Lagrange Point

How can you find objects that are hard to see in the depths of space? There is plenty of gas in a galaxy, but trying to see a cloud amongst all those starts is not easy. The further back in time you look in the history of the universe, the colder and darker it gets. How do you figure out the structure of the earliest galaxies and their cold gas? A black hole roaming across a galaxy sounds like bad sci fi horror, but may have been found. How can you spot a black hole without any frame of reference? Detecting a roaming black hole is tricky but not impossible. Kieran A. Cleary, Jowita Borowska, Patrick C. Breysse, Morgan Catha, Dongwoo T. Chung, Sarah E. Church, Clive Dickinson, Hans Kristian Eriksen, Marie Kristine Foss, Joshua Ott Gundersen, Stuart E. Harper, Andrew I. Harris, Richard Hobbs, Håvard T. Ihle, Junhan Kim, Jonathon Kocz, James W. Lamb, Jonas G. S. Lunde, Hamsa Padmanabhan, Timothy J. Pearson, Liju Philip, Travis W. Powell, Maren Rasmussen, Anthony C. S. Readhead, Thomas J. Rennie, Marta B. Silva,