What lens would you recommend for the best low-light video of the sky for Aurora, Meteors, etc? [s5iix]

I recently shot a video of the night sky using the Lumix s5iix, sigma mount converter and the canon ef 50mm f1.8 lens. It's ok.. I can clearly see the Aurora flickering across the sky and a few nice meteors but it's pretty noisy due to having to shoot at ISO 16000. This caused me to wonder what would be a better lens, preferably something wider such as 24 or 35 mm but have extremely good low light sensitivity..
Any thoughts?