A MORE PERFECT UNIVERSE
---------------------
John Pazmino
NYSkies Astronomy Inc
nyskies@nyskies.org
www.nyskies.org
2012 May 10
Introduction
--------
On 2012 May 7 the 'Science and the arts' series of public shows
presented 'Copernicus: a more perfect universe' at City University
Graduate Center on Manhattan. I and other NYSkiers regularly take in
these shows, usually as individuals. On this instance, due to the
glatt astronomy nature of the show, NYSkies made a social event of it,
with several of us seeing the show and then doing supper afterwards.
The Graduate Center is in the center of Manhattan's corporate
district, on Fifth Avenue and 34th St, near many transit lines and a
short walk from Grand Central Terminal, Port of Authority, Penn
Station. Its talks are almost always completely filled with latecomers
turned away for want of seats.
The presentation was done by Dava Sobel, astronomy author of many
excellent books. She now is trying her skill at writing astronomy
plays. This Science and the Arts program was a act-out of parts of
her play in simplified form and with her running commentary. It is
based on her current book about the Copernicus meeting with Rheticus.
Presentation
----------
Science and the Arts engages the theatrical firm 'Break-A-Leg'
that specializes in a minimalist style of acting. Actors work on bare
stage with back-curtain dropped and in street clothes. Only a bit of
styling is used in selecting the contemporary clothing.
Props are limited to simple chairs and tables, likely already on
premises for general use. There is no elaborate scenery or costume. In
most cases the same dress is worn thruout the production.
This format at first looks too schoolish. It is actually
extraordinarily effective because it focuses the audience on the
dialog with no distraction from the surrounds. The strength of the
style is in the dialog among the actors,plus commentary offstage by
the author.
This minimalist style is an excellent method for astronomy centers
not outfitted for conventional theatrical performances. It may be
employed on a simple raised stage in an auditorium or at grade-level
in the front of a classroom. The acting does have to be practiced and
honed to a professional level.
The play
------
The segments of Sobel's play shown were the meeting of Rheticus
with Copernicus. Rheticus came from Germany on foot thru dangerous
territories into Poland. He faced many travel troubles but arrived at
Copernicus's house in somewhat functional state.
Poland was a completely Catholic country, with Copernicus holding
a higher office, a canon, in the Church. He was aware of his bishop's
hate of the uprisings against the Church that brewed in other
countries in Europe. While personally tolerant of other faiths,
Copernicus did have to heel to his boss's orders.
Rheticus converted to the new Lutheran faith, then spreading
rapidly thru Germany. Poland, fearful of the competitor faith, banned
Lutherans from its land and was on the lookout for Lutheran intruders.
If found, they were punished by typical nediaeval methods.
Rheticus wanted to learn more about the Copernicus ideas of the
planetary motions. The 'De revolutionibus' was not published but some
articles were circulated among astronomers and mathematicians. Due to
the antagonism among the faiths, Rheticus could not seek a direct
invite from Copernicus. He came on his own with no advance notice.
Copernicus found him sleeping on the stoop.
The play centered on the dialog between the two men during which
Copernicus explains the new order of the planets. Copernicus is always
wary of entertaining Rheticus in his house being that as a Church
functionary he was supposed to turn the visitor over to the
authorities. At first he tries to dissuade Rheticus from staying, but
ends up hiding him in the cellar as a guest.
Rheticus
------
Georg Rheticus was chair of mathematics at the University of
Wittenberg in present-day Germany. He also was an ardent student of
astronomy. Copernicus was already well-known, before the promotion of
the heliocentric theory, as a leading astronomer, mathematician, civic
administrator, physician. Rheticus just had to meet Copernicus and
arrived at Copernicus's home in Frauenburg, Poland, in 1539.
Rheticus did many works on maths, built mathematical models and
measuring devices, compiled navigation tables, and calculated planet
positions. He also worked up horoscopes in astrology, as did pretty
much all astronomers of the time.
Rheticus knew Martin Luther as a colleague at Wittenberg and took
up his new belief system. He was, like all Lutherans and other
protestants, persona non grata in Catholic Poland. His trip was always
threatened by capture and dispatch.
He was brought up under the Ptolemaeus system of planets and
wanted to learn Copernicus's heliocentric model. The Earth-centered
viewpoint was part of almost all faiths, even Lutherism and others
protesting against the Church. Under Copernicus's mentoring Rheticus
came to accept the Sun-centered model.
By the later years of Copernicus, Rheticus was compiling and
editing the 'De revolutionibus' and arranged for its publication in
Germany. The first copy didn't reach Copernicus until he was dying in
his bed from a stroke. After seeing the book Copernicus closed his
eyes and died.
Lutherism
-------
Martin Luther, a monk in the Catholic Church, issued in 1517 a
protest against what he saw as abusive practices. He made a series of
claims, including the sale of 'indulgences' and apparent discrepancies
of theology compared to the scriptures.
His ideas were taken up by many others who felt abused by the
local Church authorities and as a unit they broke away into their own
form of Christianity. In time the faith was named Lutherism or
Lutheranism.
Lutherism is the first major break-away faith system, now being
the main faith system in Germany, Norway, Sweden, Finland, Denmark.
There is substantial Lutheran presence in all parts of the world but
the center is Germany and Scandinavia.
Mind that there was no 'Germany' in the 1500s as a consolidated
nation as yet. There were separate smaller countries which are more or
less the provinces in modern Germany.
Outside Germany other groups split off from the Catholic Church in
protest, often under the leadership of a specific person.
Collectively, even among rival factions, these belief systems are
called protestant faiths and their members are genericly Protestants.
Note well that the word is 'proh-TESS-tant', the active
participle. Over the centuries the accent slided to form 'PRO-tess-
tant' or, a bit sloppily, 'PRO-teh-zant'.
The Church was fearful of such insurrections. Poland banished
Lutherans from its land. Any found were, uh, dealt with sternly.
As barbaric as this policy seems today, many faiths protesting
against the Church engaged in nasty practices. Recall that in the
American colonies, there were ugly suppressions of alternate beliefs.
These were carried out by the very people who fleed from faith-based
persecution in Europe, Even to this 21st century, there are remanents
of this intolerant mindset in various pockets of the United States.
Most notable is the faith-based aggression against assorted
alternative lifestyles.
Planetarium
---------
Rheticus notices a large machine like a cabinet or hut and
inquiries about it. Copernicus dismisses the query but Rheticus
persists. Copernicus allows Rheticus to climb inside while he, from a
crank outside, sets the machine to rotate. There is no actual machine
on stage, but a phantom one that's acted out in mime.
Copernicus makes like he's cranking while Rheticus Injun-squats on
the floor. He squeals in delight at the scene inside the machine. He
shouts that he's sitting still but the entire machine spins around
him. He points out a few constellations as they pass around him. The
cranking gets tiring for Copernicus. He tells Rheticus that time's up.
This act in Sobel's play is entirely imaginary, like certain other
segments later. There never was such a planetarium or other device in
Copernicus's life. On the other hand one could have been built using
materials and mechanisms known at the time, after DaVinci.
Rheticus asks, after getting out how the whole room could turn so
smoothly while he was sitting still in the middle. Copernicus explains
that the hut was stationary on the floor. The seat span around.
At first, given the crude state of machinery in the 1500s, this
seems to be an unlikely achievement. It could be done by mounting the
seat on a a polished bamboo bearing lubricated by lard. The crank
could be attached to a spindle under the seat by a leather belt. Since
the rider has to squat inside, imbalance as the seat started or
stopped would be masked by the general wobbliness of the posture.
The idea of this segment is to demonstrate that motion is
relative. The sky turns around the Earth because the Earth rotates and
orbits around the Sun. The sky does not move over a stationary Earth.
Speed of Earth
------------
During the debate about the motion of the Earth,Rheticus asks how
fast must the ground move to complete one turn per day. Copernicus
does an in-head calculation, figuring 25,000 'miles' for the Earth's
circumference and 24 hours in the day. Earth's ground (at the equator)
must speed around at about 1,000 miles per hour (1,600 KMH).
In the 1500s this was a stupendous speed, one that prompts Rheticus
to argue about the blast of wind this must create, like some extra
fast ride on a wagon. In the 21st century this is still a humongous
speed, faster than most airliners travel. Only for a brief period in
the 1970s-1990s was it surpassed by the Concorde.
The use of 'miles' is Sobel's fictitious feature in her play. She
later explained that she wanted to use some ancient measuring system,
not current metrics. There really is only one such scheme, the
oldstyle British units, still familiar in the United States. Poland
and Germany never employed this scheme. They lived with other peculiar
units. These would be too obtuse for Americans.
Rheticus then asks about the speed of Earth's orbital motion
around the Sun. Here Copernicus draws a blank because he did not know
the actual distance of Earth from Sun. If he did, the answer would be
simply the circumference of that orbit divided by 8,766 hours, the
number of hours in one year (including the 1/4 fractional day).
Today we know that speed as 30 KMS (not KMH). In the De
Revolutionibus Copernicus does offer a radius for the Earth's orbit of
1,000 Earth radii (rounded), this being some 6,400,000 kilometers. I
forget where he got this figure but it is close to the Aristarchus
value of 1,200 times Earth's radius.
Using this grossly too-small value we have the orbital speed of
Earth as 1.29 KPS or 4,620 KMH. These would be insanely humongous
speeds for the 1500s mind to comprehend. They were not achieved by
humna flight until the Space Age.
Large and small Earth
-------------------
Note that Copernicus accepts the 'large Earth' school, claiming
the Earth to be 40,000km circumference. The 'small Earth' school
argued for a 25,000km circumference. The disparity came from disputes
in measuring the linear length of angular arcs, a situation not
resolved until the mid 1600s.
The two factions in the late 1400s competed for the feasibility of
sailing from Europe to China via Atlantic Ocean. It was just possible
to build and kit out a ship to last the journey (in ignorance of the
Americas) for the smaller circumference. This was Columbus's thesis
for soliciting support for his trip.
It was beyond possibility for the larger circumference. The ship
would fall apart from want of repairs and the crew would die from want
to food and drink. In the open ocean there would be no ports for
replenishing the ship and crew.
Columbus was as lucky as hell that when his ship was almost
exhausted of supplies and provisions, he hit land in the Caribbean
Sea. This land by great fortune is where China would be for the
smaller Earth. Columbus thought he was in the Indies, the islands
dotting thee Pacific Ocean near China. To this day we the Caribbean
islands are called the West Indies, preserving their initial identity
with the Indies (now East Indies) near China.
If there was no American continent but only a vast Atlantic Ocean
on the larger world, the voyage -- the one and only one! -- of
Columbus would be but a footnote in history. Europe would probably
have never again considered a westward trip to China until the era of
steamships in the 19th century.
Attachment of the air
-------------------
Rheticus argues that if the Earth moved the air would slip away,
causing massive winds. Copernicus replies that the air is attached to
the Earth and moves along with her. He's at a loss to explain why or
how the air, so tenuous a substance, can adhaere to the ground but
he's sure in his heart it must.
Rheticus had a convincing argument. If you on a wagon hold a
candle and then move forward, the smoke and flame drift backward, In
the real sky clouds move about over the ground under the push of winds
with no regard to a gross movement of the Earth. The quiet behavior of
the air, having only local motions, is evidence for a stable Earth.
Copernicus has no solid basis to elaborate why the air stays with
the Earth. He merely repeats the assertion again to Rheticus.
As late as the mid 1000s the behavior of the air was not well
appreciated. One of Verne's stories explained how a balloon allowed
his heros to escape from a comet. They waited until the comet came
close enough to Earth to join their atmospheres. The balloon then was
steered thru the united air to land safely back on Earth.
Relative motion
-------------
Rheticus asks how the Earth can be moving around the Sun if he
feels nothing of its movement. On a horse he feels the bumps and jolts
under him and feels the air blowing against him and sees the scenery
slide backward. Copernicus tries to describe the feeling on a ship
gliding on a smooth water. Inside the ship there is no feeling of
motion.
This is also an imaginary scene in the play. The concept of
relative motion, with this example from Galileo's 'Dialogues', just
wasn't in place for Copernicus. Nor was the concept of inertia, mass,
force. The lack of firm understanding of these principles hindered
Copernicus's theory of the solar system.
The Galileo demonstration was elegant. He postulates a ship with
no windows to refer to the outside scene. In it the rider has several
experiments while the ship is gliding over still calm water.
I don't recall rightly but the rider has such things as a jar of
bugs, a candle, a ball, some kind of toy. The bugs are released and
they fly around the room exactly as if they were on solid ground. The
candle flame and smoke drift upward as they do on stable ground. A
game of ball plays the same as on land. The toy works the same way on
the ship as on land.
Galileo concludes that the behavior of natural events is the same
regardless of the relative motion of the observer's platform (the ship
in this case) against another platform (the land). By this argument he
allows that the Earth can move, like the ship, within the outer frame
of the stars and Sun, as in the Copernicus model of the solar system.
This was not proof of the heliocentric theory but merely evidence
that it could be valid. It is a mistake some simple accounts of
Galileo make that he proved the Earth orbited the Sun. He didn't and
he couldn't. He gathered observations and experiments, crucial ones,
to show that the heliocentric system is plausible. His own faith in it
made him state it was an actuality.
This, the Galileo Principle, 300 years later became the foundation
of Einstein's theory of relativity. In more concise form, all the
behaviors of nature operate the same for all observers, regardless of
their motions relative to each other.
One of the behaviors of nature is the speed of light. This is
derived from physical properties and laws and not by a mechanical
measurement. As a behavior of nature it is the same for all observers.
The Sun as center
---------------
Copernicus had no way to put forth a physical reason to place the
planets around the Sun. The nature of the SUn was thoroly unfathomable
and there was no concept of attraction, force, gravity. He put out
soft arguments about the Sun being the most glorious of the orbs. He
was the body that shines light and heat on Earth, making the existence
of life possible on Earth.
He mixed in some belief features about the Sun shining his glory
like God and how we circle around God. Stuff like that. Hardly the
making of good science, but there was little enough good science in
the Renaissance to all short of.
Why should the Earth move at all rather than let the Sun and his
retinue of planets, and the stars circle Earth? COpernicus notes that
under his scheme the stars had to be immensely far away in order that
they still remain 'fixed stars' to observation. The stars, the
celestial sphere was simply 'too big and heavy' to do the moving.
Apart from Sobel's show the De Revolutionibus explains this point.
Copernicus states the size of the solar system where the Sun is 1,000
times (rounded) farther away than the Earth's radius, Saturn is 10,000
times Earth's radius from the Sun, and the stars must be perhaps
100,000 times the Earth's radius away. Such immense a world could not
turn around the Earth.
Rheticus pleads that the Copernicus world has so much wasted space
between planets, orders and orders bigger than the whole Earth. The
geocentric world nests the planets in closely fitting shells.
Copernicus has no strong response but again appeals to the grandeur of
God and the majesty of His creation.
Copernicus was skating on thin ice. With the threat of protests in
Poland the Church wasn't eager to take in new ideas outside the power
structure of the day. The scriptures speak of the heavens going around
the Earth, never minding that this could mean an apparent or relative
motion. It's best that the scriptures be taken as are than open them
to invasion by alternative beliefs.
Copernicus had to cool it, being himself part of the Church. He
had some supporters but far too many opponents to come out in public
with his heliocentric system.
As it happened, he was in his death bed when the first complete
copy of De Revolutionibus was placed in his hands. He probably didn't
notice that, altho printed in Germany, the book had a preface added by
the local protesters that declaimed the actuality of a Sun-centered
world. Even Protestants were leery of, erm, revolutionary thoughts.
Astrology
-------
It can be a shock to modern newcomers into the astronomy
profession to discover that many of their ancestral fellows did
astrology. In the 1500s there was still a general acceptance of
astrology as part of astronomy, or the other way round.
The times were such that astrology was an odium to be tolerated by
astronomers, partly as a means of subsistence. People pay to get a
fortune reading but not for learning where Mars is in the sky. And the
amount earned thru astronomy lectures and shows was too infrequent and
inconsistent to build a livelihood on.
One aim of astronomy at that time was to refine the calculation of
planet positions by tweaking the Ptolemaeus model. The value for an
excentricity was adjusted, so was the longitude of a perigee, and so
on. Some of these fixes were caused by real mutation of the orbits
over the centuries, a fact not realized by the Mediaeval and
Renaissance astronomer. He thought the revision was the result of more
and better observations or errors in previous determinations.
Rheticus and Copernicus discuss astrology as a casual part of
their careers. Copernicus notes that his heliocentric model yields
more accurate planet positions for that purpose.
De Revolutionibus Orbium Celestium
---------------------------------
Copernicus's book translates as 'Concerning the revolutions of the
celestial orbs'. The parsing is preposition 'De', ablative plural of
'revolutio', genitive plural of 'orbis', genitive plural of
'celestis'. Some negligent authors call the book '...bus Orbitum
Cel...', perhaps by thinking of orbits.
The word 'revolution' refers to the circulation of the planets.
Because the book caused a mass change of human thought and collateral
social and political change, the word came be mean 'sudden forceful
change'. Our use of the word brings up insurrection, civil uprising,
overthrow of rulers, and similar, ahem. revolutions.
De Revolutionibus was written originally in Latin, the language of
the time for scholarly works. It's available today in Latin and many
other languages. English translations are plentiful in both print for
pay and download for free.
It really is a valuable exercise to read the Latin work, taken
from a large library in modern reprint, to properly take in the mind
of Copernicus. I realize Latin is not any where so common a language
in American schools, but astronomers commonly study it on their own.
The book is large and heavy, causing many early students to wonder
why it's any better than the Ptolemaeus method of working the
planetary motions. The maths are about as convoluted for both
geocentric and heliocentric models and the results seem about equally
good when compared with the sky.
Copernicus made two major breakthrus in maths, explained in an
early part of the book. First, he employs the Hindu notation of
numbers, what we call Arabic, rather than the Roman number scheme.
This immediately eased the chore of doing even simple maths if you
ever tried doing long division with Roman numbers. (Go ahead, try it.)
He also switched to decimal notation, also from the Hindu world,
setting aside the base-60 system. This, too, vastly simplified the
maths. In fact, the change to Arabic and base-10 numbers arguably
saved De Revolutionibus from regressing into neglect.
It also is easier for us astronomers today to walk thru the book
with modern calculettes. In the Sobel show, neither point of maths was
made in the presented segments of the full play.
Unlike the Ptolemaeus method, the Copernicus method explicitly
includes the Sun in the computation of planet positions. The Sun's
motion was buried in Ptolemaeus, not put out in front as a direct part
of the work. In essence, you calculate the planet position relative to
the Sun and then the Earth's position relative to Sun. The combination
of the two yields the place of the planet relative to Earth.
Because the Sun's location, for a run of several planet calcs need
be done once for the whole run, already the maths are simplfied. Under
Ptolemaeus each planet needed its own peculiar computation. The parts
involving the Sun were there but hidden.
Some Copernicus premises
----------------------
In spite of Copernicus's sea change in perspective for the solar
system he held to a few ancient principles. These got hi into massive
troubles with the planet calculations, so much so that many opponents
questioned the need for the heliocentric model.
He insisted that all motion be uniform circular motion, constant
angular speed around a center. The center of motion did not have to be
the center of the circular path of the planet. Ptolemaeus made this
premise, too, to build his scheme. Copernicus, to duplicate the actual
path n the sky, mounted small circle on large circles and shifted
centers of motion from geometric centers of circles, much as
Ptolemaeus did.
Copernicus also insisted that the orbits of the planets be all in
the same plane, a flat plate of rings, around the Sun. Planets in
coplanar orbits would travel in the ecliptic. They don't. They wander
north and south in ecliptic latitude.
Both Ptolemaeus and Copernicus employ subsidiary circles mounted
on the main orbit to waggle and wobble to shift the planet's latitude.
Copernicus banked his calculations off of the mean Sun. It was
usual to smooth out the irregular movement of the Sun by posting a
phantom Sun that travels at a uniform speed thru the zodiac. The real
Sun moves a bit faster in northern winter and a bit slower in northern
summer. Stating positions relative to the phantom Sun made it harder
to relate the computations to the sky. A secondary worksheet was
needed to correct the planet to ride on the real Sun.
This is a superfluous exercise today but because the character of
the Sun was unknown, it could have been a ball of aethereal light. It
seemed natural to leave it alone and work with a better behaved mean
Sun, a geometric point that didn't shine.
Kepler first demonstrated that the planet orbits are rooted on the
globe of the Sun. Once he did this, in his Law #0, or #1a, Kepler
broke open the way for a vastly easier and quicker method of
calculating planet motions and positions.
One interesting point sometimes asserted is that Copernicus
predicted the phases of Venus. He didn't in the De Revolutionibus.
It is true that by letting Venus be a globe like Earth it would
display the Galileo pattern of phases as it rounds the Sun.
It would be dicey for Copernicus to banner this prediction. It was
impossible to test without the telescope, not even with daVinci's
foggy blurry lens. It would be lousy science for a Renaissance
gentleman, must more so for a fellow of civic authority.
Maybe he did so in a private letter or article, but curiously the
story didn't come out until long after Galileo found the Venus phases
by telescope. Copernicus seems to say nothing about the nature of the
planets. The planets while philosophicly worlds like Earth with Earth
being now the third of these worlds from the Sun, they could just as
well remain insubstantial points of light.
Spheres of the planets
--------------------
In the prevailing model of the Earth-centered universe it was
natural that the planets and stars circulate around the Earth. Thee
was no need of a deeper explanation.
One spinoff of this geocentric model ws the lack of external means
to set the sequence of the planets upward from Earth. In which sphere
or shell or ring did each planet run? This was a probelem for
Prolemaeus, who confessed that there was no objective way to tell the
height of each planet above Earth. They all looked like points or
discs of invariant aspect no matter where on Earth they were viewed
from. They displayed no parallax to form a surveying triangle on them.
Ptolemaeus allowed a traditional, for Greek times, order largely
based on the angular speed of each planet thru the zodiac. The Moon
was obviously the fastest, rounding the zodiac in 27 days. She also
was the only planet that altered shape, being mutable like the earthly
world. She must be closest to Earth at the lowest elevation.
In fact, she distance from Earth was actually triangulated to be
about 60 Earth radii away, a figure that by the stroke of luck is the
base of the maths system of the era, base-60. Where we say a radius is
one, or 10 or 100, unit, the Greek said it was 60 units.
The Sun passed thru the zodiac in, uh, one year, Mars in about
two, Jupiter in 12, Saturn in 29. So far so good. Sun, Mars, Jupiter,
Saturn stacked up over the Moon in that order. Saturn was up against
the sphere of the fixed stars.
Mercury and Venus were a problem. Over the long term they
circulated thru the zodiac in one year pacing the Sun. Unknown to
Prolemaeus and all time until Copernicus, these planets are tied to
the Sun and are dragged around the zodiac with him.
Mercury whacked around form morning to evening and back in 4
months while it took Venus about 19 months to do the same. Let's put
Mercury next above the Moon, then Venus, Sun, and the other planets.
Some astronomers figured differently and put the order as Moon,
Venus, Mercury, Sun, &c. There were over the millennia pitched battles
over the due and proper location of Mercury and Venus.
As history fell out, the Moon-Mercury-Venus-Sun order is used to
assign the names to our days of the week. With Venus the lower, the
days would have a different sequence of names. Because the week of
seven days in the current order was a fixture of human society for
many millennia, there is no hope of ever altering it. We must keep the
Ptolemaeus order of planets in the geocentric model for ever more.
Solar system
----------
The core of the Copernicus model was the creation of a true solar
system, a unified mechanism that somehow held the planets in orbit
around the Sun. He had no notion of what the force was to keep the
orbits intact. The whole pwah of 'force' and all that was missing from
human thought in the 1500s. Not even magnetism, coming into use for
the marine compass, was associated with the Sun.
By placing the planets around the Sun Copernicus found that the
sizes of the orbits fell into fixed steps. Mercury had to be closest
to the Sun about 4/10 the size of Earth's orbit. Saturn had to be
farthest out, some 10 times the Earth's orbit radius from the Sun. No
arbitrary scheme of orbits worked. The motions of the planets thru the
zodiac plus the centering on the Sun forced not only the sequence of
the orbits but the relative sizes.
This brings up the illustration so often shown from De
Revolutionibus. It's the solar system with neatly compacted nested
orbits centered on the Sun. Each planet is equispaced outward from the
Sun with lordly Latin captions. This is nothing but an illustration!
It does not propose to show the correct spacing of the planets.
Diagrams further in the book are drawn to correct scale, with
explanation for their construction.
Conclusion
--------
Only a few parts of the full play were presented at this show.
They were enough to spawn many questions for Sobel, with many coming
from the NYSkies delegation. She noted parts that were purely artistic
freedom in order to enhance the tuitional value of the play. There was
no such planetarium machine and there ws no such deliberate idea of
relative motion and force.
She explained about Kepler alluding to magnets in the Sun, banking
of the current work of William Gilbert in 'De magnete'. That was many
decades in the future.
After the show let out, Sobel did a book signing for the
Copernicus book. Many audience purchased a copy for her autograph. The
NYSkies party went to Brendan's restaurant, a block away, for a
lengthy supper and free-flowing chat about Copernicus, astronomy,
science, and other sundry topics.
This Dava Sobel event is the paenultimate one in the 2011-2012
running of Science and the Arts. The next season starts in October
2012. While most shows are not stricta mente related to astronomy, all
are of instructive value for any City astronomer. The events are
listed in NYC Events for each month during the series.