Loadstar 18/018.d81/when.halley

Text File | 1985-01-01 | 5.0 KB | 304 lines

 When will Halley's Comet be visible?
 ------------------------------------

  First some bad news! The very best

viewing of Halley's Comet from planet

Earth will be from south of the

Equator (South America, South Africa,

Australia, etc.), due to the current

positioning of the Earth's axis rela-

tive to the comet.  In the Southern

Hemisphere, the comet will be, on the

average, higher in the sky for longer

periods of time than in the Northern

Hemisphere.

  But, don't despair! Comet Halley

WILL be in fairly good sky positions

in North America at certain times

during its visit. However, this leads

to...

   MORE BAD NEWS!

  When Halley makes its closest and

brightest approach to Earth in late

March - early April, it will be in

very poor position on the southern

horizon, making it barely viewable

from the southern states, and almost

completely unviewable from the Great

White North.


-----------------------------
Timetable for Halley Watching
-----------------------------

  For North American observers, there

will be 4 primary observation

'windows' during which Halley will be

viewable with the naked eye, assuming

the comet achieves anticipated levels

of brightness.  The 4 periods span

from December of 1985 to April of

1986.


Halley's Watch Period #1
------------------------

December 1 - 15, 1985
Inbound toward the Sun

  This period marks the first time

Halley's Comet has been seen with the

naked eye since July, 1910.  The comet

will appear as a faint, fuzzy speck in

the region of Pisces, just south of

the Great Square in Pegasus. It can

be found in the southwest sky about

half-way between the horizon and the

zenith (straight overhead), within an

hour after sunset.

  If a tail has started to form, a

pair of binoculars or a small

telescope should be able to pick it

out.


Halley's Watch Period #2
------------------------

January 1 - 25, 1986
Still inbound, ready to turn the
corner

  The first 12 days of January will

find Halley in the west-southwestern

evening sky free from interference

from the Moon.  From the 12th on, the

Moon will begin to increase in

brightness, thus making observing

more difficult.

  At the first of the month, Halley

will be approximately 30 degrees above

the southwest horizon (90 degrees

being directly vertical), and should

then be showing a short tail.  It

will be visible for about 2 hours

after sunset. However, with each

passing night, the comet will set 6

minutes earlier, thus allowing only

30 minutes of decent viewing by the

12th.

  By the end of this period, Halley

will be located in the western sunset.

It will actually be only 2 weeks from

reaching 'perihelion' on February 9,

its close encounter with the Sun in

which it swings around and starts its

outbound leg.


Halley's Watch Period #3
------------------------

March 8 - 21, 1986
Outward bound, heading our way

  Halley re-emerges from its swing

around the Sun and begins to appear

low in the southeastern morning skies

just before sunrise.  However, the

comet will be only 5-10 degrees above

the horizon, sadly making it difficult

if not impossible to view. Neverthe-

less, it is likely that Halley will be

supercharged from its recent encounter

with the Sun and will be sporting a

bright tail.  Viewers in the mid- and

southern U.S. may get a fair glimpse

of the comet or part of its tail low

on the horizon as it makes a gradual

sojourn towards the southern horizon

during the month.

  By the end of this period, the Moon

will begin to dominate the sky, hin-

dering what little chance of viewing

is possible.

  During this period, 6 different

space probes will be making close ap-

proaches to Halley's Comet, performing

a wide assortment of data collecting

and picture taking.  We will discuss

the details of these probes in an up-

coming issue of LOADSTAR.


Halley's Watch Period #4
------------------------

April 2 - 13, 1986
Close Encounter of the
Extraterrestrial Kind!

  On April 11, Halley's Comet will

reach its closest point to the Earth

during this visit, being approximately

37 million miles away.  This is a far

cry from the stunning visit in 83

A.D. when Halley came within 3-4

million miles of Earth, exhibiting a

double tail that stretched from one

horizon to the other, shining

exceedingly bright!

  During this period, Halley should

be readily visible on the southern

horizon from the southernmost

latitudes of the continental U.S.

The farther north you live, the less

your chance of seeing the comet at

all!  The tail may be as long as 25

degrees and, therefore, may be seen

sticking up over the horizon in some

places.

  The comet will be at its highest

point above the horizon (8-10 degrees)

starting at sunrise at the beginning

of the period, backing up 30 minutes

with each subsequent night.  By the

13th, Halley will be at its highest

point around midnight.

  By the 13th, the Moon will begin to

brighten the night sky.  However,

Halley should remain distinctly

visible in spite of the lunar

interference.


-----< continued in next article >----