Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

Re: occultation



=09Yes, I did watch the occultation of Aldebaren, but not by good pla=
nning. At about 9:45,=20
after looking at Hale-Bopp through binoculars, I glanced over to the =
crescent moon and noticed=20
its proximity to Aldebaren. A closer observation lead me to guess th=
at there would be an=20
occultation so I kept an eye on the development. It really was surpr=
ising to me how fast the=20
moon moves. The occultation occured at about 10:38 =B1 2 min on my c=
lock.

=09Shortly after the occultation, the sky to the north and north-west=
lit up with a=20
spectacular display of aurorae. The solar flare on Tuesday really di=
d its thing. The auroral=20
display far surpassed the occultation in every respect as it danced a=
bout Hale-Bopp. Hopefully=20
there will be another display tonight.

Paul Williams
Red Deer, Alberta, Canada


--------------
=46rom:=09IN%"phys-l@mailer.uwf.edu" 11-APR-1997 12:30
To:=09IN%"PHYS-L@atlantis.cc.uwf.edu"
CC:=09
Subj:=09occultation

I was wondering if anyone on the list saw the lunar occultation of
Aldebaran last night? At least two of us here at Weber State did--Jo=
hn
Sohl and myself. Neither John nor I ever recall seeing an occultatio=
n of
such a bright star, and it was a spectactular happening!

According to my clock, the occultation began at 10:45 p.m., MDT last
evening (Apr. 10). That is when the leading (i.e., dark) edge of the=
moon
went in front of the star. The crescent (3-day old) moon was still s=
ufficiently
high above the horizon from Ogden, Utah, at the time, so it was easy =
to
see.

Some time ago the question was raised on the list about simple ways t=
o
measure the size of the earth using the sun. This occultation can gi=
ve a
way for students to estimate the speed, orbit radius, and size of the=
moon, if
we can get timing information from different parts of the country. T=
here are
several motions occuring all at once, of course, and they would all h=
ave to
be factored into the calculation. The main effect is the orbital spe=
ed of the
moon--roughly its diameter every hour, or 2000 mi/hr. Then the rotat=
ion of
the earth--roughly 800 mi/hr at 41 degrees North latitude--is in the =
same
direction. So, the "shadow" of the moon only moves across the surfac=
e
about 1200 mi/hr or so. Anyway, we can figure all these things out =
if
anyone else can provide additional data points to go with the one abo=
ve.

Let's hear it from anyone who witnessed last night's occultation. It=
should
have been easily visible from the west coast and all of the Mountain =
time
zone, maybe even into the western part of the Central time zone, thou=
gh
the moon would have been pretty low there at the time of occultation.

Rondo Jeffery, Weber State University, Ogden, Utah
RJeffery@weber.edu