Earlier Optical Telescopes

What if optical telescopes had been invented already around the year 1400? Would the optics of the age allowed something comparable to Galileo's designs? If yes, what sort effects this would have had? I'm especially interested in influences this could have had on science and philosophy.

In the absence of the Protestant threat, the Church would likely be more tolerant of speculative theology about how the heliocentric model might be reconciled with scripture. Cardinal Nicholas of Cusa, for example, speculated during that century on the motion of Earth. With some actual evidence to back up such speculation, the heliocentric model might be more popular earlier. However, given some of the observational problems of the heliocentric model (like lack of stellar parallax), it is likely that some variant of the Tychonic system becomes the model officially favored by the Church.

This might speed up the discovery of Uranus.

The church had no issue with the basis of the Heliocentric model. Copernicus, after all, was part of the clergy.

DominusNovus said:

The church had no issue with the basis of the Heliocentric model. Copernicus, after all, was part of the clergy.

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Not in itself. They had problems with some assumptions and implications around it, though.
However, it is likely that it would fly more easily in AD 1500 than it did around 1630.
Another interesting point is that this would likely lead to a stronger interchange with the then vibrant astronomical and optical knowledge in the Near East. The consequences of that are potentially very huge (think of an equivalent of the Scientific Revolution occurring in connection in the Europe, Western Eurasia and North Africa).
Another interesting factor is that much better astronomy in the fiteenth century could likely make more precise measurements about the dimension of Earth more available. This means that "official" contact of America may be significantly delayed.
However, I am not sure that optical theory and glassmaking technology avalaible in 1400 in Europe can be up to the task (according to Paul Feyerabend, IOTL optics in 1600 was not advanced enough to fully theorize telescopes even after Galileo had built one; going by Brecht's Lebens des Galileo, the glassmaking involved was cutting-edge to the point that Galileo had some serious trouble getting the lenses he needed. I admit that Brecht is not exactly an academic source).

it might have more to do witht he fact that galileo was trying to copy something (the dutch telescope). so trying to get the right material is always trial an error in cases like that

Falecius said:

Another interesting factor is that much better astronomy in the fiteenth century could likely make more precise measurements about the dimension of Earth more available. This means that "official" contact of America may be significantly delayed.

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It might delay contact with America somewhat, but an earlier discovery of, say, the moons of Jupiter could enable the much earlier development of astronomical almanacs that would make it possible to get precise longitude measurements. I imagine Portugal would, if those implications are realized, become a center of astronomical measurement and the creation of such almanacs--it would make their charts far more reliable.

But it might take a while for those implications to be realized--IIRC, it wasn't until the late 18th century IOTL that the use of the moons of Jupiter for longitude calculation matured.

wietze said:

it might have more to do witht he fact that galileo was trying to copy something (the dutch telescope). so trying to get the right material is always trial an error in cases like that

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Again going by Feyerabend, Galileo's mastery of optics was also far from optimal - Kepler was much well versed than him in that area.

Falecius said:

Again going by Feyerabend, Galileo's mastery of optics was also far from optimal - Kepler was much well versed than him in that area.

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??? Kepler didn't use lenses at all. AFAIK. Most of his calculations were based on Tycho Brahe's observations, which were all naked eye.

There is evidence of earlier telescopes, one was offered to the Elizabethan Navy, but they seem to have been fixed lenses. One admiral said something like "I can see a sailor on the enemy ship, but I can't see the whole ship."