Which sensor is this on the back of the rear view mirror?

[anyjungleinguy]

As title. Is it light sensor for the auto headlights? Wasn’t sure if that was kept in the black box that houses the sensors for the auto wipers. 

 

[alexp999]

It's the front light sensor for the auto dimming mirror.

It also has one on the other side and uses the difference between the two to try and work out when someone's headlights are behind you and tint the mirror

[anyjungleinguy]

Ah, thank you. I wondered whether it was something for that but then couldn’t really think of a good reason why it would be on that side. 

I’m trying to find the best placement for my dashcam. The black box sensor housing is obstructing quite a bit of the view.