Video produced before Cluster was launched. Chapters as follows 1) Intruders from the Sun: Introduction to ESA's Cluster mission that studies the Sun-Earth connection in orbit around Earth. Influence of the Sun and the solar wind on Earth, how auroras are formed, and controversial topics that Cluster is expected to settle as it investigates the magnetosphere and its workings. The four satellites give a three-dimensional picture of the region between them. SOHO studies the upheavals in the Sun itself and reports the solar weather sweeping in towards Earth, reaching Cluster an hour later. 2) Why Cluster studies the Earth's surroundings: the Sun's behaviour and its effects on Earth is still has the capacity to baffle. But many features of the Sun can only be monitored from space. Japanese Yoko satellite monitors X-rays from the Sun's atm. ESA is leading a succession of missions in partnership with NASA, including Ulysses, Eureka, SOHO, Cluster, and how all these missions are helping the Sun-Earth system. 3) The engineering mission: Footage in a cleanroom of the satellites being assembled, vibration testing. Footage of the motors of the (then new) launcher Ariane 5 being tested in France. Animation of Cluster's orbit after launch. An overview of the four satellites' main components and service modules. Footage at Main Control Room in ESOC, and a description of how the orbits are tailored to the phenomena being studied. 4) Instruments: 200 scientists from 17 countries, conduct operations from a Joint Science Operations Centre in the UK. Animations of the instruments and their workings. Cluster is special in that it can study phenomena in 3D with its four satellites. 5 and 6) Solar-terrestrial phsyics I&II: Phenomena including: Energetic particle penetration, magnetic reconnection, auroras. Terrestrial phenomena are a lot simpler than those in space.7) Solar-terrestrial physics III: Plasma-magnetic field interactions on the Sun, interaction of solar wind/plasma with Earth's magnetic field and wider applications in astronomy. Cluster is unquiely equipped to study this in 3D.