NEO Discovery Statistics

+ View the NASA Portal

NEO Discovery Statistics

NEAR-EARTH ASTEROID DISCOVERY STATISTICS

Criteria Defining these Tables and Charts were Revised on November 30, 2006

The following charts and tables have been revised to reflect improved estimates for near-Earth asteroid (NEA) reflectivities (albedos) - and hence diameters. The absolute magnitude of a NEA (H) 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. A value for H can then be converted to an effective diameter using an assumed value for the NEA's reflectivity (albedo). 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.

Until relatively recently, the mean albedo for NEAs was thought to be 0.11 so the corresponding absolute magnitude for a NEA whose effective diameter is one kilometer was thought to be H = 18.0. Tables and charts based upon H = 18.0 have been provided on this web site since its inception and these charts can still be viewed at the following link.

Recent work by Stuart (2003) and others have shown that NEAs are, in the mean, 20% brighter than previously thought so that the mean albedo for NEAs is 0.14 rather than 0.11. Using this revised mean albedo implies the absolute magnitude (H) for a NEA with an effective one kilometer diameter is 17.75. The charts and plots given below reflect this recent update.

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)	Other	Cumulative Total
1995 (1)	0	0	14	0	0	4	335
1995 (2)	0	0	12	0	0	2	349
1996 (1)	1	5	18	0	0	4	377
1996 (2)	0	5	10	0	0	2	394
1997 (1)	3	2	10	0	0	4	413
1997 (2)	14	9	4	0	0	7	447
1998 (1)	44	9	19	1	1	7	528
1998 (2)	92	2	16	6	2	6	652
1999 (1)	74	0	12	7	11	1	757
1999 (2)	87	0	7	7	19	3	880
2000 (1)	107	2	14	21	13	4	1041
2000 (2)	150	14	12	17	0	8	1242
2001 (1)	95	28	7	22	0	2	1396
2001 (2)	182	64	15	20	0	4	1681
2002 (1)	158	54	16	14	1	6	1930
2002 (2)	128	88	6	7	0	5	2164
2003 (1)	102	30	24	34	0	8	2362
2003 (2)	133	38	33	20	8	8	2602
2004 (1)	167	19	41	14	25	6	2874
2004 (2)	137	7	29	25	60	7	3139
2005 (1)	78	8	28	22	116	10	3401
2005 (2)	59	30	54	19	193	10	3766
2006 (1)	44	4	45	13	197	3	4072
2006 (2)	52	18	54	6	200	5	4407
2007 (1)	38	4	20	7	200	3	4679
2007 (2)	73	0	25	5	266	7	5055
2008 (1)	74	0	43	1	285	5	5463
2008 (2)*	10	0	8	0	59	5	5545

* Incomplete half-year (based on discovery data through 2008-Sep-11 06:00 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) Other Cumulative
Total

1995 (1) 0 0 3 0 0 2 174

1995 (2) 0 0 4 0 0 1 179

1996 (1) 0 2 2 0 0 0 183

1996 (2) 0 2 0 0 0 0 185

1997 (1) 0 1 2 0 0 1 189

1997 (2) 2 3 1 0 0 2 197

1998 (1) 7 4 2 1 0 1 212

1998 (2) 23 2 1 3 0 3 244

1999 (1) 17 0 2 5 3 0 271

1999 (2) 24 0 0 1 2 2 300

2000 (1) 28 2 0 1 4 1 336

2000 (2) 38 2 3 3 0 4 386

2001 (1) 24 9 0 3 0 0 422

2001 (2) 21 5 0 4 0 1 453

2002 (1) 31 4 2 3 0 1 494

2002 (2) 20 10 0 1 0 1 526

2003 (1) 15 3 1 5 0 1 551

2003 (2) 17 5 1 4 1 1 580

2004 (1) 14 5 1 2 2 1 605

2004 (2) 7 1 0 1 13 0 627

2005 (1) 10 0 2 1 9 1 650

2005 (2) 6 5 4 0 9 1 675

2006 (1) 3 0 2 1 9 0 690

2006 (2) 1 0 3 0 12 0 706

2007 (1) 2 0 3 0 9 1 721

2007 (2) 5 0 1 0 7 0 734

2008 (1) 2 0 1 0 9 0 746

2008 (2)* 0 0 1 0 5 0 752

* Incomplete half-year (based on discovery data through 2008-Sep-11 06:00 local)

Data compiled by Alan Chamberlin.

NUMBER OF NEOS

NASA's search program designed to discover 90% of the NEO population (1 km in diameter or larger) within 10 years is under way. 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).
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. This table is updated daily using discovery data published by the Minor Planet Center.

------------------------------------------------------------------ Date NEC Aten Apollo Amor PHA-KM PHA NEA-KM NEA NEO ---------- ---- ---- ------ ---- ------ ---- ------ ---- ---- 2008-09-09 65 464 2957 2115 140 971 752 5545 5610 2008-09-01 65 464 2948 2105 140 969 750 5526 5591 2008-08-01 65 461 2933 2091 140 963 749 5494 5559 2008-07-01 65 459 2915 2080 139 954 746 5463 5528 2008-06-01 65 455 2904 2072 139 951 745 5440 5505 2008-05-01 65 451 2873 2054 139 944 744 5387 5452 2008-04-01 65 449 2825 2024 139 941 743 5307 5372 2008-03-01 65 440 2757 1999 138 932 736 5204 5269 2008-02-01 65 428 2697 1969 137 919 734 5102 5167 2008-01-01 65 426 2669 1952 137 910 734 5055 5120 2007-12-01 65 423 2634 1936 137 901 731 5001 5066 2007-11-01 65 411 2575 1901 137 891 727 4895 4960 2007-10-01 64 397 2526 1859 137 879 726 4790 4854 2007-09-01 64 390 2488 1827 136 872 725 4713 4777 2007-08-01 64 388 2477 1817 135 867 721 4690 4754 2007-07-01 64 388 2473 1810 135 866 721 4679 4743 2007-06-01 64 383 2452 1800 134 857 718 4643 4707 2007-05-01 64 382 2440 1788 134 853 716 4618 4682 2007-04-01 64 381 2415 1771 134 849 713 4575 4639 2007-03-01 64 375 2375 1748 134 842 711 4505 4569 2007-02-01 64 367 2342 1732 133 834 707 4448 4512 2007-01-01 64 359 2322 1719 133 825 706 4407 4471 2006-12-01 64 354 2295 1701 133 821 704 4357 4421 2006-11-01 63 344 2246 1677 132 809 697 4273 4336 2006-10-01 61 337 2216 1645 132 799 695 4204 4265 2006-09-01 61 330 2179 1618 131 790 691 4133 4194 2006-08-01 61 328 2162 1605 131 785 691 4101 4162 2006-07-01 61 327 2151 1588 131 783 690 4072 4133 2006-06-01 61 326 2140 1575 131 780 690 4047 4108 2006-05-01 61 325 2112 1548 131 770 686 3990 4051 2006-04-01 60 321 2085 1533 131 760 684 3944 4004 2006-03-01 60 319 2069 1514 131 759 683 3907 3967 2006-02-01 60 316 2034 1497 131 751 680 3852 3912 2006-01-01 60 312 1977 1472 130 741 675 3766 3826 2005-12-01 60 302 1945 1451 129 730 672 3703 3763 2005-11-01 60 297 1903 1425 128 720 668 3630 3690 2005-10-01 59 289 1847 1385 127 707 658 3525 3584 2005-09-01 59 286 1813 1366 127 702 655 3469 3528 2005-08-01 59 283 1799 1350 127 696 653 3436 3495 2005-07-01 59 279 1780 1338 126 688 650 3401 3460 2005-06-01 59 275 1765 1318 126 684 645 3362 3421 2005-05-01 58 274 1749 1302 124 678 642 3329 3387 2005-04-01 58 268 1723 1284 122 665 638 3279 3337 2005-03-01 58 263 1683 1259 121 655 634 3209 3267 2005-02-01 58 262 1659 1252 120 651 631 3177 3235 2005-01-01 58 258 1635 1242 120 644 627 3139 3197 2004-12-01 57 249 1603 1220 120 635 619 3075 3132 2004-11-01 57 245 1583 1214 119 626 614 3045 3102 2004-10-01 56 238 1555 1206 118 615 612 3002 3058 2004-09-01 55 230 1517 1181 118 606 612 2931 2986 2004-08-01 55 226 1498 1158 117 599 608 2885 2940 2004-07-01 55 226 1492 1153 115 596 605 2874 2929 2004-06-01 55 223 1462 1140 114 585 602 2828 2883 2004-05-01 55 218 1443 1125 114 579 599 2788 2843 2004-04-01 55 215 1413 1113 110 569 592 2743 2798 2004-03-01 55 206 1377 1095 110 562 585 2680 2735 2004-02-01 54 204 1362 1088 109 557 584 2656 2710 2004-01-01 54 202 1328 1070 107 547 580 2602 2656 2003-12-01 54 196 1296 1058 105 534 573 2552 2606 2003-11-01 54 193 1274 1045 105 526 567 2514 2568 2003-10-01 54 188 1247 1023 105 517 565 2460 2514 2003-09-01 54 185 1227 990 103 508 558 2404 2458 2003-08-01 54 185 1215 977 100 503 554 2379 2433 2003-07-01 53 184 1208 968 100 501 551 2362 2415 2003-06-01 53 182 1192 957 100 496 546 2333 2386 2003-05-01 51 180 1178 950 99 494 544 2310 2361 2003-04-01 51 175 1158 938 99 487 540 2273 2324 2003-03-01 51 170 1139 927 99 480 536 2238 2289 2003-02-01 51 169 1119 921 99 475 532 2210 2261 2003-01-01 51 167 1092 904 98 465 526 2164 2215 2002-12-01 51 163 1065 884 98 463 524 2113 2164 2002-11-01 51 160 1050 867 97 457 520 2078 2129 2002-10-01 50 158 1026 843 96 451 511 2028 2078 2002-09-01 50 155 1006 824 95 445 503 1986 2036 2002-08-01 50 154 990 802 93 434 499 1947 1997 2002-07-01 49 152 981 796 92 428 494 1930 1979 2002-06-01 49 148 963 788 90 420 488 1900 1949 2002-05-01 49 144 945 777 89 411 478 1867 1916 2002-04-01 49 142 927 765 89 404 476 1835 1884 2002-03-01 48 136 900 752 88 394 472 1789 1837 2002-02-01 48 131 877 736 87 385 462 1745 1793 2002-01-01 48 124 842 714 87 372 453 1681 1729 2001-12-01 48 121 805 696 83 358 445 1623 1671 2001-11-01 46 120 778 680 82 350 441 1579 1625 2001-10-01 46 114 752 657 81 341 437 1524 1570 2001-09-01 46 110 723 624 80 330 426 1458 1504 2001-08-01 45 109 701 604 80 324 424 1415 1460 2001-07-01 44 108 696 591 80 323 422 1396 1440 2001-06-01 43 108 686 580 78 320 414 1375 1418 2001-05-01 42 107 674 569 76 313 406 1351 1393 2001-04-01 42 105 662 560 75 305 403 1328 1370 2001-03-01 42 101 647 546 73 296 395 1295 1337 2001-02-01 42 98 636 535 72 293 390 1270 1312 2001-01-01 42 94 621 526 72 290 386 1242 1284 2000-12-01 42 93 607 514 71 284 380 1215 1257 2000-11-01 42 90 583 497 70 281 371 1171 1213 2000-10-01 42 87 573 483 70 277 363 1144 1186 2000-09-01 42 81 555 457 69 271 354 1094 1136 2000-08-01 42 79 537 441 67 262 345 1058 1100 2000-07-01 42 77 532 431 65 259 336 1041 1083 2000-06-01 42 76 527 425 64 255 333 1029 1071 2000-05-01 42 76 514 411 64 250 328 1002 1044 2000-04-01 41 73 499 398 63 244 321 971 1012 2000-03-01 41 64 483 388 61 232 311 936 977 2000-02-01 41 62 466 377 60 221 304 906 947 2000-01-01 41 57 453 369 60 214 300 880 921 1999-12-01 41 56 443 360 58 206 293 860 901 1999-11-01 41 54 430 346 58 202 284 831 872 1999-10-01 41 54 414 332 57 197 279 801 842 1999-09-01 40 54 397 317 56 191 275 769 809 1999-08-01 40 54 397 315 56 191 275 767 807 1999-07-01 40 54 392 310 55 189 271 757 797 1999-06-01 40 51 385 300 54 184 268 737 777 1999-05-01 40 49 373 294 51 177 258 717 757 1999-04-01 40 48 360 287 50 173 251 696 736 1999-03-01 40 47 350 282 50 172 250 680 720 1999-02-01 40 47 340 277 50 169 247 665 705 1999-01-01 40 45 335 271 50 166 244 652 692 1998-12-01 40 41 325 262 50 162 236 629 669 1998-11-01 40 38 308 254 48 154 231 601 641 1998-10-01 40 36 303 248 48 152 227 588 628 1998-09-01 40 29 290 235 47 140 221 555 595 1998-08-01 40 29 280 224 45 133 215 534 574 1998-07-01 40 29 277 221 43 129 212 528 568 1998-06-01 40 29 271 214 42 127 209 515 555 1998-05-01 40 29 262 208 42 124 205 500 540 1998-04-01 40 27 254 199 42 117 204 481 521 1998-03-01 40 27 242 191 42 112 200 461 501 1998-02-01 40 26 238 191 42 110 200 455 495 1998-01-01 40 26 233 188 42 108 197 447 487 1997-01-01 40 22 204 168 40 97 185 394 434 1996-01-01 40 20 177 152 38 86 179 349 389 1995-01-01 40 19 163 135 37 83 169 317 357 1994-01-01 38 15 140 116 33 70 152 271 309 1993-01-01 38 13 117 100 31 64 138 230 268 1992-01-01 38 11 103 85 29 61 122 199 237 1991-01-01 36 9 76 74 24 49 106 159 195 1990-01-01 36 8 63 63 20 42 90 134 170 1980-01-01 33 3 27 23 12 17 45 53 86 1970-01-01 31 0 13 14 8 10 24 27 58 1960-01-01 30 0 10 10 7 8 18 20 50 1950-01-01 30 0 7 6 4 5 12 13 43 1940-01-01 26 0 3 6 2 3 8 9 35 1930-01-01 25 0 0 5 0 0 5 5 30 1920-01-01 23 0 0 3 0 0 3 3 26 1910-01-01 22 0 0 1 0 0 1 1 23 1900-01-01 20 0 0 1 0 0 1 1 21

Note: "NEC" are Near-Earth comets. "PHA-KM" and "NEA-KM" are PHAs and NEAs with diameters roughly one kilometer and larger.

Data compiled by Alan Chamberlin.

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