The 100 Hours of Astronomy Cornerstone Project is a worldwide event consisting of a wide range of public outreach activities, live science center, research observatory webcasts and sidewalk astronomy events.One of the key goals of 100 Hours of Astronomy is to have as many people as possible look through a telescope as Galileo did for the first time 400 years ago. 100 Hours of Astronomy will take place from 2-5 April when the Moon goes from first quarter to gibbous, good phases for early evening observing. Saturn will be the other highlight of early evening observing events.

One of the 100 Hours Astronomy programs, "Around the World in 80 Telescopes", is a unique live 24-hour webcast, following night and day around the globe to some of the most advanced observatories both on and off the planet. The following observatories among the NAOJ observatories are joining in the program: Hawaii Observatory (Subaru Telescope), Nobeyama Radio Observatory, Okayama Astrophysical Observatory, TAMA300, and Hinode (Solar-b).