when is the earth said to be at perihelion
Perihelion and aphelion Earth is about 147.1 million kilometers (91.4 million miles) from the Sun at perihelion around January 3, in contrast to about 152.1 million kilometers (94.5 million miles) at aphelion around July 4 â€” a difference of about 5.0 million kilometers (3.1 million miles). (These dates change over time due to precession and other orbital factors, which follow cyclical patterns known as Milankovitch cycles. For a table of these dates for various years, see Apsis.)
Equinox An equinox is commonly regarded as the moment the plane of Earth's equator passes through the center of the Sun's disk,[2] which occurs twice each year, around 20 March and 22-23 September. In other words, it is the point in which the center of the visible sun is directly over the equator. This simplified, but incorrect, understanding of Earth's orbital motion can lead to errors of up to 69 seconds from the actual time of equinox.