Earth's Newest Trojan Asteroid

Earth has a new companion in its orbit around the sun. Asteroid 2020 XL5 is only the second "Earth

Trojan" identified, and it will be along for the ride for another 4000 years.

What is Trojan Asteroid?

NASA diagram of 2020 XL5 Trojan asteroids orbital path / By NASA/JPL-SSD -;orb=1;cov=0;log=0;cad=1#orb, Public Domain,
Heliocentric orbit diagram of 2020 XL5 along with the inner planets

A Trojan asteroid is one that occupies a stable Lagrangian point in a planet's orbit around the Sun. Lagrange points are gravitationally balanced regions around two massive bodies like Jupiter and the Sun. Lagrange points are identified by their location relevant to the two.

The term 'Trojan asteroid' was coined by the scientists who first identified the asteroids in the orbit of Jupiter in 1906. Ironically, they chose the name from the Trojan War, which was fought between Troy and Greece, even though Jupiter was the Roman God of war.

An Earth Trojan is an asteroid that follows the same path around the Sun as Earth does, either ahead of or behind our planet in its orbit. Asteroid 2020 XL5 is Earth's largest Trojan at one kilometer wide. It was discovered at the planet's L4 Lagrange point - the place where the gravitational forces of the Earth and the Sun balance out and act as a tether to hold the asteroid in place.

Other planets have many Trojans. Jupiter, for example, has thousands in its orbital path. Earth may have more than two Trojans of its own, but they are hard to see.

How Was 2020 XL5 found?

Because Trojans appear adjacent to the Sun, they cannot be seen during the day because of the star's intense light. Trojan searches must be conducted as close to sunrise and sunset as possible when the atmosphere is thickest and the light is diminished. The thicker atmosphere, however, also means poorer visibility. If you've watched a sunset, you'll also know that the time at which you can look at the star before it disappears below the horizon is fairly short.

In addition, most telescopes cannot aim as low as needed to maximize a Trojan's visibility and identify its precise location and form. So scientists, in this case, used the SOAR telescope, a research facility in the southern hemisphere, to track and identify XL5. The SOAR is unique as it can point down to 16 degrees above the horizon (the lowest of any telescope) and allow for longer and clearer views.

By using SOAR and archival images to track the asteroid, astronomers were able to distinguish between its status as a Trojan and not simply an asteroid passing through our orbit.

What is Appealing about Trojan Asteroids?

Scientists are excited to find Trojan asteroids as they may offer opportunities for exploration. If a Trojan has a lower orbital inclination (the tilt of an object's orbit which could bring the object closer to earth at certain times), it could be less costly to reach than the moon and act as a "base" for further exploration of the solar system or a source for minerals.

Other points of interest

  • NASA has launched a spacecraft called Lucy to explore the Trojans of Jupiter.

  • Identifying and tracking Trojans is made more difficult by the number of satellite constellations now orbiting Earth. Satellite constellations are groups of satellites placed in complementary orbital planes that can appear as solid objects on certain telescopes.

What Does This All Have To Do With Mutual Assurance?

Let's say the 2020 XL5 breaks free from its orbit and comes hurtling towards Earth. It breaks into thousands of pieces (we don't want a disaster movie scenario) and one of those hits your home. Are you covered?

Most likely, yes, but every policy has unique provisions, so you need to check yours to make sure!

With Mutual Assurance, there are no exclusions for falling objects for your dwelling. In your personal property list, “falling objects” is a listed peril for which you are covered. There are also no exclusions for an asteroid strike that isn’t a direct hit on your home but still causes damage. What does your own policy say?

Given all of that, the likelihood of an asteroid strike in your lifetime is, well, not a likelihood at all. So you can sleep well at night.


Sources: Wikipedia, SciTechDaily, Cosmos Center for Astrophysics and Supercomputing, Britannica