A total

lunar eclipse A lunar eclipse is an astronomical event that occurs when the Moon moves into the Earth's shadow, causing the Moon to be darkened. Such an alignment occurs during an eclipse season, approximately every six months, during the full moon phase, ...

occurred at the Moon’s

ascending node An orbital node is either of the two points where an orbit intersects a plane of reference to which it is inclined. A non-inclined orbit, which is contained in the reference plane, has no nodes. Planes of reference Common planes of referenc ...

of orbit on Friday, April 22, 1921, with an umbral

magnitude Magnitude may refer to: Mathematics *Euclidean vector, a quantity defined by both its magnitude and its direction *Magnitude (mathematics), the relative size of an object *Norm (mathematics), a term for the size or length of a vector *Order of ...

of 1.0678. A lunar eclipse occurs when the

Moon The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar ...

moves into the

Earth's shadow Earth's shadow (or Earth shadow) is the shadow that Earth itself casts through its atmosphere and into outer space, toward the antisolar point. During the twilight period (both early dusk and late dawn), the shadow's visible fringe – someti ...

, causing the Moon to be darkened. A total lunar eclipse occurs when the Moon's near side entirely passes into the Earth's umbral shadow. Unlike a

solar eclipse A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby obscuring the view of the Sun from a small part of Earth, totally or partially. Such an alignment occurs approximately every six months, during the eclipse season i ...

, which can only be viewed from a relatively small area of the world, a lunar eclipse may be viewed from anywhere on the

night Night, or nighttime, is the period of darkness when the Sun is below the horizon. Sunlight illuminates one side of the Earth, leaving the other in darkness. The opposite of nighttime is daytime. Earth's rotation causes the appearance of ...

side of Earth. A total lunar eclipse can last up to nearly two hours, while a total solar eclipse lasts only a few minutes at any given place, because the Moon's

shadow A shadow is a dark area on a surface where light from a light source is blocked by an object. In contrast, shade occupies the three-dimensional volume behind an object with light in front of it. The cross-section of a shadow is a two-dimensio ...

is smaller. Occurring only about 5.6 days after

perigee An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. The line of apsides (also called apse line, or major axis of the orbit) is the line connecting the two extreme values. Apsides perta ...

(on April 16, 1921, at 16:10 UTC), the Moon's apparent diameter was larger. This lunar eclipse was the third of an almost tetrad, with the others being on May 3, 1920 (total); October 27, 1920 (total); and October 16, 1921 (partial). This was the first total lunar eclipse of

Lunar Saros 130 Saros (astronomy), Saros cycle series 130 for lunar eclipses occurs at the moon's ascending node, repeats every 18 years days. The 130th lunar saros is associated with Solar Saros 137. Lunar saros 130 contains 71 me ...

Visibility

The eclipse was completely visible over much of

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

and western

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

, seen rising over

northeast Asia Northeast Asia or Northeastern Asia is a geographical Subregion#Asia, subregion of Asia. Its northeastern landmass and islands are bounded by the Pacific Ocean, North Pacific Ocean. The term Northeast Asia was popularized during the 1930s by Ame ...

and

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

and setting over eastern South America,

western Europe Western Europe is the western region of Europe. The region's extent varies depending on context. The concept of "the West" appeared in Europe in juxtaposition to "the East" and originally applied to the Western half of the ancient Mediterranean ...

, and

west Africa West Africa, also known as Western Africa, is the westernmost region of Africa. The United Nations geoscheme for Africa#Western Africa, United Nations defines Western Africa as the 16 countries of Benin, Burkina Faso, Cape Verde, The Gambia, Gha ...

Eclipse details

Shown below is a table displaying details about this particular solar eclipse. It describes various parameters pertaining to this eclipse.

Eclipse season

This eclipse is part of an

eclipse season An eclipse season is a period, roughly every six months, when eclipses occur. Eclipse seasons are the result of the axial parallelism of the Orbit of the Moon, Moon's orbital plane (orbital inclination, tilted five degrees to the ecliptic, Earth ...

, a period, roughly every six months, when eclipses occur. Only two (or occasionally three) eclipse seasons occur each year, and each season lasts about 35 days and repeats just short of six months (173 days) later; thus two full eclipse seasons always occur each year. Either two or three eclipses happen each eclipse season. In the sequence below, each eclipse is separated by a

fortnight A fortnight is a unit of time equal to 14 days (two weeks). The word derives from the Old English term , meaning "" (or "fourteen days", since the Anglo-Saxons counted by nights). Astronomy and tides In astronomy, a ''lunar fortnight'' is hal ...

Related eclipses

Eclipses in 1921

* An annular solar eclipse on April 8. * A total lunar eclipse on April 22. * A total solar eclipse on October 1. * A partial lunar eclipse on October 16.

Metonic

* Preceded by: Lunar eclipse of July 4, 1917 * Followed by: Lunar eclipse of February 8, 1925

Tzolkinex

* Preceded by: Lunar eclipse of March 12, 1914 * Followed by: Lunar eclipse of June 3, 1928

Half-Saros

* Preceded by: Solar eclipse of April 17, 1912 * Followed by:

Solar eclipse of April 28, 1930 A total solar eclipse occurred at the Moon's ascending node of orbit on Monday, April 28, 1930, with a magnitude of 1.0003. It was a hybrid event, with only a fraction of its path as total, and longer sections at the start and end as an annular ec ...

Tritos

* Preceded by: Lunar eclipse of May 24, 1910 * Followed by: Lunar eclipse of March 22, 1932

Lunar Saros 130

* Preceded by: Lunar eclipse of April 12, 1903 * Followed by: Lunar eclipse of May 3, 1939

Inex

* Preceded by: Lunar eclipse of May 11, 1892 * Followed by: Lunar eclipse of April 2, 1950

Triad

* Preceded by: Lunar eclipse of June 21, 1834 * Followed by: Lunar eclipse of February 21, 2008

Lunar eclipses of 1919–1922

This eclipse is a member of a semester series. An eclipse in a semester series of lunar eclipses repeats approximately every 177 days and 4 hours (a semester) at alternating

nodes In general, a node is a localized swelling (a "knot") or a point of intersection (a vertex). Node may refer to: In mathematics *Vertex (graph theory), a vertex in a mathematical graph *Vertex (geometry), a point where two or more curves, lines, ...

of the Moon's orbit. The penumbral lunar eclipse on March 13, 1922 occurs in the next lunar year eclipse set.

Saros 130

Tritos series

Inex series

Half-Saros cycle

A lunar eclipse will be preceded and followed by solar eclipses by 9 years and 5.5 days (a half saros).Mathematical Astronomy Morsels, Jean Meeus, p.110, Chapter 18, ''The half-saros'' This lunar eclipse is related to two annular solar eclipses of

Solar Saros 137 Saros cycle series 137 for solar eclipses occurs at the Lunar node, Moon's ascending node. It repeats every 18 years, 11 days, and contains 70 eclipses, 55 of which are umbral eclipses. The first eclipse in the series was on 25 May 1389 and the ...

Notes

External links

* {{DEFAULTSORT:Lunar eclipse 1921-04 1921-04 1921 in science