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Traffic Timeline & Statistics

Refreshed at 1838 UTC on 5 January 2009

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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 possibly suggest that more objects fly near the Earth-Moon system during February-March than at other times of year. This illusion comes from the geographic distribution of asteroid discovery programs and follow-up observers. Most are in the northern hemisphere and have peak productivity during long Winter nights. Additionally, most discoveries are made from Arizona and New Mexico, which experience some of their cloudiest skies during the Summer. There are probably 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 monthly counts chart

Object counts		20
07		20
08		20
09

Chart of Close-Passing Object Monthly Counts
See vertical table at left for counts


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Index: Timeline by month & year

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 3 Nov. 2008, 5 Feb. 2008, 17 Oct. 2007 & 16 Oct. 2007
Inside Earth-Moon system:1 on 44 days, most recently 4 Nov. 2008

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Periods of null activity

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

FromToTotalling
0138 UTC on 19 Jan. 2009-see JPL Close Approaches
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
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
0550 UTC on 26 Feb. 2007-0839 UTC on 28 Feb. 2007=02.11736 days
0938 UTC on 29 Jan. 2007-1153 UTC on 30 Jan. 2007=01.09375 days

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Discovery Credits

Totals200920082007Who & where
92-5834-MLS - Mt. Lemmon Survey in Arizona
91-4051-CSS - Catalina Sky Survey in Arizona
59-3227-LINEAR in New Mexico
17-89-SSS - Siding Spring Survey in New South Wales
11-83-Spacewatch 0.9m telescope in Arizona
2-11-LONEOS in Arizona
1-1--Spacewatch 1.8m telescope in Arizona
125Total in 2007 = 0.34 objects per day
148Total in 2008 = 0.40 objects per day
0Total in 2009 = 0.00 objects per day (so far)
273Total discoveries for the 736-day period = 0.37 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 736-day reporting period, since 1 Jan. 2007.

Totals200920082007Who & where
6024711-ARO - Astronomical Research Obs. in Illinois
45-2520-MLS - Mt. Lemmon Survey in Arizona
4241820-Great Shefford Obs. in England
3511321-Spacewatch 1.8m telescope in Arizona
8-26-SSS - Siding Spring Survey in New South Wales
6--6-Shenton Park Obs. in Western Australia
6-6--MRO - Magdalena Ridge Obs. in New Mexico
6-33-CSS - Catalina Sky Survey in Arizona
6-15-KLENOT in the Czech Republic
J
a
n
.		less than 10 LD from Earth5126
inside Earth's Hill sphere253
less than 1 LD from Moon010
less than 1 LD from Earth110
close-passer discoveries590
F
e
b
.		less than 10 LD from Earth1726
inside Earth's Hill sphere68
less than 1 LD from Moon22
less than 1 LD from Earth22
close-passer discoveries1720
M
a
r
c
h		less than 10 LD from Earth2231
inside Earth's Hill sphere913
less than 1 LD from Moon13
less than 1 LD from Earth25
close-passer discoveries1923
A
p
r
i
l		less than 10 LD from Earth1022
inside Earth's Hill sphere311
less than 1 LD from Moon02
less than 1 LD from Earth12
close-passer discoveries817
M
a
y		less than 10 LD from Earth714
inside Earth's Hill sphere17
less than 1 LD from Moon11
less than 1 LD from Earth01
close-passer discoveries48
J
u
n
e		less than 10 LD from Earth69
inside Earth's Hill sphere03
less than 1 LD from Moon00
less than 1 LD from Earth00
close-passer discoveries76
J
u
l
y		less than 10 LD from Earth27
inside Earth's Hill sphere03
less than 1 LD from Moon00
less than 1 LD from Earth01
close-passer discoveries05
A
u
g
.		less than 10 LD from Earth43
inside Earth's Hill sphere00
less than 1 LD from Moon00
less than 1 LD from Earth00
close-passer discoveries21
S
e
p
t
.		less than 10 LD from Earth1614
inside Earth's Hill sphere25
less than 1 LD from Moon10
less than 1 LD from Earth10
close-passer discoveries126
O
c
t
.		less than 10 LD from Earth2332
inside Earth's Hill sphere1012
less than 1 LD from Moon52
less than 1 LD from Earth46
close-passer discoveries1824
N
o
v
.		less than 10 LD from Earth2224
inside Earth's Hill sphere58
less than 1 LD from Moon12
less than 1 LD from Earth11
close-passer discoveries2315
D
e
c
.		less than 10 LD from Earth1316
inside Earth's Hill sphere44
less than 1 LD from Moon00
less than 1 LD from Earth00
close-passer discoveries1014
   

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