The wonders of the universe are revealed through technological advances based on tested principles of physics. Our understanding of the cosmos draws upon models, theories and laws in our endeavour to seek explanations for the myriad of observations made at many different wavelengths. Techniques, such as imaging, photometry, astrometry and spectroscopy, allow us to determine many of the properties and characteristics of celestial objects. Explanations for events in our spectacular universe, based on our understandings of the electromagnetic spectrum, allow for insights into the relationships between supernovae, star formation and evolution, and extreme events, such as high gravity environments of a neutron star or black hole. Our understanding of celestial objects depends upon observations made from Earth or space near the Earth.
Spectroscopy is a vital tool for astronomers and provides a wealth of information.
Photometric measurements can be used for determining distance and comparing objects. The study of binary and variable stars reveals vital information about stars. Stars evolve and eventually die . In the early part of the twentieth century, many experimental and theoretical problems remained unresolved. Attempts to explain the behaviour of matter on the atomic level with the laws of classical physics were not successful.