Tycho's Hypothesis

38. According to Tycho’s hypothesis, the Earth must move around its own center

The Brahean hypothesis is now commonly accepted by all those who reject the Copernican.

They think that the Earth remains immobile. And so they think that the entire heaven, along with the stars, revolves around the Earth every day.

But this means that:

• the movement of the heavens should touch or translate to the the Earth.
• this translation is reciprocal

The same force or action should be on Earth as in the heavens. If so, the force that moves the heavens should be attributed to the Earth only.

This is because it occurs over its entire surface through the concave part contiguous to the Earth, which is very small compared to the convex.

They believe that the following are separated from the Earth:

• the concave surface of the starry heaven, and
• the convex from another heaven, the crystalline or Empyrean heaven, surrounding that concave surface

This is why they attribute that motion to the heavens rather than to the Earth.

They are unable to prove the separation of the entire convex surface of the starry heaven from that crystalline heaven surrounding it.

They invent it purely arbitrarily.

Thus, according to their hypothesis, the reason why the motion must be attributed to the Earth is certain and evident;

But the reason why they attribute it to the heavens and quiet to the Earth is uncertain and imagined solely by them.

39. It moves around the Sun with annual motion.

From the same Tycho’s hypothesis, the Sun, revolving annually around the Earth, not only carries Mercury and Venus but also Mars, Jupiter, and Saturn, which are farther from it than the Earth is.

This cannot be understood, especially in a fluid heaven, such as they suppose, without the entire interposing matter of the heavens being carried along simultaneously.

Meanwhile, the Earth being separated by some force from the parts of this matter contiguous to it and describing a circle within it.

Therefore, this separation again, which involves the entire Earth and requires a peculiar action on it, must be called its motion.

40. The translation of the Earth does not cause any change in the appearance of the Fixed Stars because of their immense distance

One problem remains in my hypothesis.

If the Sun always maintains the same position among the Fixed Stars, then it means that the Earth, which moves around it, moves closer and farther from the stars.

But this has not yet been observed from the phenomena.

But this is excused by the immense distance between us and the fixed stars.

The entire orbit of the Earth around the Sun is just a point compared to that vast distance.

This may seem incredible to those who:

• are not used to considering the wonders of God
• view the Earth as the principal part of the universe and the dwelling place of man, for whom all other things were made.

But it is not so strange to Astronomers who now know that the Earth is like a point compared to the heavens.

41. This great distance of the fixed stars is also required for the motions of Comets

Comets are now well established not to move in our atmosphere.

They require this vast space between the orbit of Saturn and the fixed stars to complete all their excursions.

This is because their motions are so varied, so vast, and so discrepant from the stability of the fixed stars and the regular revolutions of the planets around the Sun.

Without this distance, they seem not to be reconcilable with any laws of nature.

Tycho and other astronomers diligently investigated their parallaxes and stated that they are only above the Moon, towards the orbits of Venus or Mercury, but not above Saturn itself.

We should not be concerned about this, as they are incorrect as the ancients.

The ancients also believed that comets were among the sublunary meteors.

• They were content to show that they are in the heavens.
• They did not dare at all to calculate their height lest it should be less easily believed.