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Although I misunderstood M.M.'s question, it did lead
me to find some great information on the moons in our solar system.
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From:
http://science.howstuffworks.com/46011-our-amazing-solar-system.htm/printable
: "And speaking of our moon . . . the number of planets in our solar system is almost nothing compared to the number and variety of moons that revolve around every planet except Mercury and Venus. Scientists think our moon may have been ripped from Earth in a gigantic collision billions of years ago. Titan, the mega-moon that orbits Saturn, has its own atmosphere of nitrogen. It may also have lakes and possibly even its own continents. One of Jupiter's moons is the volcanic Io, whose surface is constantly being flexed by Jupiter's gravity. Another of Jupiter's moons is Europa, a striped ice moon. But scientists think it may have vast oceans underneath its icy crust. Neptune's moon, Triton, has geysers of nitrogen spewing through a layer of nitrogen ice. Triton's pockmarked surface looks like the skin of a cantaloupe. In addition, it orbits Neptune in a backward direction called "retrograde," and may eventually spiral close enough to Neptune to be torn apart by the planet's gravity. Phobos, one of Mars's moons, may, millions of years from now, crash into the surface of the Red Planet. The moons that orbit the planets in our solar system fall into two categories: icy or rocky. Rocky moons, as the name suggests, are moons made mostly of rocky material like our own moon. Icy moons are made mostly of ice, which can be frozen water, or ice made of other materials. There are only eight planets in our solar system, but there are more than a hundred moons. Scientists believe that our moon and possibly other moons in the solar system were created when a large object such as an asteroid collided with the parent planet. Some may have been asteroids that got caught up in a planet's gravitation pull. Still other moons were probably formed from material left over when the planets were formed in the early days of the solar system. Saturn has moons that are part of its magnificent ring system. Most moons have craters, which show that our early solar system was a crowded place with objects crashing into one another. The smaller object in the crash is usually destroyed, but the larger object is often left with a crater. The asteroids, comets, stars, shooting stars, meteors, and moons make our solar system a beautiful and lively arena." More than you ever need to know about our moon ! http://www.nasa.gov/worldbook/moon_worldbook.html Moons of the Solar System High Resolution Lithograph (download this): http://www.nasa.gov/pdf/145744main_Solar.System.Moons.Lithograph.h.pdf Fantastic site giving details about the various parts of our solar system. Broken down into planets, Sun, Moon, etc. , including info on moons of various planets: http://solarsystem.nasa.gov/planets/profile.cfm?Object=SolarSys
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| When we talked about the temperatures in the deepest mines, S.M. wondered how high a temperature the human body could tolerate. |
It was hard to find the answer to this. There is clearly a difference between the temperature we can tolerate for a while (e.g. standing in the noon day sun in the middle of the Sahara desert) vs. the temperature which your body could potentially heat up to (i.e. a fever). Apparently, when your body reaches a temperature of 44°C you will most certainly die. Incredibly, some patients have been able to survive a temperature of 46.5°C. For a breakdown of what happens to you at various body temperatures, visit http://en.wikipedia.org/wiki/Thermoregulation. There you will also find out how where you place the thermometer will affect what temperature is recorded! |
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| J.L. wondered about the relationship between gravity and magnetism. |
At http://helios.gsfc.nasa.gov/qa_gp_elm.html#emgrav a NASA scientist answers that question. |
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| Some time ago D.W. asked me why jade sometimes feels cold and sometimes feels warm. That question had me stumped for a while but I finally found a source that may hold the answer. If your jade is warm, the news is not good ... |
"Jade comes in many colours including white, red, yellow, green, lavender and black; within these colors there are different tones and grades. When searching for jade, there are a few things to look for: richness in color, evenness in color, clarity, size and workmanship. The richness and clarity range from transparent to opaque with the highest quality having a consistent clarity like honey. Textures range from fine to coarse and the highest quality will be clear and free of impurities. Stay away from jade that have crack lines from the front to the back. If the jade feels warm to the touch is it probably fake and made from remolded plastic or resin. Under a 10x lens, you can also see air bubbles and fold lines in fake jade. If you pay under YY1,000 for a piece of jade jewelry , it will not be high grade and was probably dyed or color enhanced to make the look or design more appealing." Source: CityWeekend.com |
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J.K. sent me an email asking about the temperature
in caves: "In class we were talking about how it gets warmer the further down you go in the earth, and that's why mines can't be deep and stuff. BUT . . . what about like caves and things . . . like, the lava cave I was in during the summer, it was freezing cold in there, but it's still going underground. So why does that happen? When does it start to get hot?" |
My reply:
The geothermal heat gradient is 15-30 °
Celsius per kilometer. That is to say, for every kilometer deeper you go,
it gets 15-30 ° C hotter. The lava cave you were in was just below the
surface. You certainly didn't go down a kilometer, right? Caves,
although underground, are cold because they are sheltered from the heat of
the sun. It's sort of like standing in the shade, it's cooler than
standing in the direct sun. The same effect can be felt in an underground
parking garage or a basement. They are usually cool as well. So,
although caves and mines are underground, the ones that they let the
public into aren't usually deep enough for you to start noticing the
effect of the geothermal heat gradient. Without the heat of the sun
getting into them they feel cold. |
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| If gold has a gold streak, why does gold jewellery sometimes leave a black mark on your skin. | Gold jewellery is actually made of gold alloys meaning that it is a mix of gold and other base metals like copper, silver, zinc, etc. When the gold jewellery is made of a low 'carat' gold alloy (e.g. 10 carat, 14 carat) the other metals can oxidize ('rust') when they are exposed to acids in perspiration or the atmosphere. It is these oxides which, when they rub off on your skin, look black. (Source: http://www.24carat.co.uk) | ||||||||||
| Freezing point of mercury |
To learn more about mercury check out this
interesting site:
Some other sites that present interesting information about mercury: Canadian Food Inspection Agency - Food Safety Facts on Mercury |
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| Finding lakes under Antarctic ice (Lake Vostok) |
Lake Vostok was found using ice
penetrating radar. The University of Texas' Institute for Geophysics has a web page that explains how ice penetrating radar works in VERY simple terms. Here are two links to NASA articles on Lake Vostok. Check out the links to find out why NASA is interested in these lakes. |
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| Rare earth magnets |
Rare earth magnets are
really strong for their size. They are made from the 'rare earth
elements' as listed on the periodic table.
Here are some websites you can check out for more information:
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| Flint |
Flint is a sedimentary rock composed of the
skeletal remains of marine microorganism which make their shells out of
silica plus some impurities which discolour it. In fact, flint is
the common name for black chert.
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Soapstone
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Soapstone is a metamorphic rock. It is actually a talc
schist.
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| Deep mines |
They're deep and they're hot!
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