Even though UFOs are seen everywhere: over the desert, over the ocean, over cities; there's no way to predict when and where they'll show up.

Well, no way except for one: build or detonate a nuclear weapon.

Since the dawn of the atomic age, UFOs have been seen -- and photographed -- during nuclear weapons tests and near nuclear weapons facilities.

The Ark of the Covenant is one of the most mysterious artifacts in human history. The Ark, a sacred chest made of wood and covered in gold, has been missing since 587 BC. Its last known location was Jerusalem, somewhere under the Temple Mount.

What does this have to do with UFOs?

In 2011, a UFO was hovering over the Dome of the Rock on the Temple Mount in Jerusalem. It emitted a flash of light, then shot straight up and disappeared into the night sky.

This could be just a coincidence. But it could be that the craft was looking for the Ark.

The Ark of the Covenant is an object of extreme religious importance to over 2 billion people. But why would a UFO be looking for it? Because it's the most dangerous weapon of mass destruction ever created.