014-02-01    94     13   811   5752  4004     154 1442     855 10580  10674
2014-01-01    94     13   804   5699  3964     154 1438     854 10480  10574
2013-12-01    94     13   799   5644  3938     154 1434     854 10394  10488
2013-11-01    94     13   798   5573  3911     154 1426     854 10295  10389
2013-10-01    94     12   786   5514  3849     153 1418     850 10161  10255
2013-09-01    94     12   780   5457  3794     153 1414     849 10043  10137
2013-08-01    94     12   778   5426  3757     153 1408     849  9973  10067
2013-07-01    94     12   773   5398  3732     153 1401     848  9915  10009
2013-06-01    94     12   770   5368  3714     153 1395     846  9864   9958
2013-05-01    94     11   765   5328  3694     153 1388     846  9798   9892
2013-04-01    94     11   760   5287  3663     153 1379     845  9721   9815
2013-03-01    94     11   755   5239  3635     153 1370     845  9640   9734
2013-02-01    93     11   750   5200  3608     153 1366     845  9569   9662
2013-01-01    93     11   743   5119  3570     153 1352     844  9443   9536
2012-12-01    93     11   735   5066  3539     153 1342     844  9351   9444
2012-11-01    92     10   727   5012  3502     153 1333     841  9251   9343
2012-10-01    92     10   721   4937  3446     153 1322     839  9114   9206
2012-09-01    92     10   717   4904  3416     153 1319     838  9047   9139
2012-08-01    92     10   712   4879  3382     153 1314     837  8983   9075
2012-07-01    91     10   711   4873  3373     153 1310     836  8967   9058
2012-06-01    91     10   706   4847  3350     153 1301     833  8913   9004
2012-05-01    91     10   704   4814  3326     153 1296     830  8854   8945
2012-04-01    91     10   702   4763  3299     153 1290     829  8774   8865
2012-03-01    91     10   696   4683  3272     153 1284     827  8661   8752
2012-02-01    91     10   686   4636  3231     153 1278     827  8563   8654
2012-01-01    91     10   676   4567  3196     153 1270     826  8449   8540
2011-12-01    91     10   672   4535  3171     153 1263     822  8388   8479
2011-11-01    91     10   669   4494  3136     151 1253     819  8309   8400
2011-10-01    91     10   662   4432  3091     150 1242     818  8195   8286
2011-09-01    90     10   661   4397  3038     150 1236     817  8106   8196
2011-08-01    90     10   661   4381  3012     150 1233     816  8064   8154
2011-07-01    89     10   659   4368  2988     150 1229     816  8025   8114
2011-06-01    89     10   659   4351  2963     150 1223     815  7983   8072
2011-05-01    89     10   656   4325  2940     150 1215     813  7931   8020
2011-04-01    89     10   645   4276  2910     150 1208     811  7841   7930
2011-03-01    89     10   634   4213  2886     150 1199     809  7743   7832
2011-02-01    89     10   624   4166  2867     150 1188     809  7667   7756
2011-01-01    89     10   618   4090  2835     150 1172     808  7553   7642
2010-12-01    89      9   609   4035  2803     150 1163     807  7456   7545
2010-11-01    89      9   598   3966  2757     150 1157     807  7330   7419
2010-10-01    89      9   588   3910  2717     150 1143     807  7224   7313
2010-09-01    89      9   582   3864  2652     150 1138     806  7107   7196
2010-08-01    89      9   579   3850  2642     150 1135     804  7080   7169
2010-07-01    89      9   574   3828  2631     150 1133     803  7042   7131
2010-06-01    88      9   568   3797  2609     150 1125     802  6983   7071
2010-05-01    87      9   560   3753  2590     149 1113     800  6912   6999
2010-04-01    87      9   552   3707  2573     149 1107     800  6841   6928
2010-03-01    87      9   544   3670  2548     148 1098     799  6771   6858
2010-02-01    87      9   540   3616  2523     148 1086     798  6688   6775
2010-01-01    87      9   535   3590  2505     148 1083     796  6639   6726
2009-12-01    87      9   531   3569  2495     148 1078     794  6604   6691
2009-11-01    86      9   520   3493  2466     148 1070     791  6488   6574
2009-10-01    86      9   511   3438  2433     148 1066     789  6391   6477
2009-09-01    86      9   506   3385  2386     148 1057     787  6286   6372
2009-08-01    86      9   504   3365  2359     148 1055     786  6237   6323
2009-07-01    86      9   504   3355  2350     147 1053     782  6218   6304
2009-06-01    85      9   501   3344  2339     146 1050     781  6193   6278
2009-05-01    85      9   499   3317  2325     146 1041     780  6150   6235
2009-04-01    85      9   496   3285  2311     146 1037     777  6101   6186
2009-03-01    85      9   491   3223  2292     146 1025     777  6015   6100
2009-02-01    85      9   487   3165  2266     145 1013     774  5927   6012
2009-01-01    85      9   481   3121  2246     145 1004     772  5857   5942
2008-12-01    84      9   480   3079  2216     145  994     771  5784   5868
2008-11-01    84      9   474   3031  2194     145  986     769  5708   5792
2008-10-01    84      8   467   2969  2144     144  976     768  5588   5672
2008-09-01    83      8   464   2938  2109     144  966     767  5519   5602
2008-08-01    83      8   461   2924  2095     144  961     766  5488   5571
2008-07-01    83      8   459   2907  2083     143  952     763  5457   5540
2008-06-01    83      8   455   2896  2075     143  949     762  5434   5517
2008-05-01    83      8   451   2866  2057     143  943     761  5382   5465
2008-04-01    83      8   449   2819  2028     143  940     760  5304   5387
2008-03-01    83      7   440   2751  2003     142  930     753  5201   5284
2008-02-01    83      7   428   2691  1973     141  916     751  5099   5182
2008-01-01    83      7   426   2664  1956     141  908     751  5053   5136
2007-12-01    83      7   423   2629  1939     141  897     748  4998   5081
2007-11-01    83      7   411   2571  1903     141  887     744  4892   4975
2007-10-01    82      7   397   2522  1861     141  877     743  4787   4869
2007-09-01    82      7   390   2484  1829     140  870     742  4710   4792
2007-08-01    82      7   388   2473  1819     139  865     738  4687   4769
2007-07-01    82      7   388   2469  1812     139  864     738  4676   4758
2007-06-01    82      7   383   2447  1803     138  855     736  4640   4722
2007-05-01    82      7   382   2434  1792     138  851     734  4615   4697
2007-04-01    82      7   381   2408  1775     138  847     730  4571   4653
2007-03-01    82      6   375   2368  1752     138  840     728  4501   4583
2007-02-01    82      6   367   2335  1736     137  832     724  4444   4526
2007-01-01    82      6   359   2315  1723     137  823     723  4403   4485
2006-12-01    81      6   354   2289  1705     137  820     721  4354   4435
2006-11-01    81      5   344   2240  1682     136  808     715  4271   4352
2006-10-01    79      5   337   2210  1650     136  798     713  4202   4281
2006-09-01    79      5   330   2173  1623     135  789     709  4131   4210
2006-08-01    79      5   328   2156  1610     135  784     709  4099   4178
2006-07-01    79      5   327   2145  1593     135  782     708  4070   4149
2006-06-01    79      5   326   2134  1580     135  779     708  4045   4124
2006-05-01    79      5   325   2106  1553     135  769     704  3989   4068
2006-04-01    78      5   321   2079  1538     135  760     702  3943   4021
2006-03-01    78      5   319   2064  1519     135  759     701  3907   3985
2006-02-01    78      5   316   2029  1502     135  751     698  3852   3930
2006-01-01    78      5   312   1974  1475     134  742     693  3766   3844
2005-12-01    78      5   302   1942  1454     133  731     690  3703   3781
2005-11-01    77      5   297   1900  1428     132  721     685  3630   3707
2005-10-01    76      4   289   1844  1388     131  709     674  3525   3601
2005-09-01    76      4   286   1810  1369     131  704     671  3469   3545
2005-08-01    76      4   283   1796  1353     131  698     670  3436   3512
2005-07-01    76      4   279   1777  1341     130  691     667  3401   3477
2005-06-01    76      4   275   1762  1321     130  687     662  3362   3438
2005-05-01    75      4   274   1745  1307     128  681     659  3330   3405
2005-04-01    75      4   268   1720  1288     126  668     655  3280   3355
2005-03-01    75      4   263   1680  1263     125  658     651  3210   3285
2005-02-01    75      4   262   1657  1255     124  654     648  3178   3253
2005-01-01    75      4   258   1633  1245     124  647     644  3140   3215
2004-12-01    74      3   249   1601  1224     124  639     636  3077   3151
2004-11-01    74      3   245   1581  1218     123  630     631  3047   3121
2004-10-01    73      3   238   1553  1210     122  619     629  3004   3077
2004-09-01    72      3   230   1515  1185     122  611     628  2933   3005
2004-08-01    72      3   226   1495  1163     121  604     624  2887   2959
2004-07-01    72      3   226   1488  1159     119  601     621  2876   2948
2004-06-01    72      3   223   1458  1146     118  590     618  2830   2902
2004-05-01    72      2   218   1439  1131     118  584     614  2790   2862
2004-04-01    72      2   215   1409  1119     114  574     607  2745   2817
2004-03-01    72      2   206   1373  1101     114  567     598  2682   2754
2004-02-01    71      2   204   1358  1094     113  562     597  2658   2729
2004-01-01    71      2   202   1324  1076     111  552     593  2604   2675
2003-12-01    71      2   196   1292  1064     108  539     585  2554   2625
2003-11-01    71      2   193   1271  1051     108  532     579  2517   2588
2003-10-01    70      2   188   1244  1029     108  523     577  2463   2533
2003-09-01    70      2   185   1224   995     106  514     570  2406   2476
2003-08-01    70      2   185   1212   982     103  509     566  2381   2451
2003-07-01    69      2   184   1205   973     103  506     563  2364   2433
2003-06-01    69      2   182   1189   961     103  501     557  2334   2403
2003-05-01    67      2   180   1175   955     102  499     555  2312   2379
2003-04-01    67      2   175   1155   944     101  491     550  2276   2343
2003-03-01    67      2   170   1136   933     101  484     546  2241   2308
2003-02-01    67      1   169   1116   927     101  478     542  2213   2280
2003-01-01    67      1   167   1089   910     100  468     537  2167   2234
2002-12-01    67      1   163   1062   890     100  466     535  2116   2183
2002-11-01    67      1   160   1047   873      99  460     531  2081   2148
2002-10-01    66      1   158   1023   850      98  454     523  2032   2098
2002-09-01    64      1   155   1003   830      97  448     514  1989   2053
2002-08-01    64      1   154    987   807      95  437     511  1949   2013
2002-07-01    63      1   152    977   800      94  430     506  1930   1993
2002-06-01    63      1   148    960   791      92  422     500  1900   1963
2002-05-01    63      1   144    942   780      91  413     489  1867   1930
2002-04-01    63      1   142    924   767      91  406     487  1834   1897
2002-03-01    62      1   136    897   753      90  396     484  1787   1849
2002-02-01    62      1   131    874   737      89  387     474  1743   1805
2002-01-01    62      1   124    840   714      89  374     466  1679   1741
2001-12-01    62      1   121    804   695      85  360     457  1621   1683
2001-11-01    60      1   120    776   680      84  353     453  1577   1637
2001-10-01    60      1   114    751   656      83  344     449  1522   1582
2001-09-01    60      1   110    722   622      82  333     438  1455   1515
2001-08-01    59      1   109    700   602      82  327     435  1412   1471
2001-07-01    58      1   108    695   589      82  326     434  1393   1451
2001-06-01    57      1   108    685   579      80  323     427  1373   1430
2001-05-01    56      1   107    673   568      78  316     419  1349   1405
2001-04-01    56      1   105    661   559      77  307     415  1326   1382
2001-03-01    56      1   101    646   545      75  298     408  1293   1349
2001-02-01    56      1    98    635   534      74  295     403  1268   1324
2001-01-01    56      1    94    620   525      74  292     399  1240   1296
2000-12-01    56      1    93    606   513      73  286     392  1213   1269
2000-11-01    56      1    90    582   496      72  283     383  1169   1225
2000-10-01    56      1    87    572   482      72  279     376  1142   1198
2000-09-01    56      1    81    554   456      71  272     367  1092   1148
2000-08-01    56      1    79    536   440      69  263     358  1056   1112
2000-07-01    56      1    77    531   430      67  260     347  1039   1095
2000-06-01    56      1    76    526   424      66  256     344  1027   1083
2000-05-01    56      1    76    513   410      66  251     337  1000   1056
2000-04-01    55      1    73    498   397      65  245     330   969   1024
2000-03-01    55      1    64    482   386      63  233     318   933    988
2000-02-01    55      1    62    465   375      62  222     311   903    958
2000-01-01    55      1    57    451   368      62  216     306   877    932
1999-12-01    54      1    56    441   359      60  208     299   857    911
1999-11-01    54      1    54    428   345      60  204     289   828    882
1999-10-01    54      1    54    412   331      59  199     285   798    852
1999-09-01    52      1    54    396   315      57  192     281   766    818
1999-08-01    52      1    54    396   313      57  192     281   764    816
1999-07-01    52      1    54    391   308      56  190     277   754    806
1999-06-01    52      1    51    384   298      56  186     274   734    786
1999-05-01    51      1    49    372   292      52  178     264   714    765
1999-04-01    51      1    48    359   285      51  174     257   693    744
1999-03-01    51      1    47    349   280      51  172     256   677    728
1999-02-01    51      1    47    339   275      51  169     253   662    713
1999-01-01    51      1    45    334   269      51  166     251   649    700
1998-12-01    51      1    41    324   260      51  162     242   626    677
1998-11-01    51      1    38    310   251      49  154     237   600    651
1998-10-01    51      1    36    306   244      49  152     233   587    638
1998-09-01    51      1    29    293   231      48  140     227   554    605
1998-08-01    51      1    29    283   220      46  133     221   533    584
1998-07-01    51      1    29    279   218      44  129     218   527    578
1998-06-01    51      1    29    273   211      43  127     215   514    565
1998-05-01    51      1    29    264   205      43  124     211   499    550
1998-04-01    51      1    27    256   196      43  117     210   480    531
1998-03-01    51      1    27    244   188      43  112     206   460    511
1998-02-01    51      0    26    240   188      42  110     205   454    505
1998-01-01    51      0    26    235   185      42  108     202   446    497
1997-01-01    51      0    22    206   165      40   97     189   393    444
1996-01-01    51      0    20    178   150      38   86     183   348    399
1995-01-01    51      0    19    163   134      37   83     173   316    367
1994-01-01    49      0    15    140   114      33   70     155   269    318
1993-01-01    49      0    13    117    98      31   64     141   228    277
1992-01-01    49      0    11    103    84      29   61     123   198    247
1991-01-01    47      0     9     76    73      24   49     105   158    205
1990-01-01    47      0     8     63    62      20   42      89   133    180
1980-01-01    43      0     3     27    22      12   17      44    52     95
1970-01-01    41      0     0     13    14       8   10      24    27     68
1960-01-01    40      0     0     10    10       7    8      18    20     60
1950-01-01    40      0     0      7     6       4    5      12    13     53
1940-01-01    35      0     0      3     6       2    3       8     9     44
1930-01-01    33      0     0      0     5       0    0       5     5     38
1920-01-01    31      0     0      0     3       0    0       3     3     34
1910-01-01    29      0     0      0     1       0    0       1     1     30
1900-01-01    27      0     0      0     1       0    0       1     1     28

Note: "NEC" are Near-Earth comets. "PHA-KM" and "NEA-KM" are PHAs and NEAs with diameters roughly one kilometer and larger. Other definitions, such as Apollo, are on the NEO groups page.

Data compiled by Alan Chamberlin.

Menu
FIRST GOV   NASA Home Page Site Manager: Don Yeomans
Webmaster: Ron Baalke
Last Updated:
Feedback Credits Privacy Mailing List NASA