******************************************************** OCEANS AND POLES ******************************************************** ************** OCEAN DEPTH ************** __________ QUESTION: How deep is the ocean near Antarctica? ANSWER from Lisa Gahagan on February 6, 1995: Depending on which part of Antarctica, at about 250 km offshore the water can reach a depth of 4000 m; it continues to deepen into the ocean basins. *************************** IMPORTANCE OF THE POLES *************************** __________ QUESTION: Which of the different poles are important? How do you figure out where they are each year? ANSWER from Jack Dibb on December 14, 1994 All three poles are important, for different reasons. The ceremonial pole is certainly fun for publicity and hero shots (nearly everyone wants to have a picture of themselves standing next to it). This one is easy to locate; they just place it in a convenient spot, close to the station but out of the way of the planes and all of the vehicle traffic. The location of the magnetic pole is important to know if you are studying magnetic properties of the Earth. This includes investigations of interactions high in the atmosphere where charged particles from outer space flying by can be trapped by the Earth's field. The location of the auroral belts (northern and southern lights) are in a band circling the north and south magnetic poles. Since the article "Will the Real South Pole Please Stand Up!" did say that compasses point straight up and down at these poles, this would seem to be an "easy" way to find them (but you would have to have a special compass and very carefully measure the inclination to ensure it was vertical). Inclinations measured at many other spots around the exact pole would also allow you to figure out where the pole is. The geographic or rotational pole is unique in that all heavenly bodies do not rise or set, rather appear to spin around at a constant height above the horizon. (You can visualize this idea with any ball. Imagine it in both directions, sitting at the pole looking out at a star or the sun, or being on this remote body, looking at the spinning "earth" whose axis of rotation is tilted.) This is hard to get used to when you are working there, since we all expect the sun to be high in the sky at noon and lower at midnight since we have lived in places where it generally sets each day. However, it does make the pole a perfect place to study the sun and stars, since you are able to make very long observations through nearly the same amount of atmosphere, hour after hour and day after day. This feature of the pole provides one way to confirm that you have found it -- if the altitude of the sun does not vary over the course of the day, you must be either at the north or south pole. Early explorers relied on this method. Of course, you have to make the measurements very precisely, because the amount of altitude variation gets smaller and smaller the nearer you get and it is not easy to "see" if you are a few km away from the true pole. Now we have new tools, including satellite positioning systems, that can help find the poles as well, but sun shots would still work. ***************************** DIFFERENCE BETWEEN POLES ***************************** __________ QUESTION: What is so different between Antarctica and the North Pole? ANSWER from Craig Mundell on December 19, 1994 There are a lot of differences between Antarctica and the Arctic (the North Pole). The biggest difference is probably that Antarctica is a continent, just like North America, and the Arctic is just ice without a land mass beneath. Another difference is that the Arctic region has an indigenous (native) population whereas Antarctica does not. The only thing that was originally on Antarctica is animals. Antarctica has seals, penguins, orca whales and skuas (a type of bird), but does not have polar bears like the Arctic. In addition, each area has its own kind of lights during the nighttime. Antarctica has the "Southern Lights" while the Arctic has the "Northern Lights," both of which are very beautiful to see. Also, you can see totally different stars in the sky depending on which area you visit. Antarctica is also dryer and colder than the Arctic. The Antarctica continent is considered to be a desert climate since it is so dry. Also, the coldest temperature ever recorded (about -128 F.) was in Antarctica at the Russian Base, Vostok. ANSWER from Eugene Miya on June 8, 1995: This is a GREAT! question. I would add only one thing to Craig's note. I have been to both the Arctic and the Antarctic, and I think the most dramatic difference between the North and South polar regions is that when you stand outside on a clear day: In the North: the Sun circles the sky in a clockwise direction In the South: the Sun circles the sky in a counter-clockwise direction. This is a real difference and you can see it every day. It takes 24-hours for this to happen, so it's subtle (it takes all day). For this reason I have become a firm proponent of the superiority of globes (real 3-D models) over maps or even computer screens. You have to image your orientation standing at either Pole and think about how the Sun appears to move with respect to the sky and the land (use stick figures or small dolls). This goes to support the idea that the world isn't flat and that a sphere is the easiest geometric object to show this. You don't need to be at either Pole to see this, just close enough. Similarly, the winter/night sky has a different set of stars and those stars in common with the Northern sky have a different orientation. **************************************** COMPARED TO POLAR ICE CAPS ON MARS **************************************** __________ QUESTION: How similar is Antarctica to the polar ice caps on Mars? ANSWER from Deane Rink: I would imagine they are pretty similar, but I'm not sure. I think the NASA scientists feel that Mars was once as geologically active as Earth and had running water. Now it appears that that activity has slowed down or stopped, whereas on Earth, it still continues. The polar caps of Mars contain ice, but it may not have exactly the same composition as frozen water ice in Antarctica. I do know that other bodies in the solar system have ice on them made of frozen methane; you would have to consult a planetary astronomy text to determine if scientists know what the Mars ice caps are composed of.