Earth's axial tilt with respect to the background stars (with respect to the plane of its orbit around the sun) causes hemispheric seasons: northern hemisphere summer is southern hemisphere winter, and vice versa.
(Earth's axial tilt with respect to the background stars (with respect to the plane of its orbit around the sun; causes; hemispheric seasons) (northern hemisphere summer; is; hemisphere winter)
Earth's axial tilt with respect to the background stars (with respect to the plane of its orbit around the sun northern hemisphere summer
causes is
hemispheric seasons
hemisphere winter