Exploring Earth's Unusual Dance with Quasi-Moons and the Fascinating World of Asteroids

Do you know that these days our planet has not one but several moons? Well, kind of. Astronomers have recently discovered another "moon" orbiting Earth, but it's not what you might be imagining. It's actually an asteroid trailing along beside our planet in a complex semi-orbit. This asteroid was named 2023 FW-13, and instead of simply orbiting our planet like the Moon does, it orbits the Sun. However, its orbit is so unusual that it causes the asteroid to circle Earth, too, keeping it in roughly the same area as our planet, even though it doesn't orbit it directly.

You've probably already realized that 2023 FW-13 isn't the kind of moon where we could send a mission. It's way smaller and farther away than our natural satellite. The newly found space object is a mere 50 feet across and is floating 9 million miles away, and that's when it's the closest to Earth. This distance is around 35 times as great as that between our planet and the Moon. On the other hand, cosmically speaking, it's just next door.

For the first time, the quasi-moon was spotted by astronomers at the Pan-STARRS Observatory on Haleakalā in Hawaii in March 2023. Now, a quasi-moon is a space object that shares a similar orbital path with a planet, even though it doesn't orbit this planet directly, and it has a steady relative position to this planet. True moons always keep a relatively consistent distance from their parent planet, but quasi-moons have more complex paths. That's because of the combined gravitational influences of the Sun and the planet itself. Quasi-moons usually have horseshoe or tadpole-like orbits.

To put it simply, you can see them travel ahead or behind a planet when it orbits the Sun. Such an orbit is truly unusual and occurs because the gravitational pull between the Sun, the planet, and the quasi-moon results in a complex dynamic, leading to a delicate balance in the trajectory of the quasi-moon. When a quasi-moon moves ahead of a planet, it tends to slow down with time and eventually falls behind due to the gravitational influence of the planet. Similarly, when a quasi-moon falls behind at first, it later starts speeding up and begins to move ahead of the planet. This is what creates that horseshoe shape. If you look at this dance from a fixed point in space, at the same time, the orbit will look like a tadpole from the perspective of the planet.

Scientists love quasi-moons because they present great research possibilities. Their interesting orbits make them perfect for studying gravitational influences and the intricacies of space mechanics. Plus, they're usually close to their apparent planet, which can also offer insights into the formation and evolution of planetary systems. And who knows, maybe at one point in the future, they'll help us with space exploration missions. Quasi-moons could give us important information about different celestial bodies and help with the exploration of the solar system.

But let's get back to our tiny moon. While it's still being studied, current data suggests that 2023 FW-13 entered its current orbit at least 2,100 years ago. According to simulations based on preliminary orbital calculations, the quasi-moon will accompany Earth for another 1,700 years or so. The good news is that the asteroid won't end up on a collision course with Earth despite traveling relatively close to our planet.

A few years ago, another asteroid was pulled into Earth's orbit and started to travel along with our planet. No larger than an average car, it was still a big deal. Out of more than one million asteroids astronomers know about, it was only the second one to orbit our planet, called 2020 CD3. It became our temporary mini-moon. It wasn't going to stay with Earth for long, though. The asteroid is following a random orbit and is slowly drifting away. 2020 CD3 will make another close pass to Earth in March 2044, though it will most likely not be caught by Earth again because of the greater approach distance.

Temporarily captured objects such as this one are rare. They need to have a specific direction and speed to be captured by Earth's gravitational pull; otherwise, they either crash into the planet or fly in another direction. In 2016, astronomers discovered another space rock and called it "Kamo'oalewa." There was one absolutely amazing thing about this space traveler: astronomers suspect that this celestial body could have formed after splitting off the Moon during an ancient collision with an asteroid. Yes, it means it might be a piece of our Moon.

When specialists examined the space body and analyzed its composition, the results didn't match any of the more than 2,000 near-Earth asteroids studied before. Kamo'oalewa was too tiny and too far away for regular telescopes to study it. That's why the researchers had to find a more powerful telescope to learn more about this unusual find. After using the Large Binocular Telescope, one of the largest optical telescopes in America, and the infrared Lowell Discovery Telescope, the scientists finally figured out what the asteroid was made of, and what they had discovered surprised them. The asteroid had light spectra similar to those of the samples of lunar material delivered to Earth by the 1960s and 1970s Apollo missions. Astronomers admit that there might be other asteroids with the same spectra, but so far, they haven't found anything like that.

Kamo'oalewa is another quasi-satellite of our planet. Its orbit is a bit tilted and slightly elongated, so the rock keeps leaping ahead and then falling behind Earth. In other words, it performs constant loops around us. At its closest, the 130-foot-wide asteroid gets to a distance of around 40 times that of the Moon. According to the result of orbital analysis, the rock has been following Earth for at least 100 years.

We've found more than 480 lunar meteorites on our planet. It may mean that pieces of our natural satellite travel through space pretty regularly, and Kamo'oalewa might as well just be the first discovered large rock split off from the Moon as a result of an ancient collision.

Now, we've already talked about quasi-moons; let's find out more about asteroids. These space bodies are often called minor planets or planetoids. They're usually rocky leftovers from the early formation of our solar system, which occurred around 4.6 billion years ago. They are mainly found in the asteroid belt between the orbits of Mars and Jupiter. Asteroids can be very different in size, from tiny dust particles and modestly sized boulders to huge bodies reaching 600 miles across. Asteroids often have irregular shapes, especially smaller ones. At the same time, large space bodies can have a more spherical shape, unlike planets. Asteroids don't consist of layers; they're made of different kinds of metals and rocks and have no atmosphere.

Funnily enough, some asteroids have moons of their own, and there are even asteroid binaries where two asteroids of similar size orbit each other. The asteroid belt located between the orbits of Mars and Jupiter has the largest number of asteroids in our solar system. There are millions of space rocks there of various shapes and sizes. But despite such a huge number of asteroids,