A large fraction of the matter content of the universe is thought to be dark matter. There are numerous experiments around the world that aim to detect dark matter or infer its properties directly or indirectly, though to date there has not yet been a conclusive direct experimental detection of a dark matter interaction. Dr Cees Carels will explore the current evidence in favour of the existence of dark matter, and cover in more detail a number of modern experiments and the challenges towards direct detection.
The Hipparcos satellite project of the European Space Agency was dedicated to measuring the accurate positions of more than 100,000 stars. Doing so from space represented a fundamentally new discipline in space science. With the publication of the scientific results from the Hipparcos mission in 1997, ESA adopted the Gaia mission, a follow-on and vastly more advanced star-mapping satellite, in 2000. Gaia was launched in 2013 and continues to operate from its advantageous location at the Sun-Earth Lagrange point, L2. Gaia is measuring the positions of more than two billion stars in our Galaxy with extreme accuracy, and is set to revolutionise many areas of astronomy and astrophysics. The talk will explain why the measurement of star positions is of such scientific importance. It will review the two thousand year history of this branch of astronomy, called astrometry, explain why these measurements are being made from space, illustrate how the very exacting measurements are made in practice, and present some of the many areas of astronomy that are being impacted by these new experimental insights.