List of asteroid close approaches to Earth in 2009 explained

Other Years
Caption:	Years
Below:	2000-2007, 2008, 2009, 2010, 2011

Asteroid Close Approaches to Earth
Subheader:	2009
Header1:	Other Years
Below:	2000-2007, 2008, 2009, 2010, 2011

Below is the list of asteroid close approaches to Earth in 2009.

Timeline of close approaches less than one lunar distance from Earth in 2009

A list of known near-Earth asteroid close approaches less than 1 lunar distance (384,400 km or 0.00257 AU) from Earth in 2009.^[1]

This list does not include any of the objects that collided with earth in 2009, none of which were discovered in advance, but were recorded by sensors designed to detect detonation of nuclear devices.

Date of closest approach	Date discovered	width=100	Object	width=205 data-sort-type="number"	Nominal geocentric distance (AU)^[2]	data-sort-type="number"	Nominal geocentric distance (LD)	data-sort-type="number"	Size (m) (approximate)	data-sort-type="number"	(H) (abs. mag)	Closer approach to Moon	width=120	Refs^[3] ^[4]
2009-02-02	2009-02-04		0.00123AU	align=center	0.48	align=center	7.3–16	align=center	27.8	align=center
2009-02-27	2009-03-03		0.00041AU	align=center	0.16	align=center	5.6–12	align=center	28.4	align=center
2009-03-02	2009-02-27		0.00048AU	align=center	0.19	align=center	18–41	align=center	25.8	align=center
2009-03-06	2009-03-02		0.00227AU	align=center	0.88	align=center	14–31	align=center	26.4	align=center
2009-03-18	2009-03-17		0.00057AU	align=center	0.22	align=center	13–28	align=center	26.6	align=center
2009-03-19	2009-03-17		0.0025AU	align=center	0.97	align=center	5.8–13	align=center	28.3	align=center	Yes
2009-05-05	2009-05-04		0.00196AU	align=center	0.76	align=center	10–23	align=center	27.1	align=center	Yes
2009-05-13	2009-05-12		0.00177AU	align=center	0.69	align=center	17–38	align=center	26.0	align=center
2009-06-01	2009-05-31		0.0019AU	align=center	0.74	align=center	12–27	align=center	26.7	align=center	Yes
2009-10-01	2009-10-02		0.00046AU	align=center	0.18	align=center	3.8–8.6	align=center	29.2	align=center
2009-10-05	2009-10-09		0.00173AU	align=center	0.67	align=center	7.7–17	align=center	27.7	align=center
2009-10-08	2009-10-10		0.00204AU	align=center	0.79	align=center	9.2–21	align=center	27.3	align=center
2009-10-17	2009-10-15		0.00232AU	align=center	0.90	align=center	5.6–12	align=center	28.4	align=center
2009-11-06	2009-11-06		0.00014AU	align=center	0.05	align=center	5.1–11	align=center	28.6	align=center
2009-11-12	2009-11-10		0.00174AU	align=center	0.68	align=center	6.5–14	align=center	28.1	align=center	Yes?^[5]
2009-11-15	2009-11-18		0.00176AU	align=center	0.69	align=center	12–26	align=center	26.8	align=center
2009-11-16	2009-11-18		0.00235AU	align=center	0.91	align=center	3.8–8.6	align=center	29.2	align=center
2009-11-20	2009-11-19		0.00119AU	align=center	0.46	align=center	8.8–20	align=center	27.4	align=center
2009-11-24	2009-11-23		0.00101AU	align=center	0.39	align=center	10–23	align=center	27.1	align=center

Warning Times by Size

This table visualizes the warning times of the close approaches listed in the above table, depending on the size of the asteroid. The sizes of each pie chart show the relative sizes of the asteroids to scale. For comparison, the approximate size of a person is also shown. This is based around the absolute magnitude of each asteroid, an approximate measure of size based on brightness.

Notes

Additional examples

An example list of near-Earth asteroids that passed more than 1 lunar distance (384,400 km or 0.00256 AU) from Earth in 2009.

(~990 meters in diameter) passed 11.33 Lunar distances (4.4 million km) from Earth on 17 January 2009.
(~285 meters in diameter) passed 4.39 Lunar distances (1.7 million km) from Earth on 18 February 2009.
(~41 meters in diameter) passed 2.82 Lunar distances (1.1 million km) from Earth on 17 March 2009.
(~95 meters in diameter) passed 1.22 Lunar distances (468,000 km) from Earth on 20 March 2009.
(410777) 2009 FD (472 meters in diameter) passed 1.62 Lunar distances (624,000 km) from Earth on 27 March 2009.
(136617) 1994 CC (~990 meters in diameter) passed 6.55 Lunar distances (2.5 million km) from Earth on 10 June 2009.
2009 MU (~41 meters in diameter) passed 2.31 Lunar distances (889,000 km) from Earth on 24 June 2009.
(~41 meters in diameter) passed 1.94 Lunar distances (745,000 km) from Earth on 11 September 2009.
(~5 meters in diameter) may have passed as close as 1.01 Lunar distances (390,000 km) from Earth on 14 September 2009, but the nominal orbit suggests an approach nearer to 2.40 LD (922,000 km).
(1277 meters in diameter) passed 9.79 Lunar distances (3.8 million km) from Earth on 8 October 2009.
(~2067 meters in diameter) passed 29.68 Lunar distances (11.4 million km) from Earth on 20 October 2009.
(~54 meters in diameter) passed 2.91 Lunar distances (112,000 km) from Earth on 1 December 2009.

Notes and References

For a list of current Earth close approaches see NEO Earth Close Approaches
Distance from the center of Earth to the center of the object. See the NASA/JPL Solar System Dynamics Glossary: Geocentric. Earth has a radius of approximately 6,400 km.
Web site: JPL Small-Body Database Browser . JPL Solar System Dynamics . NASA Jet Propulsion Laboratory.
Web site: MPC Database . IAU Minor Planet Center . International Astronomical Union . 1 January 2021.
The orbit of is known quite poorly- it could have passed as closely as 0.029 and as far as 3.1 LD from Earth, as well as anything from 3.4 LD to colliding head-on with the Moon. As such, the values are based on the nominal calculations. Considering a fireball would likely be noticed if it had collided with the Moon, as it would have created a crater over 150 meters in diameter, it can probably be concluded that the actual orbit was not too far from the nominal one- with a closest approach somewhere between 0.5 and 0.8 lunar distances.