Dear Tom,
What is "aphelion"?
Susan Bosserman Fairview, NC
Dear Susan,
Our starry-eyed sky guru, Triton College astronomer Dan Joyce, informs us that today is Aphelion Day, the one day in the year on which the Earth passes farthest from the sun. That's right: farthest. Surprising, but true. We're farther from the sun during summer than during winter (but remember, it's winter in the Southern Hemisphere now).
The average Earth-sun separation is about 93.2 million miles, but the path the Earth traces as it orbits the sun is that of an ellipse, not a circle. When the Earth arrives at the end of the ellipse most distant from the sun, as it does today at about 9 p.m. CDT, the sun will be 94.4 million miles distant. Joyce says that point, in the parlance of astronomy, is aphelion. At perihelion, the point of closest approach (Jan. 3), the Earth-sun separation is 91.3 million miles.
What is "aphelion"?
Susan Bosserman Fairview, NC
Dear Susan,
Our starry-eyed sky guru, Triton College astronomer Dan Joyce, informs us that today is Aphelion Day, the one day in the year on which the Earth passes farthest from the sun. That's right: farthest. Surprising, but true. We're farther from the sun during summer than during winter (but remember, it's winter in the Southern Hemisphere now).
The average Earth-sun separation is about 93.2 million miles, but the path the Earth traces as it orbits the sun is that of an ellipse, not a circle. When the Earth arrives at the end of the ellipse most distant from the sun, as it does today at about 9 p.m. CDT, the sun will be 94.4 million miles distant. Joyce says that point, in the parlance of astronomy, is aphelion. At perihelion, the point of closest approach (Jan. 3), the Earth-sun separation is 91.3 million miles.
