Article on how the picture was made: https://petapixel.com/2020/04/28/this-once-in-a-lifetime-meteor-photo-was-captured-by-accident/
Link to the photograph website: https://www.prasenjeetyadav.com/#explore
Article on how the picture was made: https://petapixel.com/2020/04/28/this-once-in-a-lifetime-meteor-photo-was-captured-by-accident/
Link to the photograph website: https://www.prasenjeetyadav.com/#explore
Probably nickel and/or salts of barium. Copper burns blue as a pyrotechnic colorant.
Ah ok. I was going to say nickel but I did a quick search and somehow I read that it was copper.
Depending on the salt you can make both blue and green. Copper sulphate flame test is a pretty common school lab practical isn’t it?