The European Space Agency (ESA): http://www.esa.int/

National Aeronautics and Space Administration (NASA): http://www.nasa.gov/

Space Weather: http://www.spaceweather.com/; http://www.spaceweathercenter.org/

Review of recent scientific research related to research Space: http://www.sciencedaily.com/news/space_time/

Portal to the Universe: http://www.portaltotheuniverse.org/

International Earth Rotation Service and Reference Systems: http://www.iers.org