One cold day you look up in the sky and see three suns, you're not seeing things, what you're seeing is what are called sundogs, they're cause by ice crystals in the sky reflecting the sun, the suns on the left and right of the real sun are called mock suns.(Just reflections of the sun bouncing off the ice crystals.
They're are moon dogs as well, and yes the sun or moon may have a halo around them those are also cause by ice crystals and they usually indicate it is going to rain the next day.
Rainbows are made the same way, except it is NOT cause by ice crystals, but by water droplets staying in the sky acting like a prism. Rainbows may appear after a rain.
Sundogs are usually seen in Alaska in mid-winter months. (end)