Earth is set to temporarily capture a new "mini-moon," 2020 SO, from October 2020 through May 2021. While exciting, its origins spark debate among astronomers—could it be artificial space junk?
Earth's sole natural satellite is the Moon, but smaller objects occasionally get caught in our planet's gravity, becoming temporary "mini-moons" before escaping back into space. Only two have been confirmed to date: 2006 RH120 (2006-2007) and 2020 CD3 (departed April 2020).
Astronomers predict 2020 SO will join this rare club next month, lingering until May 2021 before departing.
Simulations show 2020 SO entering and exiting via Earth's Lagrange points—stable gravitational zones influenced by the Sun-Earth interaction.
Listed as an Apollo asteroid in NASA's JPL Small-Body Database (orbits crossing Earth's), 2020 SO raises doubts about its natural origins. Experts like Paul Chodas from JPL suggest it could be space debris.
Key evidence: Its orbit aligns perfectly with Earth's (no tilt), matching eccentricity, and unusually low speed for an Apollo asteroid.
Chodas points to a specific culprit: the upper stage of an Atlas-Centaur rocket launched by NASA in 1966 for the Surveyor 2 lunar probe. Tracking such debris is challenging in the unpredictable space environment, leading to many lost objects.
2020 SO's estimated size (6.4-14 meters) fits a 1960s Centaur stage, which stood just over 12 meters tall.
The debate continues. 2020 SO reaches perigee on December 1, coming within 50,000 km of Earth. Observations then may reveal its shape or light reflection properties, settling whether it's rock or relic.
