标题： 盖亚：银河系的三维普查 显示英文标题

标题： Gaia: 3-dimensional census of the Milky Way Galaxy

摘要： 从太空进行的天体测量相较于地面观测具有独特优势：全天覆盖、相对稳定的温度和重力不变的工作环境，提供了比地面结果高几个数量级的精度、准确性和样本量。更重要的是，可以进行绝对天体测量。欧洲空间局的核心任务盖亚（Gaia）正在实现这一承诺。盖亚为银河系恒星种群的代表性样本提供了五维相空间测量——包括三个空间坐标和天球平面内的两个空间运动——包括超过20亿颗恒星，约占整个银河系约50%半径范围内恒星的1%。盖亚的视线（径向）速度为3亿颗最亮的恒星提供了完整的六维相空间数据。这些数据在从太阳系到宇宙学的尺度上对天体物理学和基础物理学做出了重大贡献。一场知识革命正在进行中。 显示英文摘要

摘要： Astrometry from space has unique advantages over ground-based observations: the all-sky coverage, 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, including over two billion stars, being about one percent of the stars over about 50 percent of the radius. Full 6-D phase space data is delivered from Gaia's 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. A knowledge revolution is underway.