Charting The Milky Way Galaxy

Science@ESA Vodcast (Episode 6, Part 1): Charting the Milky Way - Mapping the Galaxy - from Hipparcos to Gaia.

In this sixth episode of the Science@ESA vodcast series Rebecca Barnes discovers the motions of the stars, learns how astronomers measure their distances and looks at the new European mission that will really get to grips with our place in the Universe.

ESA Hipparcos Mission

Hipparcos, a European mission, pinpointed the positions of more than one hundred thousand stars to high precision, and more than one million stars to lesser precision. Hipparcos turned slowly on its axis and repeatedly scanned right around the sky at different angles. It measured angles between widely separated stars, and recorded their brightness, which were often variable from one visit to the next. Each star selected for study was visited about 100 times over four years.

• http://www.esa.int/esaSC/120366_index...
• http://sci.esa.int/science-e/www/area...

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ESA Gaia Mission

Gaia is a mission that will conduct a census of one thousand million stars in our Galaxy. It will monitor each of its target stars about 70 times over a five-year period, precisely charting their positions, distances, movements, and changes in brightness. It is expected to discover hundreds of thousands of new celestial objects, such as extra-solar planets and failed stars called brown dwarfs. Within our own Solar System, Gaia should also identify tens of thousands of asteroids.

Additional scientific benefits include detection and characterisation of tens of thousands of extra-solar planetary systems, a comprehensive survey of objects ranging from huge numbers of minor bodies in our Solar System, through galaxies in the nearby Universe, to about 500 000 distant quasars. It will also provide stringent new tests of Albert Einsteins general relativity theory.

• http://www.esa.int/esaSC/120377_index...
• http://sci.esa.int/science-e/www/area...
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