 In modern times , Earth 's perihelion occurs around 3 January , and its aphelion around 4 July . These dates change over time due to precession and other orbital factors , which follow cyclical patterns known as Milankovitch cycles . The changing Earth – Sun distance causes an increase of about 6 @.@ 9 % in solar energy reaching Earth at perihelion relative to aphelion . Because the southern hemisphere is tilted toward the Sun at about the same time that Earth reaches the closest approach to the Sun , the southern hemisphere receives slightly more energy from the Sun than does the northern over the course of a year . This effect is much less significant than the total energy change due to the axial tilt , and most of the excess energy is absorbed by the higher proportion of water in the southern hemisphere . 
