Yeah, sure, is a pretty big deal, but have you ever seen something go 6,599 miles per hour before? Can you even see that?

This video features the U.S. Air Force testing a hypersonic sled at Holloman Air Force Base in New Mexico. While you might only see a bright flash of light, what you’re actually seeing is a sled traveling at Mach 8.6. You’re going to want to turn the sound on for this one.

The threshold of hypersonic speed is Mach 5—something that this sled extremely exceeds.

The U.S. Air Force is testing a lot of things to see if they can withstand hypersonic speeds given that this is . If something is going to be moving at thousands of miles per hour, everything involved in it needs to be able to withstand high acceleration forces and heat stressors.

That includes everything from wirings to exterior coatings, which is why the military uses the on the base. The original track was completed in 1949 and grew to be ten miles in length, used by government agencies and contractors to test weapons and other things, since it’s cheaper to do that on the ground than it is to do it in the air.

This particular test, as the base noted on Instagram, saw the sled going over a mile per second.