Is someone please able to explain why Ethane is colourless? Hi guys!

I thought colourless things occur when the bonds are very tight meaning they cant vibrate and re-emit light but as far as I can tell the bonds between Ethane are incredibly weak. With my limited knowledge I would have assumed that this means the electrons in Ethane can vibrate very freely and thus re-emit light and therefore colour but no! Its colourless. So I'm somewhat stuck on my explanation of why Ethane is colourless.

Any thoughts?

Thanks!!