Liberty's Library

Originally written December 30, 2005


Mornin' Everyone,

Every now and then, I get nasty-grams from viewers. You know, when I screw up the forecast or I'm not wearing the right color shirt or my hair gets too long...etc... a few folks like to get on the horn or the e-mail and let me have it. Just part of the glamour.

Today, I received one by mail. Evidentally, someone took offense to a statement I made about a month ago when I said that the earth is closer to the sun during the winter than at any other time of year. Well, someone decided to write and tell me how much of a moron I am. They clipped an article from a local newspaper regarding the earth's seasons and from that they deduced that I was wrong.

Actually, this is how they put it:

"You seem very smart, but what you said was not very smart. Before you go on air, get your facts straight please."

That wasn't enough. These folks were too cowardly to leave their names. They just signed the note, "Dedicated viewers". They even went so far as to cut their name off of the little return address sticker they put on the envelope.

Okay, that was enough for me. I decided to use a reverse search using their address and FOUND their names (and their ages too). I then wrote what you are about to read, USING their names. The following is the response I just mailed back to them. It will go out today. Please, enjoy this and share it with someone you love.

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Mr. and Mrs. So-and-so,

Thank you for being dedicated viewers of NewsChannel 5. We make it our goal to continually increase our effectiveness in bringing you the news, weather and sports information that is important to you. It is my personal goal to educate my viewers on the truth behind popular myths and "wife's tales" when it comes to meteorology, as well as adaquately prepare you for the day ahead. I also like to throw in a whole lot of fun, I mean, hey, how serious do you wanna be at 6 AM?

One of the most misunderstood concepts in astronomy is the concept of seasons and how the earth responds to seasonal changes thanks to its tilt (23.5 degrees). Usually, I have to explain the seasons in-depth for most folks. I'm very satisfied to know that you have grasped this concept. This will make my job in the following explanation much easier.

The statement you included in your letter was:

"You made a statement on the morning show...that the sun is closest to us now - I know for a fact it isn't."

I'm glad you said that. This alludes to the difficulty that most folks have in grasping the scientific reality of the Perihelion and the Aphelion of the earth's orbit. But don't worry, I love teaching. As you know, the Terra [axial] orbital (and all other orbitals for that matter, not just that of earth) is not a circle, rather is an ellipse. An ellipse has a major axis and a minor axis thus flattening the path so that there are two oblong points... one of maximum distance and one of minimum distance. I have included a diagram so that it will be easier understood.

Please note where it says, "Planet X perihelion". This position is the closest that a planetary body will come to the sun (in orbit). At this point, the earth is 147.5 million kilometers away from the sun. Thus, earth is closest to the sun here.

Also note in the diagram the "Planet X aphelion" position. This position is the farthest a planetary body will be from the sun (in orbit). At this point, the earth is 152.6 million kilometers away from the sun. Thus, earth is farthest from the sun here.

As it happens for earth, the perihelion (closest to the sun) is always around early January. This year it will be January 4th. Conversely, the aphelion always occurs around early July. This year it will be July 4th.

Therefore, with the northern hemispheric winter beginning on December 21st, it is true that the earth is closest to the sun during the northern hemispheric winter.

Here is a note from Scott J. Badham, Department of Geology and Geophysics, University of Wyoming.

"Although it may seem that Earth's relative distance to the sun would be a prominent factor in determining seasonal changes in temperature, it pales in comparison to the prominence of the planet's axial tilt with respect to controlling temperature, or more accurately, distribution of solar energy. It is the axial tilt (presently 23.45 degrees), in fact, which determines seasonality. During Northern Hemisphere summers, the north pole is oriented in such a way as to be pointing in the general direction of (not directly at) the sun; during Northern Hemisphere winters, the north pole is pointing away from the sun. I should clarify this by saying that the north pole points in essentially the same direction throughout the year (i.e. Polaris, the North Star), regardless of where it is in its orbital path.

Incidentally, it is for just this reason that the polar regions are immersed in full to partial darkness during certain parts of the year (i.e. the north pole during northern winters.) When a region of the surface of Earth is more straightly facing the sun (like northern latitudes do during northern summers), the amount of sunlight falling on that surface is greater than when that surface is more obliquely facing the sun (like northern latitudes do during northern winters.) This seasonal change in the amount of incident solar radiation per unit area on the surface of Earth is ultimately what determines the seasonal changes in temperature. Any introductory astronomy text will have illustrations that depict what I have described here, if the mental visualization is difficult (which it certainly can be.) I hope this explanation helps."

As always, thank you for contacting us at the AccuWeather StormCenter. If you have any more questions regarding the science of this earth, the stars, or of course meteorology, please fell free to let us know!

Me
Morning/Noon Meteorologist
NewsChannel 5 (CBS)

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I truly feel sorry for some people. It took me all of 10 minutes to research for quotes and find that diagram.

I am, by no means, an infalliable expert in science. I don't claim to be an expert in anything; not even the Bible, although I know more about it now than I ever did at Harding. But seriously, there is no excuse for ignorance when the internet is literally at your fingertips any time you want. Information is all around. All we have to do is take the time and exercise the patience to look for it.

~ Be good and be God's