In this video you will learn about the Trojan asteroids of the Earth. To date, only two such asteroids are known: 2010 TK7 and 2020 XL5. Both belong to the Lagrange point L4 of the Earth–Sun system. At the beginning of the last century, Trojan asteroids were discovered near Jupiter, and now more than 15 thousand of them are known. Relatively recently, similar objects have been found near Mars, Neptune and other planets.
The first Trojan asteroid of the Earth was discovered only in 2010, its designation is 2010 TK7. Its orbit is moderately elongated and inclined to the Earth’s orbit plane by almost 21 degrees. It was possible to detect this dim object with a diameter of only about 380 meters using the WISE space telescope. In 2020 the Earth’s second Trojan asteroid, 2020 XL5, was discovered. Its orbit is more elongated than that of the first one, but it is inclined by 14 degrees to the ecliptic plane. The second asteroid is larger than the first, measuring about 1200 meters. But it turned out to be even more difficult to detect it due to its greater distance from the Earth.
2010 TK7 and 2020 XL5 make a complete revolution around the Sun in almost the same time as the Earth, that is, in one year. Both asteroids are constantly in the vicinity of our planet’s orbit. The Earth moves after these asteroids, and the average distance to them practically does not change. Since the rotation of asteroids 2010 TK7 and 2020 XL5 around the Sun is synchronized with the rotation of the Earth, a year later they find themselves at the same point in the sky as the year before. For this reason, their trajectories relative to the Earth are almost closed.
Both trajectories resemble a deformed bicycle wheel, only the trajectory of the 2020 XL5 has large dimensions. Other asteroids that are in 1:1 orbital resonance with the Earth, such as Cruithne, have a similar trajectory relative to our planet. However, Cruithne is not a Trojan asteroid of the Earth, it can be considered a quasi-satellite of our planet. An object is considered a Trojan asteroid of the Earth if it is located in the vicinity of one of the Lagrange points of the Earth–Sun system: L4 or L5.
The L4 Lagrange point moves along the Earth’s orbit 60 degrees ahead of our planet, and the L5 point moves 60 degrees behind it. The peculiarity of the Lagrange point is that a third body with a low mass can be relatively stable in it. When it is said that an asteroid is located at a Lagrange point, it does not mean that it is fixed at that point. This means that the celestial body oscillates relative to this point. The trajectories of asteroids 2010 TK7 and 2020 XL5 relative to the L4 point of the Earth–Sun system are also practically closed.
There are probably other asteroids in the vicinity of the Earth’s Lagrange points that have not yet been detected. The problem is that the points L4 and L5 are at the same distance from the Earth as the Sun: it is about 150 million km. From this distance small asteroids with a size of up to one kilometer are very difficult to detect. In addition, the angle between the Sun and any of these points is 60 degrees. It is difficult to observe this area of space from the Earth’s surface, as it appears low above the horizon after dark. Earth’s Trojan asteroids have not yet been detected at point L5, but there is a large accumulation of cosmic dust in it. The Lagrange points of the Earth–Sun system are actively used by spacecraft due to their features. Therefore, further searches for Trojan asteroids of the Earth are of interest to science.
In this video, you can observe a simulated asteroid belt. If the previous video showed only 83 thousand of the largest asteroids, then this one managed to depict all known asteroids. Thus, each moving dot on the screen is one of almost one and a half million asteroids. And each of these points moves along a calculated trajectory corresponding to the actual orbit of the asteroid.
The modeling and rendering were performed by the author of this publication using own software. The calculations took into account the mutual influence of the Sun, all the planets of the Solar system, the Moon and two asteroids on each other. Relativistic effects were also taken into account in the calculation. Throughout the video, the sizes of celestial bodies are shown to be greatly exaggerated compared to the distances between them.
The track Gabriel by Brylie Christopher Oxley sounds in this video. This track was not changed. Attribution 4.0 International license.
