Free Astronomy Magazine May-June 2020

MAY-JUNE 2020 SMALL BODIES optical detectors separated by distances of up to 1000 km (with a surface area of just 1 cm 2 each) would be sufficient to reveal any sub-relativistic meteors produced by 1 mm diameter particles. Even the shock wave generated in the atmosphere could be recorded with the help of infra- sound microphones. A part of the structures necessary for this research already exist and it would be possible to implement their experimental design, but going beyond the theoretical phase might not be so simple. Indeed, there seem to be some critical issues in the conclusions reached by Siraj and Loeb. A first doubt concerns the ex- trapolation to macroscopic di- mensions of phenomena that we know today only take place at the microscopic level, and therefore are based on different theoretical models. In this par- ticular instance, iron-60 atoms, dust grains, and agglomerations of matter as large as a grain of sand can all be accelerated at extreme speeds by a supernova. That said, they remain very dis- tant from one another on the size scale, with differences measurable in millions of times both in mass and in volume. To suggest that a grain of sand be- haves like a grain of dust or an atom when subjected to the thrust of the explosion and radi- ball. Potentially, the human eye can observe such a rapid and bright phenomenon, but no evidence of such an event has been recorded thus far. The two researchers predict that a global network of several hundred small ultrafast A brilliant fireball pho- tographed “near” the domes of the Observatoire de Saint-Véran, in the French Alps, near the Italian border, at almost 3000 meters ele- vation. [Mikael De Ketelaere, 2019] Below, the sum of many images showing a storm of over fifty Gem- inids above the Xinglong Obser- vatory, China. [Steed Yu and NightChina.net]