It was a conspiracy theorist's dream. Last year, after decades of official denials, the US government finally put together a panel of NasaThe National Aeronautics and Space Administration, responsible for the US space programme. scientists to report on the existence of UFOsUnidentified Flying Objects.

That panel reported their findings this week. But it turns out they have more questions than answers.

They examined around 800 reports of UFOs - or what they now call "unidentified anomalous phenomena", UAPs. They said they could not find explanations for between 2 and 5% of reported sightings.

Nasa cautions against assuming that these unexplained sightings must be of extraterrestrial origin.

But some reports are truly baffling. They describe objects that move in ways nothing on Earth can, that can climb to 30,000 feet and reach hypersonic speeds despite having no engine.¹

That is why some think it is worth preparing for the likelihood that we will make contact with aliens soon. And for philosophers, this raises many interesting questions.

Some argue that if we are the only sentientAble to perceive or feel things. species to exist then we might have a moral duty to populate other worlds. 

This is because humans would then be the only beings in the universe capable of creating meaning. If we do not spread and we die out on Earth, the universe goes back to being meaningless.

On the other hand, some argue, it is not justifiable to coloniseTo move to a place and attempt to take it over, at the expense of any existing people. other planets just to fill the universe with meaning.

Finding sentient life would only give us more moral problems, others say. While moral codes differ across the world, every human society has the same basic rules: no killing, no stealing, no torturing.

But aliens might have a completely unrecognisable understanding of morality. This would force us to question our own deep-held moral beliefs.

Yes: Philosophers have always thought the existence of aliens is likely. Some have even dedicated their lives to working out the logical questions that they would raise.

No: Aliens give philosophers all kinds of fun and interesting thought experiments. But in the end the question of whether or not they actually exist is not a philosophical question, but a scientific one.

Or... If aliens do exist, then much of what we know about philosophy will be turned on its head. So one important question is: if aliens exist, can we continue to be philosophers?