Bob Moler's Ephemeris Blog

This is Ephemeris for Thursday, July 6th. Today the Sun will be up for 15 hours and 26 minutes, setting at 9:30, and it will rise tomorrow at 6:04. The Moon, halfway from full to last quarter, will rise at 12:16 tomorrow morning.

Today, the Sun is at its farthest distance from the Earth. It’s called aphelion. The exact time actually occurred at 4:59 this morning at a distance of 94 and a half million miles away. Because of the gravitational pull of the Moon and planets on the Earth, especially Jupiter and Venus and gravitational pull of the planets, especially Jupiter on the Sun, the aphelion and perihelion, the closest date in January don’t occur on the same date or same distance every year. The date wanders by a day or two each year. The entire distance variation of the Earth from the Sun is plus or minus 1.5 million miles (2.4 million kilometers) over the year, makes summer the longest season by a few days because the Earth moves slower when farther from the Sun, than when it is nearer.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT –4 hours). They may be different for your location.

Note: Apoapsis and Periapsis are generic terms for the farthest and nearest points in an orbit to the central body. For a body orbiting the Sun, it’s aphelion and perihelion. For a satellite of the Earth, it’s apogee and perigee.