World's richest person Elon Musk has returned to Twitter two days after tweeting, "Off Twitter for a while." He tweeted about SpaceX launching 60 Starlink satellites, said Falcon 9's landing was "a tough one", tweeted "Doge" and also shared a meme on dogecoin. Last week, Musk tweeted in support of dogecoin, a digital currency that was launched as a joke.