, provisional designation , is a sub-kilometer sized asteroid and temporary

quasi-satellite A quasi-satellite is an object in a specific type of co-orbital configuration (1:1 orbital resonance) with a planet (or dwarf planet) where the object stays close to that planet over many orbital periods. A quasi-satellite's orbit around the Sun t ...

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 f ...

.Discovery of the first quasi-satellite of Venus (press announcement, Tuorla Observatory)
/ref> It was the first such object to be discovered around a major

planet A planet is a large, rounded astronomical body that is neither a star nor its remnant. The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud collapses out of a nebula to create a you ...

in the

Solar System The Solar System Capitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar ...

. In a frame of reference rotating with Venus, it appears to travel around it during one Venerean year but it actually orbits the Sun, not Venus.Asteroid 2002 VE68, a quasi-satellite of Venus
/ref>

Discovery, orbit and physical properties

It was discovered on 11 November 2002 at Lowell Observatory. As of February 2013, has been observed telescopically 457 times with a data-arc span of 2,947 days and it was the target of Doppler observations in 5 occasions; therefore, its

orbit In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as ...

is very well determined. Its semi-major axis of 0.7237 AU is very similar to that of Venus but its eccentricity is rather large (0.4104) and its orbital inclination is also significant (9.0060°). The spectrum of implies that it is an

X-type asteroid The X-group of asteroids collects together several types with similar spectra, but probably quite different compositions. Tholen classification In the Tholen classification the X-group consists of the following types: * E-type – with high al ...

and hence an

albedo Albedo (; ) is the measure of the diffuse reflection of 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 that refl ...

of about 0.25 should be assumed. The body is calculated to measure 236 meters in diameter. Its

rotational period The rotation period of a celestial object (e.g., star, gas giant, planet, moon, asteroid) may refer to its sidereal rotation period, i.e. the time that the object takes to complete a single revolution around its axis of rotation relative to the b ...

is 13.5 hours and its

light curve 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 ...

has an amplitude of 0.9 mag which hints at a very elongated body, perhaps a

contact binary In astronomy, a contact binary is a binary star system whose component stars are so close that they touch each other or have merged to share their gaseous envelopes. A binary system whose stars share an envelope may also be called an overconta ...

Quasi-satellite dynamical state and orbital evolution

The existence of retrograde satellites or quasi-satellites was first considered by J. Jackson in 1913Retrograde satellite orbits
/ref> but none was discovered until almost 100 years later. was the first quasi-satellite to be discovered, in 2002, although it was not immediately recognized as such. was identified as a quasi-satellite of Venus by

Seppo Mikkola Seppo Mikkola (born 1947) is a Finnish astronomer. He is a senior lecturer at the University of Turku and staff member at Tuorla Observatory. Mikkola is a leading expert in celestial mechanics. He has made fundamental contributions to the theory ...

, Ramon Brasser, Paul A. Wiegert and Kimmo Innanen in 2004, two years after the actual discovery of the object. From the perspective of a hypothetical observer in a frame of reference rotating with Venus, it appears to travel around the planet during one Venusian year although it does not orbit Venus but the Sun like any other asteroid. As quasi-satellite, this minor body is trapped in a 1:1 mean-motion resonance with Venus. Besides being a Venus co-orbital, this

Aten asteroid The Aten asteroids are a dynamical group of asteroids whose orbits bring them into proximity with Earth. By definition, Atens are Earth-crossing asteroids . The group is named after 2062 Aten, the first of its kind, discovered on 7 January ...

is also a

Mercury grazer A Mercury crosser is an asteroid whose orbit crosses that of Mercury. The Mercury crossers proper have aphelia outside Mercury's (0.4667 AU) and perihelia inside Mercury's (0.3075 AU), whereas those listed here as outer grazers have perihelia wit ...

and an Earth crosser. exhibits

resonant 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 oscilla ...

(or near-resonant) behavior with Mercury, Venus and

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

.On the dynamical evolution of 2002 VE68
/ref> It seems to have been co-orbital with Venus for only the last 7,000 years, and is destined to be ejected from this orbital arrangement about 500 years from now. During this time, its distance to Venus has been and will remain larger than about 0.2 AU (3·10⁷ km).

Potentially hazardous asteroid

is included in the Minor Planet Center list of Potentially Hazardous Asteroids ( PHAs) because it comes relatively frequently to within 0.05 AU of Earth. Approaches as close as 0.04 AU occur with a periodicity of 8 years due to its near 8:13 resonance with Earth. was discovered during the close approaches of 11 November 2002. During the last close encounter on 7 November 2010, approached Earth within 0.035 AU (13.6 Lunar distances), brightening below 15th magnitude. Its next fly-by with Earth happened on 4 November 2018 at . Numerical simulations indicate that an actual

collision In physics, a collision is any event in which two or more bodies exert forces on each other in a relatively short time. Although the most common use of the word ''collision'' refers to incidents in which two or more objects collide with great fo ...

with Earth during the next 10,000 years is not likely, although dangerously close approaches to about 0.002 AU are possible, a distance potentially within Earth's

Hill sphere The Hill sphere of an astronomical body is the region in which it dominates the attraction of satellites. To be retained by a planet, a moon must have an orbit that lies within the planet's Hill sphere. That moon would, in turn, have a Hill sph ...

Numbering and naming

This

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 ''mino ...

was numbered by the Minor Planet Center on 18 May 2019 (). As of 2020, it has not been named.

References

External links

Minor Planet Center

(PHAs)
Image acquired during the last 2002 VE68 close approach, 7 November 2010Martin Mobberley's Astronomical Images web site

Light curve
(Ondřejov NEO Photometric Program)

* * * {{DEFAULTSORT:524522 Aten asteroids Discoveries by LONEOS Venus co-orbital minor planets Potentially hazardous asteroids Venus-crossing asteroids Earth-crossing asteroids 20021111