 |
| Tradition and
innovation in the Thyconic system ... |
i
«... Tycho,
in the scenario of his times, appears both as a "great
mediator", and
also as the "main
opponent" to
the Ptolemaic system ...
i
His cosmological system, in fact, is a kind of
compromise between the Ptolemaic vision and the Copernican vision. By the
time his system reaches its apex [1584],
according to our modern way of thinking, it becomes totally equivalent
to the Copernican system … the only difference is that the
Earth is stationary, while the Sun orbits the Earth, and
the planets orbit
the Sun ...
i
However, in the folds of this system, that apparently
seems to advocate the ancient learning, a great revolution is present ...
the orbits of the planets, in particular the
orbit of Mars, cross the orbit of the Sun
... which means a farewell to the
"impenetrable crystalline spheres",
a reminiscence of Ptolemy ... it really means
the end of a metaphysics that gratified people for a long spell of time,
lasted 1500 years ...
1
Moreover, his system still shows a "
still archaic aspect of his thought ",
as his cosmos is physically baseless, but "again
is totally kinetic"
... The equivalency between the Thyconic
and the Copernican system [they
differ only for a single observational record]
will never allow to foster one system more than the other one in a deciding
way, until much later times ...
i
The true proof that Earth revolves and, therefore,
that this is a tangible motion was given by James Bradley, who measured
the aberration of ? Draconis
with the use of a telescope, accurately fastened in nearly vertical position
to a chimney, (? Draconis
passes very near to the London’s Zenith). Measurements were taken within
the period of a year’s time (Earth orbits the Sun totally) … the star effected
an ellipse similar to the Earth’s orbit, with an amplitude equal to 41
arc-seconds [announced to Royal Society in
January 1729].
...
i
On the contrary, rotation will be proved measuring
the separation among heavy bodies while falling from the Asinelli Tower
in Bologna and, later on, in a definitive and less complicated way, with
the Foucault’s pendulum [1851]
...»
i
z |
z
z
James Bradley - Measurement
of the annual aberration ... 1729
z |
image credit Perseus 
image credit Perseus |
| Due to the yearly revolution motion,
Eltanin should be visible in the expected position ...
observation shows it is 20,5 arc-seconds
backwards ... therefore,
the Earth’s velocity is approx. 30
km/sec ... the angle (annual
aberration) formed by the light (white
vector) is:
30
km/s / 300.000
km/s = 0,0001
radians = 0,0001 * 180 / p
= 0,00573 degrees
= 0,00573 * 3600 = 20,5 arc-seconds
(approx.)
z |
The pendulum
of Foucault and Earth’s rotation ... 1851
z
z |
| The animation of the
Foucault’s pendulum, which in this case
is located in the Northern hemisphere,
emphasizes the clockwise direction.
The rotation velocity is greatly emphasized
with respect to reality. |
 |
A true Foucault’s pendulum,
released from its rest
point, does
not directly pass through its position
of equilibrium, in
contrast with what happens in the
animation.
credit: Wikipedia ( reversed rotation
) |
|
z
z
At the North pole
the pendulum effects a complete clockwise
rotation in a sidereal day
... at intermediate latitudes
it effects a partial rotation in a longer
time ... at
the equator it does not rotate,
but always swings in the same direction ( period
= infinity )
...
z
z
z
z
z
z
z
z |
| Tycho tries many
times to overthrow the Ptolemaic system ... |
1
«... In
the Thyconic system, when Mars is at opposition, it is, indeed, nearer
to the Earth than the Sun is ...
1
Erroneously, the distance of the Sun, at Tycho’s
times, was so much underestimated, that the parallax of the Sun was assumed
to be 3 arc-minutes ... as so, the parallax
of Mars, at opposition, should be much more extended ...
1
Tycho spent much of his time and money trying
to measure the parallax of Mars ... as a matter of fact it exists, but
is very small. Also the parallax of the Sun is small [modern
values are respectively 11,87 and 8,794 arc-seconds]
...
1
Obviously, this
measurement was not within the range of Thyco’s instruments, that had the
precision of 1 arc-minute....
1
The parallax of Mars was calculated by Cassini
through two concomitant observations, one carried out in Paris and the
other one at Cayenne - French Guyana [South America]...
1
Tycho collected quite a number of contradictory
measurements in his works and did not report any value for the parallax
of Mars in his treatise: "De
Mundi Aetherei Recentioribus Phaenomenis"
...»
1 |
| z |
|
| z |
|
i
i
Tycho’s strange cosmos...
with a central Earth and the planets orbiting the Sun ... |
 |