The Shaping of the Galaxy

Through his work on binary stars, Herschel proved that stars, not just planets, had motion. This was significant data, considering that until that time, stars were regarded as fixed objects in the celestial sphere. Herschel began to ask himself if the Sun in our own solar system was on the move, which he showed was precisely the case.

Using his superior instruments, Herschel was able to determine the stars' proper motion. He determined that in one part of the sky, the stars seemed to be moving away from one another, and stars in the opposite part of the sky seemed to be moving together. He suggested that the Sun was in motion with the stars that seemed to be moving away, and he also indicated the direction in which the entire galaxy was moving. This was another scientific discovery that rocked the core of ancient belief that the solar system, hence humankind, was the absolute center of the universe. If the Sun were in motion, then around what did it revolve? Where was the center of the universe, if a center truly even existed? It was finally decided


The greater the density of stars, the farther they exist from the Sun.

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Our Sun

This is a reproduction of Herschel's rendering of the structure of the Milky Way according to his disc theory, which appeared in his paper "On the Construction of the Heaven," published in 1785.

that the Sun and our solar system were in motion near the center of the universe, and that was still close enough for most people's perception of a divine design.

Herschel went further with his studies by inventing a systematic method that counted the number of stars in selected areas of the sky in order to determine the shape of the Milky Way. After compiling extensive data, he proposed a number for the amount of stars in the Milky Way, which was around 300 million. He also stated that its shape was like that of a wispy pancake, with a diameter four times its thickness. He applied this same disc-with-tendrils shape to similar celestial objects that appeared remote, which came to be known as galaxies, the Greek word for Milky Way. In this way, Herschel was the first to scientifically verify the existence and overall shape of galaxies.

Herschel also made observations of the Sun and kept a log. Between 1779 and 1806, he recorded his observations and devised his own unique terminology for his discoveries, such as the word openings for sunspots. He also confirmed that the Sun was gaseous in nature.

In 1800, as a result of his solar observations, he became the first to detect the existence of infrared radiation. Initially, he was merely curious about the various temperatures produced as sunlight passed through the different colored filters he used to observe the Sun. By experimenting with a prism that divided light into all known spectrums, Herschel discovered that the highest temperature in the spectrum of visible light came from the red spectrum. Using a thermometer with a blackened tip, he investigated further and found that a form of invisible light (radiation) existed beyond the visible red spectrum, made evident by the continued rise in temperature where apparently no light existed beyond red. Through these experiments with light spectrums and their individual heat readings, Herschel was the first to record the existence of "light," or electromagnetic radiation, beyond visible light. This energy would later come to be known as infrared light.

By 1802, Herschel finished a 16-year-long study on nebulae. He recorded 2,514 nebulae and was the first to identify many of them as being heavy clusters of stars rather than just dust clouds, and that some were perhaps distant galaxies. In his papers, he touched on a theory of stellar evolution by proposing that the universe began as nebulous clouds. He hypothesized that these nebulae gradually gathered into varying gravitational masses that over time evolved into separate star clusters. He theorized that through collapse of some of these clusters, new nebulae would form and split away as newborn diffuse clouds, and then the process would begin again.

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  • armi
    How were the planets and stars formed big bang theory?
    2 years ago

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