, provisional designation , is a sub-kilometer

asteroid An asteroid is a minor planet of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic or icy bodies with no atmosphere. ...

, classified as

near-Earth object A near-Earth object (NEO) is any small Solar System body whose orbit brings it into proximity with Earth. By convention, a Solar System body is a NEO if its closest approach to the Sun (Apsis, perihelion) is less than 1.3 astronomical unit ...

and potentially hazardous asteroid of the

Apollo group Apollo Education Group, Inc. is an American corporation based in the South Phoenix area of Phoenix, Arizona, with an additional corporate office in Chicago, Illinois. The company owns and operates several higher-learning institutions, includin ...

. It has a diameter of about . It was removed from the

Sentry Risk Table Sentry is a highly automated impact prediction system operated by the JPL Center for NEO Studies (CNEOS) since 2002. It continually monitors the most up-to-date asteroid catalog for possibilities of future impact with Earth over the next 100+ y ...

on 21 December 2012 and as such it now has a rating of 0 on the Torino Scale. It was recovered in December 2022 extending the observation arc from 4.8 years to 14 years. As of 2023, the distance between the orbits of Earth and is

Description

was discovered on 8 January 2011 by the

Mount Lemmon Survey Mount Lemmon Survey (MLS) is a part of the Catalina Sky Survey with observatory code G96. MLS uses a cassegrain reflector telescope (with 10560x10560-pixel camera at the f/1.6 prime focus, for a five square degree field of view) operated by ...

at an

apparent magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's ...

of 19.6 using a

reflecting telescope A reflecting telescope (also called a reflector) is a telescope that uses a single or a combination of curved mirrors that reflect light and form an image. The reflecting telescope was invented in the 17th century by Isaac Newton as an alternati ...

Pan-STARRS The Panoramic Survey Telescope and Rapid Response System (Pan-STARRS1; obs. code: F51 and Pan-STARRS2 obs. code: F52) located at Haleakala Observatory, Hawaii, US, consists of astronomical cameras, telescopes and a computing facility that is ...

precovery In astronomy, precovery (short for pre-discovery recovery) is the process of finding the image of an object in images or photographic plates predating its discovery, typically for the purpose of calculating a more accurate orbit. This happens mos ...

images from 8 November 2010 extended the observation arc to 317 days. Observations by the Gemini telescope at Mauna Kea recovered the asteroid on October 20, 21 and 27, 2012, and extended the observation arc to 719 days. The October 2012 observations reduced the orbit uncertainties by more than a factor of 60, meaning that the Earth's position in February 2040 no longer falls within the range of possible future paths for the asteroid. On 4 February 2040 the asteroid will pass no closer than (~2.8 LD) from Earth. Until 21 December 2012 it was listed on the

with a rating on the Torino Scale of Level 1. A Torino rating of 1 is a routine discovery in which a pass near the Earth is predicted that poses no unusual level of danger. It is estimated that an impact would produce the equivalent of 100

megatons TNT equivalent is a convention for expressing energy, typically used to describe the energy released in an explosion. The is a unit of energy defined by that convention to be , which is the approximate energy released in the detonation of a ...

of TNT, roughly twice that of the most powerful nuclear weapon ever detonated (

Tsar Bomba The Tsar Bomba () ( code name: ''Ivan'' or ''Vanya''), also known by the alphanumerical designation "AN602", was a thermonuclear aerial bomb, and the most powerful nuclear weapon ever created and tested. Overall, the Soviet physicist Andrei ...

). This is powerful enough to damage a region at least a hundred miles wide.

Older risks

Virtual clones of the asteroid that fit the mid-2012 uncertainty region in the known trajectory showed four potential impacts between 2040 and 2047. It had a 1 in 500 chance of impacting the Earth on 5 February 2040. In September 2013, there was an opportunity to make additional observations of when it came within of Earth. The 2013 observations allowed a further refinement to the known trajectory. The asteroid will also pass from the Earth on 3 February 2023. The 2023 gravitational keyhole was 227 miles (365 kilometers) wide. With a Palermo Technical Scale of -1.00, the odds of impact by were about 10 times less than the background hazard level of Earth impacts which is defined as the average risk posed by objects of the same size or larger over the years until the date of the potential impact.

References

External links

UH Observations Result in "All Clear" for Potential Asteroid Impact
(Institute for Astronomy at the University of Hawaii December 21, 2012)

(

Phil Plait Philip Cary Plait (born September 30, 1964), also known as The Bad Astronomer, is an American astronomer, skeptic, and popular science blogger. Plait has worked as part of the Hubble Space Telescope team, images and spectra of astronomical objec ...

Dec. 22, 2012)
Table of next close approaches
(Sormano Astronomical Observatory)

(Sormano Astronomical Observatory) * * * {{DEFAULTSORT:2011 AG5 367789 367789 367789 367789 20110108 20230203 20110108