What's a Trillion to CNN?
Clearly CNN has remained untaunted for too long. Perhaps they have decided to get revenge on me for my previous complaints about their innumeracy and lack of rounding prowess by running this stunningly preposterous item. Or perhaps they picked up this dog's breakfast of ridiculous numbers verbatim from Reuters. Either way, they are to blame, and I shall be charging them, along with society, of course. Copyright be damned, it's a short article and almost every paragraph is afflicted with a greater or lesser howler. I quote it in its risibly erroneous entirety.
LONDON, England (Reuters) -- A huge daisy-shaped shield that would block out light from parent stars could be used to find Earth-like planets in other solar systems, an American astronomer said on Wednesday.
I don't imagine he's proud to be an "American Astronomer" after
reading how they described his project.
Of course that's not exactly what it is. It's actually a pinhole lens with a 30-foot hole in the center. But what's a crucial detail or many? However, according to Google, which provides answers in seconds and doesn't require you to develop "sources," 50 yards = 45.72 meters, or properly rounding, 46 M. Not a critical or even significant error — I'm sure the 50 yards is a gross approximation (the "football field effect"), but why not get it right?
Finding other planets is
very difficult because their parent stars are about 10 times brighter.
The earth has a radius of 4,000 miles, and thus a circular area of about 50 million square miles. (Of course the earth is spherical, but we're talking about the effective area that intercepts sunlight.) The earth's distance from the sun is 93 million miles, and the sun radiates its energy in all directions, i.e., spherically. So the light intercepted by the earth is a percentage equal to the surface area of a sphere with a radius of 93 million miles, which is 1.08*10^17 square miles divided by 5*10^7 square miles. This would mean that the brightest the earth can be is about two billionths of the brightness of the "parent star." So their number is off by more than factor of a billion. The earth's "albedo" or reflectance is less than perfect, too, as presumably are those of planets around other stars. This, I think, makes the extreme difficulty of the task more apparent than the one-tenth mentioned in the article.
"We think this is a
compelling concept, particularly because it can be built today with
existing technology," said Professor Webster Cash of the University of
Look! Another trillion! The space shuttle orbits
hundreds of miles above the earth. Our communications
satellites orbit thousands of miles above the earth. The
moon is about a quarter of a million miles up. The outer
planets, which only a tiny number of probes have reached after decades
of travel, are single-digit billions of miles away. But
look! We're going to send this project a trillion miles, a
good fraction of the distance to the nearest star, just to look for
planets. I wish! If we could do that, or even a tiny
fraction of that, we would have colonized the planets already and not
just be looking for them. A trillion miles, incidentally, is about
two light-months. At that distance, if we sent a command to
the telescope it would receive it in two months and we'd get our reply
two months later. Again I don't actually know the distance of the
but it is most likely to be somewhere in the high thousands to the very
low millions of miles. That's a factor of about one million off from the
silly number in the article, the equivalent of provisioning the Nina, Pinta, and Santa Maria to borrow a cup of sugar from your neighbor.
While they have missed the whole point of how the system works — it's a lens, not properly a shield, at least they've managed to produce a paragraph that has a number in it that isn't obviously wrong. The telescope is unlikely, for instance, to have three trillion thrusters Even so, I have no faith the "three" is correct after having seen the other bizarre numbers. I wonder how many thrusters it really has.
So much for CNN.
Fortunately we have the stately Wall Street Journal (05 July 2006, page A17), whose journalists and editors meet a much higher standard, and produce far better researched items, such as this excerpt about the new Chinese train that travels at high altitude to Tibet.
I checked the original article and they fixed the orbit:
And, when I checked a day later, they "fixed" the