Gaia provides splendid astrometry, but at the limits of the data small systematic errors are present. A good understanding of the Hipparcos–Gaia astrometry concept, and of the data collection and processing, provides insights into the origins of the systematic errors and how to mitigate their effects.

A selected set of results from Gaia highlight the breadth of exciting science and unexpected results, from the Solar System to the distant Universe, to creative uses of the data.

Gaia data release 2 provides, for the first time, a dense sampling of Galactic phase space with high-precision astrometry, photometry, and radial velocities, allowing researchers to uncover subtle features in phase space and the observational Hertzsprung–Russell diagram.

In the coming decade, we can look forward to more accurate and richer Gaia data releases, and new photometric and spectroscopic surveys coming online that will provide essential complementary data.

The longer term promises exciting new opportunities for microarcsecond astrometry and beyond, including the plans for an IR version of Gaia that would offer the dense sampling of phase space deep into the Milky Way's nuclear regions.

盖亚提供了出色的天体测量，但在数据的限制下，存在小的系统误差。对 Hipparcos- Gaia天体测量概念以及数据收集和处理的良好理解，可以深入了解系统误差的起源以及如何减轻其影响。

来自盖亚的一组精选结果突出了令人兴奋的科学和意想不到的结果的广度，从太阳系到遥远的宇宙，再到数据的创造性使用。

Gaia数据发布 2 首次提供了具有高精度天体测量、光度测量和径向速度的银河相空间的密集采样，使研究人员能够发现相空间中的细微特征和观测赫兹-罗素图。

在接下来的十年里，我们可以期待更准确、更丰富的盖亚数据发布，以及新的光度和光谱调查上线，这些调查将提供必要的补充数据。

从长远来看，微弧秒天体测量及其他领域有望带来激动人心的新机遇，包括计划开发红外版本的盖亚，该版本将提供深入银河系核区的相空间密集采样。