"Strongest argument against aliens," he tweeted. He posted two charts indicating that despite improvements in camera resolution, the resolution for UFO images remained the same.
The post picked up more than 37,000 retweets by Tuesday afternoon and got a like from Twitter CEO Jack Dorsey.
Musk's tweet came after what appeared to be heightened speculation surrounding government knowledge of UFOs.
At the end of last month, an American Airlines flight crew made an apparent UFO sighting.
"We just had something go right over the top of us," the pilot said in a radio transmission. "I hate to say this but it looked like a long cylindrical object that almost looked like a cruise-missile type of thing. Moving really fast and went right over the top of us."