Starwatch: We're 94 Million Miles from the Sun This Week

One of the big misconceptions that people have about the seasons is that they are a function of Earth-sun distance. Nothing could be further from the truth.  They are attributed to the Earth’s axial tilt which “leans” the Northern Hemisphere towards the sun in the summer, so that Sol is higher in the sky and we receive more direct energy from the sun. This also allows the sun to be visible for a longer period of time throughout the day.  

The net result is an excess of energy, the Northern Hemisphere warms, and everyone goes outside to play.  You can demonstrate this effect with a flashlight and a wall. The wall is the Earth’s surface; the flashlight represents the sun. Shine the flashlight straight down onto the wall, and note the area of the wall which the beam illuminates. Keeping the flashlight at the same distance from the wall, allow the light to strike the wall at angles which are less and less steep. 

You’ll notice the beam expanding into an oval which will elongate itself and cover more and more wall area.  It’s the same energy but all spread out. This is what happens in winter when the Earth’s axis “leans back.”  Daylight decreases, and the sun appears much lower in the sky.   

The energy received from the sun lessens and so do the temperatures. All of this leaning towards and away from the sun seems to indicate that the Earth’s axis flips back and forth during a year’s time.  This is not the case at all.  For now it points towards the North Starkeeping the stars of the nighttime sky in step with the calendar.  Oh, and how far are we from the sun on Friday, July 5?  

The number in miles turns out to be 94,508,200. 

© Gary A. Becker—www.astronomy.org

Moravian College Astronomy