1421 Esperanto in the outer asteroid belt at a distance of 2.8–3.4 AU once every 5 years and 5 months (1,983 days; semi-major axis of 3.09 AU). Its orbit has an eccentricity of 0.08 and an inclination of 10° with respect to the ecliptic. The body's observation arc begins with its first observation as at Heidelberg Observatory in October 1906, almost 30 years prior to its official discovery observation at Turku. This minor planet was named by the discoverer after the artificial language, Esperanto, which was created by inventor and writer, Ludwik Lejzer Zamenhof (1859–1917), who used the pseudonym "Doktoro Esperanto". The
Ludwik Hirszfeld Hirszfeld was the first to foresee the serological conflict between mother and child, which was confirmed by the discovery of the Rhesus factor. Upon this basis he developed, in the last years of his life, an "allergic" theory of miscarriage and recommended antihistamine therapy. Hirszfeld also investigated tumors and the serology of tuberculosis. His discovery of the infectious agent of paratyphoid C had far-reaching consequences for differential diagnosis. Ludwik Hirszfeld Ludwik Hirszfeld (5 August 1884 in Warsaw – 7 March 1954 in Wrocław) was a Polish microbiologist and serologist. He is considered a co-discoverer of the inheritance of ABO blood