Astrophysics is the branch of astronomy that employs the principles of physics and chemistry "to ascertain the nature of the heavenly bodies, rather than their positions or motions in space." Among subjects studied are heliophysics, stellar physics, orbital mechanics, interstellar medium and the cosmic microwave background.
- ↑ Keeler, James E. (November 1897), "The Importance of Astrophysical Research and the Relation of Astrophysics to the Other Physical Sciences", The Astrophysical Journal 6 (4): 271–288, doi:10.1086/140401, Bibcode: 1897ApJ.....6..271K, "[Astrophysics] is closely allied on the one hand to astronomy, of which it may properly be classed as a branch, and on the other hand to chemistry and physics.… It seeks to ascertain the nature of the heavenly bodies, rather than their positions or motions in space–what they are, rather than where they are.… That which is perhaps most characteristic of astrophysics is the special prominence which it gives to the study of radiation."
- ↑ "astrophysics". Merriam-Webster, Incorporated. Archived from the original on 10 June 2011. https://web.archive.org/web/20110610085146/http://www.merriam-webster.com/dictionary/astrophysics. Retrieved 2011-05-22.
- ↑ "Focus Areas - NASA Science". nasa.gov. https://science.nasa.gov/astrophysics/focus-areas/.
- ↑ "astronomy". Encyclopædia Britannica. http://www.britannica.com/EBchecked/topic/40047/astronomy.