2003 YN 107

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2003 YN 107
Properties of the orbit ( animation )
Orbit type Aten type
Major semi-axis 0.997  AU
eccentricity 0.021
Perihelion - aphelion 0.974 AU - 1.021 AU
Inclination of the orbit plane 4.267 °
Sidereal period 1 a
Mean orbital velocity 29.78 km / s
Physical Properties
Medium diameter 10-30 m
Albedo 0.04-0.20
Absolute brightness 26.2-26.7 mag
Spectral class C to S type
Explorer LINEAR
Date of discovery December 20, 2003
Source: Unless otherwise stated, the data comes from JPL Small-Body Database Browser . The affiliation to an asteroid family is automatically determined from the AstDyS-2 database . Please also note the note on asteroid items.

2003 YN 107 is a very small near-Earth asteroid that was discovered on December 20, 2003 by the automatic sky monitoring LINEAR (Lincoln Near Earth Asteroid Research). The diameter of the asteroid is only about 10 to 30 meters. It is an earth orbit cruiser and is therefore classified as an Aten type (after the eponymous asteroid Aten ) and orbits the sun on an almost circular orbit that is very similar to the earth's orbit . Another special feature is that its mean period around the sun corresponds approximately to a sidereal year . Its most notable peculiarity, however, is that from 1996 to 2006 it never moved further than 0.1 AU (approx. 15 million km) from the earth and that it slowly orbited the earth once within a year. 2003 YN 107 was not a second moon on earth because it was not firmly bound to it. He is the first known representative of a group of co-ordinate objects , the quasi-satellites , which have been postulated for a long time and have these orbital properties. Before 1996, 2003 YN 107 was in a so-called horseshoe orbit along the Earth's orbit around the Sun, which was very similar to that of the asteroid 2002 AA 29 . Since 2006 he has been in such an orbit again for some time. Such an orbit change seems to be relatively frequent with these co-ordinate companions, since 2002 AA 29 will also be a quasi-satellite of the earth for some time in about 600 years.


Orbit data

The orbit of 2003 YN 107 is located with a solar distance of between 0.974 AU for the perihelion , the point closest to the Sun, and 1.021 AU for the aphelion , the point furthest from the Sun , for the most part within Earth orbit. The orbits of most asteroids, however, are in the asteroid belt between Mars and Jupiter and outside the orbit of Neptune in the Kuiper belt . Due to orbital disturbances of the large gas planets , mainly due to Jupiter, and the Jarkowski effect , i.e. the change in orbit due to asymmetrical irradiation and radiation of infrared radiation , asteroids are deflected into the inner solar system , where their orbits are then further influenced by further close flights to the inner planets become. When asteroids are deflected into the inner solar system by Jupiter and the other planets, however, orbits with high eccentricity are usually created . 2003 YN 107 with an eccentricity of 0.021 has a similarly low value as the earth with 0.0167 and thus has an almost circular orbit. So it is less likely that it was hurled from orbit in the outer solar system into the inner solar system by Jupiter or another planet. Due to its low eccentricity, it is speculated that it has always been on a near-earth orbit and that it or a precursor body thus arose near the earth's orbit. One possibility in this case would be that it could be a detached fragment from the collision of a medium-sized asteroid with the earth or the moon .

The mean period of orbit of 2003 YN 107 is a sidereal year . After it was deflected into the inner solar system or formed on an orbit near the earth's orbit, the asteroid must have got onto an orbit corresponding to the earth. On this orbit it was repeatedly distracted from the earth in such a way that its own period of rotation was the same as that of the earth around the sun. In its current orbit, the earth will always keep it synchronized with its own orbit.

Due to its slight orbit inclination of 4.3 ° against the ecliptic ( orbit plane of the earth), its orbit is not congruent with that of the earth, but slightly inclined towards that of the earth.

Track shape

Quasi-satellite orbit of the asteroid 2002 AA 29 around the Earth in 2589 as viewed perpendicular to the ecliptic. The left side shows the orbits of 2002 AA 29 and the earth from a reference system in which the sun rests. The right-hand side shows an enlarged section of the same orbit from 2002 AA 29 , viewed from the reference system that moves with the movement of the earth; Image: JPL

If one looks at the orbit of 2003 YN 107, which is almost congruent with the earth's orbit, from the reference system that moves with the earth's movement around the sun , one notices that it slowly circles the earth - almost like a second moon; however, it takes a year to complete one cycle. Its slow orbit around the earth within a year is caused by its slightly different eccentricity. The radial movement component is caused directly by the difference in the eccentricities between the earth and 2003 YN 107 , while the movement component along the earth's orbit is caused by the slightly different speed in the perihelion and aphelion. In perihelion it overtakes the earth from within, while in aphelion it falls further outside in relation to the earth. In the course of a year, it becomes a complete orbit around the earth. Since it is not firmly bound to the earth like the moon, but is mainly under the influence of gravity from the sun, these bodies are called quasi-satellites . This is roughly analogous to two cars that drive next to each other at the same speed and overtake each other, but are not firmly bound to each other. See also the adjacent graphic of the future orbit of the asteroid 2002 AA 29 , which will be similar to that of 2003 YN 107 . 2003 YN 107 has been a quasi-satellite of the earth since 1996 and remained so until 2006. Due to the gravitation of the earth, however, after one orbit around the earth it does not come back exactly at the starting point, but rather describes open loops around the earth. On December 21, 2003, it came very close to earth with 0.0149 AU (2.23 million km), which is less than 6 times the distance between earth and moon.

After 2006, he left the vicinity of the earth and orbited the sun in a horseshoe orbit along the earth's orbit, hurrying ahead of the earth along its orbit. The name horseshoe orbit becomes clear if one only looks at the relative movement of 2003 YN 107 from the reference system that moves with the earth . He describes a large arc of 360 ° along the orbit of the earth, the shape of which is reminiscent of a horseshoe . When moving along the earth's orbit, it winds itself around it in a spiral, whereby it takes a year for a spiral turn. This spiral movement in the reference system that moves with the earth is due to its eccentricity and orbital inclination, which deviates slightly from the earth's orbit, whereby the difference in the orbital inclination is responsible for the vertical and that of the eccentricity for the horizontal part of the projected spiral movement.

Horseshoe orbit of the asteroid 2002 AA 29 along the earth's orbit over the course of 95 years, viewed from the reference system moving with the earth's orbital motion. However, the orbit loops of 2003 YN 107 are further apart and flatter, as it only takes 66.5 years to move along the earth's orbit and has a low orbit inclination; Image: JPL

In the year 2066, in 2003 YN 107 will again reach the earth on the other side from behind and come close to it to within about 0.026 AU (3.9 million km). It comes under the influence of gravity again and is thus lifted into a slower orbit a little further away from the sun. As a result, he can no longer keep up with the speed of the earth until it reaches him again in the year 2120. At this renewed encounter with the earth, however, YN 107 will come very close to it in 2003 and will be very strongly distracted by it. Very likely in 2003 YN 107 will then be captured by the earth and become a real second moon on earth . However, the calculations become chaotic , so that no specific information can be given about the time after 2120.

If one calculates the orbit of 2003 YN 107 backwards in time, one finds that he was also in a horseshoe orbit before 1996, whereby the period for a full swing back and forth was 133 years. This horseshoe orbit can be calculated back to the year 1750. In 1750 there was a chaotic transition between quasi-satellite orbit and horseshoe orbit, so that nothing can be said about the time before 1750.

Physical Properties

Little is known about 2003 YN 107 other than its orbit. From its low absolute brightness of 26.2–26.7 and a presumed albedo (reflectivity) of 0.04–0.20 one concludes, however, that it is only about 10–30 m in diameter and is therefore a very small asteroid. Only because of its very earth-like orbit one suspects that it could be a detached piece of earth or moon, which was formed in a collision with a medium-sized asteroid.


Because of its very Earth-like orbit, the asteroid is relatively easy to reach for space probes . 2003 YN 107 would be a suitable study object for a more detailed investigation of the structure and composition of asteroids and the temporal development of their orbits around the sun. Due to its small size and the therefore practically complete lack of attraction , the structure and composition of this celestial body can hardly be determined by land emissions.

Because of its proximity to the earth, the orbit of 2003 YN 107 can be tracked and measured very precisely using radar astronomy . As a result, the predicted Jarkowski effect , which leads to a slight change in orbit and was recently confirmed for the asteroid Golevka , can be determined and checked more precisely after a relatively short time of a few years.

See also


  • M. Connors, C. Veillet, R. Brasser, P. Wiegert, PW Chodas, S. Mikkola, K. Innanen: Horseshoe Asteroids and Quasi-satellites in Earth-like Orbits. in: 35th Lunar and Planetary Science Conference, 15. – 19. March 2004. Lunar and planetary science, abstracts of papers subm. to the Lunar and Planetary Science Conference. Lunar and Planetary Institute, Abstract No. 1565. Johnson Space Center, League City, Texas 2004.3. ISSN  0197-274X (English, PDF; 933 kB)
  • R. Brasser, KA Innanen, M. Connors, C. Veillet, P. Wiegert, Seppo Mikkola, PW Chodas: Transient co-orbital asteroids . in: Icarus . Elsevier, San Diego Ca 171.2004,1 (Sept), pp. 102-109. ISSN  0019-1035 (article online on the Icarus server, English: doi : 10.1016 / j.icarus.2004.04.019 )
  • D. Vokrouhlický, D. Čapek, SR Chesley and SJ Ostro: Yarkovsky detection opportunities. I. Solitary asteroids. in: Icarus. Elsevier, San Diego Ca 2004. ISSN  0019-1035 (Article online on the Icarus server, English: doi : 10.1016 / j.icarus.2004.08.002 )


This article was added to the list of excellent articles on January 20, 2005 in this version .