The reason it took
so long to understand what the emission
lines were telling us about the corona
was that until then no one had even considered
the possibility that the Sun's atmosphere
could be so hot, a lot hotter than its surface.
Some lateral thinking was required!
I have to be very
careful when investigating the Sun's spectrum.
I need to know how hot that part of the Sun
I'm studying is before I can identify the
lines for certain. Only then can I measure
the brightness of the emission lines and
work out what the Sun is made of.