GalileoMobile (GM, www.galileo-mobile.org) is a non-profit, itinerant education initiative that brings Astronomy to young people in areas with limited access to outreach programmes. Started in 2009 by a group of volunteers, it now performs astronomy-related activities in schools and communities all over the world, and encourages follow- up activities through teacher training workshops and the donation of telescopes and educational resources. Since its creation, GM has organised expeditions to Chile, Bolivia and Peru (2009), Bolivia (2012), India (2012), Uganda (2013), Brazil and Bolivia (2014), and extended actions in Portugal (2012,2013), Nepal (2013) and the United States (2013), reaching over 10,300 students and 1,500 teachers. With its Constellation project, GM aims to establish a South American network of schools committed to the long- term organisation of astronomical outreach activities amongst their pupils and local communities, and to provide the teachers of those schools with the material, training and support required to do so.Each school in the network will benefit from: – the donation of educational material and telescopes; – a personalised long-distance training program for all educators involved; – a plan of outreach activities to be carried out at the schools throughout the school year; – a two-day visit by the GM team, involving outreach activities and teacher training workshops; – access to an online platform created especially for the network, which will facilitate interactions among the schools and with GM. The project will involve twenty-one schools in seven countries (Peru, Brazil, Bolivia, Colombia, Ecuador, Chile and Argentina), directly reaching at least 100 teachers and 6,000 students. Thanks to the long-term sustainability of the project, more students will benefit from the project through events organised independently by the schools. The Constellation project is a Major Cosmic Light programme in support of the IAU’s IYL2015.