This picture shows the changes in Comet Hartley over a period of 8 days. The image on the left was taken on 10-8-10 when Hartley was near the Perseid Double Cluster. The right image was taken on 10-16-10 and shows the change in size and the development of the tail. All the images were taken with a Televue 101NPis and a Canon 20Da. The left image is a stack of 57 and the right one a stack of 41. Each individual image was 4 minutes long. Images were stacked in Images Plus.