One of the payloads recently delivered to the Int. Space Station recently by the SpaceX Dragon spacecraft is the High Definition Earth Viewing (HDEV) experiment. It consists of cameras attached to the exterior of the station that stream views of the earth. You can watch the feed at ISS HD Earth Viewing Experiment
The High Definition Earth Viewing (HDEV) experiment aboard the International Space Station (ISS) was activated April 30, 2014. It is mounted on the External Payload Facility of the European Space Agency’s Columbus module. This experiment includes several commercial HD video cameras aimed at the earth which are enclosed in a pressurized and temperature controlled housing. Video from these cameras is transmitted back to earth and also streamed live on this channel.
While the experiment is operational, views will typically sequence though the different cameras. Between camera switches, a gray and then black color slate will briefly appear. Since the ISS is in darkness during part of each orbit, the images will be dark at those times. During periods of loss of signal with the ground or when HDEV is not operating, a gray color slate or previously recorded video may be seen.
Analysis of this experiment will be conducted to assess the effects of the space environment on the equipment and video quality which may help decisions about cameras for future missions. High school students helped with the design of some of the HDEV components through the High Schools United with NASA to Create Hardware (HUNCH) program. Student teams will also help operate the experiment. For a display of the real time ISS location plus the HDEV imagery, visit here: eol.jsc.nasa.gov/HDEV/ To learn more about the HDEV experiment, visit here: www.nasa.gov/mission_pages/station/research/experiments/917.html
Emphasis mine. At the moment of this posting the display is gray.