This sighting happened in South Africa, Northriding on the 15th of April at 19:00.My friend and I was watching the Orion stars and we both noticed this object moving across the sky at a rapid speed. The object's shape was a half moon and was huge. Its wing span was from the top star of Orion's belt to the bottom star. It was approximately 30000ft altitude. We are situated in between two airports and constantly see planes flying over the night sky and this object was unlike any we have seen. We have a full view of the night sky and this object moved from one end of the sky to the other in a matter of 20 seconds.The object was not an orb or shiny or had any lights on, this is why it was not a plane. The object seemed to camouflage itself to the night sky. It was like you could see through it but had some sort of structure to it because we could see the shape of a half moon. It looked like a cloud but there was no clouds at the time and it was to solid but clouds break up when they move and this object was really moving fast and clouds do not keep their structure like that when moving. It was weird, like seeing something from a Star Trek movie were they have a cloaking device on the plane. No sound was coming from the object and some planes past over the same position later that evening and you could hear the planes. You could fit 10 747 planes in this object.I know what I saw and it was not a plane, swamp gas, clouds some natural phenomena or a drone ( drones are not that huge ). This object flew across the night sky and made a turn at the end of the other horizon. Nothing man made can move from one end of the sky to the other so quick.