If you have a Nikon camera with a detachable lens but you do not know know the difference between a full frame and crop sensor, chances are you have a Nikon DX or cropped sensor camera. All of these cameras work fine for the aurora and there is not a substantial low light performance gap from the cheapest to the most expensive. Therefor, if you are planning on picking one up, your best value will be in getting an inexpensive DX sensor camera and spend your money on a lens where you can meaningfully improve your low light performance.
Nikon DX Cameras with January 2019 Amazon Pricing
Most of the 3000 and 5000 series cameras come with a kit lens, the 18-55mm F3.5 lens like seen in the photo above. The kit lens can work for the aurora but it is difficult to manually focus in the dark due to no focus markings on the focus ring and it is at best moderately capable for low light. You will have a vastly improved experience and photos by pairing one of the suggested lenses below with your Nikon DX camera.
If you are in the market for a new DX Nikon camera for aurora photography, I would suggest you get the D3500 based on today's prices and pair it with the Tokina 11-16mm F2.8. If that lens is too expensive I would instead sift through the used market and get a Tamron 17-50mm F2.8. If you already have a DX Nikon camera I still suggest the same lens pairings as I did for a new one. Don’t forget to bring a tripod and an extra battery (3000 and 5000 series battery).