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Closest Observed Approaches to the Earth by Minor Planets

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 its 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 1 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 2 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 its 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 its 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

22

2008 JL24

LINEAR discovered 2008 JL24 at 06:05 UT on 11 May 2008, already magnitude +17 and moving South-East at 46"/min in Virgo, about midway between Arcturus and Spica and it had already made its closest approach to the Earth some 29 hours earlier at distance of 0.448 L.D. At discovery it was at 0.95 L.D. and would pass outside the orbit of the Moon less than 2 hours later. It was confirmed from Great Shefford Observatory 18 hours after discovery at 18th magnitude, moving at 20"/min and had already receded to 1.43 L.D. from Earth. This is believed to be the first time that a NEO discovered while closer than the Moon has been confirmed from another observatory. 2008 JL24 was overtaking the Earth having been at perihelion three months before discovery at q=0.92 and passing Earth with the very low relative velocity of 3.5 km/s, staying within 1 L.D. for the unusually long time of 2 days 13 hours. Indeed this was the slowest fly-by of Earth of any object observed within 1 L.D. apart from the unusual object 2006 RH120 which had been temporarily trapped in Earth orbit. See a JPL list of fly-bys nearer than 5 L.D. in order of ascending relative velocity (note this includes many passages of NEOs that were not actually observed).

See also the pseudo-MPEC for 2008 JL24.

23

2008 TC3

2008 TC3 was the first asteroid ever discovered that was found to be on a collision course with Earth. It was destroyed in the Earth's atmosphere 20 hours after discovery. A full account is given here.

See the pseudo-MPEC for 2008 TC3.

24

2008 TS26

Discovered by Andrea Boattini with the 1.5-m reflector on Mt. Lemmon at 8:57 UT on 09 Oct 2008 when it was moving at 44"/min  and at 0.71 L.D., but then found on other images taken just over an hour earlier when it was moving at 71"/min and only 0.58 L.D. from Earth.

It was about magnitude +20 when first seen and faded by about one magnitude during the 2.6 hours it was under observation. When last reported at 10:31 UT on 09 Oct 2008 it was moving at 23"/min and at 0.91 L.D. was still within the orbit of the Moon.

Closest approach had been at 03:30 UT the same day, 4 hours before it was first detected, when it skimmed past at a distance of 12,600Km, or slightly less than one Earth radius from the surface of the Earth. 2008 TS26 at the time of observation was by far the smallest minor planet ever observed, with an absolute magnitude of +33.2 it is likely to have been only about 0.5 meters in diameter. The previous record had been 2007 RS1.

See the pseudo-MPEC for 2008 TS26.

25

2009 DD45

Picked up on 27 Feb 2009 at 12:25 UT by Rob McNaught at Siding Spring when it was in southern Puppis at a declination of -47, 2009 DD45 was mag. +19 and moving at an unremarkable 0.5"/min when first imaged. However, the telltale signs were there of an impending close approach, in the 156 minutes it was kept under observation on the discovery night its speed almost tripled. 2009 DD45 was at 5.7 LD and 73 hours away from passing Earth at a distance of just 0.188 LD. During the approach it moved further south and had reached a declination of -51 when first reported inside the orbit of the Moon from CEAMIG-REA Observatory in Brazil at 03:12 UT on 02 Mar 2009. By then it was mag. +14, moving at 59"/min and still closing rapidly. It was also followed on the way in from Hibiscus Observatory, Tahiti, Mount John Observatory, New Zealand and from Kambah and Marsfield observatories in Australia. Siding Spring caught it just 40 minutes before closest approach at 0.194 LD, travelling at 1480"/min and at mag. +11. By then it was at a declination of -26 and moving rapidly north. 10 hours later it was picked up from Great Shefford at 0.80 LD, having faded by 3 magnitudes and had slowed to a speed of 91"/min. It was also observed from Siegen in Germany before passing beyond 1 LD at 02:16 UT on 03 Mar 2009.

26

2009 EW

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27

2009 FH

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28

2009 TM8

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29

2009 VA

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30

2009 WJ6

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Closest Observed Approaches of NEOs to Earth
 
The diagonal line marks where the dots would be if the asteroids had been seen at the moment of closest approach (2004 FH was reported seen almost at that instant, whereas 2004 FU162 which approached to 0.03 lunar distances or 12,900 Km from the centre of the Earth was observed only just inside the orbit of the Moon).

The red line at top marks the distance of the Moon.
The red line at bottom marks the surface of the Earth.

There are two dots for 2008 TC3 (which impacted the Earth on 07 Oct 2008). The upper one at 0.108 L.D. marks the last reported astrometry, the lower at 0.086 L.D. marks the distance when last observed, entering the Earth's shadow, though no astrometry was reported.


All distances given are geocentric (measured from the centre of the Earth).


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