<P> In ancient China, the 2nd century astronomer Zhang Heng became convinced that space must be infinite, extending well beyond the mechanism that supported the Sun and the stars . The surviving books of the Hsüan Yeh school said that the heavens were boundless, "empty and void of substance". Likewise, the "sun, moon, and the company of stars float in the empty space, moving or standing still". </P> <P> The Italian scientist Galileo Galilei knew that air had mass and so was subject to gravity . In 1640, he demonstrated that an established force resisted the formation of a vacuum . However, it would remain for his pupil Evangelista Torricelli to create an apparatus that would produce a partial vacuum in 1643 . This experiment resulted in the first mercury barometer and created a scientific sensation in Europe . The French mathematician Blaise Pascal reasoned that if the column of mercury was supported by air, then the column ought to be shorter at higher altitude where the air pressure is lower . In 1648, his brother - in - law, Florin Périer, repeated the experiment on the Puy de Dôme mountain in central France and found that the column was shorter by three inches . This decrease in pressure was further demonstrated by carrying a half - full balloon up a mountain and watching it gradually expand, then contract upon descent . </P> <P> In 1650, German scientist Otto von Guericke constructed the first vacuum pump: a device that would further refute the principle of horror vacui . He correctly noted that the atmosphere of the Earth surrounds the planet like a shell, with the density gradually declining with altitude . He concluded that there must be a vacuum between the Earth and the Moon . </P> <P> Back in the 15th century, German theologian Nicolaus Cusanus speculated that the Universe lacked a center and a circumference . He believed that the Universe, while not infinite, could not be held as finite as it lacked any bounds within which it could be contained . These ideas led to speculations as to the infinite dimension of space by the Italian philosopher Giordano Bruno in the 16th century . He extended the Copernican heliocentric cosmology to the concept of an infinite Universe filled with a substance he called aether, which did not resist the motion of heavenly bodies . English philosopher William Gilbert arrived at a similar conclusion, arguing that the stars are visible to us only because they are surrounded by a thin aether or a void . This concept of an aether originated with ancient Greek philosophers, including Aristotle, who conceived of it as the medium through which the heavenly bodies move . </P>

What is the temperature outside of earth's atmosphere