Comet C/2011 L4 (PANSTARRS) was discovered in June 2011. At that time it was a long way from the sun and very faint. Now it’s closer to the sun than the Earth, and it’s bright enough to see with the naked eye.
This week you can see comet Panstarrs (C/2011 L4) near the horizon in the west, about 40 minutes after sunset. It’s close to the moon, so the best nights are the 12th and 13th, when the moon is a thin crescent.