Take the 2-minute tour ×  Space shuttle nozzle flame  Why is
there some space between the flame and the nozzle on the space
shuttle? (see above picture)  share|improve this question The
flame is inside the combustion chamber, up at the top of the
bell. What you see is very hot supersonic steam, which is clear.
The visible light below is, I think, the very first shock
diamond, but maybe somebody else knows for sure. –  Mike
Dunlavey Sep 15 '13 at 17:42 Isn't the nozzle just so hot, that
the blackbody radiation emitted by the hot gas molecules has
slightly peeked into the UV region (which our eyes can't see)?
–  Waffle's Crazy Peanut Sep 15 '13 at 17:51  1 Answer 1  up
vote 12 down vote accepted  According to Wikipedia,   (The
picture they provide is the same or very similar to that in the
question). So, maybe Crazy Buddy is right.  share|improve this
answer You can often see the same phenomenon close too the wick
of a candle. –  jdj081 Sep 16 '13 at 4:47  Your Answer