What is Light curve?
[[Image:201 Penelope light curve.png |thumb |Light curve of the asteroid [[201 Penelope]] based on images taken on 6 October 2006 at [[Mount John University Observatory]]. Shows just over one full rotation, which lasts 3.7474 hours.]] In [[astronomy]], a '''light curve''' is a [[graph]] that shows the brightness of light from a [[celestial object]] or region, over a certain amount of time. The light is usually in a particular frequency interval or band. Light curves can be periodic, that is they repeat in a regular pattern. Examples are [[eclipsing binary|eclipsing binaries]] and [[cepheid variable]]s. Light curves can also be [[aperiodic]], that is they are irregular with no pattern.<ref>{{cite web |url= http://www.credoreference.com/entry/apdst/aperiodic |title=Aperiodic|first= |last= |work= Academic Press Dictionary of Science and Technology |year=1992 |accessdate= 31 December 2011}}</ref> Examples include the light curve of a [[nova]], a [[cataclysmic variable star]], a [[supernova]] or other event. The study of the light curve, together with other observations, gives information about the physical process that produces it or constrains the physical theories about it.<ref>S.V.H. Haugan ''Separating intrinsic and microlensing variability using parallax measurements'' (astro-ph/9508112. August 1995) [http://usparc.ihep.su/spires/find/hep/www?eprint=astro-ph/9508112] {{Webarchive|url=https://web.archive.org/web/20110929180704/http://usparc.ihep.su/spires/find/hep/www?eprint=astro-ph%2F9508112 |date=2011-09-29 }}</ref> ==Planetology== In the study of planets ([[planetology]]), a light curve can be used to work out the [[rotation period]] of a [[minor planet]], [[natural satellite|moon]], or [[comet]] nucleus. From the [[Earth]] many objects are so small that even the most powerful telescopes are unable to see objects clearly. Because of this astronomers measure the amount of light produced by the object over a period of time, its light curve. The time between the peaks on the graph gives the rotational pe