In the Earth’s outer core, there is liquid iron. Its motion generates a magnetic eld. Every few hundred thousand years, the poles interchange. How? Why? We don’t know.

Jerry Ehman, while working for the Search for Extra Terrestrial Intelligence in 1977, got a 72 second signal from the constellation Sagittarius. No one knows who sent the signal.

Death Valley in California is a big patch of dry earth. Stones somehow manage to slide on this dry earth surface by them-
selves.

Scientists unearthed an iron screw inserted in a rock in Moscow, in 1998. This screw was probably 320 million years old; which is older than dinosaurs.

Arkansas in the US witnessed tons of dead black birds falling from the sky, in 2012. No one knows why this happened.