Near-Earth Asteroid 2012 BX34: Record Close Pass by our Planet

Asteroid 2012 BX34 passing close to Earth on January 27, 2012 — The faint light trail traces the trajectory of near-Earth object 2012 BX34 during its passage on January 27, 2012. It passed at 59,044 km from Earth, inside the geostationary orbit, located at 35,786 km altitude.
Image source: Ernesto Guido-Giovanni Sostero-Nick Howes (new window)

Scientific summary

Astronoo's article presents the near-Earth asteroid 2012 BX34, a small body of the solar system whose passage at 59,000 km from Earth on January 27, 2012 provided a unique observation opportunity. Thanks to radar and photometric data, astronomers have refined orbital models and the physical characterization of these objects. The study of its trajectory, influenced by gravitational perturbations, highlights the importance of continuous monitoring of near-Earth asteroids. This event illustrates the ability of current detection programs to track small objects, thus contributing to planetary protection and the understanding of the near-Earth object population.

What makes the passage of asteroid 2012 BX34 so remarkable for astronomers?

This article is dedicated to the near-Earth asteroid 2012 BX34, a small body about 8 to 11 meters in diameter that passed exceptionally close to Earth on January 27, 2012. But what makes this passage so special for astronomers? The answer lies in the combination of its extreme proximity — only 59,000 km, less than one-fifth of the Earth-Moon distance — and the precision of the observations it enabled. This event provided a rare opportunity to test and refine orbital prediction models, while demonstrating the effectiveness of surveillance networks such as the Catalina Sky Survey. Furthermore, the study of 2012 BX34 has helped to better understand the composition and dynamics of Apollo-type asteroids, which regularly cross Earth's orbit. This close pass, although harmless, underscores the importance of early detection of NEOs (near Earth Object) and paves the way for future planetary defense missions.

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A remarkably precise passage

On January 27, 2012, asteroid 2012 BX34 flew past Earth at a distance of approximately 59,000 km, barely 0.15 times the Earth-Moon distance. This small object, estimated at only 8 to 11 meters in diameter, belongs to the category of NEOs (near Earth Object), and more precisely NEAs (near Earth Asteroid) of the Apollo type, whose orbit regularly crosses that of Earth.

Discovered by the Catalina Sky Survey program in Arizona, 2012 BX34 sparked great scientific interest because it passed inside the orbit of many geostationary satellites. Its relative speed at the time of the flyby reached approximately 13.4 km/s, a value consistent with the average speeds of small near-Earth objects.

N.B. :
Apollo-type asteroids belong to a class of NEOs (near Earth Object) whose semi-major axis is greater than 1 astronomical unit (AU), but whose perihelion is less than 1.017 AU. In other words, their orbit intersects that of Earth. Discovered by Karl Reinmuth (1892-1979) in 1932, the Apollo family today constitutes the most numerous population of NEAs (near Earth Asteroids), representing more than 60% of known near-Earth objects.

Physical and orbital characteristics

Composition and albedo

Radar and photometric data collected during its approach allowed an estimate of a moderate albedo, suggesting a silicaceous composition typical of S-type asteroids. The heliocentric orbit of 2012 BX34 is characterized by a sidereal period of 1.08 years and an eccentricity of 0.36. Its perihelion distance is 0.68 AU and its aphelion reaches 1.45 AU.

Hazard and model precision

Its passage near Earth posed no impact danger, the calculated probability being less than \(10^{-7}\). This type of approach nevertheless allows testing the precision of gravitational prediction models and the margins of error related to orbital perturbations (gravitational perturbations linked to the Moon and planets).

Monitoring and orbital calculations

Law of universal gravitation

Orbital calculations are based on the law of universal gravitation formulated by Isaac Newton (1643-1727), according to which the force between two masses is given by: \( F = G \frac{m_1 m_2}{r^2} \)

Numerical integration and perturbations

In the case of near-Earth asteroids, perturbations due to Earth and the Moon continuously modify orbital parameters: inclination, eccentricity and argument of perihelion. These variations are calculated by numerically integrating the equations of motion with a temporal resolution of less than one hour, in order to maintain trajectory accuracy over several years.

A record among known passages

Before 2012, only a few asteroids of comparable size had been observed so close to our planet, notably 2008 TC3 and 2011 CQ1. The latter, about 1 meter in diameter, still holds the record for the closest passage, at only 5,480 km from Earth, but it disintegrated in the atmosphere. In comparison, 2012 BX34 passed much farther, without experiencing atmospheric braking or mechanical alteration.

These observations are valuable for NEO (near Earth Object) models because they allow improving early detection strategies. NASA estimates that nearly 95% of objects larger than 1 km are now cataloged, but less than 30% of asteroids smaller than 100 meters are regularly tracked.

N.B. :
Radar and optical observations today allow tracking objects larger than 10 meters up to a distance of about 1 million kilometers. Future missions such as NEO Surveyor will strengthen this capability within the next decade.

Comparative table: Passages of small near-Earth asteroids

Close passages and impacts of asteroids under 15 meters (2008–2023)
Asteroid name	Passage date	Minimum distance (km)	Estimated diameter (m)	Relative velocity (km/s)	Remark
2008 TC3	October 7, 2008	0 (impact)	≈ 4	≈ 12.4	First asteroid detected before impact; disintegrated at 37 km altitude above the Nubian Desert (Sudan). Origin of Almahata Sitta meteorites.
2011 CQ1	February 4, 2011	5,480	0.8–2.6	≈ 9.7	Held the record for the closest non-impacting flyby known, until 2020 QG in 2020.
2012 BX34	January 27, 2012	59,044	8–11	≈ 8.9	Discovered only two days before its passage by the Catalina Sky Survey.
2020 QG	August 16, 2020	2,950	3–6	≈ 12.3	Closest non-impacting flyby ever recorded at the time; detected only 6 hours after its passage.
2023 CX1	February 13, 2023	0 (impact)	≈ 0.72	≈ 17.4	Seventh asteroid detected before impact; disintegrated over the English Channel, near the coast of Normandy (France).

References

FAQ: Everything you need to know about asteroid 2012 BX34

What is asteroid 2012 BX34?

2012 BX34 is a small near-Earth asteroid discovered on January 25, 2012 by Alex Gibbs, astronomer and software engineer of the Catalina Sky Survey program (University of Arizona). It belongs to the class of Apollo asteroids, whose orbit crosses that of Earth. It passed near our planet two days after its discovery, on January 27, 2012 at 15:25 UT.

Why was this passage important for science?

This passage was an exceptional opportunity for astronomers to test the precision of orbital prediction models and to observe a small asteroid at very close range. The asteroid was ranked among the 20 closest approaches ever recorded. Its trajectory was tracked by NASA radars (Goldstone Deep Space Communications Complex), allowing refinement of physical and orbital parameters. Its rapid detection also demonstrated the effectiveness of surveillance programs such as the Catalina Sky Survey.

What was the size of 2012 BX34?

Its size is estimated between 8 and 11 meters in diameter, according to sources. Some initial estimates placed it between 6 and 19 meters. It is a relatively small object, comparable to the size of a bus or a small house. Its absolute magnitude (H) is 27.6.

Did it pose any danger to Earth?

No danger. The asteroid passed about 59,000 km from Earth — about 0.17 times the Earth-Moon distance — which represents about 15 times Earth's radius. Even if it had been on a collision trajectory, it would have disintegrated in the atmosphere due to its small size. NASA even tweeted: "It wouldn't make it through our atmosphere intact even if it dared to try."

How do astronomers track this type of object?

Astronomers use a network of optical telescopes and radars, such as the Catalina Sky Survey or the ATLAS system. The method consists of taking a series of images (four images spaced 10 to 12 minutes apart), then using specialized software to detect objects that move from one image to the next. The data is centralized by the Minor Planet Center (MPC) at the Smithsonian Astrophysical Observatory, then analyzed by centers such as CNEOS at NASA to calculate trajectories and assess risks.

What made the discovery of 2012 BX34 particularly unusual?

The discovery was unusual: after its initial detection on January 25, no one was able to find it the next day. Astronomer Rik Hill eventually discovered a "new" object nearby, which Alex Gibbs identified as being the same asteroid, whose brightness and apparent motion had increased considerably due to its growing proximity to Earth. Astronomers then realized it was going to pass exceptionally close to our planet.

What exact distance did 2012 BX34 pass at?

According to NASA data, the minimum distance was 36,750 miles (59,044 km) from Earth's surface. The asteroid reached an apparent magnitude of about 13.9 at its closest approach, a brightness comparable to that of Pluto. Its angular velocity in the sky was then about 729 degrees per day.