It is named after International Year of Astronomy of 2009 (MMIX in Roman numerals).
Marking the International Year of Astronomy, Astronomy Class released their second album, Pursuit Of Happiness, on 2 May 2009.
In addition to being the theme song of Misia's Hoshizora no Live V Just Ballade tour, "Ginga" was also chosen as the official image song for the International Year of Astronomy and its music video, which features the position, size and distance data of stars and other celestial bodies, presented in 4-D, was created in collaboration with the National Astronomical Observatory of Japan.
ATP International Series | International Monetary Fund | International Red Cross and Red Crescent Movement | ATP International Series Gold | International Space Station | Amnesty International | International Olympic Committee | BirdLife International | International Finance Corporation | International Organization for Standardization | International Telecommunication Union | International Criminal Court | One Day International | International Nonproprietary Name | International Labour Organization | International Civil Aviation Organization | International Boxing Federation | Toronto International Film Festival | New Year's Day | International Atomic Energy Agency | astronomy | International Maritime Organization | International Development Association | John F. Kennedy International Airport | New Year's Eve | Los Angeles International Airport | International Bank for Reconstruction and Development | International Court of Justice | International Fund for Agricultural Development | Rotary International |