The 3rd Wetton lecture, 19th June 2018 delivered by Professor David W. Hogg, Center for Cosmology and Particle Physics, New York University In the last 20 years, the astronomical community has found thousands of planets around other stars, and we now know that many or even most stars in our Galaxy host planets. These planets have been found by making exceedingly precise measurements of stars. Some of the planets we find are extremely strange; most known planetary systems are very different from our own Solar System. Here we will look at how these measurements are made, and how planets are found in the data. The data analysis - the search for the planets in the mountains of data - involves cutting-edge ideas from data science and machine learning. These technologies are transforming our capabilities in astronomy.