I've heard it's not possible to take a picture of the northern lights with a GoPro. Is it possible to do it with a GoPro 4, since you can take pictures in the dark? I'll visit Iceland soon, so I'd like to know which camera I should buy. Since I'm not a fantastic photographer, I'd like to buy a goPro instead of a Canon.
Looking at the specifications for the Hero 4, I don't see any reason it cannot be used. They offer a night mode with time lapse functionality that allows for exposures for up to 30 seconds. The key to successful shots there will be stability of the camera, just make sure it is firmly in place and then go to work.
Rent equipment for the trip. Look at existing photos to see what stuff they used. Do they hold steady enough for time exposures? That will open your options considerably (and lower the price): instead of very 'fast' lenses, spend money on support equipment. Steady is the key, even with wind and people walking around and vibrations and such. Use a (cheap) cable release or Intervalometer to do long-exposure shots with bracketing automatically or leave it running while you sleep.
Maybe you can borrow stuff, rent lens for sure, and invest in a tripod that's sturdy enough but light enough that you'll take it with you. Get a Chinese generic intervelometer for sure.
Look at what other people have done: assess how large of a form factor you need for the kind of pictures you want. Then approach someone with a boatload of expensive kit that he obviously is ecstatic at using every bit of it, and ask him for a copy of his picture :) Or ask him to shoot one of you, on your memory card.
If the lights are bright enough where you are located, you could use any camera and a GoPro would certainly fall under that umbrella. The most current GoPros have steadily been improving in low light abilities so you might want to consider that when you purchase one. Will a GoPro be the best at capturing the aurora? Far from it, but it is certainly possible.
The GoPro Hero4 certainly can do it using its night mode but you need to use Protune.
The following settings can be used. It's worth trying a few different White Balance settings. - Night Lapse - Protune On - ISO 800 - White balance 5500K - Exposure 30 secs - Sharpness Soft - Colour Neutral - Continuous If you would like to see the results of a timelapse using those settings, check this blog post out here. I had access to a GoPro HERO4, a Panasonic Lumix and a good quality Nikon (sorry it was borrowed and can't remember the model). Obviously the DSLR won out in terms of quality, the Panasonic was also very nice. The GoPro did a decent job and I was able to leave it out in a weatherproof enclosure as described in the blog post, automatically scheduled to turn on each evening using the CamDo Blink GoPro Time Lapse controller so I didn't have to stay up all night every night, although in the end I did!