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Traffic Timeline & Statistics

Updated at 1803 UTC on 1 March 2010

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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 Hill sphere (about 3.9 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 a better 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 two locations in Arizona and New Mexico. 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 2007 data and statistics list only objects that made one close passage during the year. Not included is 2006 RH120, which was apparently a temporary natural Earth satellite. It made three close passages in 2007 before departing Earth's vicinity: 1.4 LD on January 3rd, 0.9 LD on March 25th, and 0.7 LD on June 14th.

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

Object counts		20
07		20
08		20
09		20
10

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


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Index: Timeline by month & year

2010-Jan.Feb.MarchAprilMayJuneJulyAug.Sept.Oct.Nov.Dec.
2009-Jan.Feb.MarchAprilMayJuneJulyAug.Sept.Oct.Nov.Dec.
2008-Jan.Feb.MarchAprilMayJuneJulyAug.Sept.Oct.Nov.Dec.
2007-Jan.Feb.MarchAprilMayJuneJulyAug.Sept.Oct.Nov.Dec.

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Maximum daily counts of known objects

Within ten LD of Earth:16 on 9 March 2008, 8 March 2008 & 6 March 2008
Inside Earth's Hill sphere:6 on 9 March 2008
Within one LD of the Moon:2 on four days, most recently 3 Nov. 2008 & 5 Feb. 2008
Inside Earth-Moon system:1 on 69 days, most recently 16 Feb. 2010 & 13 Jan. 2010

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Periods of apparent null activity

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

FromToTotalling
2157 UTC on 1 March 2010-see JPL Close Approaches
1658 UTC on 8 Jan. 2010-2239 UTC on 8 Jan. 2010=05.683 hours
0.237 days total in 2010
2246 UTC on 1 Aug. 2009-1841 UTC on 4 Aug. 2009=02.82986 days
1708 UTC on 3 July 2009-1056 UTC on 24 July 2009=20.74167 days
0111 UTC on 15 June 2009-0851 UTC on 21 June 2009=06.31944 days
0025 UTC on 5 June 2009-0548 UTC on 6 June 2009=01.22431 days
0227 UTC on 16 April 2009-0619 UTC on 18 April 2009=02.16111 days
33.276 days total in 2009
1657 UTC on 24 Aug. 2008-0914 UTC on 31 Aug. 2008=06.67847 days
2235 UTC on 2 Aug. 2008-2146 UTC on 19 Aug. 2008=16.96597 days
0130 UTC on 1 July 2008-2043 UTC on 11 July 2008=10.80069 days
34.445 days total in 2008
0014 UTC on 3 Dec. 2007-1303 UTC on 3 Dec. 2007=12.817 hours
1510 UTC on 18 Nov. 2007-1715 UTC on 19 Nov. 2007=01.08681 days
2343 UTC on 18 Aug. 2007-0713 UTC on 28 Aug. 2007=09.31250 days
0339 UTC on 31 July 2007-1400 UTC on 8 Aug. 2007=08.43125 days
0619 UTC on 7 July 2007-0037 UTC on 28 July 2007=20.76250 days
1356 UTC on 29 June 2007-2348 UTC on 1 July 2007=02.41111 days
2256 UTC on 6 June 2007-1946 UTC on 13 June 2007=06.86806 days
0405 UTC on 17 May 2007-1659 UTC on 24 May 2007=07.53750 days
2217 UTC on 2 May 2007-0039 UTC on 3 May 2007=02.367 hours
2330 UTC on 6 April 2007-1858 UTC on 7 April 2007=19.467 hours
0643 UTC on 7 March 2007-0752 UTC on 7 March 2007=01.150 hours
0551 UTC on 26 Feb. 2007-0839 UTC on 28 Feb. 2007=02.11667 days
0938 UTC on 29 Jan. 2007-1153 UTC on 30 Jan. 2007=01.09375 days
61.112 days total in 2007

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Discovery Credits

Totals2010200920082007Who & where
1719714051CSS - Catalina Sky Survey in Arizona
1519505834MLS - Mt. Lemmon Survey in Arizona
864233227LINEAR in New Mexico
30-1389SSS - Siding Spring Survey in New South Wales
17-683Spacewatch 0.9m telescope in Arizona
2-11-Spacewatch 1.8m telescope in Arizona
2--11LONEOS in Arizona
1-1--Wildberg Obs. in Germany
1-1--Taunus Obs. in Germany
1-1--La Sagra Obs. in Spain
1-1--Hibiscus Obs. in Tahiti
125Total in 2007 = 0.34 objects per day
148Total in 2008 = 0.40 objects per day
168Total in 2009 = 0.46 objects per day
22Total in 2010 = 0.39 objects per day (so far)
463Total discoveries for the 1153-day period = 0.40 objects per day

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Last Observation Credits

A list of those who often succeed in acquiring the last optical data points during an asteroid's apparition, including a count of how many close-passing objects they were last to catch within the 1153-day reporting period, since 1 Jan. 2007.

Totals2010200920082007Who & where
90-334611ARO - Astronomical Research Obs. in Illinois
692291820Great Shefford Obs. in England
611152520MLS - Mt. Lemmon Survey in Arizona
593221321Spacewatch 1.8m telescope in Arizona
25520--Tenagra II Obs. in Arizona
17107--ARO Westfield in Illinois
15-915SSS - Siding Spring Survey in New South Wales
12-633CSS - Catalina Sky Survey in Arizona
9-621Schiaparelli Obs. in Italy
9-45-MRO - Magdalena Ridge Obs. in New Mexico
811-6Shenton Park Obs. in Western Australia
8-53-Mauna Kea in Hawaii
8-53-Tholen team/Mauna Kea - David Tholen's team
8-431Mt. John Obs. in New Zealand
J
a
n
.		less than 10 LD from Earth5122115
inside Earth's Hill sphere2594
less than 1 LD from Moon0101
less than 1 LD from Earth1101
close-passer discoveries591611
F
e
b
.		less than 10 LD from Earth17262611
inside Earth's Hill sphere6895
less than 1 LD from Moon2211
less than 1 LD from Earth2221
close-passer discoveries17201911
M
a
r
c
h		less than 10 LD from Earth2231321
inside Earth's Hill sphere913130
less than 1 LD from Moon1340
less than 1 LD from Earth2540
close-passer discoveries1923240
A
p
r
i
l		less than 10 LD from Earth102316
inside Earth's Hill sphere3116
less than 1 LD from Moon022
less than 1 LD from Earth120
close-passer discoveries8178
M
a
y		less than 10 LD from Earth71412
inside Earth's Hill sphere177
less than 1 LD from Moon112
less than 1 LD from Earth012
close-passer discoveries488
J
u
n
e		less than 10 LD from Earth6910
inside Earth's Hill sphere032
less than 1 LD from Moon001
less than 1 LD from Earth001
close-passer discoveries764
J
u
l
y		less than 10 LD from Earth273
inside Earth's Hill sphere030
less than 1 LD from Moon000
less than 1 LD from Earth010
close-passer discoveries051
A
u
g
.		less than 10 LD from Earth4312
inside Earth's Hill sphere001
less than 1 LD from Moon000
less than 1 LD from Earth000
close-passer discoveries219
S
e
p
t
.		less than 10 LD from Earth161425
inside Earth's Hill sphere259
less than 1 LD from Moon101
less than 1 LD from Earth101
close-passer discoveries12619
O
c
t
.		less than 10 LD from Earth233230
inside Earth's Hill sphere101211
less than 1 LD from Moon522
less than 1 LD from Earth464
close-passer discoveries182424
N
o
v
.		less than 10 LD from Earth222432
inside Earth's Hill sphere5815
less than 1 LD from Moon123
less than 1 LD from Earth115
close-passer discoveries231529
D
e
c
.		less than 10 LD from Earth131712
inside Earth's Hill sphere443
less than 1 LD from Moon000
less than 1 LD from Earth000
close-passer discoveries10147
   

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