Many companies use blimps to advertise their products. Unmanned blimps are usually tethered to the ground, although this tether will usually not be visible at a distance. They tend to remain stationary or slowly glide across the sky. There are also ones which are controlled remotely, these can of course perform slow turns or changes in altitude.

As blimps tend to be unlit, they are usually quite hard to see after dark unless made out against passing cloud or in front of the moon, at which point they can appear as a black oval/lozenge shaped object.