Caption: 这幅星系团 ZwCl0024+1652 的图像是利用哈勃太空望远镜（HST）的观测数据数学建模制作而成的。 哈勃望远镜的观测数据是由高级巡天照相机（ACS）于 2004 年 11 月拍摄的。ACS 的分辨率非常高，可以对星团中的引力透镜进行非常详细的测量。星系团中暗物质分布以蓝色的云雾状叠加在照片之上，在观测中并不可见，而是根据引力透镜数据建立的数学模型。 图像中出现的 "暗物质环 "是迄今为止证明暗物质存在的最有力证据之一。观测数据提供的证据表明，暗物质约占宇宙的 1/4，并被认为构成了宇宙的基本结构。此外，星系和星系团中很大一部分质量是暗物质，通过直接观测是看不到的。
Credit: 美国国家航空航天局、欧空局、M.J. Jee 和 H. Ford（约翰霍普金斯大学） credit link

Caption: This image shows a map of the distribution of galaxies and is based on redshift data from the Sloan Digital Sky Survey (SDSS). Redshift measurements provides information on the distances, positions and motions of the galaxies. The Earth is located at the center of the image, and each dot represents a galaxy. The outer circle represents a ""distance"" of about 2 billion light years. The idea of distance in cosmology is complex because the usual measurement of distance is the separation between two points in space at the same time. However, because of the speed of light, the further a distance, the farther back in time we are observing. The numbers on the outer circle are Right Ascension coordinates mapped onto a flat circle, and provides information on the position of the galaxies on the sky. The colours used represent the ages of the stars in the galaxies, the redder, more strongly clustered points represent galaxies comprising of older stars. The dark wedges that do not contain any dots are regions that were not mapped by the SDSS due to dust from the Milky Way galaxy obscuring the view.
Credit: M. Blanton and Sloan Digital Sky Survey credit link