NEO Discovery Statistics

+ View the NASA Portal

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 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)	Other	Cumulative Total
1995 (1)	0	0	14	0	0	0	4	335
1995 (2)	0	0	12	0	0	0	2	349
1996 (1)	1	5	18	0	0	0	4	377
1996 (2)	0	5	10	0	0	0	2	394
1997 (1)	3	2	10	0	0	0	4	413
1997 (2)	14	9	4	0	0	0	7	447
1998 (1)	44	9	19	1	1	0	7	528
1998 (2)	92	2	15	6	2	0	5	650
1999 (1)	74	0	12	6	11	0	1	754
1999 (2)	87	0	7	7	19	0	3	877
2000 (1)	108	2	14	21	13	0	4	1039
2000 (2)	150	14	12	17	0	0	8	1240
2001 (1)	95	28	7	22	0	0	2	1394
2001 (2)	184	64	15	20	0	0	4	1681
2002 (1)	158	56	16	14	1	0	6	1932
2002 (2)	128	89	6	7	0	0	5	2167
2003 (1)	102	30	23	33	0	0	9	2364
2003 (2)	133	38	33	21	8	0	8	2605
2004 (1)	167	19	41	14	25	0	6	2877
2004 (2)	137	7	29	25	60	0	6	3141
2005 (1)	78	8	29	22	116	0	10	3404
2005 (2)	59	30	54	19	193	0	10	3769
2006 (1)	44	4	45	13	196	0	3	4074
2006 (2)	52	17	54	7	199	0	5	4408
2007 (1)	38	4	20	7	200	0	3	4680
2007 (2)	74	0	25	5	266	0	7	5057
2008 (1)	74	0	43	1	280	0	5	5460
2008 (2)	66	0	43	0	278	0	11	5858
2009 (1)	50	0	32	0	261	0	18	6219
2009 (2)	58	0	31	0	314	0	17	6639
2010 (1)	29	0	21	0	257	0	97	7043
2010 (2)	75	0	22	0	345	18	52	7555
2011 (1)	40	0	17	0	332	68	15	8027
2011 (2)	30	0	15	0	253	105	23	8453
2012 (1)	25	0	13	0	353	120	7	8971
2012 (2)	29	0	13	0	277	131	26	9447
2013 (1)*	3	0	10	0	254	132	12	9858

* Incomplete half-year (based on discovery data through 2013-May-21 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) Other Cumulative
Total

1995 (1) 0 0 3 0 0 0 2 179

1995 (2) 0 0 4 0 0 0 1 184

1996 (1) 0 2 2 0 0 0 0 188

1996 (2) 0 2 0 0 0 0 0 190

1997 (1) 0 1 2 0 0 0 1 194

1997 (2) 2 3 1 0 0 0 2 202

1998 (1) 7 4 2 1 0 0 2 218

1998 (2) 24 2 1 3 0 0 3 251

1999 (1) 15 0 2 4 4 0 0 276

1999 (2) 24 0 1 1 2 0 2 306

2000 (1) 31 2 1 1 4 0 1 346

2000 (2) 39 2 3 5 0 0 4 399

2001 (1) 24 8 0 4 0 0 0 435

2001 (2) 25 5 0 4 0 0 1 470

2002 (1) 32 4 2 3 0 0 1 512

2002 (2) 21 10 0 1 0 0 1 545

2003 (1) 15 3 1 6 0 0 2 572

2003 (2) 17 5 1 4 2 0 1 602

2004 (1) 16 5 1 2 3 0 1 630

2004 (2) 9 1 0 1 12 0 0 653

2005 (1) 10 0 2 1 9 0 1 676

2005 (2) 6 5 5 0 10 0 1 703

2006 (1) 3 0 2 1 9 0 0 718

2006 (2) 1 0 2 0 12 0 0 733

2007 (1) 2 0 3 0 9 0 1 748

2007 (2) 5 0 1 0 7 0 0 761

2008 (1) 2 0 1 0 8 0 0 772

2008 (2) 3 0 1 0 5 0 0 781

2009 (1) 1 0 0 0 9 0 0 791

2009 (2) 6 0 0 0 6 0 2 805

2010 (1) 0 0 1 0 5 0 3 814

2010 (2) 1 0 0 0 1 0 4 820

2011 (1) 1 0 0 0 6 1 0 828

2011 (2) 0 0 1 0 6 4 0 839

2012 (1) 0 0 0 0 9 1 0 849

2012 (2) 1 0 0 0 5 2 0 857

2013 (1)* 0 0 0 0 2 1 0 860

* Incomplete half-year (based on discovery data through 2013-May-21 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).

(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 ---------- ---- ----- ---- ------ ---- ------ ---- ------ ---- ---- 2013-05-19 94 12 768 5366 3712 155 1401 860 9858 9952 2013-05-01 94 11 765 5331 3693 155 1395 860 9800 9894 2013-04-01 94 11 760 5291 3663 155 1386 859 9725 9819 2013-03-01 94 11 755 5244 3635 155 1377 859 9645 9739 2013-02-01 94 11 750 5204 3608 155 1373 858 9573 9667 2013-01-01 94 11 743 5123 3570 155 1359 857 9447 9541 2012-12-01 94 11 735 5070 3539 155 1349 857 9355 9449 2012-11-01 93 10 727 5016 3502 155 1340 854 9255 9348 2012-10-01 93 10 721 4941 3446 155 1329 852 9118 9211 2012-09-01 93 10 717 4908 3416 155 1326 851 9051 9144 2012-08-01 93 10 712 4883 3382 155 1321 850 8987 9080 2012-07-01 92 10 711 4877 3373 155 1316 849 8971 9063 2012-06-01 92 10 706 4852 3350 155 1307 846 8918 9010 2012-05-01 92 10 704 4819 3326 155 1302 843 8859 8951 2012-04-01 92 10 702 4769 3298 155 1296 842 8779 8871 2012-03-01 92 10 696 4689 3271 155 1290 840 8666 8758 2012-02-01 92 10 686 4642 3230 155 1283 840 8568 8660 2012-01-01 92 10 676 4572 3195 155 1275 839 8453 8545 2011-12-01 92 10 672 4540 3170 155 1268 835 8392 8484 2011-11-01 92 10 669 4499 3135 153 1258 832 8313 8405 2011-10-01 92 10 662 4437 3090 152 1247 831 8199 8291 2011-09-01 91 10 661 4402 3035 152 1241 829 8108 8199 2011-08-01 91 10 661 4386 3009 152 1238 828 8066 8157 2011-07-01 90 10 659 4373 2985 152 1234 828 8027 8117 2011-06-01 90 10 659 4356 2960 152 1229 827 7985 8075 2011-05-01 90 10 656 4330 2938 152 1220 826 7934 8024 2011-04-01 90 10 645 4280 2908 152 1213 824 7843 7933 2011-03-01 90 10 634 4217 2884 152 1203 822 7745 7835 2011-02-01 90 10 624 4170 2865 152 1192 822 7669 7759 2011-01-01 90 10 618 4094 2833 152 1176 820 7555 7645 2010-12-01 90 9 609 4039 2801 152 1167 819 7458 7548 2010-11-01 90 9 598 3970 2755 152 1161 819 7332 7422 2010-10-01 90 9 588 3914 2715 152 1147 819 7226 7316 2010-09-01 90 9 582 3868 2650 152 1142 818 7109 7199 2010-08-01 90 9 579 3854 2640 152 1139 816 7082 7172 2010-07-01 90 9 574 3832 2628 152 1137 814 7043 7133 2010-06-01 89 9 568 3801 2606 152 1129 812 6984 7073 2010-05-01 88 9 560 3757 2587 151 1117 810 6913 7001 2010-04-01 88 9 552 3711 2570 151 1111 810 6842 6930 2010-03-01 88 9 544 3674 2545 150 1102 809 6772 6860 2010-02-01 88 9 540 3620 2520 149 1090 807 6689 6777 2010-01-01 88 9 535 3594 2501 149 1087 805 6639 6727 2009-12-01 88 9 531 3573 2491 149 1082 803 6604 6692 2009-11-01 87 9 520 3496 2464 149 1075 800 6489 6576 2009-10-01 87 9 511 3441 2431 149 1071 798 6392 6479 2009-09-01 87 9 506 3388 2384 149 1062 796 6287 6374 2009-08-01 87 9 504 3368 2357 149 1060 795 6238 6325 2009-07-01 87 9 504 3358 2348 148 1058 791 6219 6306 2009-06-01 86 9 501 3346 2338 147 1055 790 6194 6280 2009-05-01 86 9 499 3319 2325 147 1046 789 6152 6238 2009-04-01 86 9 496 3287 2311 147 1042 786 6103 6189 2009-03-01 86 9 491 3225 2292 147 1030 786 6017 6103 2009-02-01 86 9 487 3167 2266 146 1018 783 5929 6015 2009-01-01 86 9 481 3122 2246 146 1009 781 5858 5944 2008-12-01 85 9 480 3080 2216 146 999 780 5785 5870 2008-11-01 85 9 474 3032 2194 146 991 778 5709 5794 2008-10-01 85 8 467 2971 2144 145 981 777 5590 5675 2008-09-01 84 8 464 2940 2110 145 971 776 5522 5606 2008-08-01 84 8 461 2926 2096 145 966 775 5491 5575 2008-07-01 84 8 459 2908 2085 144 957 772 5460 5544 2008-06-01 84 8 455 2897 2077 144 954 771 5437 5521 2008-05-01 84 8 451 2867 2060 144 948 771 5386 5470 2008-04-01 84 8 449 2820 2031 144 945 770 5308 5392 2008-03-01 84 7 440 2752 2006 143 935 763 5205 5289 2008-02-01 84 7 428 2693 1975 142 921 761 5103 5187 2008-01-01 84 7 426 2666 1958 142 913 761 5057 5141 2007-12-01 84 7 423 2631 1941 142 902 758 5002 5086 2007-11-01 84 7 411 2573 1905 142 892 754 4896 4980 2007-10-01 83 7 397 2524 1863 142 882 753 4791 4874 2007-09-01 83 7 390 2486 1831 141 875 752 4714 4797 2007-08-01 83 7 388 2475 1821 140 870 748 4691 4774 2007-07-01 83 7 388 2471 1814 140 869 748 4680 4763 2007-06-01 83 7 383 2449 1805 139 860 746 4644 4727 2007-05-01 83 7 382 2436 1794 139 856 744 4619 4702 2007-04-01 83 7 381 2411 1777 139 852 740 4576 4659 2007-03-01 83 6 375 2372 1753 139 845 738 4506 4589 2007-02-01 83 6 367 2339 1737 138 837 734 4449 4532 2007-01-01 83 6 359 2319 1724 138 828 733 4408 4491 2006-12-01 82 6 354 2293 1706 138 825 731 4359 4441 2006-11-01 82 5 344 2244 1683 137 813 725 4276 4358 2006-10-01 80 5 337 2214 1651 137 803 723 4207 4287 2006-09-01 80 5 330 2177 1623 136 794 719 4135 4215 2006-08-01 80 5 328 2160 1610 136 789 719 4103 4183 2006-07-01 80 5 327 2149 1593 136 787 718 4074 4154 2006-06-01 80 5 326 2138 1580 136 784 718 4049 4129 2006-05-01 80 5 325 2110 1553 136 774 714 3993 4073 2006-04-01 79 5 321 2083 1538 136 764 712 3947 4026 2006-03-01 79 5 319 2067 1519 136 763 711 3910 3989 2006-02-01 79 5 316 2032 1502 136 755 708 3855 3934 2006-01-01 79 5 312 1976 1476 135 746 703 3769 3848 2005-12-01 79 5 302 1944 1455 134 735 700 3706 3785 2005-11-01 78 5 297 1902 1429 133 725 695 3633 3711 2005-10-01 77 4 289 1846 1389 132 713 684 3528 3605 2005-09-01 77 4 286 1812 1370 132 708 681 3472 3549 2005-08-01 77 4 283 1798 1354 132 702 679 3439 3516 2005-07-01 77 4 279 1779 1342 131 695 676 3404 3481 2005-06-01 77 4 275 1764 1322 131 691 671 3365 3442 2005-05-01 76 4 274 1747 1307 129 685 668 3332 3408 2005-04-01 76 4 268 1722 1288 127 672 664 3282 3358 2005-03-01 76 4 263 1681 1264 126 662 660 3212 3288 2005-02-01 76 4 262 1657 1256 125 658 657 3179 3255 2005-01-01 76 4 258 1633 1246 125 651 653 3141 3217 2004-12-01 75 3 249 1601 1225 125 642 645 3078 3153 2004-11-01 75 3 245 1581 1219 124 633 640 3048 3123 2004-10-01 74 3 238 1553 1211 123 622 638 3005 3079 2004-09-01 73 3 230 1515 1186 123 614 637 2934 3007 2004-08-01 73 3 226 1496 1163 122 607 633 2888 2961 2004-07-01 73 3 226 1490 1158 120 604 630 2877 2950 2004-06-01 73 3 223 1460 1145 119 593 627 2831 2904 2004-05-01 73 2 218 1441 1130 119 587 623 2791 2864 2004-04-01 73 2 215 1411 1118 115 577 616 2746 2819 2004-03-01 73 2 206 1375 1100 115 570 607 2683 2756 2004-02-01 72 2 204 1360 1093 114 565 606 2659 2731 2004-01-01 72 2 202 1326 1075 112 555 602 2605 2677 2003-12-01 72 2 196 1294 1063 109 542 594 2555 2627 2003-11-01 72 2 193 1272 1050 109 534 588 2517 2589 2003-10-01 71 2 188 1245 1028 109 525 586 2463 2534 2003-09-01 71 2 185 1225 994 107 516 579 2406 2477 2003-08-01 71 2 185 1213 981 104 511 575 2381 2452 2003-07-01 70 2 184 1206 972 104 508 572 2364 2434 2003-06-01 70 2 182 1190 960 104 503 566 2334 2404 2003-05-01 68 2 180 1176 954 103 501 564 2312 2380 2003-04-01 68 2 175 1156 943 103 494 559 2276 2344 2003-03-01 68 2 170 1137 932 103 487 555 2241 2309 2003-02-01 68 1 169 1117 926 103 481 551 2213 2281 2003-01-01 68 1 167 1090 909 102 471 545 2167 2235 2002-12-01 68 1 163 1063 889 102 469 543 2116 2184 2002-11-01 68 1 160 1048 872 101 463 539 2081 2149 2002-10-01 67 1 158 1024 849 100 456 530 2032 2099 2002-09-01 65 1 155 1004 830 99 450 521 1990 2055 2002-08-01 65 1 154 988 807 97 439 517 1950 2015 2002-07-01 64 1 152 978 801 96 432 512 1932 1996 2002-06-01 64 1 148 960 793 94 424 506 1902 1966 2002-05-01 64 1 144 942 782 93 415 495 1869 1933 2002-04-01 64 1 142 924 769 93 408 493 1836 1900 2002-03-01 63 1 136 897 755 92 398 489 1789 1852 2002-02-01 63 1 131 874 739 91 389 479 1745 1808 2002-01-01 63 1 124 840 716 91 376 470 1681 1744 2001-12-01 63 1 121 804 697 87 362 461 1623 1686 2001-11-01 61 1 120 776 682 85 355 456 1579 1640 2001-10-01 61 1 114 750 659 84 346 452 1524 1585 2001-09-01 61 1 110 721 624 82 334 439 1456 1517 2001-08-01 60 1 109 699 604 82 328 436 1413 1473 2001-07-01 59 1 108 694 591 82 327 435 1394 1453 2001-06-01 58 1 108 684 580 80 324 428 1373 1431 2001-05-01 57 1 107 672 569 78 317 420 1349 1406 2001-04-01 57 1 105 660 560 77 308 416 1326 1383 2001-03-01 57 1 101 645 546 75 299 408 1293 1350 2001-02-01 57 1 98 634 535 74 296 403 1268 1325 2001-01-01 57 1 94 619 526 74 293 399 1240 1297 2000-12-01 57 1 93 605 514 73 287 392 1213 1270 2000-11-01 57 1 90 581 497 72 284 383 1169 1226 2000-10-01 57 1 87 571 483 72 280 375 1142 1199 2000-09-01 57 1 81 553 457 71 273 366 1092 1149 2000-08-01 57 1 79 535 441 69 264 357 1056 1113 2000-07-01 57 1 77 530 431 67 261 346 1039 1096 2000-06-01 57 1 76 525 425 66 257 343 1027 1084 2000-05-01 57 1 76 512 411 66 252 337 1000 1057 2000-04-01 56 1 73 497 398 65 246 330 969 1025 2000-03-01 56 1 64 481 387 63 234 318 933 989 2000-02-01 56 1 62 464 376 62 223 311 903 959 2000-01-01 56 1 57 450 369 62 217 306 877 933 1999-12-01 55 1 56 440 360 60 209 299 857 912 1999-11-01 55 1 54 427 346 60 205 289 828 883 1999-10-01 55 1 54 411 332 59 200 284 798 853 1999-09-01 53 1 54 395 316 57 193 280 766 819 1999-08-01 53 1 54 395 314 57 193 280 764 817 1999-07-01 53 1 54 390 309 56 191 276 754 807 1999-06-01 53 1 51 383 299 56 186 273 734 787 1999-05-01 52 1 49 371 294 52 178 264 715 767 1999-04-01 52 1 48 358 287 51 174 257 694 746 1999-03-01 52 1 47 348 282 51 172 256 678 730 1999-02-01 52 1 47 338 277 51 169 253 663 715 1999-01-01 52 1 45 333 271 51 166 251 650 702 1998-12-01 52 1 41 323 262 51 162 242 627 679 1998-11-01 52 1 38 309 253 49 154 237 601 653 1998-10-01 52 1 36 305 246 49 152 233 588 640 1998-09-01 52 1 29 292 233 48 140 227 555 607 1998-08-01 52 1 29 282 222 46 133 221 534 586 1998-07-01 52 1 29 279 219 44 129 218 528 580 1998-06-01 52 1 29 273 212 43 127 215 515 567 1998-05-01 52 1 29 264 206 43 124 211 500 552 1998-04-01 52 1 27 256 197 43 117 210 481 533 1998-03-01 52 1 27 244 189 43 112 206 461 513 1998-02-01 52 0 26 240 189 42 110 205 455 507 1998-01-01 52 0 26 235 186 42 108 202 447 499 1997-01-01 52 0 22 206 166 40 97 190 394 446 1996-01-01 52 0 20 178 151 38 86 184 349 401 1995-01-01 52 0 19 163 135 37 83 174 317 369 1994-01-01 50 0 15 140 115 33 70 156 270 320 1993-01-01 50 0 13 117 99 31 64 142 229 279 1992-01-01 50 0 11 103 85 29 61 124 199 249 1991-01-01 48 0 9 76 74 24 49 106 159 207 1990-01-01 48 0 8 63 63 20 42 90 134 182 1980-01-01 44 0 3 27 23 12 17 45 53 97 1970-01-01 42 0 0 13 14 8 10 24 27 69 1960-01-01 41 0 0 10 10 7 8 18 20 61 1950-01-01 41 0 0 7 6 4 5 12 13 54 1940-01-01 36 0 0 3 6 2 3 8 9 45 1930-01-01 34 0 0 0 5 0 0 5 5 39 1920-01-01 32 0 0 0 3 0 0 3 3 35 1910-01-01 30 0 0 0 1 0 0 1 1 31 1900-01-01 28 0 0 0 1 0 0 1 1 29

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.

Site Manager: Don Yeomans
Webmaster: Ron Baalke
Last Updated: