I was thinking about how some religions suggest people to pray facing east, Jerusalem, or Mecca. Quoting Wikipedia, “Prayer in a certain direction is characteristic of many world religions, such as Judaism, Christianity, Islam and the Bahá’í Faith.” I couldn’t help pursue the question. What happens if you’re on Mars? How would you figure out the direction to one of these places from Mars? What if we achieved interstellar travel?[…] Keep reading →