f you’re one of the lucky ones living across a broad swath of the
United
States from the
Pacific
Northwest to north
Texas, you’re in for a rare treat this evening.
It’s called an “annular solar eclipse,” which happens when the moon slides
over the sun, blocking out the center and leaving a glowing ring called an
“annulus.”
We could get into “umbra,” “penumbra,” and “antumbra” but you’ll have to
Google
those yourselves. The main thing is, the difference between an annular solar
eclipse and a total eclipse of the sun has to do with how far away the moon is
from the earth.
The closer to the earth it is, the larger the moon appears – blocking out
more of the sun. When the moon is farther away from the earth, it appears
smaller, leaving that “ring of fire” when it appears to pass in front of the
sun. Right now, the moon is at its greatest distance from the earth, hence an
especially wide fiery ring.
Actually, it’s not only Americans along that swath who’ll be able to witness
this very occasional solar-lunar event. (The last one was in 1994.)
It’ll start in southern
China, then move across the southern coast of
Japan,
crossing the Pacific just south of the
Aleutian
Islands before hitting the US near the
Oregon-
California
border. (Speaking of “ring of fire,” the Aleutians are part of another “ring of
fire” – the volcanic rim around the Pacific from
South
America to
New Zealand. It has nothing to do with
Johnny Cash,
however.)
These
graphics by the United Kingdom Hydrographic Office are especially good.
The main advice in observing this evening’s annular eclipse and its “ring of
fire” is be careful.
Ron Hipschman, who describes himself on
Twitter
as the “loose cannon at the Exploratorium” in
San
Francisco, offers this warning:
“As a kid, did you ever take a magnifying glass out into the sun and burn
leaves? If so, you probably remember that when the focused sunlight coming
through the lens was refracted and concentrated to a small spot, the energy
available there was truly remarkable. Guess what? You have a lens just like
that in your eye. If you look at the sun, your eye-lens will concentrate the
sun's light and focus it to a very small spot on the back of your retina. This
can cause permanent eye damage or blindness. Additionally, there are no pain
sensors back there so you won't even know it's happening! Have I scared the
willies out of you? Good!”
On
this
website, Mr. Hipschman gives directions for safely observing any solar
eclipse.
As you might have done in your junior high school science class, you can
build a pinhole projector using a long box, a piece of aluminum foil, a pin,
and a sheet of white paper. What a great opportunity to do something with your
kids!
This site shows how to build such a projector using a
dark-colored plastic cup, wax paper, scissors, a rubber band, and a pushpin.
The
Clark Planetarium in
Salt
Lake City has good directions for making a simple pinhole projector
here.
“Getting even more basic, you can use your own hands,” Hipschman explains.
“Just hold up both hands with your fingers overlapping at right angles. The
holes between your fingers make pinholes.”
Clark Planetarium director Seth Jarvis says forget about the old suggestions
of putting soot from a candle flame on a piece of glass, using exposed black-and-white
film, or doubling up on sunglasses. None offer adequate protection, and he
recommends against trying to use welder’s goggles to peer at the sun unless
they are rated for arc-welding (at least grade 14).
So enjoy this evening’s light show, but do it carefully.
LOS ANGELES — He already has a Super Bowl ring, and now football star Donald
Driver can add the "Dancing With the Stars" mirrorball trophy to his
awards collection.
