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The Minor Planet Center maintain a list of the Closest
Approaches to the Earth by Minor Planets, including all approaches
to within 0.01 AU (or a little less than four times the distance of the
Moon) but for the majority of those approaches, the minor planets were
not actually under observation when at their closest.
This page includes those Minor Planets that have had astrometry
(accurate positions) reported while they have been as close or closer than the distance of the Moon.
Much of the numeric details have been derived from the original
astrometry where available and geocentric distances are given.
In the notes below LD = Lunar Distance = 384,400 Km. The diameter of
the Earth is 12,756 Km or 0.033 LD. FindOrb has been used to provide
pseudo MPEC details for some of the objects, including orbital elements,
the original astrometry, residuals and 1 minute step geocentric
ephemerides covering the time the objects were within the orbit of the
Moon.
Near Earth Objects observed within 1 Lunar Distance of Earth:
| 1 |
2004 FH
2004 FH was well observed, both during its two
day approach towards the Earth/Moon system following its discovery
on 16 March 2004 by LINEAR and also during it's very close
approach inside the Moons orbit. It was 17-18th magnitude at
discovery and moving at 4"/min and brightened rapidly,
reaching 15th mag by the time it passed inside the Moons orbit at
07:23 UT on 18 March 2004. It had reached mag +10-11 when
picked up from the Sormano Observatory in Italy at 21:14 UT on 18
March at an altitude of just 5°, 54 minutes before closest
approach, zooming along at 1732"/min and only 0.14 LD away or
less than 4 Earth diameters above the surface of the Earth. The
only reported observations after closest approach were a pair of
positions from Tenagra II Observatory at 02:47 UT on 19 March when
it was still at 0.34 LD and had slowed down to 291"/min. See
the 19 March 2004 entry on the Tenagra What's
New page for an image of the NEO streaking away from Earth.
2004 FH remained inside the Moons orbit for a total of 29.5 hours.
See also excellent 2004 FH coverage on A/CC's Major News about
Minor Objects from 17,
18
and 19
March 2004 and also the pseudo MPEC. |
| 2 |
2004 FY15
2004 FY15 was a magnitude
+17 Catalina Sky Survey discovery on 26 March 2004, moving
almost due south at 18"/min. The Mount John Observatory in
New Zealand caught it at mag +14 inside the Moons orbit at 0.87 LD
at 12:20 UT on 27 March when it was moving at 215"/min. It
was not reported again, but reached its closest to Earth 8 hours
later at 0.62 LD at a declination of -57°. See pseudo
MPEC. |
| 3 |
2004 FU162
2004 FU162 was discovered
by LINEAR on 31 March 2004, but unusually was announced over 4
months later on 22 Aug 2004 in MPEC 2004-Q22.
Only observed for 44 minutes it has however a very determinant
orbit and this indicated that it had passed about 1 Earth radii
above the surface of the Earth around 15:30 UT on 31 March.
However at discovery it was mag +16 and only just inside the Moons
orbit (at 0.84 LD), accelerating from 20"/min to 24"/min
during the short time it was observed. See A/CC's Major News about
Minor Objects 'Closest
by Far' and 'More
about 2004 FU162' for interesting details on this
story. See also pseudo
MPEC. |
|
4
|
2004 XB45
Discovered on 13
December 2004 by Andrew Tubbiolo using the 0.9-m f/3 Spacewatch
reflector at Kitt Peak,
2004 XB45 was magnitude
+20 and moving at an unremarkable 2"/min, some 14 LD from
Earth. 32 hours later when the discovery was announced on MPEC 2004-X71
it was about 8 LD away, had tripled in apparent speed and was
brightening fast. It crossed inside the Moons orbit at 15:49 UT on
16 December and it was followed 1½ hours later between 17:00 -
17:12 UT at magnitude +14 and moving at 574"/min from the Bisei
Spaceguard Center in Japan while at 0.89 LD. Closest approach
occurred 2 hours later at a distance of 0.85 LD but 2004 XB45
was not reported again. See pseudo MPEC.
|
| 5 |
2005 UW5
LINEAR discovered 2005 UW5 at 06:00 UT
on 2005 Oct 27 at about mag +19.5V and moving at about
6"/min. It crossed inside the Moons orbit 2½ days later at
14:36 UT on 29 October and was observed inside the Moons orbit
from Great Shefford and also from Gnosca in Switzerland by Stefano
Sposetti. It was last reported at 21:12 UT from Great Shefford at
magnitude +14, moving at 516"/min and at 0.56 LD. Closest
approach was 3 hours later at 00:16 UT on 30 October at a distance
of 0.49 LD. As well as the link above, see pseudo
MPEC. |
| 6 |
2005 WN3
On 25 Nov 2005, 2005 WN3
was discovered by the Mt Lemmon Survey and followed for 2h 23 minutes
during which time it approached from 3.1 to 2.6 LD. It was briefly observed
10 hours
later at 19:39 UT from
Great Shefford at 17th magnitude, moving at 178"/min at a distance
of 0.88 LD. Closest approach was at 00:31 UT on 26 November at
just 0.22 LD or 6 Earth diameters from the surface of the Earth.
As well as the link above, see pseudo
MPEC. |
| 7 |
2006 BV39
On 26 Jan 2006, 2006 BV39 was discovered by Spacewatch and
observed on 29 Jan 2006 from Great Shefford for 4 hours while inside the orbit of the Moon,
moving at fastest at 277"/min. |
| 8 |
2006 DD1
On 22 Feb 2006, 2006 DD1 was discovered by
the Catalina Sky Survey and on 23 Feb 2006 was followed by three
observatories while inside the Moons orbit. It was finally observed
by Catalina within 12 minutes of it's closest approach to the Earth,
travelling at over 1,800"/min at a distance of only 0.306 L.D. |
| 9 |
2006 EC
On 03 Mar 2006, 2006 EC was discovered by the Catalina Sky
Survey and 5 days later on 08 Mar 2006 was observed by John Broughton
from Reedy Creek, Australia about 1 hour after closest approach, while
still inside the Moons orbit. At that time it was moving at
345"/min. |
| 10 |
2006 OK3
On 22 Jul 2006, 2006 OK3 was discovered by Rob McNaught at
the Siding Spring site of the Catalina Sky
Survey using the Uppsala 0.5-m Schmidt just 20 hours before passing
Earth at 0.7 L.D. The Mt. Lemmon survey tracked it to about 1 hour
before closest approach, at a distance of 280,260 Km when it was moving at
630"/min |
| 11 |
2006 QM111
On 31 Aug 2006, 2006 QM111 was also discovered by Rob McNaught at Siding Spring
using the Uppsala 0.5-m Schmidt and first reported at 12:50 UT when it
was about mag +16.5 and moving at 100"/min. Rob followed it for the
next 6h 40mins by which time it was 2 magnitudes brighter and racing
along at 856"/min. It had passed inside the orbit of the Moon at
16:14 UT and was at just 0.53 L.D. when last seen moving into bright
twilight at 19:32 UT. Closest approach occurred at 21:29 UT at a
distance of 160,070 Km or 0.42 L.D. but it was not reported by any other
observers. |
| 12 |
2007 BD
On 16 Jan 2007, 2007 BD was discovered by Eric Christensen at
the Catalina Sky
Survey using the 0.68-m Schmidt. It was only 3 L.D. away and already
17th mag, moving at 27"/min. It passed inside the Moons orbit 32
hours later, reaching a minimum distance from Earth of 0.84 L.D. on 18
Jan 2007 at 02:53UT and was well observed from the Crimea-Nauchnij,
Gnosca and Modra observatories and also from the Catalina Sky Survey
during the 16 hours it remained inside the Moons orbit. It was last
caught from Modra 42 minutes before closest approach, travelling at
303"/min at mag +13. It was then picked up again from Catalina 52
minutes after closest approach. 2007 BD is an Aten minor planet with an
orbit smaller than the Earth's, taking just 230 days to orbit the Sun
and with an aphelion distance of 0.986 AU is almost an Apohele (orbit
being entirely inside that of the Earth), but with the Earth at
perihelion in January and the object reaching aphelion literally on the
day of close approach, it passed just outside the Earths orbit and was
therefore well placed for observers. |
| 13 |
2007 EH
2007 EH was discovered by the Catalina Sky Survey on 9th March 2007
and passed 0.44 lunar distances from the Earth on 11 March 2007. It was
followed right through the close approach from Great Shefford when it
reached a speed of 1,250"/min and was also caught
inside the Moons orbit during the approach, from Golden Hill Observatory in the UK by Richard
Miles. A detailed account of the fly-by is given here. |
| 14 |
2007 EK
2007 EK was discovered 20 minutes before 2007 EH on 9th March 2007
with the 0.9-m reflector of the Steward Observatory on Kitt Peak. It
passed 0.69 lunar distances from the Earth two days after 2007 EH, on 13
March 2007 and was followed inside the Moons orbit by the Remanzacco
Observatory in Italy and from Great Shefford. When last recorded from
Great Shefford it was moving at 382"/min, just 1h 45mins before
it's closest point. |
| 15 |
2007 HB15
2007 HB15 was discovered on 23
April 2007 by Alex Gibbs using the Catalina Sky Survey's 0.68-m
Schmidt, already just 2.3 LD from Earth, mag +17 and moving at
18"/min. It crossed inside the Moons orbit at 07:01 UT the
next day and was observed while closer to the Earth than the Moon
from Sandlot Observatory and also by Robert Hutsebaut from Belgium
observing remotely from the RAS Observatory, Mayhill. It was last
reported from the Tiki Observatory in Tahiti at 11:24 UT when it
was at 0.80 LD, 15th magnitude and moving at 179"/min. 9 hours later at 20:31
UT it
passed Earth at 0.57 LD . See pseudo
MPEC. |
| 16 |
2006 RH120 (= 6R10DB9)
Discovered on 14 September 2006 and given the temporary observer
assigned designation 6R10DB9 this very unusual object was dismissed
a day later by the Minor Planet Center as 'not
a minor planet', being mistaken for a small piece of man-made
space debris in orbit around the Earth. However, it was recognised
in the coming weeks as being in a temporary, unstable orbit around
Earth and likely to be a natural object. Finally, 17 months after
discovery it received an official designation as a minor planet 2006
RH120 in
MPEC 2008-D12. It came within the orbit of the Moon on 11 June 2007
and stayed closer than the Moon for a record 7 days, reaching its
closest at 05:28 UT on 14 June 2007 at a distance of 276,850 Km, or
0.72 L.D. It was observed from Great Shefford from 22:48 -
23:30 UT on 15 June 2007
when at a distance of 0.82 L.D., moving at 47"/min and shining at
about mag. +19. See a full account here
and a pseudo
MPEC of the June 2007 encounter which was the only one of its
two perigees within the Moons orbit when it was actually under observation. |
| 17 |
2007 RS1
Steve Larson picked up 2007 RS1 on 04
September 2007 with the Mt. Lemmon 1.5-m
reflector as part of the Catalina Sky Survey. It was less than
double the Moon's distance away at that time and approaching very
fast. It was next picked up at 19:57 UT from Great Shefford, about
15 hours after discovery, by which time it had
approached to about half the distance of the Moon. During the 40
minutes it was under observation it accelerated from 193"/min to
246"/min with a brightness of mag. +17 - 18. Closest approach
was about 5 hours later at 01:18 UT on 05 September 2007 at a
distance of 0.19 L.D., i.e. less than 6 Earth diameters away, but it
was not reported again. See
pseudo
MPEC. 2007 RS1 is listed by the JPL
as having an absolute magnitude of +31.0 ±0.4,
which translates to an estimated diameter of roughly 1 - 4 meters
and makes it probably the smallest NEO with a well determined orbit
to have been seen up to that point, the previous records being
2003 SQ222 with an
absolute magnitude of +30.0 ±0.7 and
2006 RH120 ( =
6R10DB9)
with an absolute magnitude of 30.2 ±0.2. |
| 18 |
2007 VF189
Passing the Earth less than 7 hours after the fly-by of the Rosetta
spacecraft, 2007 VF189 also had remarkably similar orbital elements to
the spacecraft, though it was soon apparent that the two objects
were unrelated and the orbital similarity was just coincidental. Rosetta had been
'discovered' a week earlier earlier by the Catalina Sky Survey and
initially given the Minor Planet designation
2007 VN84 before its artificial nature was recognised. Here the
fly-by circumstances and orbital elements of the two objects are compared:
| |
2007 VF189 |
Rosetta |
| Closest approach time UT |
2007 Nov 14.14 |
2007 Nov 13.87 |
| Closest approach distance Km |
233837 |
11670 |
| Perihelion time UT (T) |
2008 Jan 10.6 |
2008 Jan 10.4 |
| eccentricity (e) |
0.390 |
0.339 |
| semi-major axis (a) |
1.205 |
1.185 |
| Perihelion distance (q) |
0.735 |
0.783 |
| Argument of perihelion (ω) |
84 |
80 |
| Longitude of ascending Node (Ω) |
52 |
51 |
| Inclination (i) |
7 |
2 |
| Period (years) |
1.32 |
1.29 |
2007 VF189 was moving at
10"/min when discovered by the Mt. Lemmon 1.5-m telescope on 12 Nov
2007. It was tracked again the next night by the 0.6-m Schmidt of the
Catalina Sky Survey having accelerated to an apparent
speed against the sky of 46"/min. It was just over twice as far
away as the Moon at that time. Later on Nov 13th it was followed from the Shenton Park
station of the Tenagra Observatory, with an account by Paulo
Holvorcem given
here. The last two positions reported were made just a few
minutes after the Minor Planet had come inside the orbit of the Moon
and when last reported was 17th magnitude and moving at 230"/min. Just
over 7 hours later it passed over the Earth's south pole at a
distance of 0.61 L.D.
See an account of the discovery by Richard Kowalski
here and a pseudo MPEC. |
19 |
2008 AF3
Another Catalina Sky Survey discovery with the 0.68-m Schmidt,
this time by Rik Hill on 10 Jan 2008, 2008 AF3 was observed by the
same instrument at 02:43 UT on 13 Jan 2008, just a few minutes
after passing the 1 L.D. marker. By 04:46 UT Andrew Lowe remotely
observing using the facilities at the RAS Observatory, Mayhill in
New Mexico picked it up and followed it for over 1.5 hours during
which time it reached its fastest observed apparent speed of
110"/min. Farpoint Observatory, Eskridge observed it about 1.5 hours
later between 07:54-07:58 UT by which time it was slightly closer to
the Earth at 0.980 L.D. moving at 106"/min and at magnitude +15.
Closest approach was just over 1 hour later at 09:13 UT on 13 Jan
2008 at a distance of 0.979 L.D., just 8,000 Km inside the orbit of
the Moon, but the next time the NEO was observed, at 19:06 UT 13 Jan
2008 it had already receded beyond 1 L.D. It had spent just over 13
hours closer to the Earth than the Moon. See
pseudo-MPEC. |
| 20 |
2008 EZ7
Discovered by Gordon Garradd and Rob McNaught at 11:44 UT on 07
March 2008 using the 0.5-m Uppsala Schmidt of the Siding Spring
Survey. At that time it was moving at 9.5"/min and was 18th mag. but
when last recorded by them 3 hours later it had already accelerated
to 14.5"/min and was obviously heading toward a close approach to
Earth. It was followed from five observatories during the next 25
hours and observed again from Siding Spring at 13:29 UT on 09 Mar.
moving at 103"/min, within a minute of passing inside the distance
of the Moon. It was then observed from Siding Spring, Eschenberg,
Mallorca, Naef and Crimea-Nauchnij observatories before closest approach, reaching a
speed of 572"/min, mag. +14 at a distance of 0.44 L.D. when last
reported from Crimea-Nauchnij at 23:37 UT on 08 Mar. Closest approach
occurred at 01:21 UT on 09 Mar. at a distance of 0.419 L.D. and 53
minutes later it was picked up from Great Shefford at 0.424 L.D., as
bright as mag.+13 and moving at 623"/min.
2008 EZ7 was kept under
observation for nearly three more hours as it receded from the Earth
and was within the orbit of the Moon for a total of 24 hours. At the
time of the closest approach it was the third closest approach ever
observed, with only 2004 FH and 2006 DD1
having been observed at a closer distance. See
pseudo-MPEC. |
| 21 |
2008 FP
Richard Kowalski working with the 1.5-m reflector on Mt. Lemmon
picked up 2008 FP at 08:32 UT on 28 March 2008, a 19th magnitude
object, moving at a relatively sedate 6"/min, 8 L.D. from Earth. It
was followed for nearly 4h from Mt Lemmon, Sabino Canyon and Tiki
observatories that night. 14 hours later it was observed from Great
Shefford and Schiaparelli observatories in Europe by which time it
had approached to 2.4 L.D. and was moving at 74"/min.
Just over 3 hours later at 07:02 UT on 29 March
2008 it was picked up again, this time by the Catalina Sky Survey (CSS)
and it passed inside the distance of the Moon at 08:42 UT. CSS
reported it at 08:52 UT, moving at 508"/min, at magnitude +14 and
followed it for the next 2h 48 min, last reporting it at 11:30 UT
when it was at 0.445 L.D. only 7 minutes before closest approach. It
had sped up to an apparent speed against the sky of 2354"/min,
equivalent to covering the diameter of the Moon in about 48 seconds!
It was not reported again. This was
(at the time of observation) the fastest observed speed of a Near
Earth Asteroid, exceeding the observed speeds of 2008 EZ7
(623"/min at 0.424 L.D.), 2004 FH (1732"/min at 0.142 L.D.) and 2006
DD1 (1843"/min at 0.306 L.D.), all of which were observed
closer to Earth than 2008 FP. 2008 FP crossed the orbit of the Earth
at an unusually sharp angle of about 56°, on its way to perihelion
on 08 May 2008 at just 0.28 AU. The other three NEOs crossed at much
shallower angles and with much less velocity relative to Earth.
Indeed, 2008 FP is listed by
JPL as having the fastest relative velocity (32.6 km/s) of any
NEO predicted to have approached within the orbit of the Moon
between 1900 A.D. and 2200 A.D. In comparison, 2008 EZ7
had a relative velocity of only 8.4 km/s.
See the pseudo-MPEC for 2008 FP |
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