Penumbra at HighBeam Research
Penumbra on Wikipedia
Pictures from Google Image Search ...
Penumbra - faint outer shadow. Penumbral lunar eclipses occur when the Moon passes through the penumbral shadow but are very difficult to observer so are of internest mainly to astonomers.
penumbra Portion of the shadow cast by an eclipsing object in which the eclipse is seen as partial.
perihelion The closest approach to the Sun of any object in orbit about it.
period The time needed for an orbiting body to complete one revolution about another body.
penumbra -- the part of a shadow (as of the Moon) within which the source of light (the Sun) is only partially blocked out.
perigee -- the point in the orbit of the Moon that is closest to the Earth.
penumbra: A dark region that surrounds an even darker central area of a sunspot.
photosphere: The visible portion of the Sun.
~: The brighter area that surrounds the darker umbra or umbrae at the center of a sunspot. (go to first use in the text) ...
~. The sunspot area that may surround the darker umbra or umbrae. It consists of linear bright and dark elements radial from the sunspot umbra.
(a) Less than full shadow (umbra).
(b) The portion of a shadow in which light from an extended source is partially but not completely cut off by an intervening body; the area of partial shadow surrounding the umbra.
Shadowed area in an eclipse where only part of the light source is blocked. Observers in the ~l shadow of a solar eclipse see a partial eclipse.
~ Literally "next to the umbra". (i) The shadow that results when only part of the bright object is occulted; e.g. an observer will see a partial eclipse when he is in the ~ of the shadow of the moon. (ii) The lighter area surrounding a sunspot.
~- the outer part of an eclipse shadow; also, the lighter area surrounding the center of a sunspot
Perihelion- a planet or comet's closest approach to the sun
Periodic time- (see sidereal period) ...
The portion of a shadow in which only part of the light source is covered by an opaque body.
~l lunar eclipse
A lunar eclipse in which the Moon passes only through the Earth's ~.
The outer portion of the shadow during an eclipse. A partial eclipse will occur as the eclipsed object is not completely covered. The ~ also refers to the outer region of a sunspot.
A Partial blocking of the Sun by the Earth creates an ~ Shadow. The Sunlight is dimmed but not extinguished.
~ Eclipse ...
the area of partial illumination surrounding the darkest part of a shadow caused by an eclipse.
the point in the orbit closest to the planet.
~. (1). The lighter part of a sunspot. (2). The area of partial shadow either side of the main umbra cone of shadow cast by the Earth.
Perigee. The position of the Moon in its orbit when it is closest to the Earth.
~: The portion of a shadow that is only partially shaded.
~l eclipse: A lunar eclipse in which the moon enters the ~ of Earth's shadow but does not reach the umbra.
perigee: The orbital point of closest approach to Earth.
~ - The outer part of the shadow of a body where sunlight is partially blocked by the body
Perihelion - The point in the orbit of a body when it is closest to the Sun
Period - The time it takes for a regularly repeated process to repeat itself ...
- ~l Eclipse. Observers in western North America can see the Moon pass partly through the edge of Earth's shadow on Feb. 9. The northern part of the Moon will appear darkest.
The Planets ...
The ~ is the outer, relatively light region of a sun spot. It is shaped like an annulus (a ring) surrounding the darker, cooler umbra.
~l lunar eclipse
Europe, e Africa, Asia, Aus., Pacific, N.A.
Partial lunar eclipse ...
The ~ is the area of partial shadow (compare to umbra).
For an object orbiting the Earth, the perigee is the point in each orbit which is closest to the Earth. The perigee varies a small amount from orbit to orbit. The closest perigee is called the proxigee.
~ - (n.)
(a.) For an eclipse, the part of the shadow from which the sun or other radiating body is only partially occulted; (b) of a sunspot, the outer region of the sunspot, not as dark as the central umbra.
perfect cosmological principle - (n.) ...
A ~l eclipse of the Moon. [H76]
Rotation of the line of apsides in the plane of the orbit; (in a binary) precession of the line of apsides due to mutual tidal distortion. [H76]
Apsides, Line of ...
The ~l eclipse ends.
Annular Solar Eclipse : 29 April
Annular Eclipse Visibility:
March 29, 2526
All Saros Series follow this progression.
(northern edge of shadow)
As described above, the Saros cycle is based on the recognition that 223 synodic months is to a good approximation equal to 242 draconic months and 239 anomalistic months.
~ See umbra. ~l eclipse See lunar eclipse, note. Per, Pers International Astronomical Union abbreviations for Perseus. See constellation. perfect fluid In simplifying assumptions, a fluid chiefly characterized by lack of viscosity and, usually, by incompressibility.
~ portion of the shadow from which part of the light source is excluded when a body passes over the light source. perfect cosmological principle proposition in the steady state theory that the Universe looks the same everywhere at all times.
~ region of partial shadow that is outside the umbra; the light source is partially blocked.
~ literally, "dim light"; the outer filamentary region of a sunspot. perihelion the point in its orbit where a planet is closest to the Sun. when referring to objects orbiting the Earth the term perigee is used; the term periapsis is used for orbits around other bodies.
A complex magnetic configuration of a solar sunspot group consisting of opposite polarity UMBRAe within the same ~. Gamma. A complex ACTIVE REGION in which the positive and negative polarities are so irregularly distributed as to prevent classification as a bipolar group.
A lighter part surrounding the umbra, in which the light is only partly cut off, is called the ~.
2. The darker central portion of a sun spot, surrounded by the lighter ~. Umbriel (NASA Thesaurus / NASA SP-7, 1965) A satellite of Uranus at a mean distance of 267,000 kilometers.
The shadow cast by the Moon can be divided by geometry into the completely shadowed umbra and the partially shadowed ~.
Types of Solar Eclipses
The preceding figure allows three general classes of solar eclipses (as observed from any particular point on the Earth) to be defined: ...
Lunar eclipses can be full - the Moon passes completely through the Earth's umbral shadow, partial - it passes only through part of the umbral shadow, or ~l - it only passes through the ~.
I did some quick trigonometry, and I get that the fuzzy outer part of the eclipse shadow (called the ~) should be about 1000 km across or so, while the deep shadow (the umbra) is a little bit bigger than the size of Titan itself, or about 5200 km (again, these are pretty rough numbers).
For example, the ratio of the umbral areas (the darker part of the sunspot) to total spot area (including the lighter ~) changes abruptly in 1941/1942 and the ratio of the total sunspot area to the sunspot number changes dramatically with the start of the USAF/NOAA data.
Observers located in the much broader outer shadow of the Moon (the ~) see such an eclipse. At the edge of the ~, the Moon seems to "take a bite out of the Sun". Further within the ~, the Sun's disk takes the shape of a
After totality the partial phase starts with the left limb of the Moon brightening in the far less noticeable ~l shadow. In London the Moon will still only be seven or so degrees up at half partial phase around 10.35pm; in Edinburgh it is a mere three degrees up.
The dark centre of a spot is called the umbra; the outer, lighter ring, the ~. Spots may be several times larger than the Earth or so small that telescopic observation is difficult. They may last for months.
Like all shadows of light from an extended source the shadow produced by the Earth has an umbra, where all the light from the Sun is shadowed, and a ~, where only some of it is. ~l eclipses of the Moon occur when the Moon passes only through the Earth's ~l shadow.
Outside the umbra is the ~ wherein the light source is partially visible. During solar eclipses, the eclipse can only be seen as total from within the umbral part of the Moon's shadow.
The second shadow is called the ~. This shadow becomes larger as it reaches the Earth. A total solar eclipse, or a complete blocking out of the Sun's light, can only be seen by those who live in the area covered by the umbra.
The shadow of the Earth can be divided into two distinctive parts: the umbra and ~. Within the umbra, there is no direct solar radiation.
When viewed through a telescope, sunspots have a dark central region known as the umbra, surrounded by a somewhat lighter region called the ~. Sunspots are dark because they are cooler than the surrounding photosphere. They are the site of strong magnetic fields.
Particularly if the partial eclipse is nearly total, the unobscured part of the sun acts as an approximate line source of light. This means that objects cast shadows which have a very narrow ~ in one direction, but a broad ~ in the perpendicular direction.
The shaded gray dot in the center of the graph is the ~l shadow of the Earth at L2. In the center of the shadow the solar power to run MAP is cut by 80% so the trajectory is planned to avoid eclipses for as long as possible.
Sunspots are regions of strong magnetic field on the sun's photosphere. They appear as dark areas on the sun's surface (the umbra) surrounded by a less dark ~. They may persist for days or even months.
See also: What is the meaning of Earth, Sun, Solar, Astro, Eclipse?