Skip to main content

coronagraph

coronagraph (kərō´nəgrăf´), device invented by the French astronomer B. Lyot (1931) for the purpose of observing the corona of the sun and solar prominences occurring in the chromosphere. Because of the intense light of the sun, the corona and chromosphere can ordinarily be seen only during a total eclipse. The coronagraph consists of two refracting telescopes in tandem. A solid disk placed in front of the prime focus of the first telescope plays the part of the moon and eclipses the sun's image in the telescope so that only the outer layers of the sun's atmosphere are focused by the second telescope onto photographic film. A monochromatic filter is also used to improve optical clarity and remove chromatic aberration.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"coronagraph." The Columbia Encyclopedia, 6th ed.. . Encyclopedia.com. 19 Oct. 2017 <http://www.encyclopedia.com>.

"coronagraph." The Columbia Encyclopedia, 6th ed.. . Encyclopedia.com. (October 19, 2017). http://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/coronagraph

"coronagraph." The Columbia Encyclopedia, 6th ed.. . Retrieved October 19, 2017 from Encyclopedia.com: http://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/coronagraph

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.