The 1932 discovery-photo of the positron track in Carl Anderson´s cloud chamber has been shown in numerous books and articles over the years. The 63 MeV positron strangely went upwards in the chamber, a fact not much discussed over the years. In his 1961 article about the early work on the positron and muon[1] Anderson writes: ”Curiously enough, despite the strong admonitions of Dr. Millikan that upward-moving cosmic-ray particles were rare, this indeed was an example of one of those very rare upward-moving cosmic ray particles.” However, no explanation about the origin of the upward going positron has been published. In this work we discuss different positron sources and give a detailed explanation of the likely origin of Anderson´s upward going positron.