But what is the legal status of these aliens? They weren't invited, so they must be ordered to return home:
A man who has shown a video of what he claims is an alien visitor to earth to bolster his case for greater public scrutiny of UFOs is to take his campaign to the Democratic Party convention in August, where Barack Obama will formally win the presidential nomination.
Jeff Peckman revealed a video of what he believes is an extra-terrestrial, at a press conference in Denver, Colorado.
Mr Peckman, a website entrepreneur, is campaigning in support of a ballot initiative that would let the people of Denver vote in November on a plan to establish a city-wide extra-terrestrial affairs commission.
Under his proposal, which he says would cost $75,000 (£38,000) a year, the new body would ensure that government offices, police and firefighters are trained to deal with extra-terrestrial visitors. It would also release details of UFO sightings which it judged to be credible.
It'd be cool if the aliens actually showed up at the convention. Under Democratic rules, I'm pretty sure they'd have to be seated and have at least half their delegates counted.