7 space mysteries that scientists can't explain

It's no secret that space is full of mysteries.

Our species has barely gone past our own planet's moon, and only one of our probes, Voyager 1, has even left the solar system. Much of what we've learned about deep space has been pieced together from falling objects and views from telescopes.

Some of the famous (and chilling) space mysteries, like the face on Mars (it was shadows), or the black knight satellite "UFO" (it's satellite debris), have been solved.

But space is rife with unexplained phenomena that put those two mere optical illusions to shame.

And some of the seven included in this slideshow could hold the key to understanding the universe.