But I realize that some people don't have enough money to employ
researchers. So I'm here to offer you my services. When you have a question
about science, email
stevesax@yodellingllama.com, with "Steve Sax's Science Sack" in the subject
line. Then I'll send my crack team of investigators to work, interviewing
real life scientists and everything. Pretty neat, eh? Then I'll post the
results here.
My first question comes from my nephew, Peter:
Steve, what is the difference between a lunar eclipse
and a solar eclipse?
Petey, I had no idea that there even were different kinds of eclipses.
Color me red. Here we go:
A lunar eclipse occurs when the Earth blocks all sunlight from the moon.
See, the moon doesn't actually produce light. It only reflects it. Like a
mirror. Kind of. So when the moon is in the Earth's shadow, we don't see it.
Hence, an "eclipse."
A solar eclipse occurs when the moon blocks all the sunlight from the
Earth. This is what we normally think of as an eclipse.
You can also think about the difference in terms of the phases of the
moon. When we get a full moon, it is on the far side of Earth during the
night. When we have a new moon, it is on the near side of Earth during
the night. A lunar eclipse is basically a special (completely dark) version
of a full moon. Whereas a solar eclipse is a special case of a new moon.
Only during the day.
Did that help, Petey? I hope so.
My second question sort of comes from
Lore Sjoberg:
"[S]ilicon is a pretty good option [to carbon], for reasons I don't
really understand or care about."
Well, Lore, I wasn't even sure what you were talking about when I read
this. What is a "carbon-based life form"? How does a "silicon-based life
form" differ? (Oh, and since I'm stuck in March 1982, is the difference
due to cup size?) So I asked my researchers.
Apparently, all life on Earth is "carbon-based." Which means that the bulk
of the main molecules--simple sugars, lipids, amino acids, and
nucleotides--that collectively form life have carbon as a major component.
Why might this be? Well, because of carbon's atomic structure, it has
four free electrons in its outer-most valence. See electrons like to pair up.
If it had eight electrons in its outer-most valance, like neon, it would be
"noble" and wouldn't bond with squat because its electrons would all have
partners. If it had one, like lithium, it would only be able to bond with
one other atom. If it had six, like oxygen, four of its electrons
would pair up with each other and it would only have two little guys going
stag. But carbon has four. Which means it can hook up with four other
atoms. Neat! And convenient when you're making sugars like glucose
(C6H12O6) that involve quite a few atoms.
So why silicon? Well, silicon, like carbon, has four swingers, more than
most of its immediate neighbors. Why not germanium or some other atom with
a whole bunch of guys without dates? Well, my researchers suggested that most
other atoms are too big. Carbon is pretty small and common. Silicon is
a bit bigger, but still pretty small. You get some of these atoms that are
so big and complicated that they don't even exist in nature (I'm talking to you,
Erbium).
So that's it. Carbon and silicon are both pretty small, common and similar
in atomic structure in such a way as too allow big ol' molecules. Happy,
Lore? Of course not. You didn't care. But I did.
Until next time, this has been Steve Sax, relaying scientific information.
