Julius Heinrich Franz (28 June 1847 – 28 January 1913) was a German

astronomer An astronomer is a scientist in the field of astronomy who focuses on a specific question or field outside the scope of Earth. Astronomers observe astronomical objects, such as stars, planets, natural satellite, moons, comets and galaxy, galax ...

. Franz was born in

Rummelsburg Rummelsburg () is a subdivision or neighborhood (''Ortsteil'') of the Boroughs and neighborhoods of Berlin, borough (''Bezirk'') of Lichtenberg, Berlin, Lichtenberg of the German capital, Berlin. History Rummelsburg was founded in 1669. On 30 Jan ...

Prussia Prussia (; ; Old Prussian: ''Prūsija'') was a Germans, German state centred on the North European Plain that originated from the 1525 secularization of the Prussia (region), Prussian part of the State of the Teutonic Order. For centuries, ...

Pomerania Pomerania ( ; ; ; ) is a historical region on the southern shore of the Baltic Sea in Central Europe, split between Poland and Germany. The central and eastern part belongs to the West Pomeranian Voivodeship, West Pomeranian, Pomeranian Voivod ...

, he studied at the Universities of Greifswald, Halle and

Berlin Berlin ( ; ) is the Capital of Germany, capital and largest city of Germany, by both area and List of cities in Germany by population, population. With 3.7 million inhabitants, it has the List of cities in the European Union by population withi ...

, after which he was the principal astronomer at the Royal Observatory in

Königsberg Königsberg (; ; ; ; ; ; , ) is the historic Germany, German and Prussian name of the city now called Kaliningrad, Russia. The city was founded in 1255 on the site of the small Old Prussians, Old Prussian settlement ''Twangste'' by the Teuton ...

. In 1882 he was a member of a team sent to the town of

Aiken, South Carolina Aiken is the most populous city in, and the county seat of, Aiken County, South Carolina, United States. According to 2020 census, the population was 32,025, making it the 15th-most populous city in South Carolina, and one of the two largest ci ...

, to observe the

transit of Venus A transit of Venus takes place when Venus passes directly between the Sun and the Earth (or any other superior planet), becoming visible against (and hence obscuring a small portion of) the solar disk. During a transit, Venus is visible as ...

. Toward the end of the century he replaced Johann Galle as the director of the observatory at the

University of Breslau A university () is an educational institution, institution of tertiary education and research which awards academic degrees in several Discipline (academia), academic disciplines. ''University'' is derived from the Latin phrase , which roughly ...

.obituary
/ref> He is most noted for his measurements of features near the lunar limbs. He published a popular book about 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 ...

1906 Events January–February * January 12 – Persian Constitutional Revolution: A nationalistic coalition of merchants, religious leaders and intellectuals in Persia forces the shah Mozaffar ad-Din Shah Qajar to grant a constitution, ...

called ''Der Mond''. In this work Julius named some

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 ...

s along the limb the

Mare Orientale Mare Orientale (Latin ''orientāle'', the "eastern sea") is a lunar mare. It is located on the western border of the near side and far side of the Moon, and is difficult to see from an Earthbound perspective. Images from spacecraft have revea ...

, Mare Autumni and Mare Veris. The later two were later renamed to the

Lacus Autumni Lacus Autumni (Latin ''autumnī'', "Lake of Autumn") is a region of lunar mare that lies near the western limb of the Moon. Along this side of the lunar surface is a huge impact basin centered on the Mare Orientale. Two concentric mountain rings ...

and Lacus Veris.

Bibliography

* ''Die Figur des Mondes'', 1899,

. * ''Der Mond'', 1906,

Leipzig Leipzig (, ; ; Upper Saxon: ; ) is the most populous city in the States of Germany, German state of Saxony. The city has a population of 628,718 inhabitants as of 2023. It is the List of cities in Germany by population, eighth-largest city in Ge ...

. ** Second edition: *

Honors

* The crater Franz on the

is named after him.

References

1847 births 1913 deaths People from Miastko People from the Province of Pomerania Astronomers from the Kingdom of Prussia 20th-century German astronomers 19th-century German astronomers University of Greifswald alumni University of Halle alumni Academic staff of the Humboldt University of Berlin Academic staff of the University of Breslau Academic staff of the University of Königsberg Humboldt University of Berlin alumni {{Germany-astronomer-stub