, provisional designation ', is a risk–listed

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 a

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 (perihelion) is less than 1.3 astronomical units (AU). ...

and

potentially hazardous asteroid A potentially hazardous object (PHO) is a near-Earth object – either an asteroid or a comet – with an orbit that can make close approaches to the Earth and is large enough to cause significant regional damage in the event of impact. They are ...

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, including ...

, approximately in diameter. It once had the highest known

probability Probability is the branch of mathematics concerning numerical descriptions of how likely an Event (probability theory), event is to occur, or how likely it is that a proposition is true. The probability of an event is a number between 0 and ...

of impacting Earth. In 2002, it had the highest Palermo rating with a value of 0.17 for a possible collision in 2880. Since that time, the estimated risk has been updated several times. In December 2015, the odds of an Earth impact were revised to 1 in 8,300 (0.012%) with a Palermo rating of −1.42. As of 2022, It is listed on 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 ...

with the second highest cumulative Palermo rating of −2.05 (impact risk of 1-in-34,000). is not assigned a

Torino scale The Torino scale is a method for categorizing the impact hazard associated with near-Earth objects (NEOs) such as asteroids and comets. It is intended as a communication tool for astronomers and the public to assess the seriousness of collision pre ...

rating, because the 2880 date is over 100 years in the future.

Discovery and nomenclature

' was first discovered on 23 February 1950 by

Carl A. Wirtanen Carl Alvar Wirtanen (November 11, 1910 – March 7, 1990) was an American astronomer and discoverer of comets and minor planets who worked at Lick Observatory. He was of Finnish ancestry. Wirtanen was born in Kenosha, Wisconsin. After visiti ...

Lick Observatory The Lick Observatory is an astronomical observatory owned and operated by the University of California. It is on the summit of Mount Hamilton, in the Diablo Range just east of San Jose, California, United States. The observatory is managed by th ...

. It was observed for seventeen days and then

lost Lost may refer to getting lost, or to: Geography *Lost, Aberdeenshire, a hamlet in Scotland * Lake Okeechobee Scenic Trail, or LOST, a hiking and cycling trail in Florida, US History *Abbreviation of lost work, any work which is known to have bee ...

because this short observation arc resulted in large uncertainties in Wirtanen's orbital solution. On 31 December 2000, it was recovered at

Lowell Observatory Lowell Observatory is an astronomical observatory in Flagstaff, Arizona, United States. Lowell Observatory was established in 1894, placing it among the oldest observatories in the United States, and was designated a National Historic Landmark ...

and was announced as on 4 January 2001. Just two hours later it was recognized as .

Observations

On 5 March 2001, ' made a close approach to Earth at a distance of . It was studied by radar at the Goldstone and

Arecibo Arecibo (; ) is a city and municipality on the northern coast of Puerto Rico, on the shores of the Atlantic Ocean, located north of Utuado and Ciales; east of Hatillo; and west of Barceloneta and Florida. It is about west of San Juan, the ...

observatories from March 3 to 7, 2001. The studies showed that the asteroid has a mean diameter of 1.1 km, assuming that ' is a retrograde rotator. Optical

lightcurve In astronomy, a light curve is a graph of light intensity of a celestial object or region as a function of time, typically with the magnitude of light received on the y axis and with time on the x axis. The light is usually in a particular frequ ...

analysis by Lenka Sarounova and

Petr Pravec Petr Pravec (born September 17, 1967) is a Czech astronomer and a discoverer of minor planets, born in Třinec, Czech Republic. Pravec is a prolific discoverer of binary asteroids, expert in photometric observations and rotational lightcurves a ...

shows that its rotation period is hours. Due to its short rotation period and high radar

albedo Albedo (; ) is the measure of the diffuse reflection of sunlight, solar radiation out of the total solar radiation and measured on a scale from 0, corresponding to a black body that absorbs all incident radiation, to 1, corresponding to a body ...

, ' is thought to be fairly dense (more than 3.5 g/cm³, assuming that it has no internal strength) and likely composed of

nickel Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive but large pieces are slow to ...

–

iron Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in f ...

. In August 2014, scientists from the

University of Tennessee The University of Tennessee (officially The University of Tennessee, Knoxville; or UT Knoxville; UTK; or UT) is a public land-grant research university in Knoxville, Tennessee. Founded in 1794, two years before Tennessee became the 16th state, ...

determined that ' is a

rubble pile In astronomy, a rubble pile is a celestial body that is not a monolith, consisting instead of numerous pieces of rock that have coalesced under the influence of gravity. Rubble piles have low density because there are large cavities between the ...

rotating faster than the breakup limit for its density, implying the asteroid is held together by

van der Waals force In molecular physics, the van der Waals force is a distance-dependent interaction between atoms or molecules. Unlike ionic or covalent bonds, these attractions do not result from a chemical electronic bond; they are comparatively weak and th ...

s rather than gravity. ' made a distant approach to Earth on 5 February 2021. However, at that time it was half an AU away from Earth, preventing more useful

astrometrics Astrometry is a branch of astronomy that involves precise measurements of the positions and movements of stars and other Astronomical object, celestial bodies. It provides the kinematics and physical origin of the Solar System and this galaxy, th ...

and timing that occurs when an object is closer to Earth. The next close approach that presents a good opportunity to observe the asteroid will be on 2 March 2032, when it will be from Earth. The following table lists next five approaches closer than 0.10 AU. By 2136 the close approach solutions are becoming notably more divergent.

Possible Earth impact

That ' has one of the best-determined asteroid orbital solutions is due to a combination of: * an orbit moderately

inclined Incline, inclined, inclining, or inclination may refer to: *Grade (slope), the tilt, steepness, or angle from horizontal of a topographic feature (hillside, meadow, etc.) or constructed element (road, railway, field, etc.) *Slope, the tilt, steepn ...

(12 degrees) to the

ecliptic plane The ecliptic or ecliptic plane is the orbital plane of the Earth around the Sun. From the perspective of an observer on Earth, the Sun's movement around the celestial sphere over the course of a year traces out a path along the ecliptic again ...

(reducing in-plane perturbations); * high-precision radar astrometry, which provides its distance and is complementary to the measurements of angular positions; * a 68-year

observation arc In observational astronomy, the observation arc (or arc length) of a Solar System body is the time period between its earliest and latest observations, used for tracing the body's path. It is usually given in days or years. The term is mostly use ...

; * an uncertainty region controlled by

resonance Resonance describes the phenomenon of increased amplitude that occurs when the frequency of an applied periodic force (or a Fourier component of it) is equal or close to a natural frequency of the system on which it acts. When an oscillatin ...

. Main-belt asteroid

78 Diana Diana (minor planet designation: 78 Diana) is a large and dark main-belt asteroid. It was discovered by German astronomer Karl Theodor Robert Luther, Robert Luther on March 15, 1863, and named after Diana (goddess), Diana, Roman mythology, Roman ...

(~125 km in diameter) will pass about from ' on 5 August 2150. At that distance and size, Diana will perturb ' enough so that the change in trajectory is notable by 2880 (730 years later). In addition, over the intervening time, ' rotation will cause its orbit to slightly change as a result of the

Yarkovsky effect The Yarkovsky effect is a force acting on a rotating body in space caused by the anisotropic emission of thermal photons, which carry momentum. It is usually considered in relation to meteoroids or small asteroids (about 10 cm to 10 km i ...

. If ' continues on its present orbit, it may approach Earth on 16 March 2880, though the mean trajectory passes many millions of kilometres from Earth, so ' does not have a significant chance of impacting Earth. As of the 7 December 2015 solution, the probability of an impact in 2880 is 1 in 8,300 (0.012%). The energy released by a collision with an object the size of ' would cause major effects on the

climate Climate is the long-term weather pattern in an area, typically averaged over 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteorologic ...

and

biosphere The biosphere (from Greek βίος ''bíos'' "life" and σφαῖρα ''sphaira'' "sphere"), also known as the ecosphere (from Greek οἶκος ''oîkos'' "environment" and σφαῖρα), is the worldwide sum of all ecosystems. It can also be ...

, which would be devastating to

human Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, ...

civilization A civilization (or civilisation) is any complex society characterized by the development of a state, social stratification, urbanization, and symbolic systems of communication beyond natural spoken language (namely, a writing system). Ci ...

. The discovery of the potential impact heightened interest in

asteroid deflection strategies Asteroid impact avoidance comprises the methods by which near-Earth objects (NEO) on a potential collision course with Earth could be diverted away, preventing destructive impact events. An impact by a sufficiently large asteroid or other NEOs ...

Discovery and nomenclature

Observations

Possible Earth impact

See also

Notes

References

External links