Hi Chris

usually names kind of 'emerge' by concensus in solar physics. The first person to observe a phenomenon might dream up a name, and if the name fits then other people use it and it sticks. If it is not a good description then it disappears and is replaced by something else. To my knowledge there is no organisation that decides what name something has, unlike for new asteroids, for example. Sometimes words become over-used, such as the word 'filament', which has at least three, and possibly four, different meanings in solar physics.

The name 'umbra' means 'shadow', from Latin as you maybe know. 'Penumbra' means 'almost the umbra'. My Oxford English Dictionary tells me that 'umbra' was in use for sunspots since at least 1788, and in 1860 and 1868 was used by the astronomers Olmsted and Lockyer respectively.

However, since Latin was the language of science for hundreds of years, anyone from Galileo onwards could have been the first to use the name! Or maybe even before, but as Galileo had made telescope observations of the sun in 1611, he would have been able to see the umbra and penumbra clearly.