THE SOUTHWORTH PLANETARIUM
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43.6667° N                   70.2667° W
Altitude:  10 feet below sea level
Founded January 1970
Julian date: 2458780.16
2019-2020:  XXXVIII
                   "Nearer the gods no mortal may approach."
                                  -Edmond Halley


THE DAILY ASTRONOMER
Thursday, October 24, 2019
Rober Carolinum

[image: Edmond_Halley_072.jpg]
*Edmond Halley*
(1656-1741)

In December 2023, Halley's Comet, the most famous of all the ice-encrusted
interlopers that periodically infiltrate our inner solar system, will reach
aphelion, its farthest point from the Sun, at a distance 35 times greater
than Earth's average heliocentric distance.   After reaching this far
point, the comet will slowly swing around and begin a long, initially
lethargic trek back toward the Sun. It's due to adorn our night sky again
in 2061.

It is from this comet's renown that the British mathematician/astronomer
Edmond Halley (1656-1741) derives most of his posthumous fame.     He was
the one who first proposed that the comet, which was first recorded by
Chinese astronomers in 240 BC and which appeared in various texts in
subsequent centuries, most notably in 1066 AD during the time of the Battle
of Hastings, was actually the same comet that revisited the inner solar
system every 76 years or so.   In late 1759, the comet reappeared, just as
Halley had predicted.  (Halley died eighteen years prior to its predicted
return.)   From that time on, the comet has borne his name.

What is less known is that Edmond Halley made another attempt to place his
personal stamp indelibly onto the firmament.  He created the constellation
known as Rober Carolinum, "Charles' Oak."    Have you heard of it?    No
worries.  It doesn't exist, anymore.  In fact, it only lasted about 50
years.  This constellation, composed of stars now comprising the ship
constellation "Argo Navis," didn't last principally because Halley was
motivated more by political flattery than artistic impulse.


[image: robur.jpg]
*Rober Carolinum "Charles' Oak." * A now extinct constellation here
seen in Johannes Bode's 1801 Uranographia.    Bode labeled it
Rober Caroli II.   Bode's Uranographia was the last publication to
contain Halley's constellation.

Halley developed this constellation in 1676 to honor English king Charles
II.  This king had lived in exile for years following the House of Stuart's
defeat in the English civil war, a war that during which his father,
Charles I, was executed in 1649.   During Charles II exile, England was
governed first by Oliver Cromwell and then, briefly, by his less formidable
son, Richard.   Richard ruled for less than a year, which allowed for the
prompt restoration of the monarchy in 1660.

[image: Selection_766.png]
*Charles II. * Started his reign in 1660 after he spent
years in exile during the Cromwellian period.


The constellation Rober Carolinum was supposed to depict the tall oak in
which Charles Stuart, as he was then known, hid following his disastrous
loss at the Battle of Worcester in 1651. After this battle the Civil War
ended with the Roundheads prevailing over the Cavaliers.

Halley mapped out the constellation's component stars following a visit to
St Helena he made in order to observe the southern sky.   In 1678, he
published his catalog, "Catalogus Stellarum Australium," (Catalog of
Southern Stars) which included this newly crafted constellation.  Halley
intended is as a permanent stellar monument to glorious king.      However,
it was not last.   Within less than a century, French astronomer Nicolas
Louis de Lacaille developed a more comprehensive map of the southern sky.
He erased all traces of Rober Carolinum from his maps and restored the
stars back to the Argo Navis.

Although Johannes Bode made a valiant attempt to establish Halley's
constellation as a fixed structure by including it in his 1801
Uranographia, Rober Carolinum soon vanished from all maps and joined the
sad list of "extinct constellations.

One interesting astronomica note pertaining to this constellation:   it was
the first to include the eruptive variable star Eta Carinae, a star whose
explosive nebula structure was so beautifully captured by the Hubble Space
Telescope.

[image: 080318_eta_3.jpg]
*Eta Carinae*

Edmond Halley is truly one of astronomy's immortals, for his cometary
namesake is due to return to Earth's sky many more times before it becomes
a dead comet.     It might have pleased Halley to know that his name
persists, even if his tribute to King Charles II has been long forgotten.

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