Saturday, December 18, 1999
12/18/99 7:26:14 AM
Behind the bright full moon.
Surely you've seen the email about the full moon coming on
December 22. By a rare conjunction of the full moon with the
winter solstice and the lunar perigee, it's supposed to be
a once-in-a lifetime moonrise, according to the Old Farmer's
Almanac. TBTF Irregular and crack Web historical researcher
EM Ganin traced the roots of this much-forwarded meme and found
offering some balance to the story of the "brightest full moon
in 133 years."
In September 1998, the Old Farmer's Almanac published their 1999
edition. It contained an article enttitled "The Astonishing Lunar
Illumination of December 22, 1999" by Randy Miller.
At some point this past summer, the Almanac editors
posted the article
on their web site.
Someone lifted the story and sent it around in email to their friends.
As the summer turned to fall, the story gained momentum. It hit the
newsgroups no earlier than December 1st (the oldest copy I can find on
DejaNews). In the last week, the story spread by private email to many
thousands of people. It reached the national media in the last few days,
with articles in newspapers and TV spots.
The Web search engines have no record of the story other than the
Farmer's Almanac entry. HotBot recorded the Farmer's Almanac URL on
November 17th. Other search engines also index the Farmer's Almanac
story but don't list a date. No date is listed on the Farmer's Almanac
web site either, but the context
of the parent article indicates that it was posted before September 14, 1999.
All of this implies that the search engines can't keep up with the
growth of the Web. Alta Vista, HotBot, NorthernLight, Google,
DirectHit, Lycos, Yahoo, Webcrawler all have not yet indexed relevant
articles that discuss (and refute) some of the claims made in the
Almanac story. Examples are:
Robot-based Web search engines appear to be a bad choice for anyone
looking for information on current events.
-- EM Ganin
Wednesday, December 15, 1999
12/15/99 10:45:09 PM
FDA approves lenses to correct colorblindness.
TBTF Irregular Eric Scheid notes that ColorMax Technologies has
approval to sell its color enhancement lenses in the US. After
proper prescription and fitting, the lenses are said to improve
color discrimination in 95% of colorblind people (who number 12M in
the US, 250M worldwide). How the lenses work is not obvious to me
from reading this passage:
ColorMax Lenses alter the spectral energy composition of the
retinal stimulus to enhance color vision discrimination. Each
lens attenuates specific portions of the visible light energy
spectrum in one of five different attenuation configurations.
Each attenuation configuration alters the spectral energy
distribution of the retinal stimulus to permit enhanced color
discrimination in the area of the visible spectrum where
wavelength discrimination is reduced.
12/15/99 6:02:05 PM
12/15/99 5:08:15 PM
12/15/99 3:16:50 PM
Galaxies' dark-matter halos far larger than suspected.
See this NY
Times article (free registration and cookies required) for an an
important new finding from the Sloane
Digital Sky Survey. Each galaxy is embedded in a sphere of dark
matter, and people have been trying for two decades to determine the
size and mass of these invisible galactic "atmospheres." (It is not
known whether the dark matter consists of burned-out stars, brown
dwarves, exotic particles, or what exactly.) The dark matter was
first inferred from the rotation rates of galaxies -- most of them
are spinning too fast to hold onto their stars, so something besides
the starstuff must be adding to the gravitational pull of the
Researchers from the University of Michigan used early SDSS data to
look for the gravitational bending of distant galaxies' light in the
dark-mater halos of nearer galaxies. They found that, on average,
a galaxy's halo is 1.3 million light-years in diameter and contributes
to a total mass equivalent to 5 trillion suns
Our galaxy is pretty typical. It's a fat spiral disk about 100,000
light-years across, consisting (as far as visible matter goes) of
around 100 billion stars. According to the new research, its dark
halo masses 50 times more than all the matter we can see. We can
picture the Milky Way as a quarter-dollar coin at the center of an
The SDSS observatory
is in New Mexico, 9150 feet above sea level. The 2.5-meter telescope
uses 6 strips of CCDs to record a large swath of the sky in mosaic
form. The telescope stares fixedly into the sky and the earth's
rotation positions it for each successive image. In a single image
the telescope can drink in a piece of the sky the size of the Big
Dipper's bowl. Over 5 years the SDSS will map in detail one-quarter of
the entire sky, determining the positions and brightnesses of more
than 100 million objects. It will also measure the distances to more
than a million galaxies and quasars. SDSS is in test mode now -- its
early results, the "commissioning data," represent less than 3% of the
torrent that the project will eventually pour upon astronomers' heads.
Here is a tiny piece of the Sloan telescope's
image (165K), captured last May. The entire image is 5,000 times
Monday, December 13, 1999
12/13/99 11:55:07 AM