Astronomers have identified 2021 PH27, an asteroid just one kilometer wide that orbits the Sun faster than any known counterpart. Discovered from Chile about ten days ago, it sets a new record for orbital speed.
Dubbed 2021 PH27, this asteroid completes an orbit around the Sun every 113 Earth days—the shortest period of any known asteroid in the Solar System. Among all objects like asteroids, comets, planets, and moons, only Mercury surpasses it with 88 days. Its highly elliptical path brings it within 20 million kilometers of the Sun's surface, heating the asteroid to around 500°C—hot enough to melt lead.
First detected on August 13 using the 570-megapixel Dark Energy Camera (DECam) at Chile's Cerro Tololo Inter-American Observatory, its orbit was confirmed through follow-up observations from DECam, Las Campanas Observatory in Chile, and facilities in South Africa.
This proximity to the Sun subjects 2021 PH27 to the Solar System's strongest gravitational perturbations, causing subtle oscillations in its orbit. Studies suggest it may collide with the Sun, Mercury, or Venus in several million years.
Scott Sheppard, astronomer at the Carnegie Institution for Science and lead discoverer, estimates its diameter at about one kilometer. It likely originated in the main asteroid belt between Mars and Jupiter, nudged inward by planetary gravitational interactions.
Alternatively, its 32-degree orbital inclination hints at outer Solar System origins, possibly a extinct comet nucleus. Further observations, expected early next year when it reemerges from behind the Sun, will clarify its nature.
