Editing Umbra, penumbra and antumbra (section)

==Umbra==
{{Redirect|Umbra}}
[[File:Antumbra.jpg|thumb|200px|right|Umbra, penumbra, and antumbra formed through windows and shutters]]

The '''umbra''' ({{langnf|la||shadow}}) is the innermost and darkest part of a shadow, where the light source is completely blocked by the occluding body. An observer within the umbra experiences a total [[occultation]]. The umbra of a round body occluding a round light source forms a [[cone|right circular cone]]. When viewed from the cone's [[apex (geometry)|apex]], the two bodies [[angular diameter|appear the same size]].

The [[lunar distance (astronomy)|distance]] from the [[Moon]] to the apex of its umbra is roughly equal to that between the Moon and [[Earth]]: {{cvt|384402|km|mi}}. Since [[Earth's diameter]] is 3.7 times the Moon's, its umbra extends correspondingly farther: roughly {{convert|1.4|e6km|mi|abbr=unit}}.<ref>{{cite web |url=http://www.astronomy.ohio-state.edu/~pogge/Ast161/Unit2/eclipses.html |title=Lecture 9: Eclipses of the Sun & Moon |work=Astronomy 161: An Introduction to Solar System Astronomy |first=Richard |last=Pogge |publisher=[[Ohio State University]] |access-date=July 16, 2015}}</ref>