Astronomical phenomenon in two types of gold, one captured by artist (6)
I believe the answer is:
aurora
'astronomical phenomenon' is the definition.
'aurora' can be an answer for 'phenomenon' (aurora is a kind of phenomenon). I am not sure about the 'astronomical' bit.
'two types of gold one captured by artist' is the wordplay.
'two types of' becomes 'au' (I can't justify this - if you can you should give a lot more credence to this answer).
'gold' becomes 'or' ('or' is the heraldic name for gold).
'one captured by' is an insertion indicator.
'artist' becomes 'RA' (Royal Academician, member of Royal Academy of Arts).
'or' placed into 'ra' is 'rora'.
'au'+'rora'='AURORA'
'in' is the link.
Can you help me to learn more?
(Other definitions for aurora that I've seen before include "Northern/southern lights" , "Roman goddess of the dawn" , "Roman Godess of the Dawn" , "'... borealis, the northern lights (6)'" , "Dawn goddess; polar lights" .)