Astrometry from space has unique advantages over ground-based observations: it offers all-sky coverage, while the relatively stable and temperature- and gravity-invariant operating environment delivers precision, accuracy and sample volume several orders of magnitude greater than ground-based results.
Even more importantly, absolute astrometry is possible. The European Space Agency Cornerstone mission Gaia is delivering that promise. Gaia provides 5-D phase space measurements – 3 spatial coordinates and two space motions in the plane of the sky, for a representative sample of the Milky Way’s stellar populations (over 1 billion stars, being ~1% of the stars over 50% of the volume). Full 6-D phase space data is delivered from line-of-sight (radial) velocities for the 300 million brightest stars. These data make substantial contributions to astrophysics and fundamental physics on scales from the Solar System to cosmology, from asteroids to gravitational waves. A few example results illustrating the rapidly changing understanding of the history of our Milky Way will be given.
Professor Gerry Gilmore grew up in New Zealand, where he studied physics and maths and was awarded the first NZ PhD in astronomy. He worked at the Royal Observatory Edinburgh as Senior Research Fellow, before moving to Cambridge in 1984. He has been successively, Advanced Research Fellow, The Royal Society Smithson Fellow at King's College, and John Couch Adams Astronomer, and is now Professor of Experimental Philosophy at the Institute of Astronomy in the University of Cambridge. He is also a Fellow of the Royal Society. He leads the effort to understand the structure and origin of our Galaxy and his team has provided us with our current understanding of how the masses of stars are distributed at birth. He is the UK Principal Investigator for the European Space Agency Gaia mission, a billion-euro satellite that is currently mapping the distribution in space of one billion stars, providing humankind’s first 3-D view of our own Milky Way.
Image credit: Clive Inglis