Fig. 1
From: A role for orbital eccentricity in Earth’s seasonal climate
A schematic of the Earth’s orbit around the Sun. The Earth’s orbit is elliptical with the Sun (S) at one focal point and with the closest approach at perihelion (at a distance rp) and furthest at aphelion (ra). The direction of the orbit is counterclockwise. The eccentricity e, defined in the figure, measures how elliptical the orbit is; currently, e = 0.01671. The equinox and solstice points are named following Northern hemisphere seasons. The longitude of perihelion (LOP) relative to the moving vernal equinox is defined as the angular distance from vernal equinox to perihelion following Earth’s orbit (\(\widetilde{\omega }\), in degrees), subtracted by 180°. Perihelion, as drawn in the schematic, is positioned for modern day, with an LOP of about 103° and date of around 3 January. Figure and caption adapted from Chiang et al. (2022), Fig. 1