Sedna Planitia [SEP] located on astronomical body
Sedna Planitia
Sedna Planitia is a large lowland area of Venus, south of Ishtar Terra. 
It is thought to be lava-covered and similar to a lunar mare. Its name is derived from the Inuit sea goddess.
Ogygis Undae
Ogygis Undae is the only named southern hemisphere dune field on Mars. It is named after one of the classical albedo features on Mars, "Ogygis Regio". Its name, which refers to Ogyges, a primeval mythological ruler in ancient Greece, was officially approved by the International Astronomical Union (IAU) on September 17th, 2015. It is situated just outside Argyre Planitia, a plain located in the southern highlands of Mars. The dunes of Ogygis Undae extend from latitude −49.94°N to −49.37°N