changes in the number of sunspots which seems to vary in an 11-year cycle, changes in the ellipticity of the earth's orbit, which roughly follows a 100 000-year cycle, and changes in the earth's axis of rotation, which alters the season of perihelion, and which follow an approximately 100 000-year cycle.
(the number of sunspots; seems; to vary in an 11-year cycle) (the number of sunspots; to vary; L:in an 11-year cycle) (the earth's orbit; roughly follows; a 100 000-year cycle) (rotation; alters; the season of perihelion) (changes in the ellipticity of the earth's orbit, which roughly follows a 100 000-year cycle, and changes in the earth's axis of rotation; follow; an approximately 100 000-year cycle)
the number of sunspots the number of sunspots the earth's orbit rotation changes in the ellipticity of the earth's orbit, which roughly follows a 100 000-year cycle, and changes in the earth's axis of rotation
seems to vary roughly follows alters follow
to vary in an 11-year cycle
L:in an 11-year cycle
a 100 000-year cycle
the season of perihelion
an approximately 100 000-year cycle