The cosmic microwave background is the oldest light in the universe, emitted about 14 billion years ago and now seen as faint microwave radiation filling the sky. As these photons travel through galaxy clusters, which contain hot gas of high-energy electrons, they gain a tiny boost of energy. This is the Sunyaev-Zel'dovich effect, first observed over thirty years ago. Detecting it is difficult, but it reveals where massive clusters are and how they are distributed. In this case, Hubble observed the cluster RX J1347.5-1145, about 5 billion light-years away, while the ALMA telescope in Chile measured the microwave signal from it.

Hampi is a UNESCO World Heritage Site in Karnataka, India, with more than 1,600 surviving remains spread over 4,100 hectares. It was the capital of the Vijayanagara Empire from 1336 to 1565. Travellers from Persia and Portugal described it as a prosperous, wealthy and grand city with temples, markets and farms along the Tungabhadra River. By 1500 it was estimated to be the world's second-largest city after Beijing, and probably India's richest at the time. In 1565 a coalition of Muslim sultanates defeated the Vijayanagara Empire, its capital was conquered and destroyed, and the city was left in ruins. Hampi remains a religious centre, with the active Virupaksha Temple at its heart.