21 (number)

21 (twenty-one) is the natural number following 20 and preceding 22.

In science

• The atomic number of scandium

In astronomy,

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: Messier object M21, a magnitude 7.0 open cluster in the constellation Sagittarius

Related Topics:
Messier object - M21 - Magnitude - Open cluster - Constellation - Sagittarius

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: The New General Catalogue object NGC 21, a barred spiral galaxy in the constellation Andromeda

Related Topics:
New General Catalogue - NGC 21 - Barred spiral galaxy - Constellation - Andromeda

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:The Saros number of the solar eclipse series which began on -2275 May 5 and ended on -995 June 11. The duration of Saros series 21 was 1280.1 years, and it contained 72 solar eclipses.

Related Topics:
Saros - Solar eclipse - -2275 - May 5 - -995 - June 11

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:The Saros number of the lunar eclipse series which began on -1973 February 11 and ended on -639 April 22. The duration of Saros series 21 was 1334.2 years, and it contained 75 lunar eclipses.

Related Topics:
Lunar eclipse - -1973 - February 11 - -639 - April 22

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