2012 HD: A Rare Asteroid Flyby
On April 29, 2023, a small asteroid named 2012 HD will make a close approach to Earth, passing within 0.85 lunar distances (about 325,000 kilometers) of our planet. This is a rare opportunity for astronomers and skywatchers to observe a near-Earth object (NEO) that is both relatively large and bright.
2012 HD was discovered on April 18, 2012 by the Catalina Sky Survey, a project that scans the sky for NEOs that could pose a threat to Earth. The asteroid is estimated to be between 20 and 50 meters in diameter, and has an orbital period of about 1.4 years. It belongs to the Apollo group of asteroids, which have orbits that cross the Earth’s orbit.
According to NASA’s Center for Near-Earth Object Studies (CNEOS), 2012 HD poses no danger of impacting Earth, either during this flyby or in the foreseeable future. However, it is classified as a potentially hazardous asteroid (PHA), because it has the potential to come closer than 0.05 astronomical units (about 7.5 million kilometers) to Earth.
The closest approach of 2012 HD will occur at 10:13 UTC on April 29, when the asteroid will be at a distance of about 0.0023 astronomical units (about 345,000 kilometers) from Earth’s center, or about 0.85 lunar distances from Earth’s surface. At that time, the asteroid will be traveling at a relative speed of about 6.7 kilometers per second.
2012 HD will be visible to amateur astronomers with small telescopes or binoculars, as it will reach a peak brightness of about magnitude 13.5 on April 29. It will be located in the constellation of Leo, near the bright star Regulus. The best time to observe it will be around midnight local time, when it will be highest in the sky.
2012 HD is one of several NEOs that will fly by Earth in April and May 2023. The most notable one is 1998 OR2, a large asteroid that will pass within 6.3 lunar distances (about 2.4 million kilometers) of Earth on April 29, just hours before 2012 HD. 1998 OR2 is estimated to be between 1.8 and 4.1 kilometers in diameter, and will be visible to the naked eye as a faint star-like object.
These flybys are a reminder of the dynamic nature of our solar system, and the importance of monitoring and studying NEOs. NASA and other space agencies are constantly tracking and cataloging these objects, as well as developing missions and technologies to deflect or destroy them if they ever pose a threat to Earth.
One of the missions that aims to test the feasibility of asteroid deflection is the Double Asteroid Redirection Test (DART), which is scheduled to launch in July 2021. DART will target a small moonlet orbiting a larger asteroid named Didymos, and attempt to change its orbit by crashing into it at high speed. The impact will be observed by a companion spacecraft called LICIACube, as well as by ground-based telescopes.
Another mission that will explore the nature and origin of NEOs is the Near-Earth Asteroid Scout (NEA Scout), which is expected to launch in November 2021. NEA Scout will use a solar sail to propel itself to a small asteroid named 1991 VG, and perform a close flyby with a camera and a spectrometer. The mission will demonstrate the potential of using low-cost CubeSats for asteroid exploration.
As 2012 HD and other NEOs fly by Earth, they offer us a chance to learn more about these fascinating and diverse objects, as well as to prepare ourselves for any future encounters that might be less benign. By observing and studying them, we can gain insight into the history and evolution of our solar system, and also protect our planet from any potential hazards.