We went to a place 2 hours away from Kolkata, India, called Diamond Harbour. We were on the terrace of our hotel at 1:00 am looking up. Then we saw a dimly lit object in flying in the sky. It was coloured light brown, and shaped like an arrowhead. It initially moved slowly, but then suddenly sped up. We saw it flying very fast for 5 seconds then it disappeared behind a cloud. My friends thought it could be aliens. I'm a little sceptical and think it could be a stealth plane.