The Physics To Go website will be unavailable Friday evening through Saturday afternoon as electrical work occurs in the American Center of Physics server room. Down time will begin at 6PM Eastern Time on Friday. Service is expected to resume by 6PM on Saturday, July 30.

Shock Diamonds and Mach Disks Feature Summary

From Physics Research
Shock Diamonds and Mach Disks
When the speed of the gases in a jet or rocket exhaust exceeds the speed of sound, a dazzling pattern results called "shock diamonds" or "Mach disks," as shown in this photo of the SR-71 Blackbird. The diamonds are created by crisscrossing shock waves in the exhaust.

You can see shock diamonds in a static rocket test in this NASA video. For more information, check out Shock Diamonds and Mach Disks.
Image credit <a href=" http://" target="_blank">NASA</a>; <a href=" " target="_blank">Image source</a>; <a href="" target="_blank">larger image</a>
Image credit NASA; Image source; larger image
Image URL:
June 16, 2010 - July 1, 2010