Earth has officially been joined in its orbit around the Sun by a new trojan asteroid.
Named 2020 XL5, this chunk of rock is only the second object of its type ever to have been conclusively identified. Its discovery suggests that perhaps Earth trojans may be more common than we knew, and offers new insights into these mysterious rocks.
Like the first trojan, astronomers predict that 2020 XL5 will hang around for at least 4,000 years before zipping off to parts elsewhere.
“The discovery of a second Earth trojan asteroid may enhance our knowledge of the dynamics of this elusive population,” scientists write in a new paper. “By comparing the orbital nature of the two Earth trojans known so far, we can better understand the mechanisms that allow for their transient stability.”
Trojan asteroids are asteroids (also known as minor planets) that share the orbital path of larger planetary bodies in the Solar System. They can be found in two gravitationally stable regions leading and trailing the planet, known as Lagrange points.
These are pockets where the gravitational pulls of the planet and the Sun balance perfectly with the centripetal force of any small body in that region to basically hold it in place.
Each two-body system has five Lagrange points, as seen in the diagram below. There are five between Earth and the Moon; and another five between Earth and the Sun. The Lagrange points where trojans can be found are leading L4 and trailing L5 regions.