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Traffic Timeline & Statistics

Refreshed at 1840 UT on 22 June 2017

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Boundary crossing times and distances at time of observation are interpreted by A/CC from JPL SSD Horizons data. Boundary crossing times should be considered approximate since they can be off by many minutes or even hours, depending on the length of an object's observation time span and other factors. See JPL's Close Approach Tables for nominal vs. minimum passage time and distance estimates. Note that there is no exact boundary for a gravitational sphere of incluence (about 2.41 lunar distances for Earth's own), and ten lunar distances from Earth is a useful arbitrary "bubble" within which to organize this reporting but has no special astronomical importance.

The chart below seems to suggest a flux in how many objects fly near the Earth-Moon system during different times of year. This illusion comes from not having an even distribution of asteroid discovery programs and follow-up observers to counter observational gaps caused by changes in length of night and regional weather as well as by program down times. As it is today, most observers are in the northern hemisphere, and most discoveries are made from Arizona with some help previously from New Mexico and now from Hawaii. There probably are always more objects in Earth's neighborhood than are known, including some traveling in our daytime and twilight skies (radar works in daytime but not for discovery).

Note that the data and statistics here list only objects that are in solar rather than geocentric orbits. This excludes tiny 2006 RH120 (links), which apparently was captured as a temporary natural Earth satellite in 2006, first coming within a distance of ten LD from our planet on April 16th and remaining closer than that until October 20th of the following year. It wasn't discovered until 14 September 2006 and at first it was believed to be a human artifact. It approached Earth four times during these months in temporary orbit: 2.2 LD on Sepember 16th, 1.4 LD on January 3rd, 0.9 LD on March 25th, and 0.7 LD on June 14th. (The Earth's Hill sphere -- the theoretical region within which our planet can retain natural satellites rather than lose them to solar orbit, extends out to about 3.89 LD, which this object was within from November 25th until July 13th.)

All data on this page derived from orbit solutions comes from the NASA JPL Solar System Dynamics (SSD) Group through its Horizons system. All information about optical observations comes from the IAU Minor Planet Center (MPC) and info about radar observations comes from JPL SSD. NASA, JPL, and the MPC are not affilliated with this page or A/CC, and responsibility for the interpretation of this information and its use here rests entirely with A/CC.

timeline 3-year monthly counts chart

Three-Year Chart of Close-Passing Object Monthly Counts
See vertical table below left for counts & click to see complete chart 2007-present

Object counts
less than 10 LD from Earth29364739
inside Earth SOI710612
less than 1 LD from Moon6233
less than 1 LD from Earth5343
close-passer discoveries26253340
less than 10 LD from Earth27406660
inside Earth SOI681714
less than 1 LD from Moon0253
less than 1 LD from Earth1373
close-passer discoveries17315040
less than 10 LD from Earth36426484
inside Earth SOI9102417
less than 1 LD from Moon51113
less than 1 LD from Earth54109
close-passer discoveries24375668
less than 10 LD from Earth54385757
inside Earth SOI12101311
less than 1 LD from Moon0434
less than 1 LD from Earth1456
close-passer discoveries50303434
less than 10 LD from Earth51233233
inside Earth SOI14857
less than 1 LD from Moon2114
less than 1 LD from Earth5213
close-passer discoveries29222225
less than 10 LD from Earth26202515
inside Earth SOI4383
less than 1 LD from Moon3020
less than 1 LD from Earth3130
close-passer discoveries1812206
less than 10 LD from Earth1111211
inside Earth SOI3340
less than 1 LD from Moon0100
less than 1 LD from Earth2020
close-passer discoveries83170
less than 10 LD from Earth172019
inside Earth SOI231
less than 1 LD from Moon100
less than 1 LD from Earth111
close-passer discoveries151513
less than 10 LD from Earth402363
inside Earth SOI12519
less than 1 LD from Moon315
less than 1 LD from Earth318
close-passer discoveries291943
less than 10 LD from Earth442868
inside Earth SOI5715
less than 1 LD from Moon224
less than 1 LD from Earth325
close-passer discoveries361858
less than 10 LD from Earth274870
inside Earth SOI5921
less than 1 LD from Moon259
less than 1 LD from Earth247
close-passer discoveries263854
less than 10 LD from Earth315642
inside Earth SOI8117
less than 1 LD from Moon130
less than 1 LD from Earth220
close-passer discoveries204921

Neighborhood timeline index by month & year


Maximum daily counts of known objects

Within ten LD of Earth:29 on 18 March 2017
Inside Earth SOI:6 on 5 May 2014 & 4 May 2014
Within one LD of the Moon:3 on 8 Sept. 2010
Inside Moon SOI:1 on 29 March 2014 & 13 Oct. 2011
Inside Earth-Moon system:3 on 8 Sept. 2010

Designation Credits 2010-2017

This is a list of observing facilities that have been assigned designation credit since late 2010 for a key early observation of a close-passing (within ten LD)object during its discovery apparition, which may or may not lead to receiving formal discovery credit for that object if and when numbered by the IAU.

Totals20172016201520142013201220112010Who & where
755125219849663836322MLS - Mt. Lemmon Survey in Arizona
539289010910472714718CSS - Catalina Sky Survey in Arizona
34143788559382513-PS1 - Pan-STARRS 1 in Hawaii
49-----172012LINEAR in New Mexico
40-16519----Allen/DECam - Lori Allen
16---44251La Sagra Obs. in Spain
15546-----SST Atom Site - Space Surveillance Telescope Atom Site in New Mexico
15----3651SSS - Siding Spring Survey in New South Wales
1477------ATLAS Haleakala in Hawaii
12--111----PTF - Palomar Transient Factory in southern California
91431----SONEAR in Brazil
7--1-1131Spacewatch 0.9m telescope in Arizona
3-111----WISE in Earth polar orbit
3---3----ESA OGS - ESA Optical Ground Station in the Canary Islands
211------Steward Mt. Lemmon Sta. - Steward Obs. Mt. Lemmon Station in Arizona
2-----11-Spacewatch 1.8m telescope in Arizona
11-------Xuyi Sta. - Purple Mtn. Obs. Xuyi Station in China
11-------Nyukasa Obs. in Japan
11-------GINOP-KHK in Hungary
1-1------Galad/La Silla - Adrian Galad in Slovakia
1--1-----SZTE - SZTE Asteroid Program in Hungary
1--1-----Vaduvescu/La Palma - Ovidiu Vaduvescu
1--1-----MRO - Magdalena Ridge Obs. in New Mexico
1--1-----ISON-NMO - ISON New Mexico Obs. in New Mexico
1----1---Oukaimeden Obs. in Morocco
1----1---Micheli/Mauna Kea - Marco Micheli
1----1---MASTER-II Tunka in Russia
1-----1--Tenagra II Obs. in Arizona
1-----1--Sandlot Obs. in Kansas
1------1-Crni Vrh Obs. in Slovenia

55Total in 2010 = 0.74 objects per day
158Total in 2011 = 0.43 objects per day
208Total in 2012 = 0.57 objects per day
184Total in 2013 = 0.50 objects per day
298Total in 2014 = 0.82 objects per day
299Total in 2015 = 0.82 objects per day
421Total in 2016 = 1.15 objects per day
213Total in 2017 = 1.23 objects per day
1836Total designation credits for the 2439-day period = 0.75 objects per day

Discovery Credits 2007-2010

This is a list of observing facilities that discovered close-passing objects during the 1,387-day period from January 2007 through mid-October 2010, when the Minor Planet Center changed its policy to state that "Discoverers will be defined only when an object is numbered." Few objects that have passed close since 2007 have been numbered, so we have instead implemented a tally (immediately above) of observing facilities assigned designation credit for a key early observation of an object during its discovery apparition, which may or may not result in receiving future formal discovery credit for that object.

Totals2010200920082007Who & where
20540744051CSS - Catalina Sky Survey in Arizona
19550515836MLS - Mt. Lemmon Survey in Arizona
10321233227LINEAR in New Mexico
3221389SSS - Siding Spring Survey in New South Wales
234784Spacewatch 0.9m telescope in Arizona
3111-Spacewatch 1.8m telescope in Arizona
211--La Sagra Obs. in Spain
2--11LONEOS in Arizona
11---WISE in Earth polar orbit
1-1--Wildberg Obs. in Germany
1-1--Taunus Obs. in Germany
1-1--Hibiscus Obs. in Tahiti

128Total in 2007 = 0.35 objects per day
148Total in 2008 = 0.40 objects per day
173Total in 2009 = 0.47 objects per day
120Total in 2010 = 0.41 objects per day
569Total discoveries for the 1387-day period = 0.41 objects per day

Last Observation Credits

A list of observing facilities that have succeeded often in acquiring the last optical data point during an asteroid's apparition, including a count of how many close-passing objects they were last to catch within the 3826-day reporting period, since 1 Jan. 2007.

Totals20172016201520142013201220112010200920082007Who & where
2754110554259-12020--Tenagra II Obs. in Arizona
26715392824273937508--ARO Westfield in Illinois
2331514183120282325241322Spacewatch 1.8m telescope in Arizona
2212221231818231712291820Great Shefford Obs. in England
203346384229259353-Mauna Kea in Hawaii
180181692012181313152620MLS - Mt. Lemmon Survey in Arizona
176-40303726249253-Tholen team/Mauna Kea - David Tholen's team
111182629154452431Mt. John Obs. in New Zealand
95--------344813ARO - Astronomical Research Obs. in Illinois
931050276-------Apache Point - Apache Point Obs. in New Mexico
921049276-------Nault/Apache Point - Kristie Nault
831123866236----CTIO - Cerro Tololo Inter-American Obs. in Chile
811123866234----Holmes/CTIO - Robert Holmes in Illinois
8061461597104621Schiaparelli Obs. in Italy
803798151091045-MRO - Magdalena Ridge Obs. in New Mexico
52232423-------Steward Mt. Lemmon Sta. - Steward Obs. Mt. Lemmon Station in Arizona
46691112125----PS1 - Pan-STARRS 1 in Hawaii
34----3736825SSS - Siding Spring Survey in New South Wales
321814---------Tholen 2.24m - UH/Tholen NEO Follow-Up 2.24m Telescope in Hawaii
2924585131---KPNO - Kitt Peak Natl. Obs. in Arizona
27-1-24422633CSS - Catalina Sky Survey in Arizona
27--17732331-Sandlot Obs. in Kansas
269511-111241Spacewatch 0.9m telescope in Arizona
253778-------Cerro Paranal in Chile
25367531-----Micheli/Mauna Kea - Marco Micheli
25-2320-------Allen/DECam - Lori Allen
25-2320-------DECam in Chile
173761-------Micheli/Paranal - Marco Micheli
162435-1-1---Spacewatch/KPNO - Spacewatch
13-411--1--15KLENOT in the Czech Republic
1222-3221----ESA OGS - ESA Optical Ground Station in the Canary Islands

Periods of apparent null activity

When no objects known to be within 10 LD of Earth (italics = future)

0319 UT on 31 July 2017-see JPL Close Approaches
2223 UT on 26 June 2017-1106 UT on 16 July 2017=19.52986 days
19.530 days total in 2017
0053 UT on 24 June 2016-1820 UT on 25 June 2016=01.72708 days
1.727 days total in 2016
0135 UT on 13 July 2015-2153 UT on 13 July 2015=20.300 hours
0.846 days total in 2015
1504 UT on 30 July 2014-1815 UT on 4 Aug. 2014=05.13264 days
1118 UT on 11 July 2014-1042 UT on 12 July 2014=23.400 hours
0935 UT on 5 July 2014-1117 UT on 6 July 2014=01.07083 days
7.178 days total in 2014
1834 UT on 4 Dec. 2013-0308 UT on 6 Dec. 2013=01.35694 days
0340 UT on 17 Aug. 2013-1714 UT on 17 Aug. 2013=13.567 hours
0633 UT on 15 July 2013-1720 UT on 18 July 2013=03.44931 days
2208 UT on 15 June 2013-0228 UT on 30 June 2013=14.18056 days
2143 UT on 28 May 2013-1924 UT on 2 June 2013=04.90347 days
24.456 days total in 2013
0322 UT on 28 July 2012-1549 UT on 31 July 2012=03.51875 days
0206 UT on 12 July 2012-1047 UT on 22 July 2012=10.36181 days
0122 UT on 6 May 2012-0456 UT on 10 May 2012=04.14861 days
0310 UT on 9 Feb. 2012-1642 UT on 10 Feb. 2012=01.56389 days
19.593 days total in 2012
1855 UT on 28 Nov. 2011-0235 UT on 30 Nov. 2011=01.31944 days
1234 UT on 10 Sept. 2011-0926 UT on 11 Sept. 2011=20.867 hours
0117 UT on 30 Aug. 2011-0823 UT on 2 Sept. 2011=03.29583 days
0901 UT on 4 Aug. 2011-1606 UT on 10 Aug. 2011=06.29514 days
11.780 days total in 2011
2220 UT on 23 Aug. 2010-1736 UT on 24 Aug. 2010=19.267 hours
0154 UT on 13 Aug. 2010-2120 UT on 19 Aug. 2010=06.80972 days
1434 UT on 20 July 2010-1638 UT on 23 July 2010=03.08611 days
0753 UT on 16 June 2010-1800 UT on 23 June 2010=07.42200 days
1035 UT on 4 June 2010-0242 UT on 13 June 2010=08.67153 days
1658 UT on 8 Jan. 2010-2239 UT on 8 Jan. 2010=05.683 hours
27.029 days total in 2010
2246 UT on 1 Aug. 2009-1841 UT on 4 Aug. 2009=02.82986 days
1351 UT on 11 July 2009-1056 UT on 24 July 2009=12.87847 days
0111 UT on 15 June 2009-0851 UT on 21 June 2009=06.31944 days
0227 UT on 16 April 2009-0619 UT on 18 April 2009=02.16111 days
24.189 days total in 2009
1657 UT on 24 Aug. 2008-0914 UT on 31 Aug. 2008=06.67847 days
2235 UT on 2 Aug. 2008-2146 UT on 19 Aug. 2008=16.96597 days
0130 UT on 1 July 2008-2043 UT on 11 July 2008=10.80069 days
34.445 days total in 2008
0014 UT on 3 Dec. 2007-1300 UT on 3 Dec. 2007=12.767 hours
1510 UT on 18 Nov. 2007-1715 UT on 19 Nov. 2007=01.08681 days
2343 UT on 18 Aug. 2007-0713 UT on 28 Aug. 2007=09.31250 days
0339 UT on 31 July 2007-1400 UT on 8 Aug. 2007=08.43125 days
0607 UT on 14 July 2007-0037 UT on 28 July 2007=13.77083 days
1356 UT on 29 June 2007-2348 UT on 1 July 2007=02.41111 days
0405 UT on 17 May 2007-1659 UT on 24 May 2007=07.53750 days
2217 UT on 2 May 2007-0049 UT on 3 May 2007=02.533 hours
2330 UT on 6 April 2007-1858 UT on 7 April 2007=19.467 hours
0643 UT on 7 March 2007-0752 UT on 7 March 2007=01.150 hours
0947 UT on 29 Jan. 2007-1153 UT on 30 Jan. 2007=01.08750 days
45.134 days total in 2007

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