How is Earth's rotation axis oriented relative to the revolution orbit?
◦ It varies somewhat randomly over small angles, less than 23.5 degrees.
◦ It is fixed and always points toward the North Star regardless of season.
◦ It changes with time so that it is perpendicular in June and December.
◦ We don't really know how much it varies because we have not been able to make observations from space for more than about 60 years.