The Mesoarchean atmosphere contained high levels of atmospheric methane and carbon dioxide, which could be an explanation for the high temperatures during this era.
In spiral galaxies, open clusters are largely found in the spiral arms where gas densities are highest and so most star formation occurs, and clusters usually disperse before they have had time to travel beyond their spiral arm.
Earth in the early Hadean had a very thick carbon dioxide- and methane-rich prebiotic atmosphere, but eventually oceans made of liquid water were formed.
