It is 87.4  km in diameter. It was named after British physicist Oliver Heaviside; the name was approved in 1973 by the International Astronomical Union (IAU) Working Group for Planetary System Nomenclature (WGPSN).   37th (Tyne Electrical Engineers) Searchlight Regiment, Royal Artillery  The 37th (Tyne Electrical Engineers) Searchlight Regiment, Royal Artillery was an air defence unit of Britain's Territorial Army (TA) during World War II. It served in the Battle of France, when it was one of the last British units evacuated. It then served in Anti-Aircraft Command defending the UK, particularly against V-1 flying bombs. The unit was formed in 1936, as 37th (Tyne Electrical Engineers) Anti-Aircraft Battalion, Royal Engineers, by expanding 307th (Tyne) AA Company, RE, an independent searchlight company based in Tynemouth, near Newcastle upon Tyne. 307 Company was part of the Tyne Electrical Engineers (TEE), a longstanding TA unit of the Royal Engineers (RE). During World War I the TEE had been the parent unit for almost half the anti-aircraft (AA) searchlight companies formed for service both at home and overseas. When the TA's AA organisation was established in the early 1920s, one of the TEE's companies was re-converted to the searchlight role as 307 Company in 1924. (The other independent companies were numbered 309–18: the number 308 was kept vacant in case of expansion of the TEE.) In 1936, as part of the further expansion of AA defences, 307 AA Company was expanded into a full battalion, with the following organisation:  37th AA Battalion formed part of 30th (Northumbrian) AA Group (later Brigade) based at Sunderland, in 2 AA Division. The TA's AA units were mobilised on 23 September 1938 during the Munich Crisis, with units manning their emergency positions within 24 hours, even though many did not yet have their full complement of men or equipment. The emergency lasted three weeks, and they were stood down on 13 October. When the TA doubled in size following the Munich Crisis, the TEE formed a duplicate unit as a Light Anti-Aircraft (LAA) regiment of the Royal Artillery (RA), designated 37th (Tyne Electrical Engineers) LAA Regiment, RA (TA), which and was still in course of formation at Tynemouth when World War II broke out in September 1939.