Dust blew over the Red Sea on May 2, 2011, according to a NASA statement. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Aqua satellite took this picture the same day.
The dust extends from the interior of the Arabian Peninsula across the eastern half of the Red Sea, stopping short of Sudan.
Abundant sand seas, including the Rub' al Khali (Empty Quarter), cover much of the Arabian Peninsula. The dust likely arose from one or more of those areas.