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

NOTICE: The NEO Program Office website is being retired. Please use the new CNEOS site (update your bookmarks and links). The legacy NEO site will be available until late March 2017, after which you will be automatically redirected to the new CNEOS site.

NEO Discovery Statistics

NUMBER OF NEAR-EARTH ASTEROIDS DISCOVERED

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. Many of the charts and tables below depend on diameters that can only be roughly inferred from an asteroid's estimated absolute magnitude (H) and an assumed reflectivity, or albedo.

The absolute magnitude H is a measure of the asteroid’s intrinsic mean brightness, estimated from measurements of its apparent magnitudes at the various times it has been observed, at various distances from the Sun and Earth, and at various phase angles. Also, since the actual shape of the asteroid is usually unknown, it is simply assumed to be spherical.

To estimate the size of an asteroid, we must know its average reflectivity, or albedo, but this is usually unknown. For main-belt asteroids, Pravec et al. (2012) showed that there is a rough correlation between albedo and taxonomic spectral class: asteroids in the C/G/B/F/P/D spectral classes have mean albedos of about 6%, while those in the S/A/L classes have mean albedos of about 20%. But since the taxonomic class of most NEAs is unknown, we simply use an assumed mean albedo of 14% to estimate all NEA sizes. With this assumption, a one kilometer spherical NEA corresponds to an H value of 17.75. Since the estimated H values are uncertain, and likely biased by a few tenths (Pravec et al., 2012), and the single 14% albedo is only a rough mean representing a bimodal albedo distribution, the estimated numbers of objects larger than a given size in the tables below are very rough. Nonetheless, these statistics are useful for monitoring the annual NEA discovery progress.

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).
[read more...]

The following chart shows the cumulative number of known Near-Earth Asteroids (NEAs) versus time. Totals are shown for NEAs of all sizes, those NEAs larger than ~140m in size, and those larger than ~1km in size.

The following chart shows the current total number of known NEAs grouped according to their estimated sizes. The first size bin represents NEAs smaller than ~30m in diameter. The last bin represents NEAs with diameters larger than ~1km.

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 asteroids constrained by size (PHA-KM, NEA-KM, and NEA140) are rough estimates (see introductory note above). The "-KM" suffix indicates NEAs larger than approximately 1km, while the "140" suffix indicates NEAs larger than approximately 140m. This table is updated daily using discovery data published by the Minor Planet Center.

"NEC" are Near-Earth comets. "PHA-KM" and "NEA-KM" are PHAs and NEAs with diameters roughly one kilometer and larger. "NEA140" are NEAs with diameters roughly 140 meters and larger. Other definitions, such as Apollo, are on the NEO groups page.
-----------------------------------------------------------------------------------
   Date      NEC  Atira  Aten Apollo  Amor  PHA-KM  PHA  NEA-KM NEA140  NEA    NEO
----------  ----  ----- ----- ------ -----  ------ ----  ------ ------ -----  -----
2017-02-21   106     16  1140   8510  5992     157 1785     875   7548 15658  15764
2017-02-01   106     16  1139   8473  5979     157 1782     875   7533 15607  15713
2017-01-01   106     16  1125   8345  5925     157 1764     873   7474 15411  15517
2016-12-01   106     16  1119   8273  5889     157 1751     872   7429 15297  15403
2016-11-01   106     16  1103   8153  5835     157 1743     872   7376 15107  15213
2016-10-01   106     16  1085   8032  5759     157 1734     872   7327 14892  14998
2016-09-01   106     16  1073   7950  5682     157 1731     871   7286 14721  14827
2016-08-01   106     16  1070   7898  5602     157 1720     871   7239 14586  14692
2016-07-01   106     16  1064   7862  5542     157 1710     871   7196 14484  14590
2016-06-01   106     16  1058   7806  5504     157 1704     871   7153 14384  14490
2016-05-01   105     16  1042   7740  5460     157 1695     871   7114 14258  14363
2016-04-01   105     16  1028   7653  5403     156 1687     870   7072 14100  14205
2016-03-01   105     16  1004   7511  5342     156 1676     869   7013 13873  13978
2016-02-01   105     16   992   7405  5279     155 1661     868   6967 13692  13797
2016-01-01   105     16   979   7311  5213     155 1644     866   6901 13519  13624
2015-12-01   103     16   959   7194  5159     155 1633     865   6843 13328  13431
2015-11-01   103     16   950   7104  5110     155 1629     864   6806 13180  13283
2015-10-01   103     16   947   7032  5044     155 1614     864   6750 13039  13142
2015-09-01   103     16   940   6979  4979     155 1607     864   6716 12914  13017
2015-08-01   103     16   938   6939  4941     155 1602     864   6683 12834  12937
2015-07-01   103     16   935   6913  4909     155 1596     864   6649 12773  12876
2015-06-01   103     15   934   6873  4869     155 1592     863   6612 12691  12794
2015-05-01   103     15   922   6811  4805     155 1582     863   6575 12553  12656
2015-04-01   102     15   917   6729  4743     154 1574     862   6536 12404  12506
2015-03-01   102     15   906   6619  4705     154 1561     859   6484 12245  12347
2015-02-01   101     14   898   6536  4666     154 1549     859   6446 12114  12215
2015-01-01   100     14   889   6452  4600     154 1535     857   6375 11955  12055
2014-12-01   100     14   880   6388  4563     154 1526     855   6322 11845  11945
2014-11-01   100     14   874   6315  4498     154 1517     852   6276 11701  11801
2014-10-01    99     14   867   6225  4435     154 1512     852   6236 11541  11640
2014-09-01    99     14   861   6172  4380     154 1506     852   6204 11427  11526
2014-08-01    99     14   856   6119  4307     154 1497     852   6145 11296  11395
2014-07-01    99     14   854   6076  4275     154 1486     852   6111 11219  11318
2014-06-01    99     14   845   6039  4219     153 1478     848   6066 11117  11216
2014-05-01    99     14   838   5972  4173     153 1465     847   6021 10997  11096
2014-04-01    99     14   826   5855  4064     153 1457     846   5965 10759  10858
2014-03-01    99     13   819   5798  4039     153 1452     846   5935 10669  10768
2014-02-01    99     13   811   5753  4001     153 1445     846   5900 10578  10677
2014-01-01    99     13   804   5700  3961     153 1441     845   5866 10478  10577
2013-12-01    99     13   799   5645  3935     153 1437     845   5834 10392  10491
2013-11-01    99     13   798   5573  3909     153 1429     845   5801 10293  10392
2013-10-01    98     12   786   5514  3847     152 1421     841   5760 10159  10257
2013-09-01    98     12   780   5458  3791     152 1417     840   5723 10041  10139
2013-08-01    98     12   778   5427  3754     152 1410     840   5695  9971  10069
2013-07-01    98     12   773   5399  3729     152 1403     838   5666  9913  10011
2013-06-01    98     12   770   5370  3710     152 1397     836   5636  9862   9960
2013-05-01    98     11   765   5331  3689     152 1390     836   5605  9796   9894
2013-04-01    98     11   760   5290  3659     152 1381     836   5571  9720   9818
2013-03-01    98     11   755   5242  3631     152 1372     836   5545  9639   9737
2013-02-01    97     11   750   5203  3604     152 1369     836   5520  9568   9665
2013-01-01    97     11   743   5122  3567     152 1355     835   5467  9443   9540
2012-12-01    97     11   735   5069  3536     152 1344     835   5431  9351   9448
2012-11-01    96     10   727   5015  3500     152 1337     833   5398  9252   9348
2012-10-01    96     10   721   4940  3445     152 1326     832   5344  9116   9212
2012-09-01    96     10   717   4907  3414     152 1323     831   5317  9048   9144
2012-08-01    96     10   712   4881  3381     152 1318     830   5284  8984   9080
2012-07-01    95     10   711   4875  3372     152 1313     829   5269  8968   9063
2012-06-01    95     10   706   4850  3348     152 1304     826   5234  8914   9009
2012-05-01    95     10   704   4817  3324     152 1298     823   5208  8855   8950
2012-04-01    95     10   702   4766  3297     152 1293     822   5178  8775   8870
2012-03-01    95     10   696   4686  3271     152 1287     820   5146  8663   8758
2012-02-01    95     10   686   4639  3230     152 1282     820   5112  8565   8660
2012-01-01    95     10   676   4570  3195     152 1273     819   5076  8451   8546
2011-12-01    95     10   672   4538  3171     152 1266     816   5050  8391   8486
2011-11-01    95     10   669   4497  3138     150 1255     813   5015  8314   8409
2011-10-01    95     10   662   4435  3093     149 1244     811   4978  8200   8295
2011-09-01    94     10   661   4400  3041     149 1238     810   4942  8112   8206
2011-08-01    94     10   661   4384  3014     149 1235     808   4921  8069   8163
2011-07-01    93     10   659   4371  2990     149 1231     808   4902  8030   8123
2011-06-01    93     10   659   4353  2966     149 1225     807   4874  7988   8081
2011-05-01    93     10   656   4327  2944     149 1216     806   4845  7937   8030
2011-04-01    93     10   645   4279  2914     149 1209     803   4801  7848   7941
2011-03-01    93     10   634   4216  2890     149 1200     801   4767  7750   7843
2011-02-01    93     10   624   4171  2873     149 1189     801   4743  7678   7771
2011-01-01    93     10   618   4097  2839     148 1173     800   4695  7564   7657
2010-12-01    93      9   609   4042  2808     148 1165     800   4658  7468   7561
2010-11-01    93      9   598   3973  2764     148 1159     800   4620  7344   7437
2010-10-01    93      9   588   3917  2726     148 1145     800   4580  7240   7333
2010-09-01    93      9   582   3869  2662     148 1140     798   4547  7122   7215
2010-08-01    93      9   579   3856  2651     148 1138     795   4531  7095   7188
2010-07-01    93      9   574   3833  2640     148 1135     794   4501  7056   7149
2010-06-01    92      9   568   3802  2618     148 1127     793   4461  6997   7089
2010-05-01    91      9   560   3758  2598     147 1114     791   4420  6925   7016
2010-04-01    91      9   552   3713  2579     147 1110     790   4386  6853   6944
2010-03-01    91      9   544   3676  2553     146 1101     788   4355  6782   6873
2010-02-01    91      9   540   3622  2529     146 1089     787   4312  6700   6791
2010-01-01    91      9   535   3594  2510     146 1084     786   4290  6648   6739
2009-01-01    89      9   481   3124  2253     143 1005     761   3943  5867   5956
2008-01-01    85      7   426   2666  1963     139  911     741   3556  5062   5147
2007-01-01    83      6   359   2317  1730     135  824     714   3212  4412   4495
2006-01-01    79      5   312   1977  1480     132  741     684   2847  3774   3853
2005-01-01    76      4   258   1637  1248     123  648     634   2471  3147   3223
2004-01-01    72      2   202   1327  1080     110  553     585   2130  2611   2683
2003-01-01    68      1   167   1091   914     100  470     530   1813  2173   2241
2002-01-01    64      1   124    840   718      89  375     460   1428  1683   1747
2001-01-01    58      1    94    620   527      73  292     393   1075  1242   1300
2000-01-01    57      1    57    451   369      61  216     303    765   878    935
1990-01-01    48      0     8     63    61      20   42      88    132   132    180
1980-01-01    44      0     3     27    21      12   17      43     51    51     95
1970-01-01    41      0     0     13    14       8   10      24     27    27     68
1960-01-01    40      0     0     10    10       7    8      18     20    20     60
1950-01-01    40      0     0      7     6       4    5      12     13    13     53
1940-01-01    35      0     0      3     6       2    3       8      9     9     44
1930-01-01    33      0     0      0     5       0    0       5      5     5     38
1920-01-01    31      0     0      0     3       0    0       3      3     3     34
1910-01-01    29      0     0      0     1       0    0       1      1     1     30
1900-01-01    27      0     0      0     1       0    0       1      1     1     28
NEAR-EARTH ASTEROID DISCOVERY STATISTICS BY SURVEY

The following three charts show the number of NEA discoveries per year, by survey. The first chart shows the totals for NEAs of all sizes, the second for NEAs that are ~140m and larger, and the third for NEAs ~1km and larger. The data used to create each chart can be displayed by clicking on the button at the bottom of each chart. A separate table containing WISE discoveries for NEAs and comets is available.

Menu
  NASA Home Page Site Manager: Paul Chodas
Webmaster: Ron Baalke
Last Updated:
Feedback Credits Privacy Mailing List NASA