system
Given the following post, respond as if you're commenting on Reddit:
human
Does a nuclear weapon detonating in a vacuum create the characteristic double flash?

From what I've read, the shockwave of the nuclear detonation briefly obscures the light from the nuke, which creates the double flash used by satellites to verify an atmospheric nuclear test. 

But would a nuclear detonation in space cause the same effect? I did not see any mention of it for nuclear weapons tested in space.
gpt
Wikipedia says,

> This signature, with a double intensity maximum, is characteristic of atmospheric nuclear explosions and is the result of the Earth's atmosphere becoming opaque to visible light and transparent again as the explosion's shock wave travels through it. [...]  The effect is unambiguous for explosions below about 30 kilometres (19 mi) altitude, but above this height a more ambiguous single pulse is produced. 

Without air you won't get this effect.