The first asteroid was discovered in 1801 by Giuseppe Piazzi at Palermo Astronomical Observatory on 1 January of that year. In the following few years, a new asteroid was discovered on average once a year, until four were known.
Fast forward to April 2020 and approximately nine new Near Earth asteroids were being discovered every single night. Yet this acceleration in discovery rates was extremely slow to get going. Following the identification of the first four asteroids (Ceres, Pallas, Juno, Vesta), almost four decades passed before another asteroid was discovered, Astraea in 1845. Since then the pace of discovery has been rising at exponential rates. The 10th asteroid was discovered in 1849, and the 100th in 1868. Ten thousand were known by 1989, 100,000 by 2005 and this year astronomers found their one millionth asteroid.
Asteroid 1998 O2
This huge leap in discoveries has been brought about by the dedicated use of telescopes, software and robotic technologies for the task, which began in the 1990s. But is it fast enough?
In December 2014, simultaneous press conferences in London and San Francisco announced the launch of Asteroid Day by reading out the 100x asteroid declaration. That document called attention to the fact that detection rates for near Earth asteroids needed to be increased by a factor of 100 times (100x) to more completely reveal the population of near Earth objects, and understand how many of them could one day pose a threat to Earth.
Orbital Diagram of Asteroid 2019 AQ3 Credit: NASA/JPL-Caltech
The good news is that the rate of discovery shows no sign of dropping and remains the best way to understand the Near Earth Object (NEO) population. As new facilities come on line, especially the extraordinary survey telescope housed at the Vera C. Rubin Observatory in Chile, the discovery rate will accelerate even further. With these new discoveries, the challenge will be tracking them all afterwards so that their orbits can be calculated.
The more we learn about the NEO population, the chances are that we will discover more asteroids making close passes to Earth. This highlights that even stronger cooperation will be needed between scientists and science communicators to ensure that the public remains properly informed.