Imaginaplanet. It's only see-able from a distance, like an illusion, because it no matter how close you get to it it stays the same size, thus anable to really examine. No one knows what it's made of, but we suspect it's made of the same vapor that makes Rainbows. We plan to try and find it of course! if we can get Rockets that almost match the speed of Light then it could just as well be possible to visit!
Thanks to @O_o_ME
