Image 1 Caption: Thomas Digges' (c.1546--1595) diagram (presented in his book A Perfit Description of the Caelestiall Orbes according to the most aunciente doctrine of the Pythagoreans, latelye revived by Copernicus and by Geometricall Demonstrations approved (1576)) of a heliocentric solar system surrounded by an infinite (or quasi-infinite) space (i.e., an infinite (or quasi-infinite) universe) with stars spread throughout perhaps to an infinite extent (No-296).

Features:

1. The colorization is modern.

2. Thomas Digges' caption for Image 1 (which is right on Image 1 in the orbital paragraph) reads:
   This orbe of the starres fixed vp extendeth hit self in altitvde sphericallye and therefore immovable the pallace of the foelicitye garnished with the perpetvall shininge gloriovs lightes innvmerable, farr excellinge ovr sonne both in qvantitye and qvalitye the very covrt of ceoleestialll angelles devoyd of greefe and eplenished with perfite endlesse joye the habitacle for the elect.

   See, Early Modern English (c.1485--c.1660 isn't so tough. Now on to Gorboduc (1561 play).

3. Digges' theory of the universe can be called the Copernican cosmos as opposed the Copernican heliocentric solar system of Nicolaus Copernicus (1473--1543) himself.

   Copernicus, in fact, continued to hold the theory of a real celestial sphere of the stars. This theory posited that there was a real celestial sphere of the stars confining the Solar System with the stars pasted on it. It was held by most astronomers in western Eurasia from the time of Presocratic philosophers (c.600--c.350 BCE) (notably Democritus (c.460--c.370 BCE) to circa 1600. The real celestial sphere of the stars also became a basic part of Aristotelian cosmology, and so was also held by strict Aristotelians.

4. Before Digges, others had theorized infinite universes (e.g., Democritus (c.460--c.370 BCE) and Nicholas of Cusa (1401--1464)), but Digges seems to have been first in the context of Copernican heliocentrism (No-296).

5. The theory that the stars could be other suns with their own planets probably suggested itself pretty quickly to those who few who accepted Copernicanism even in the 16th century. Their theorizing (which may include the theorizing of Thomas Digges himself) may have been as follows:

   1. Heliocentrism requires the celestial sphere of the stars be very large since stellar parallax is NOT observed.
   2. This means the stars are very far off, and so must be very bright.
   3. But then the stars could be comparably bright as the Sun.
   4. But then they could be other suns.
   5. But then why are they are pasted on a celestial sphere of the stars? They are NOT. They are spread throughout space which may be infinite or quasi-infinite.
   6. There is NO physical celestial sphere of the stars, just an imaginary celestial sphere useful for sky maps (AKA star charts) and celestial globes.
   7. The other suns could have planetary systems and their planets could have extraterrestrial beings (Wikipedia: Cosmic pluralism: Renaissance).
   8. There could be a plurality of worlds---which means the Earth and Solar System are NOT special places---they are infinitesimal. These ideas caused Giordano Bruno (1548--1600) to get into trouble with the Roman Inquisition (Wikipedia: Cosmic pluralism: Renaissance).
   9. The foregoing is piling speculation on speculation, but it all turned out to be essentially right.

6. Probably, some/many/all astronomers thought other planetary systems existed from the late 17th century on. But proof only came in the late 20th century with the discovery of exoplanets. Now we know that exoplanets are at least as common as stars.

7. By the way, Isaac Newton (1643--1727) thought of the spread out stars as being the fixed stars and these fixed stars defined the singular fundamental inertial frame called absolute space. The idea of absolute space did NOT survive the early 20th century and the discovery of general relativity, the Friedmann equation (FE) models of cosmology, and the expansion of the universe. However, measuring rotation relative to the fixed stars well approximates measuring rotation relative to the observable universe (which is absolute rotation in our current thinking) for most purposes for the celestial frame of the Solar System. So celestial dynamicists before the early 20th century using just Newtonian physics with the absolute space theory explained the motions of the Solar System adequately for the observations of that time.

   

8. Image 2 Caption: Portrait of Sir Dudley Digges (1583--1639).

   There seems to be NO portraits of Thomas Digges (c.1546--1595), but maybe the son was the spit of the father---except for looking like a musketeer.

Images

1. Credit/Permission: Thomas Digges (c.1546--1595), 1576, Colorized by Jean Gagnon (AKA User:Jeangagnon), 2007 / Public domain.
   Image link: Wikipedia: File:ThomasDiggesmap.JPG.
   
2. Credit/Permission: School of Cornelius Johnson (1593--1661), circa 1630 (uploaded to Wikimedia Commons by User:MarmadukePercy, 2013) / Public domain.
   Image link: Wikipedia: File:Sir Dudley Digges (c. 1583 - 1639).jpeg.