Christmas is a time of reflection, a time to think deeply about some of the important questions the Yuletide brings to mind. For example:
Q. How come Christmas trees keep sucking up water even after they’ve been cut down?
A. A tree slurps up six or seven litres when you first put it up, and as much as a litre or two a day thereafter. This seems like strange behavior for something that’s dead; but of course, the tree doesn’t realize that it’s dead.
Trees draw water up into themselves, whether from their roots or from a little red-and-green metal stand, because of evaporation. The needles constantly lose water to the relatively dry atmosphere. The cells in those needles contain large cavities called vacuoles, designed to hold water. As water evaporates out of the cell, the cell draws more water into the vacuole from other cells deeper inside the tree. Eventually this leads to the tubules, like tiny pipelines, in the trunk, and from there it’s more or less direct to the water supply. Unfortunately, the amount of water it can draw up its trunk doesn’t come close to the amount it needs, and without its root system (which has access to far greater amounts of water because of its much larger surface area), it eventually dries out and dies for good.
Q. Why do Christmas tree balls and tinsel sparkle?
A. Christmas balls sparkle because they’re essentially spherical mirrors, and a spherical mirror has an interesting property: some of any light that strikes the half of the sphere you’re looking at will be reflected into your eye. As a result, a Christmas tree ball will reflect light, not just from a Christmas tree light that happens to be close to it, but from other lights on the tree, lights in the room, even the fireplace. Its shape also means, however, that most of the reflected images are quite small, which add to their sparkling, star-like appearance.
Tinsel sparkles because it consists of lots of reflective strands pointing in many different directions. At any given time, some of those strands are reflecting light into your eyes and some aren’t. As you move, the strands that are in position to reflect light at you change, and so the tinsel seems to almost twinkle. (This is the same reason snow sparkles in the sunlight: the snowflakes are piled in many different orientations, so the ones reflecting light at you change as you move.)
Q. What the heck is mistletoe, anyway?
Mistletoe is a tree parasite–in fact, it can sometimes causes serious damage to its host. Although it contains chlorophyll and can therefore manufacture its own food, it has no roots, instead attaching itself to its host with sucker-like organs called haustoria, through which it draws out water and nutrients.
Q. And what the heck is eggnog?
A. Eggnog consists of milk or cream, sugar and eggs beaten together and often mixed with an alcoholic liquor such as rum or brandy.
Q. “Batteries not included” is a phrase sure to strike terror into the heart of a parent when discovered unexpectedly on a just-opened Christmas present. What is a battery, anyway?
A. A battery is a portable device for generating electricity through a chemical reaction. Inside the typical “flashlight battery” is a paste called the “electrolyte,” which is basically an acidic substance that conducts electricity. It does something else, as well; it causes two different substances immersed in it to gain or lose electrons, so that they take on opposite electrical charges. If you attach a wire–or a toy–to both of these substances (in a flashlight battery, a carbon post down the centre and the zinc casing of the battery itself), you can cause electrons to flow between them–and through your toy–in an attempt to balance these charges.
Q. I’ve heard of saskatoon berries, blueberries and raspberries, but what exactly is a cranberry?
A. The cranberry is a plant that grows in bogs and marshes in the northern U.S. and parts of Canada. It’s harvested by flooding the bog and churning the water to shake the fruit loose, then scooping it up as it floats to the surface.
There! With all these burning questions answered, you can forget about further reflection this Christmas and just concentrate on the holiday itself. Have a merry one!
