On Top of the World

No, It's Not upside Down!

No, It’s Not upside Down!

   For the past week we have not seen the Sun much – even nights have been cloudy, and the temperature has been below freezing for more than a week. So combining those conditions with thoughts of warmer climes, and recent correspondence (aka e-mail) with a long-time friend living in New Zealand brought back memories of a trip I took with my wife, Sue, to New Zealand to attend an Astronomical Conference in New Zealand.
   Remember the 80’s song by Men at Work that asked the musical question “Do you come from a land down under?” That lyric gained new meaning for me while at that conference. I was politely corrected when I said that I came down to New Zealand. “No, no,” my hosts said, “You came up to New Zealand.”
   Have you ever wondered why we refer to folks from Australia and New Zealand as being from down under? How did their neck of the woods become down under and ours, conversely, up top? How is it that north is assumed to be at the top of the Earth and south at the bottom of the Earth? For that matter, is there really a top or bottom to the Earth?
   Try this: Hold a ball in one hand. Touch the top of the ball with your other hand. Directly opposite this point is the bottom of the ball. Turn the ball around in random directions a few times and again touch the top of the ball. Turn the ball around in random directions a second time and again touch the top of it. Did you touch the same spot on the ball each time? Was the bottom the same each time? So where would the top or the bottom of the ball be? Think of the ball as the Earth and each of the spots that were the ‘tops’ as different places on the surface of the Earth.
Nosotros casa es su casa

Nosotros casa es su casa

   Now try this: Take either a reticulated Earth globe or a globe that can be taken off of its mounting and set it in a large cup or bowl that will serve as the base. Adjust the globe so that your location on Earth is at the top. Mark this location on the globe with a straight pin or matchstick held with putty. Next, rotate the base so that globe’s north pole is aligned with true north and it’s south pole with true south. The Earth globe is now positioned with respect to the Sun exactly as the Earth is positioned in space with respect to the Sun. (Note that the shadow of your marker will mirror the shadows of all other objects cast on Earth with regards to compass direction.) From this ‘space’ perspective, you are clearly at the top of the Earth. Notice what point on the surface of the Earth is directly opposite your location, or at the bottom of the globe.
   If there is land at that location, imagine your counterpart doing this same activity. Who do you think your counterpart would consider to be at the bottom?    Imagine doing this for other locations around the Earth. What does this tell you about where the top and bottom of the Earth is?
   Your answer would have to be based on your frame of reference (you are on top wherever you are). This, unfortunately, is not the traditional way of looking at things around the globe.
"Be Careful Opening the Overhead Bins"

“Be Careful Opening the Overhead Bins”

   It has been a common and accepted convention to think of north as being at the top and south at the bottom. This thinking has established our perceived understanding of our place on the Earth and the vocabulary associated with this line of thinking.
This Northern Hemisphere–bias has even influenced how many astronomy books depict the Moon and constellation patterns. To someone from south of the equator, constellations and Moon phases are upside down according to the Northern Hemisphere–based star maps.
   So, is there actually a top or a bottom to the Earth? It’s up (or down) for you to decide.

   Thanks to Eric Jackson for planting these ideas in my head!
Click here to go to the Qué tal in the Current Skies web site for more observing information.

Hanging from the Tropic of Capricorn

Hanging from the Tropic of Capricorn!

Hanging from the Tropic of Capricorn!

   With the recent change of seasons on the December Solstice I was reminded of a favorite teaching tool of mine. Developed in New Zealand, what may appear to be a unique design for a climbing frame is in reality a ‘unique design for a climbing frame’. However it is not just the design as this climbing frame is also an outdoor Planetarium of sorts. This is Pipehenge, and it is a climbing frame that is made specifically for the latitude where it will be installed. And when set up the Pipehenge is positioned to be aligned with local compass directions. PipehengeThere is a circumpolar ring centered on the North Pole star, or the South Celestial Point, a horizon bar, and bars representing the celestial equator, both ‘Tropic’ parallels, and several bars for Hour Circles. The structure of the Pipehenge is such that when seated on a stool in the center you could imagine sitting inside a Celestial Sphere.
   Update: Pipehenge and the desktop Earth-Space Simulator may no longer be available. An Internet search shows that the two web sites for Pipehenge and the ‘ESS’ are no longer available, aka no longer in use. The best references for the Pipehenge are on a web page written by one of the developers, John Dunlop of New Zealand. Also, click here to go to the Pipehenge YouTube web page to see a collection of short video clips featuring Eric Jackson explaining and demonstrating the Pipehenge model.solar_noon1
   Watch a short demonstration of the Portable Pipehenge by Steve Bevan.

ess   Bring the Pipehenge indoors with a desktop model called the Earth Space Simulator. This arrives in kit form and takes a short while to assemble into a hands-on model that simulates the apparent motions of the sky for any time of the year and for any latitude. It is an ideal teaching tool, for example, the effect latitude has on the Sun’s daily and seasonal apparent motion from sunrise to sunset.


Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to return to bobs-spaces.

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