Asteroids and Meteors

[void4]

Some cool stuff I came across:

There exist quite a few camera networks all around the world which capture vast areas of the night sky, like the Australian Desert Fireball Network (https://dfn.gfo.rocks/) , and the European AllSky7 network, capturing hundreds of meteors each year and other interesting phenomena. Using these videos, and other sensors like radar or infrasound, they can not only triangulate the atmospheric entry point of the meteor, but also calculate its orbit before entry and its trajectory afterward (including the "dark flight" phase) - eventually leading to an estimation of the strewn field.

People are now researching using drones and machine learning to automate the search of these often large areas.

In rare cases (only 7 so far), the impact of an asteroid can be predicted before it happens, with the first one being 2008 TC3 and the most recent one 2023 CX1:

a metre-sized asteroid that entered Earth's atmosphere on 13 February 2023 02:59 UTC and disintegrated as a meteor over the coast of Normandy, France along the English Channel

leading to many cool intentional sightings, photos and video recordings: https://karmaka.de/?p=32369

This was also one of only three of such predicted-impact asteroids of which fragments were later successfully found on the ground.

Measurements are submitted from hundreds of professional and amateur observatories around the world to the Minor Planet Center, and analyzed by many other institutions' programs, like JPL CNEOS Sentry, which has fun risk tables.

There are about 1.3 million known asteroids currently, nicely visualized here: https://eyes.nasa.gov/apps/asteroids/

One piece of magical software that can predict asteroid orbits from observations is find_orb. With 2023 CX1 it blinks menacingly :D

One rather disconcerting fact about Near Earth Asteroids (NEOs) is that "if you can see them, it's probably too late"

In this chart I plotted the apparent motion of 3 objects that impacted Earth, and it didn't surpass 1.5 arcseconds ('') per minute (the usual apparent speed for 99% of all known asteroids, the vast majority of them main belters) until just a few days before they hit.

Their motion is hard to distinguish and predict in time unless their unusual orbit is recognized, and the initial observations are followed up with more immediately.

The Minor Planet Center has a page where potential NEOs are listed: https://www.minorplanetcenter.net/iau/NEO_dev/toconfirm_tabular.html