Editing Astronomical object (section)

== History ==
{{Further|History of astronomy}}{{See also|Scientific Revolution|Copernican Revolution}}
Astronomical objects such as [[star]]s, [[planet]]s, [[nebula]]e, [[asteroid]]s and [[comet]]s have been observed for thousands of years, although early cultures thought of these bodies as [[deities]]. These early cultures found the movements of the bodies very important as they used these objects to help navigate over long distances, tell between the seasons, and to determine when to plant crops. During the [[Middle Ages]], cultures began to study the movements of these bodies more closely. Several astronomers of the Middle East began to make detailed descriptions of stars and nebulae, and would make more accurate calendars based on the movements of these stars and planets. In Europe, astronomers focused more on devices to help study the celestial objects and creating textbooks, guides, and [[universities]] to teach people more about astronomy.

During the [[Scientific Revolution]], in 1543, [[Nicolaus Copernicus|Nicolaus Copernicus's]] [[Heliocentrism|heliocentric model]] was published. This model described the [[Earth]], along with all of the other planets as being astronomical bodies which orbited the [[Sun]] located in the center of the [[Solar System]]. [[Johannes Kepler]] discovered [[Kepler's laws of planetary motion]], which are properties of the orbits that the astronomical bodies shared; this was used to improve the heliocentric model. In 1584, [[Giordano Bruno]] proposed that all distant stars are their own suns, being the first in centuries to suggest this idea. [[Galileo Galilei]] was one of the first astronomers to use telescopes to observe the sky, in 1610 he observed the four largest moons of [[Jupiter]], now named the [[Galilean moons]]. Galileo also made observations of the phases of [[Venus]], craters on the [[Moon]], and [[Sunspot|sunspots]] on the Sun. Astronomer [[Edmond Halley]] was able to successfully predict the return of [[Halley's Comet]], which now bears his name, in 1758. In 1781, [[Sir William Herschel]] discovered the new planet [[Uranus]], being the first discovered planet not visible by the naked eye. 

In the 19th and 20th centuries, new technologies and scientific innovations allowed scientists to greatly expand their understanding of astronomy and astronomical objects. Larger telescopes and observatories began to be built and scientists began to print images of the Moon and other celestial bodies on photographic plates. New [[wavelength]]s of light unseen by the human eye were discovered, and new telescopes were made that made it possible to see astronomical objects in other wavelengths of light. [[Joseph von Fraunhofer]] and [[Angelo Secchi]] pioneered the field of [[spectroscopy]], which allowed them to observe the composition of stars and nebulae, and many astronomers were able to determine the masses of binary stars based on their [[orbital elements]]. Computers began to be used to observe and study massive amounts of astronomical data on stars, and new technologies such as the [[Photoelectric effect|photoelectric]] [[photometer]] allowed astronomers to accurately measure the color and luminosity of stars, which allowed them to predict their temperature and mass. In 1913, the [[Hertzsprung–Russell diagram]] was developed by astronomers [[Ejnar Hertzsprung]] and [[Henry Norris Russell]] independently of each other, which plotted stars based on their luminosity and color and allowed astronomers to easily examine stars. It was found that stars commonly fell on a band of stars called the [[main-sequence]] stars on the diagram. A refined scheme for [[stellar classification]] was published in 1943 by [[William Wilson Morgan]] and [[Philip Childs Keenan]] based on the Hertzsprung–Russell diagram. Astronomers also began debating whether other galaxies existed beyond the [[Milky Way]], these debates ended when [[Edwin Hubble]] identified the [[Andromeda Galaxy|Andromeda nebula]] as a different galaxy, along with many others far from the Milky Way.