Atlas-V rocket at Vandenberg Air Force Base
4K HD Wallpaper: Atlas-V rocket at Vandenberg Air Force Base
New image from NASA that looks really good and can be downloaded under CC By license. Here's optimized for use in desktop backgrounds and homescreen phones.
Widescreen Desktop / Macbook (Retina): 2880x1800 (fits on: 2560x1600, 1920x1200, 1440x900)
High Definition HD 1080p: 1920x1080 (fits on: 1600x900, 1366x768, 1280x720)
Samsung Galaxy Tab & iPad: 2048x2048 (compatible with many tablets)
HTC, Samsung Galaxy & iPhone: 1080x1920 (compatible with many phones)