Tychonic system

[3] A similar cosmological model was independently proposed in the Hindu astronomical treatise Tantrasamgraha (c. 1500 CE) by Nilakantha Somayaji of the Kerala school of astronomy and mathematics.

[5] Tycho admired aspects of Copernicus's heliocentric model, but felt that it had problems as concerned physics, astronomical observations of stars, and religion.

By contrast, the Earth (where objects seem to have motion only when moved) and things on it were composed of substances that were heavy and whose natural state was rest.

[7] Thus while Tycho acknowledged that the daily rising and setting of the Sun and stars could be explained by the Earth's rotation, as Copernicus had said, still such a fast motion could not belong to the earth, a body very heavy and dense and opaque, but rather belongs to the sky itself whose form and subtle and constant matter are better suited to a perpetual motion, however fast.

Tycho had determined that a typical star measured approximately a minute of arc in size, with more prominent ones being two or three times as large.

[12] Copernicans offered a religious response to Tycho's geometry: titanic, distant stars might seem unreasonable, but they were not, for the Creator could make his creations that large if he wanted.

[13] In fact, Rothmann responded to this argument of Tycho's by saying [W]hat is so absurd about [an average star] having size equal to the whole [orbit of the Earth]?

It was a system that Tycho said violated neither the laws of physics nor sacred scripture—with stars located just beyond Saturn and of reasonable size.

In this regard, he was anticipated in the 15th century by the Kerala school astronomer Nilakantha Somayaji, whose geoheliocentric system also had all the planets revolving around the Sun.

[22][23][24] The difference to both these systems was that Tycho's model of the Earth does not rotate daily, as Heraclides and Nilakantha claimed, but is static.

[26] This was foreshadowed by the Irish Carolingian scholar Johannes Scotus Eriugena in the 9th century, who went a step further than Capella by suggesting both Mars and Jupiter orbited the sun as well.

On the other hand, because of the intersecting deferents of Mars and the Sun (see diagram), it went against the Ptolemaic and Aristotelian notion that the planets were placed within nested spheres.

[32] The discovery of stellar aberration in the early 18th century by James Bradley proved that the Earth did in fact move around the Sun and Tycho's system fell out of use among scientists.