Meteorite Rain

20 May 2017

At ... an interesting read at this link (also sent in by Jovan). Extraterrestrial material is constantly raining down on the Earth - most of it microscopic in size (at a rate of 100 tons a day). Most of it burns up in the atmosphere but some of it reaches the surface. Scientists have found some of the samples of this originate from a single event that has been raining down on us for 466 million years. They arrived at this number in a quite simple fashion when they decided to look at what was raining down on Earth during the Ordovician period (from a site near St Petersburg). Some 600 pounds of Ordovician rock was dissolved in acid and sieved - looking for tiny grains from meteorites. It seems the Ordovician was associated with a major bombardment event - and some of it is still raining down on today. Hence, the dust and debris is out there in space and Earth interacts it during its orbit around the Sun. However, it is not the most prominent meteorite debris hitting the Earth as the remains of H and L type chondrites (source unmentioned) are much more common.

At ... (also sent in by Jovan) discusses sending a spacecraft beyond the solar system. The target preferred is Proxima b, an exoplanet.