is a

near-Earth asteroid 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). ...

of the Atira group. It was discovered by Scott Sheppard using the

Dark Energy Survey The Dark Energy Survey (DES) is an astronomical survey designed to constrain the properties of dark energy. It uses images taken in the near-ultraviolet, Visible spectrum, visible, and near-infrared to measure the expansion of the universe using ...

DECam The Dark Energy Survey (DES) is an astronomical survey designed to constrain the properties of dark energy. It uses images taken in the near-ultraviolet, visible, and near-infrared to measure the expansion of the universe using Type Ia supernov ...

imager at

NOIRLab NSF’s NOIRLab (National Optical-Infrared Astronomy Research Laboratory) is a United States federally funded research and development center for ground-based, nighttime optical and infrared astronomy. History Before the foundation of the NOIR ...

Cerro Tololo Inter-American Observatory The Cerro Tololo Inter-American Observatory (CTIO) is an astronomical observatory located on Cerro Tololo in the Coquimbo Region of northern Chile, with additional facilities located on Cerro Pachón about to the southeast. It is approximately ...

on 13 August 2021. has the smallest

semi-major axis In geometry, the major axis of an ellipse is its longest diameter: a line segment that runs through the center and both foci, with ends at the two most widely separated points of the perimeter. The semi-major axis (major semiaxis) is the long ...

and shortest

orbital period The orbital period (also revolution period) is the amount of time a given astronomical object takes to complete one orbit around another object. In astronomy, it usually applies to planets or asteroids orbiting the Sun, moons orbiting planets ...

among all known asteroids , with a

velocity Velocity is the directional speed of an object in motion as an indication of its rate of change in position as observed from a particular frame of reference and as measured by a particular standard of time (e.g. northbound). Velocity is a ...

perihelion An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any ellip ...

of . It also has the largest relativistic perihelion shift of any object orbiting the Sun, 1.6 times that of Mercury. With an

absolute magnitude Absolute magnitude () is a measure of the luminosity of a celestial object on an inverse Logarithmic scale, logarithmic Magnitude (astronomy), astronomical magnitude scale. An object's absolute magnitude is defined to be equal to the apparent mag ...

of 17.7, the asteroid is estimated to be larger than in diameter.

Discovery

was discovered by astronomer Scott Sheppard using the

's DECam imager at

Cerro Tololo Observatory The Cerro Tololo Inter-American Observatory (CTIO) is an astronomical observatory located on Cerro Tololo in the Coquimbo Region of northern Chile, with additional facilities located on Cerro Pachón about to the southeast. It is approximately ...

in Chile on 13 August 2021, two days after the asteroid had reached

aphelion An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any ellip ...

(its furthest distance from the Sun.) The observations were conducted at

twilight Twilight is light produced by sunlight scattering in the upper atmosphere, when the Sun is below the horizon, which illuminates the lower atmosphere and the Earth's surface. The word twilight can also refer to the periods of time when this il ...

to search for undiscovered

minor planet According to the International Astronomical Union (IAU), a minor planet is an astronomical object in direct orbit around the Sun that is exclusively classified as neither a planet nor a comet. Before 2006, the IAU officially used the term ''minor ...

s situated at low elongations from the Sun. The object was discovered at

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 li ...

19, with a

solar elongation In astronomy, a planet's elongation is the angular separation between the Sun and the planet, with Earth as the reference point. The greatest elongation of a given inferior planet occurs when this planet's position, in its orbital path around t ...

of 37

degree Degree may refer to: As a unit of measurement * Degree (angle), a unit of angle measurement ** Degree of geographical latitude ** Degree of geographical longitude * Degree symbol (°), a notation used in science, engineering, and mathematics ...

s when it was on the far side of the Sun at an Earth distance of . It was then reported to the

Minor Planet Center The Minor Planet Center (MPC) is the official body for observing and reporting on minor planets under the auspices of the International Astronomical Union (IAU). Founded in 1947, it operates at the Smithsonian Astrophysical Observatory. Function ...

Near-Earth Object Confirmation Page The Near-Earth Object Confirmation Page (NEOCP) is a web service listing recently-submitted observations of objects that may be near-Earth objects (NEOs). It is a service of the Minor Planet Center (MPC), which is the official international archive ...

under the temporary designation v13aug1. Over five days, follow-up observations were conducted by various observatories including

Las Campanas Las Campanas Observatory (LCO) is an astronomical observatory owned and operated by the Carnegie Institution for Science (CIS). It is in the southern Atacama Desert of Chile in the Atacama Region approximately northeast of the city of La Serena. ...

Las Cumbres Las Cumbres is a corregimiento in Panamá District, Panamá Province Panamá is a province of Panama. It is the location of the national capital Panama City, which also serves as the provincial capital. The governor of the province is Judy M ...

, , , and , SONEAR , and iTelescope . The object was then provisionally designated by the Minor Planet Center and announced on 21 August 2021. Even in April 2021, the asteroid was never more than 45 degrees from the Sun.

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 ...

observations of were found in archival Dark Energy Survey images from 16 July 2017. These observations were published by the Minor Planet Center on 10 October 2021.

Orbit and classification

orbits the Sun at a distance of 0.13–0.79 AU once every 4 months (114 days;

of 0.46 AU). Its orbit has an

eccentricity Eccentricity or eccentric may refer to: * Eccentricity (behavior), odd behavior on the part of a person, as opposed to being "normal" Mathematics, science and technology Mathematics * Off-center, in geometry * Eccentricity (graph theory) of a v ...

of 0.71 and an

inclination Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a Plane of reference, reference plane and the orbital plane or Axis of rotation, axis of direction of the orbiting object ...

of 32 degrees with respect to the

ecliptic 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 ...

. It is 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). ...

(NEO) due its

distance being less than 1.3 AU. It also falls under the NEO category of

Atira asteroid Atira asteroids or Apohele asteroids, also known as interior-Earth objects (IEOs), are asteroids whose orbits are entirely confined within Earth's orbit; that is, their orbit has an aphelion (farthest point from the Sun) smaller than Earth's peri ...

s, whose orbits are confined entirely within Earth's orbit at 1 AU from the Sun. Its orbit crosses the paths of

Mercury Mercury commonly refers to: * Mercury (planet), the nearest planet to the Sun * Mercury (element), a metallic chemical element with the symbol Hg * Mercury (mythology), a Roman god Mercury or The Mercury may also refer to: Companies * Merc ...

and

Venus Venus is the second planet from the Sun. It is sometimes called Earth's "sister" or "twin" planet as it is almost as large and has a similar composition. As an interior planet to Earth, Venus (like Mercury) appears in Earth's sky never fa ...

, with nominal

minimum orbit intersection distance Minimum orbit intersection distance (MOID) is a measure used in astronomy to assess potential close approaches and collision risks between astronomical objects. It is defined as the distance between the closest points of the osculating orbits of ...

s of 0.11 AU and 0.015 AU, respectively. , holds the record for the smallest semi-major axis (0.46 AU) and shortest

(114 days) of any known asteroid, supplanting and

594913 ꞌAylóꞌchaxnim 594913 ꞌAylóꞌchaxnim (provisional designation ) is a large near-Earth asteroid discovered by the Zwicky Transient Facility on 4 January 2020. It is the first asteroid discovered to have an orbit completely within Venus's orbit, and is thus ...

(0.56 AU, 151 days). For comparison, Mercury has a semi-major axis of 0.39 AU and an orbital period of 88 days. Being so close to the Sun, at perihelion the asteroid is moving at . The relativistic perihelion shift of this object is 1.6 times that of Mercury, which is 42.9 arcseconds per century. With an

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 ...

over 4 years, the orbit quality of is well secured, with an

uncertainty parameter The uncertainty parameter ''U'' is introduced by the Minor Planet Center (MPC) to quantify the uncertainty of a perturbed orbital solution for a minor planet. The parameter is a logarithmic scale from 0 to 9 that measures the anticipated longit ...

of 3. Nonetheless, additional observations are necessary to constrain uncertainties in its orbit by the time the asteroid approaches perihelion and enters

conjunction Conjunction may refer to: * Conjunction (grammar), a part of speech * Logical conjunction, a mathematical operator ** Conjunction introduction, a rule of inference of propositional logic * Conjunction (astronomy), in which two astronomical bodies ...

with the Sun in October 2021, during which it will become unobservable at solar elongations less than 20 degrees. It currently comes closer to Venus than to any of the other planets. Deep close encounters with Venus control its long-term orbital evolution. As with many other Atira asteroids, it is subjected to the von Zeipel-Lidov-Kozai

secular resonance A secular resonance is a type of orbital resonance between two bodies with synchronized precessional frequencies. In celestial mechanics, secular refers to the long-term motion of a system, and resonance is periods or frequencies being a simple nu ...

Physical characteristics

Temperature

At perihelion is heated up to temperatures of over 1000 K. Due to the resulting temperature differences between 's lit-up and shadowed areas,

thermal shock Thermal shock is a type of rapidly transient mechanical load. By definition, it is a mechanical load caused by a rapid change of temperature of a certain point. It can be also extended to the case of a thermal gradient, which makes different par ...

is theorized to have caused numerous surface fractures on the asteroid.

Numbering and naming

As of 2023, this

has neither been numbered nor named by the

Notes

References

External links

Record breaking Atira recently discovered
2 September 2021, NEO Coordination Centre,

European Space Agency , owners = , headquarters = Paris, Île-de-France, France , coordinates = , spaceport = Guiana Space Centre , seal = File:ESA emblem seal.png , seal_size = 130px , image = Views in the Main Control Room (1205 ...

* * {{DEFAULTSORT:2021 PH27 # Minor planet object articles (unnumbered) Discoveries by Scott S. Sheppard 20210813