Mare Humboldtianum (

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

''humboldtiānum'', the "Sea of

Alexander von Humboldt Friedrich Wilhelm Heinrich Alexander von Humboldt (14 September 1769 – 6 May 1859) was a German polymath, geographer, natural history, naturalist, List of explorers, explorer, and proponent of Romanticism, Romantic philosophy and Romanticism ...

") is a

lunar mare The lunar maria ( ; mare ) are large, dark, basaltic plains on Earth's Moon, formed by lava flowing into ancient impact basins. They are less reflective than the "highlands" as a result of their iron-rich composition, and hence appear dark to ...

located just to the east of

Mare Frigoris Mare Frigoris (Latin ''frīgōris'', the "Sea of Cold") is a lunar mare in the far north of the Moon. It is located in the outer rings of the Procellarum basin, just north of Mare Imbrium, and stretches east to north of Mare Serenitatis. It is j ...

, in the center of Humboldtianum basin. It is located along the northeastern limb of 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 ...

, and continues on to the

far side ''The Far Side'' is a single-panel comic created by Gary Larson and syndicated by Chronicle Features and then Universal Press Syndicate, which ran from December 31, 1979, to January 1, 1995 (when Larson retired as a cartoonist). Its surrealis ...

. Due to its location, the visibility of this feature can be affected by

libration In lunar astronomy, libration is the cyclic variation in the apparent position of the Moon that is perceived by observers on the Earth and caused by changes between the orbital and rotational planes of the moon. It causes an observer to see ...

, and on occasion it can be hidden from view from

Earth Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...

. The basin material is of the

Nectarian The Nectarian Period of the lunar geologic timescale was from 3.920 billion years ago to 3.850 billion years ago. It is the period during which the Nectaris Basin and other major basins were formed by large impact events. Ejecta from Nectaris for ...

epoch In chronology and periodization, an epoch or reference epoch is an instant in time chosen as the origin of a particular calendar era. The "epoch" serves as a reference point from which time is measured. The moment of epoch is usually decided b ...

, with the mare material being of the

Upper Imbrian The Imbrian is a lunar geologic period divided into two epochs, the Early and Late. Early Imbrian In the lunar geologic timescale, the Early Imbrian epoch occurred from 3,850 million years ago to about 3,800 million years ago. It overlaps the en ...

epoch (3.4–3.7 Ga). The lighter gray area to the southeast of the dark mare material is a region of hills within the basin. The rim of this basin forms a mountain range that can be seen under oblique lighting conditions. This mare is centered at 56.9° N, 81.5° E, and its maximal size is 230 km. However the surrounding basin extends for a diameter of over 600 km. The walled plain Bel'kovich spills over the northwestern portion of Mare Humboldtianum, and the flooded crater Bel'kovich A lies across the southwestern rim of Bel'kovich and part of the floor of the mare. At the center of the Humboldtianum basin is a

mascon In astronomy, astrophysics and geophysics, a mass concentration (or mascon) is a region of a planet's or moon's crust that contains a large positive gravity anomaly. In general, the word "mascon" can be used as a noun to refer to an excess distr ...

, or gravitational high. The mascon was first identified by Doppler tracking of the

Lunar Prospector ''Lunar Prospector'' was a spacecraft that orbited the Moon for 19 months in 1998-99. From a low polar orbit, it mapped surface composition including lunar hydrogen deposits, measured magnetic and gravity fields, and studied lunar outgassing e ...

spacecraft. This mare is situated between near (visible) and far sides of the Moon, like a link between known and unknown. That's why Johann Mädler named it after

, a prominent explorer of unknown lands. It is one of only two lunar maria that are named after people, the other being

Mare Smythii Mare Smythii (Latin for "Smyth's Sea") is a lunar mare located along the equator on the easternmost edge of the Moon's near side, named for the 19th-century British astronomer William Henry Smyth. It is one of only two lunar maria that are named ...

(named after British astronomer

William Henry Smyth Admiral William Henry Smyth (21 January 1788 – 8 September 1865) was an English Royal Navy officer, hydrographer, astronomer and numismatist. He is noted for his involvement in the early history of a number of learned societies, for his hy ...

) which is located along the eastern lunar limb.

Popular culture

* In an episode of the 1967 TV Series

Captain Scarlet and the Mysterons ''Captain Scarlet and the Mysterons'', often shortened to ''Captain Scarlet'', is a British science fiction television series created by Gerry Anderson, Gerry and Sylvia Anderson and filmed by their production company AP Films#Century 21, Centu ...

, a Mysteron outpost was shown to be located somewhere in the Humboldt Sea.

External links

Mare Humboldtianum Constellation region of interest
Lunar Reconnaissance Orbiter Camera (LROC) article, Posted by Bashar Rizk on June 3, 2010
Map with current names of surface featuresarchive
.
Geological Map of the Humboldtianum Basin and its deposits
abstract from the Lunar and Planetary Science Conference, 2017.
Geological Map of the Humboldtianum Basin and its deposits poster
poster presentation from the Lunar and Planetary Science Conference, 2017.

References

{{Lunar maria Humboldtianum Alexander von Humboldt Humboldtianum Humboldtianum