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Near Earth Object Program
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NOTICE: JPL's Center for NEO Studies (CNEOS), which operates neo.jpl.nasa.gov, will substantially upgrade the site in early 2017, giving it a new look-and-feel, improved navigation and added content. Scripts which extract data from HTML on the current site will have to be revised to use the related API on the new site. The new APIs are now functional, and specifics on them are now available at http://ssd-api.jpl.nasa.gov/.

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
----------  ----  ----- ----- ------ -----  ------ ----  ------ ------ -----  -----
2017-01-12   106     16  1127   8383  5932     157 1768     875   7487 15458  15564
2017-01-01   106     16  1125   8345  5924     157 1763     874   7473 15410  15516
2016-12-01   106     16  1119   8273  5889     157 1750     873   7429 15297  15403
2016-11-01   106     16  1103   8153  5834     157 1742     873   7375 15106  15212
2016-10-01   106     16  1085   8032  5758     157 1733     873   7326 14891  14997
2016-09-01   106     16  1073   7950  5681     157 1730     872   7285 14720  14826
2016-08-01   106     16  1070   7898  5601     157 1718     872   7237 14585  14691
2016-07-01   106     16  1064   7862  5541     157 1709     872   7194 14483  14589
2016-06-01   106     16  1058   7806  5503     157 1703     872   7151 14383  14489
2016-05-01   105     16  1042   7740  5459     157 1694     872   7112 14257  14362
2016-04-01   105     16  1028   7653  5402     156 1686     871   7070 14099  14204
2016-03-01   105     16  1004   7511  5341     156 1675     870   7011 13872  13977
2016-02-01   105     16   992   7405  5278     155 1660     869   6965 13691  13796
2016-01-01   105     16   979   7311  5212     155 1643     867   6899 13518  13623
2015-12-01   103     16   959   7194  5158     155 1632     866   6841 13327  13430
2015-11-01   103     16   950   7104  5109     155 1628     865   6804 13179  13282
2015-10-01   103     16   947   7032  5043     155 1613     865   6748 13038  13141
2015-09-01   103     16   940   6979  4978     155 1606     865   6714 12913  13016
2015-08-01   103     16   938   6939  4940     155 1601     864   6681 12833  12936
2015-07-01   103     16   935   6913  4908     155 1595     864   6647 12772  12875
2015-06-01   103     15   934   6873  4868     155 1591     863   6610 12690  12793
2015-05-01   103     15   922   6811  4804     155 1581     863   6573 12552  12655
2015-04-01   102     15   917   6729  4742     154 1573     862   6534 12403  12505
2015-03-01   102     15   906   6619  4704     154 1560     859   6482 12244  12346
2015-02-01   101     14   898   6536  4665     154 1548     859   6444 12113  12214
2015-01-01   100     14   889   6452  4599     154 1534     857   6373 11954  12054
2014-12-01   100     14   880   6388  4562     154 1525     855   6320 11844  11944
2014-11-01   100     14   874   6315  4497     154 1516     852   6274 11700  11800
2014-10-01    99     14   867   6225  4434     154 1511     852   6234 11540  11639
2014-09-01    99     14   861   6172  4379     154 1505     852   6202 11426  11525
2014-08-01    99     14   856   6119  4306     154 1496     852   6143 11295  11394
2014-07-01    99     14   854   6076  4274     154 1485     852   6109 11218  11317
2014-06-01    99     14   845   6039  4218     153 1477     848   6064 11116  11215
2014-05-01    99     14   838   5972  4172     153 1464     847   6019 10996  11095
2014-04-01    99     14   826   5855  4063     153 1456     846   5963 10758  10857
2014-03-01    99     13   819   5798  4038     153 1451     846   5933 10668  10767
2014-02-01    99     13   811   5753  4000     153 1444     846   5898 10577  10676
2014-01-01    99     13   804   5700  3960     153 1440     845   5864 10477  10576
2013-12-01    99     13   799   5645  3934     153 1436     845   5832 10391  10490
2013-11-01    99     13   798   5573  3908     153 1428     845   5799 10292  10391
2013-10-01    98     12   786   5514  3846     152 1420     841   5758 10158  10256
2013-09-01    98     12   780   5458  3790     152 1416     840   5721 10040  10138
2013-08-01    98     12   778   5427  3753     152 1409     840   5693  9970  10068
2013-07-01    98     12   773   5399  3728     152 1402     838   5664  9912  10010
2013-06-01    98     12   770   5370  3709     152 1396     836   5634  9861   9959
2013-05-01    98     11   765   5331  3688     152 1389     836   5603  9795   9893
2013-04-01    98     11   760   5290  3658     152 1380     836   5569  9719   9817
2013-03-01    98     11   755   5242  3630     152 1371     836   5543  9638   9736
2013-02-01    97     11   750   5203  3603     152 1368     836   5518  9567   9664
2013-01-01    97     11   743   5122  3566     152 1354     835   5465  9442   9539
2012-12-01    97     11   735   5069  3535     152 1343     835   5429  9350   9447
2012-11-01    96     10   727   5015  3499     152 1336     833   5396  9251   9347
2012-10-01    96     10   721   4940  3444     152 1325     832   5342  9115   9211
2012-09-01    96     10   717   4907  3413     152 1322     831   5315  9047   9143
2012-08-01    96     10   712   4881  3380     152 1317     830   5282  8983   9079
2012-07-01    95     10   711   4875  3371     152 1312     829   5267  8967   9062
2012-06-01    95     10   706   4850  3347     152 1303     826   5232  8913   9008
2012-05-01    95     10   704   4817  3323     152 1297     823   5206  8854   8949
2012-04-01    95     10   702   4766  3296     152 1292     822   5176  8774   8869
2012-03-01    95     10   696   4686  3270     152 1286     820   5144  8662   8757
2012-02-01    95     10   686   4639  3229     152 1281     820   5110  8564   8659
2012-01-01    95     10   676   4570  3194     152 1272     819   5074  8450   8545
2011-12-01    95     10   672   4538  3170     152 1265     816   5048  8390   8485
2011-11-01    95     10   669   4497  3137     150 1254     813   5013  8313   8408
2011-10-01    95     10   662   4435  3092     149 1243     811   4976  8199   8294
2011-09-01    94     10   661   4400  3040     149 1237     810   4940  8111   8205
2011-08-01    94     10   661   4384  3013     149 1234     808   4919  8068   8162
2011-07-01    93     10   659   4371  2989     149 1230     808   4900  8029   8122
2011-06-01    93     10   659   4353  2965     149 1224     807   4872  7987   8080
2011-05-01    93     10   656   4327  2943     149 1215     806   4843  7936   8029
2011-04-01    93     10   645   4279  2913     149 1208     803   4799  7847   7940
2011-03-01    93     10   634   4216  2889     149 1199     801   4765  7749   7842
2011-02-01    93     10   624   4171  2872     149 1188     801   4741  7677   7770
2011-01-01    93     10   618   4097  2838     148 1172     800   4693  7563   7656
2010-12-01    93      9   609   4042  2807     148 1164     800   4656  7467   7560
2010-11-01    93      9   598   3973  2763     148 1158     800   4618  7343   7436
2010-10-01    93      9   588   3917  2725     148 1144     800   4578  7239   7332
2010-09-01    93      9   582   3869  2661     148 1139     798   4545  7121   7214
2010-08-01    93      9   579   3856  2650     148 1137     795   4529  7094   7187
2010-07-01    93      9   574   3833  2639     148 1134     794   4499  7055   7148
2010-06-01    92      9   568   3802  2617     148 1126     793   4459  6996   7088
2010-05-01    91      9   560   3758  2597     147 1113     791   4418  6924   7015
2010-04-01    91      9   552   3713  2578     147 1109     790   4384  6852   6943
2010-03-01    91      9   544   3676  2552     146 1100     788   4353  6781   6872
2010-02-01    91      9   540   3622  2528     146 1088     787   4310  6699   6790
2010-01-01    91      9   535   3594  2509     146 1083     786   4288  6647   6738
2009-01-01    89      9   481   3124  2252     143 1004     761   3941  5866   5955
2008-01-01    85      7   426   2666  1962     139  911     741   3555  5061   5146
2007-01-01    83      6   359   2317  1729     135  824     714   3211  4411   4494
2006-01-01    79      5   312   1977  1479     132  741     684   2846  3773   3852
2005-01-01    76      4   258   1637  1247     123  648     634   2470  3146   3222
2004-01-01    72      2   202   1327  1079     110  553     585   2129  2610   2682
2003-01-01    68      1   167   1091   913     100  470     529   1812  2172   2240
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.

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