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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. Specifics on the new APIs will be provided here a month before the site transition takes place.

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
----------  ----  ----- ----- ------ -----  ------ ----  ------ ------ -----  -----
2016-12-06   106     16  1119   8293  5898     157 1755     874   7438 15326  15432
2016-12-01   106     16  1118   8270  5892     157 1750     874   7429 15296  15402
2016-11-01   106     16  1103   8153  5837     157 1743     874   7377 15109  15215
2016-10-01   106     16  1085   8032  5760     157 1734     874   7327 14893  14999
2016-09-01   106     16  1073   7950  5683     157 1731     873   7286 14722  14828
2016-08-01   106     16  1070   7898  5603     157 1719     873   7238 14587  14693
2016-07-01   106     16  1064   7862  5543     157 1710     873   7195 14485  14591
2016-06-01   106     16  1058   7806  5505     157 1704     873   7152 14385  14491
2016-05-01   105     16  1042   7740  5461     157 1695     873   7113 14259  14364
2016-04-01   105     16  1028   7653  5404     156 1687     872   7071 14101  14206
2016-03-01   105     16  1004   7511  5343     156 1676     871   7012 13874  13979
2016-02-01   105     16   992   7405  5280     155 1661     870   6966 13693  13798
2016-01-01   105     16   979   7311  5214     155 1644     868   6900 13520  13625
2015-12-01   103     16   959   7194  5160     155 1633     868   6842 13329  13432
2015-11-01   103     16   950   7104  5111     155 1629     867   6805 13181  13284
2015-10-01   103     16   947   7032  5045     155 1614     867   6749 13040  13143
2015-09-01   103     16   940   6979  4980     155 1607     867   6715 12915  13018
2015-08-01   103     16   938   6939  4942     155 1602     866   6682 12835  12938
2015-07-01   103     16   935   6913  4910     155 1596     866   6648 12774  12877
2015-06-01   103     15   934   6873  4870     155 1592     865   6611 12692  12795
2015-05-01   103     15   922   6811  4806     155 1582     865   6574 12554  12657
2015-04-01   102     15   917   6729  4744     154 1574     864   6535 12405  12507
2015-03-01   102     15   906   6619  4706     154 1561     861   6483 12246  12348
2015-02-01   101     14   898   6536  4667     154 1549     861   6445 12115  12216
2015-01-01   100     14   889   6452  4601     154 1535     859   6374 11956  12056
2014-12-01   100     14   880   6388  4564     154 1526     857   6321 11846  11946
2014-11-01   100     14   874   6315  4499     154 1517     854   6275 11702  11802
2014-10-01    99     14   867   6225  4436     154 1512     854   6235 11542  11641
2014-09-01    99     14   861   6172  4381     154 1506     854   6203 11428  11527
2014-08-01    99     14   856   6119  4308     154 1497     854   6144 11297  11396
2014-07-01    99     14   854   6076  4276     154 1486     854   6110 11220  11319
2014-06-01    99     14   845   6039  4219     153 1478     850   6064 11117  11216
2014-05-01    99     14   838   5972  4173     153 1465     849   6019 10997  11096
2014-04-01    99     14   826   5855  4064     153 1457     848   5963 10759  10858
2014-03-01    99     13   819   5798  4039     153 1452     848   5933 10669  10768
2014-02-01    99     13   811   5753  4001     153 1445     848   5898 10578  10677
2014-01-01    99     13   804   5700  3961     153 1441     847   5864 10478  10577
2013-12-01    99     13   799   5645  3935     153 1437     847   5832 10392  10491
2013-11-01    99     13   798   5573  3909     153 1429     847   5799 10293  10392
2013-10-01    98     12   786   5514  3847     152 1421     843   5758 10159  10257
2013-09-01    98     12   780   5458  3791     152 1417     842   5721 10041  10139
2013-08-01    98     12   778   5427  3754     152 1410     842   5693  9971  10069
2013-07-01    98     12   773   5399  3729     152 1403     840   5664  9913  10011
2013-06-01    98     12   770   5370  3710     152 1397     838   5634  9862   9960
2013-05-01    98     11   765   5331  3689     152 1390     838   5603  9796   9894
2013-04-01    98     11   760   5290  3659     152 1381     838   5569  9720   9818
2013-03-01    98     11   755   5242  3630     152 1372     838   5542  9638   9736
2013-02-01    97     11   750   5203  3603     152 1369     838   5517  9567   9664
2013-01-01    97     11   743   5122  3566     152 1355     837   5464  9442   9539
2012-12-01    97     11   735   5069  3535     152 1344     837   5428  9350   9447
2012-11-01    96     10   727   5015  3499     152 1337     835   5395  9251   9347
2012-10-01    96     10   721   4940  3444     152 1326     834   5341  9115   9211
2012-09-01    96     10   717   4907  3413     152 1323     833   5314  9047   9143
2012-08-01    96     10   712   4881  3380     152 1318     832   5281  8983   9079
2012-07-01    95     10   711   4875  3371     152 1313     831   5266  8967   9062
2012-06-01    95     10   706   4850  3347     152 1304     828   5231  8913   9008
2012-05-01    95     10   704   4817  3323     152 1298     825   5205  8854   8949
2012-04-01    95     10   702   4766  3296     152 1293     824   5175  8774   8869
2012-03-01    95     10   696   4686  3270     152 1287     822   5143  8662   8757
2012-02-01    95     10   686   4639  3229     152 1282     822   5109  8564   8659
2012-01-01    95     10   676   4570  3194     152 1273     821   5074  8450   8545
2011-12-01    95     10   672   4538  3170     152 1266     818   5048  8390   8485
2011-11-01    95     10   669   4497  3137     150 1255     815   5013  8313   8408
2011-10-01    95     10   662   4435  3092     149 1244     813   4976  8199   8294
2011-09-01    94     10   661   4400  3040     149 1238     812   4940  8111   8205
2011-08-01    94     10   661   4384  3013     149 1235     810   4919  8068   8162
2011-07-01    93     10   659   4371  2989     149 1231     810   4900  8029   8122
2011-06-01    93     10   659   4353  2965     149 1225     809   4872  7987   8080
2011-05-01    93     10   656   4327  2943     149 1216     808   4843  7936   8029
2011-04-01    93     10   645   4279  2913     149 1209     805   4799  7847   7940
2011-03-01    93     10   634   4216  2889     149 1200     803   4765  7749   7842
2011-02-01    93     10   624   4171  2871     149 1189     803   4741  7676   7769
2011-01-01    93     10   618   4097  2838     148 1173     802   4693  7563   7656
2010-12-01    93      9   609   4042  2807     148 1165     802   4656  7467   7560
2010-11-01    93      9   598   3973  2763     148 1159     802   4618  7343   7436
2010-10-01    93      9   588   3917  2725     148 1145     802   4578  7239   7332
2010-09-01    93      9   582   3869  2661     148 1140     800   4545  7121   7214
2010-08-01    93      9   579   3856  2650     148 1138     797   4529  7094   7187
2010-07-01    93      9   574   3833  2639     148 1135     796   4499  7055   7148
2010-06-01    92      9   568   3802  2617     148 1127     795   4459  6996   7088
2010-05-01    91      9   560   3758  2597     147 1114     793   4418  6924   7015
2010-04-01    91      9   552   3713  2578     147 1110     792   4384  6852   6943
2010-03-01    91      9   544   3676  2552     146 1101     790   4353  6781   6872
2010-02-01    91      9   540   3622  2528     146 1089     789   4310  6699   6790
2010-01-01    91      9   535   3595  2508     146 1085     787   4288  6647   6738
2009-01-01    89      9   481   3125  2251     143 1006     762   3941  5866   5955
2008-01-01    85      7   426   2667  1961     139  913     742   3555  5061   5146
2007-01-01    83      6   359   2318  1728     135  826     715   3211  4411   4494
2006-01-01    79      5   312   1978  1478     132  742     685   2846  3773   3852
2005-01-01    76      4   258   1638  1246     123  649     635   2470  3146   3222
2004-01-01    72      2   202   1328  1078     110  554     586   2129  2610   2682
2003-01-01    68      1   167   1092   912     100  471     530   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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