Probably a really easy thing for those who know, but i don't. 
This morning I got into my car, put key in ignition, turned it a few clicks over, all the dash lights came on as normal, fully lit. I then turned it to start and I get a churning noise which gets slower and slower then eventually stops. While this is happening the lights on the dash (hand brake light) gets dimmer and dimmer. This has been worse during colder days.
Tried it a few times, still didn't work. I put some WD40 on the battery connectors thinking it might just be a loose connection to the battery, still no joy.
So any ideas? Battery? Starter motor? Something else?
Thanks for any help!

This morning I got into my car, put key in ignition, turned it a few clicks over, all the dash lights came on as normal, fully lit. I then turned it to start and I get a churning noise which gets slower and slower then eventually stops. While this is happening the lights on the dash (hand brake light) gets dimmer and dimmer. This has been worse during colder days.
Tried it a few times, still didn't work. I put some WD40 on the battery connectors thinking it might just be a loose connection to the battery, still no joy.
So any ideas? Battery? Starter motor? Something else?
Thanks for any help!
