Yesterday’s chondrule session has seen some heated discussions about the formation of chondrules. There seem to be two opposing sides which don’t agree with each other at all and a lot of neutral people are thinking that a mixture of both ideas is probably right.
Chondrules are small spherical objects found in chondritic meteorites which show signs of flash-heating and rapid cooling. The old idea is that these chondrules have been little “dust balls” which somehow have been melted (and there are lots of different ideas for this but none very convincing) and cooled quickly to form the chondrules before being integrated into larger objects. A different approach is the idea that the chondrules are from glancing impacts of planetesimals (very good explanation for the heating, problems explaining some chondrule features though) which are still molten and produce lots of liquid droplets which then rapidly cool.
There is also evidence that chondrules picked up presolar grains, which are found in the chondrule rims, before incorporation into meteorites. This is in contrast to older theories that chondrule rims are from alteration in their parent body. Again, both theories explain subsets of the experimental data and different chondrule types.
What it boils down to is that the history of chondrules is more complex and diverse than most people want to admit leading to “entertaining” discussions. Lots of work still has to be done and many conferences will follow before this question will be answered which probably will make for quite some “entertainment” in the future. 😉