Misc: at what angle above the horizon must the sun be to create a rainbow?

Questions

USSR calendar conversion.?

St. Valentine's Day Massacre in Chicago, 7 gangsters killed by rivals disguised as cops (The Night Chicago Died).?

Florence Henderson (in Indiana), actress (Alice in The Brady Bunch), born.?

Gregory Hines, actor, dancer, born.?

Element 103, lawrencium, first produced in Berkeley, California lab.?