Stars

Since the dawn of recorded civilization, stars have played a key role in religion and proved vital to navigation, according to the International Astronomical Union. Astronomy, the study of the heavens, may be the most ancient of the sciences. The invention of the telescope and the discovery of the laws of motion and gravity in the 17th century prompted the realization that stars were just like the sun, all obeying the same laws of physics. In the 19th century, photography and spectroscopy, the study of the wavelengths of light that objects emit, made it possible to investigate the compositions and motions of stars from afar, leading to the development of astrophysics. A star develops from a giant, slowly rotating cloud that is made up entirely or almost entirely of hydrogen and helium. Due to its own gravitational pull, the cloud behind collapses inward, and as it shrinks, it spins more and more quickly, with the outer parts becoming a disk while the innermost parts become a roughly spherical clump.