MARCH 1998
MARCH STAR MAP |
INDEX
- 079a
MARCH 1-4, 1998: Occultation of Aldebaran
- You may recall the close encounter that Saturn experienced last November 11,
when the moon slid under the Ringed World. It was a beautiful sight amidst the
scudding clouds of a late, warm autumn evening. This Wednesday, Aldebaran, the
reddish eye of Taurus, the Bull, is posed for a direct "hit" when it passes
behind the Queen of the Night at approximately 7:35 p.m. Unlike the Saturn
observations, where the moon was nearly full and extremely bright, the moon,
this time, is a fat crescent and far less obtrusive. Aldebaran, the 13th
brightest star of the night, is also occulted against the moon’s unlit surface.
This will simplify observations through telescopes and binoculars by making
Aldebaran much easier to spot. The Mid-Atlantic and Northeast will have the
best vantage points because it will be completely dark throughout the entire
event. Aldebaran reappears from behind the sun-washed surface of the moon
approximately 50 minutes later, about 8:25 p.m. If you would like to watch
this event unfold, start observing the crescent moon tonight and watch as it
moves towards Aldebaran over the next several evenings. Bright Aldebaran
can be located by following the line created by the three belt stars of Orion,
the Hunter. Continue upward along this path about 2-1/2 clenched fist widths.
Start observing at least one-half hour before Aldebaran is occulted.
-
- 079b
MARCH 5-6, 1998: Finger Angles
- When people try to explain the separation between objects in the sky, they
often use terms like, "they were about two inches apart." This is very common
for UFO sightings because most of these observations are make by individuals
with little or no training in sky observations. The heavens are considered
to be a dome over our heads, and as such, distances measured between stars or
the heights of objects above the horizon must be measured as angles. There are
90 degrees between the horizon and the zenith, the point directly overhead, and
360 degrees around the horizon circle, which is where the sky "touches" the Earth. The
hand and various fingers held at arm’s length are marvelous tools for measuring
angular separations. The index finger covers about 1 degree of sky, while the entire
fist when held in a clenched (fighting) position covers about 10 degrees. Use the
index, middle, and fourth fingers to hide about 5 degrees of sky, while the pinkie
and thumb spread to their maximum extent reach across 25 degrees of the heavens.
The index and pinkie fingers span about 15 degrees. That last one, I still can’t
perform well, nor can I make the famous Vulcan "V" with the index/middle
fingers separated from the fourth and pinkie. Enough of this finger manipulation,
I’m getting a bit nervous. More about this in two weeks.
-
- 080
MARCH 8, 1998: Venus Ablaze
- With the full moon occurring on Friday, the 13th, the landscape and sky will
be flooded with light. It is once again time to focus upon other bright celestial
objects. The best of them all is the planet Venus, third brightest object in the
sky, after the sun and the moon. Last December, Venus was a striking object in
the early evening sky, becoming visible even before sunset, if you knew just
where to look. Venus was to the east of the sun. Then Venus disappeared as
its orbital motions carried it between the Earth and sun to reemerge in the
morning sky, west of Sol. By early February, it was ablaze in the southeast
through leafless trees as I helped carry my wife’s book crate to the car, prior
to her 6:45 a.m. pilgrimage to school. Venus’s western elongation (distance)
from the sun has now increased so that the planet rises about 4 a.m., over two
hours before the sun appears. If you want to see Venus and understand why the
ancients called her the goddess of beauty, check her out about 5:45 a.m.
low in the east, southeast, a dazzling beacon of reflected sunlight. A partial
penumbral lunar eclipse also occurs on Thursday, the 12th. Maximum immersion
happens at 11:20 p.m. From certain parts of the moon, one would see the Earth
hiding upwards of one half of the sun’s disk. However, from the Earth, you’ll
basically be unaware that anything is happening.
-
- 081
MARCH 15, 1998: Dipper Angles
- Two weeks ago, I spoke about using your hand and fingers as angle
measuring devices. The separations between celestial bodies in the sky
are all measured as angles, not as a linear distances. At arm’s length
your index finger equals 1 degree; a clenched fist is 10 degrees; index, middle, and
fourth fingers 5 degrees; while your pinkie and index fingers spread wide is 15 degrees;
pinkie and thumb extended, 25 degrees. The stars of the Big Dipper, now visible
in the northeast during the early evening hours, can be used to provide
us with a "hands on" experience. The Dipper’s position at 7:30 p.m. is
handle down, bowl up. Let’s number the stars of the Dipper starting
with the lowest of the handle stars as one. Following the arc of the
handle to the bowl and upward to the two pointer stars finishes the
count at seven. Now we are ready to examine how handy our hands really
can be. The angular separation between stars 1 and 7 is 25 degrees, between
stars 3 and 7, 15 degrees, and between stars 4 and 7, 10 degrees. The pointer stars,
6 and 7, which lead you to the North Star are separated by 10 degrees. The
angular measure between star 7 of the Dipper and the North Star is 28 degrees,
a little more than the span between your pinkie and thumb spread wide.
Be sure to take off your gloves to increase your accuracy and to experience
some of the true joys of late winter observing.
-
- 082
MARCH 22, 1998: Dipper Directions
- If you are a weekly reader of this column, then you know that the sky talk lately
has been about the Big Dipper. It is such a handy grouping of stars. Last Friday,
at 2:55 p.m. the sun crossed the celestial equator and spring was sprung. For the
week surrounding the Vernal Equinox, the rising and setting positions of the sun
are almost due east and west respectively. They are good locations to know since
we spend so much time navigating around in our cars. The Big Dipper can also
provide you with a similar homing capability at night. Presently, high in the
northeast after evening twilight, the two pointer stars (top of the bowl) lead
you left to the North Star. Extending a line segment from the Pole Star to the
horizon points you directly north. Now make a quarter turn to the right
(clockwise) and you’re looking east; another quarter turn, south; another
quarter turn west; and a final quarter turn to return to north. Keep in mind
the mnemonic device, "North never Eats Soggy Waffles." That’s what I did when
I got lost on the first date with the woman whom I was destined to marry.
Disoriented and nervous, I pulled over on a dark deserted road to get my
bearings. Thank goodness, it was clear with the Dipper and North Star plainly
visible, or who knows what "direction" my life would have taken! She was duly
impressed with my navigational expertise, and I knew the second date was in the
bag!
-
- 083
MARCH 29, 1998: Whirling Sky
- The Big Dipper is high in the northeast during the earliest part of evening,
with its two uppermost pointer stars in the bowl leading you downward and to the
left, to the North Star or Polaris, nearly midway up in the sky. Its location is
less than one degree from the true position where the Earth’s axis points, the
true position about which the sky wheels. This makes the position on the horizon
directly beneath the North Star an excellent indicator of the true direction north.
Note the location of the Pole Star and the other stars around it. Then go out
several hours later and observe how the sky has changed, everything circling slowly
around Polaris. This effect is created by the rotation (spinning) of the Earth on
its axis. You can create the same illusion by simply leaning back and fixing your
gaze on any bright star nearly overhead. Your body is now the Earth, and the star
overhead is the location to which your axis points. Spin slowly, and note how
all of the other stars pinwheel around it, creating the same circular motion
that is evident in the sky. Just be careful when you straighten up. The first
time I demonstrated this lesson with my students in the darkness of the
planetarium, I became disoriented. Unable to tell up from down, I immediately
"fell" victim to the force of gravity. Needless to say my students were highly
amused by my "crash and burn" acrobatics. The lesson, however, was a smashing
success.
-