Al-Shirazi Dorsum

Al-Shirazi Dorsum is a ridge (dorsum) on the planet Mercury, approved by the International Astronomical Union and named for the Persian astronomer Qutb al-Din al-Shirazi (1236–1311)¹. It lies in the planet's southern hemisphere within the H-12 quadrangle and is 188 km across¹.

Location and mapping

The feature sits at southern mid-latitudes, with its center at −48.33° latitude and 162.36° longitude in the planetographic coordinate system used by the Gazetteer of Planetary Nomenclature¹. Its mapped extent runs from longitude 159.00° to 165.67° and from latitude −48.20° to −49.38°, and it falls in quadrangle H-12¹. The position is tied to the MESSENGER Team control network, the coordinate framework built from data returned by NASA's MESSENGER spacecraft, which orbited Mercury from 2011 to 2015¹. The Gazetteer notes that boundaries shown on its maps are approximate and portray only the rough extents of named features¹.

Name and namesake

The name honors Qutb al-Din al-Shirazi, a Persian astronomer, physicist, and poet who lived from 1236 to 1311 and who suggested that the "black dots" seen on the Sun were Mercury and Venus transiting across its disk¹. The gazetteer entry lists the name's continent of origin as Asia and its ethnicity as Persian, with the Biographical Encyclopedia of Astronomers (edited by Thomas Hockey and eight others, Springer, 2007) as the reference source¹.

Earlier examples on Mercury include Antoniadi Dorsum and Schiaparelli Dorsum, both approved in 1976 and named for Italian astronomers².

Tectonic context

Mercury's surface is dominated by contractional tectonic landforms, which fall into three broadly distributed classes: lobate scarps, high-relief ridges, and wrinkle ridges³. These features record global crustal shortening as the planet's interior cooled and its solid inner core grew³. In IAU nomenclature, ridges of this kind carry the descriptor dorsum or dorsa; they are typically broad, low-relief arches often superposed by a narrow ridge, and are symmetrical in cross-section⁴. Wrinkle ridges are confined to younger smooth plains and are interpreted as combinations of folding and faulting, involving a thrust fault or a thrust fault with a secondary backthrust³.

References

1. Al-Shirazi Dorsum, Gazetteer of Planetary Nomenclature, USGS Astrogeology Science Center
2. Gazetteer of Planetary Nomenclature table, USGS Bulletin 2129
3. Watters, T. R. et al. (2015). Distribution of large-scale contractional tectonic landforms on Mercury: Implications for the origin of global stresses. Geophysical Research Letters 42, 3755–3763.
4. Mercury global structural mapping of contractional structures, INAF Open Access

Initially written Oct 20, 2026 · Edited: Oct 25, 2026

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