Has Earth gained a second moon? Only temporarily.

From Sept. 29 through Nov. 25 this year, Earth’s gravity pulls a house-sized asteroid into a loop around Earth — a second moon!

Asteroid 2024 PT5 — its official name — actually orbits the sun once a year, but this autumn, its path passes close enough to Earth to fall into a lazy loop around us. It’s not the first time Earth has captured an asteroid. Object 2022 NX 1 was pulled into an Earth orbit for a short visit in 2022, and 2024 PT5 will orbit us next in January, and once again in 2055.

PT5 was first sighted 353,000 miles away in August by the Asteroid Terrestrial-Impact Last Alert System (ATLAS) sky survey. The all-sky viewing system was developed by the University of Hawaii and is funded by NASA. ATLAS uses telescopes in Hawaii, Chile, and South Africa to scan the entire sky several times every night, looking for moving objects.

PT5’s orbital pass will only bring it to within a million miles of Earth, so there’s no danger of impact. At just 30 feet in diameter, the space rock is so small and dim, it might be seen only with a very large telescope.

By comparison, the solar system’s largest asteroid, Vesta, is almost 330 miles in diameter, approximately the distance from Philadelphia to Pittsburgh.

Asteroids are small, rocky bodies left over from the formation of our solar system 4.6 billion years ago. Most asteroids orbit the sun in the asteroid belt, located between the orbits of Mars and Jupiter.

PT5 belongs to the Arjuna class of asteroids that orbit the sun at nearly the same distance as Earth. The similarity of orbits allows Arjuna asteroids to fall into Earth-circling orbits occasionally. Some Arjunas may orbit Earth for a few days to a few months, while others stay a year or more.

To be captured by Earth’s gravity, the passing asteroid has to be less than three million miles away and traveling less than 2,200 miles an hour. Once they complete their Earth loops, they fall back into a solar orbit. Using ATLAS and other sky surveys, NASA carefully searches for and tracks thousands of asteroids to figure out which ones should be classified as “near-Earth objects,” including possible Earth impactors. So far, NASA sees no impending doomsday impactors for at least 100 years.

Earth’s gravity will grab PT5 on Sunday. This “second moon” will curve around Earth for 53 days, eventually slipping far enough from us by Nov. 24 to resume its original solar orbit.

Located in the north polar constellation Draco this month, PT5 passes through Ursa Minor, home of the Little Dipper, during the first two weeks of November.

Sound exciting? Here’s the problem: 2024 PT5 is tiny and dim. No, I mean like really dim. Like “I don’t see anything!” dim. Even in a large telescope.

The excitement you may hear is just social media mania.

Astronomers are not particularly excited about PT5 because it’s not on a collision course with Earth, and there are dozens of asteroids zipping past Earth every month. You’ll find plenty of YouTube videos about PT5, but not many serious talks (if any), and there won’t be public star parties to view it, either.

The giant orange star of Orion, Betelgeuse, possibly going supernova this month? Yes, exciting! But not a tiny passing asteroid.

So, what should we be excited to see this fall? Saturn through a telescope! It’s bright, colorful, easy to see, and has those marvelous rings. In the coming weeks, astronomy clubs across the Delaware Valley will feature Saturn as the showpiece of the night sky at their monthly star parties. It’s well worth an evening of your time.

The next step for parents with kids interested in astronomy is to take them to see planetarium shows and astronomy exhibits, then take them to astro club star parties to see these amazing objects through well-run telescopes. Do not buy them telescopes. It’s the fastest way to kill interest in kids ‘cause they can’t make it work like they see on TikTok.

Derrick Pitts is the chief astronomer of the Franklin Institute. He also serves as president of the board of directors for the Astronomical Society of the Pacific, one of the nation’s most prestigious astronomy education organizations. His motto is “Eat, breathe, do science. Sleep later.”