Space X's Starship Raptor rocket engine is part of the company's ambition to transport humans to the moon and beyond.
Musk has been teasing his Twitter followers for days with the promise of a video of the new engine's first firing.
On Sunday night, he tweeted two spectacular videos of the engine in action at Space X's test facility in Texas.
In replies to followers, he explained the iridescent flames. "Engine use methox torch igniters. Green tinge is either camera saturation or a tiny bit of copper from the chamber," he said.
Musk tweeted in December that the Raptor had undergone a "radical redesign." He also said the engine has 200 metric tons of thrust, which he says will help the rocket reach the moon "as fast as possible."
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