Guest Author - Barbara Melville

Those interested in astronomy may be confused about the similar sounding terms used. Broadly speaking, “astronomy” is concerned with what lies beyond the Earth’s atmosphere, and is an umbrella term for many different branches. It is sometimes defined further to include the observation of objects in the sky – this may seem redundant but it is sometimes preferred. “Stargazer” is a more informal term, referring to anyone who looks at the stars (for whatever reason).

The term “astrophysics”, as its name suggests, refers to the physics branch of astronomy. This term is often used interchangeably with “astronomy”. This is generally considered acceptable since physics is involved in even the most basic applications of astronomy. When choosing to study astronomy/astrophysics, it is worth checking how the course-holder defines these terms in case the physics content doesn’t suit.

“Cosmology” is another term amateur astronomers are likely to come across. It is the branch of astrophysics concerned with the universe on a large scale, including how it’s evolved and what it’s made up of. The big bang is a good example of a topic that would come under cosmology. It is not to be confused with “cosmonaut”, the term that describes a Russian or Soviet astronaut. An “astronaut” is defined as a person trained with the necessary skills and knowledge to work in space travel.

“Astrology” is another term that causes confusion. It is a divination characterized by the observation of positions of celestial objects, and their use in understanding human personality and predicting future events. Although astronomy and astrology are historically related (and do sound a bit similar), there is now little relationship between them. Both astrologers and astronomers may be stargazers, but for very different reasons.

“Astrobiology” is another popularly used term, referring to the study of life in the universe. “Exobiology” is an older term that is often accepted as a synonym. However, there is a difference – astrobiology is broader as it encompasses study of understanding life on Earth as well as outside the Earth’s atmosphere. If it doubt, astrobiology is the safer term.

For those interested in astronomy definitions, Oxford’s A Dictionary of Astronomy (2nd edition), edited by Ian Ridpath, is a useful reference.

Sources

A Dictionary of Astronomy (Oxford Paperback Reference), published by OUP Oxford in September 2007, editor: Ian Ridpath

Ask an Astrobiologist, NASA Astrobiology Institute website, accessed 21st September 2008, author: David Morrison

Cosmology: The Study of the Universe, NASA Universe 101 website, accessed 21st September 2008, no author specified