July 5, 2021: Our planet Earth reaches its farthest point in its yearly trek around the sun. Our seasons are not related to Earth’s distance from the sun. Coincidentally, the moon is at its farthest point from Earth today.
by Jeffrey L. Hunt
Today (at 5:27 p.m. CDT) Earth reaches its farthest point from the sun in its yearly route.
Our planet’s orbital path is not a perfect circle, but it is slightly elliptical. In the properties of shapes, the eccentricity of a circle is zero. Earth’s orbital eccentricity is 0.017. Only Venus and Neptune have orbital paths that are more circular than Earth.
In the solar system, we measure distances from the sun in Astronomical Units (AU), the earth’s average distance from the sun, 1.0 AU. In round numbers, this is 93 million miles.
Earth’s distance from the sun varies throughout the year, although the difference is small. In January, we reach our closest spot to the sun, known as perihelion. This year that distance was 0.983 AU.
Today at aphelion, the distance is 1.017 AU.
Seasons are from Earth’s tilt. During the warmer months in the northern hemisphere, the sun shines most directly at the northern half of Earth. During the colder months, the sunlight is most directed south of the equator.
The moon has a similar close approach and farthest extreme during its monthly sojourn through its obit. Coincidentally, the moon is at its farthest point today (apogee) at 9:47 a.m. CDT (251,846.9 miles). It is closest (perigee) on July 21 at 5:25 a.m. CDT (226,526.9 miles).
Happy Earth Perihelion Day and Lunar Apogee Day!
Articles and Summaries
October 22. 2021: Speedy Mercury is low in the east before sunrise. It is putting on its best morning performance of the year. Arcturus, in the east-northeast, is about the same altitude as Mercury.
October 21-November 1, 2021: Brilliant Venus steps through Ophiuchus to the upper left of the star Antares in the southwest after sunset . Afterward, the planet steps farther eastward.
October 21, 2021: The bright moon is low in the west about an hour before sunrise. Mercury is in the east at about the same altitude as Arcturus. Venus, Saturn, and Jupiter shine from the evening sky.
December 18, 2021: This is the anticipated launch date of the James Webb Space Telescope, the largest and most sophisticated space telescope view the universe.
October 20, 2021: Mercury is brightening in the morning sky. Brilliant Venus, Jupiter, and Saturn are in the evening sky. The bright moon starts the evening low in the eastern sky.