Search for new celestial objects using microlensing effect

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The main goals of the MOA project are the search for non-luminous astrophysical objects comprising a significant fraction of dark matter of the Galaxy, and also the search for Earth-like planets orbiting distant stars in the Galaxy. The phenomenon of gravitational microlensing offers a practical procedure for carrying out both these goals. To accomplish the goals, a wide-field optical telescope of diameter 1.8m was assembled in Japan during 2003. A telescope dome of diameter 8m, and a large CCD camera with 80 million pixels, were also fabricated in Japan at the same time. During 2004, the telescope, dome and camera were installed at the Mt. John Observatory of the University of Canterbury in New Zealand. First light occurred on March 1^<st> 2005.Main results: the first clear discovery of an extra-solar planet by gravitational microlensing occurred in July 2003. The discovery was made jointly by the MOA and OGLE groups. Additional measurements were subsequently made by the Hubble Space Telescope. The planet discovered in this event is similar to Jupiter.Its mass is 2.6 times that of Jupiter, and it orbits a star of 0.63 solar mass at an orbital radius of 4.3 AU.Another Jovian mass planet was found in March 2005. This discovery was made in a microlensing event of high magnification in collaboration with the OGLE, MicroFUN and PLANET/Robonet groups. During April 2005, a Neptune-like planet was found in an event of high magnification in collaboration with the OGLE and MicroFUN groups. Finally, in August 2005, an Earth-like planet was found in collaboration with the PLANET and OGLE/Robonet groups. The latter discoveries imply that our solar system is not a lonely system in our Galaxy