Comet Hartley is back and will be at its nearest approach in the next few days. It's just visible with the unaided eye near the star Capella, but won't look like much without binoculars.
An interesting feature is that it is
green, as you can see in the picture below taken by Doug Zubenel, which is on the SpaceWeather.Com website.
Here is a sky map showing the comet over the next several days:
Sky map to find Comet Hartley Comet Hartley by Doug Zubenel