ASTRONOMY COLLOQUIUM<br>Mohler Prize Lecture<br>Lighting up the Universe: Witnessing Cosmic Dawn</br>
Thirteen and a half billion years ago, four hundred thousand years after the Big Bang, the universe had expanded and cooled enough for hydrogen atoms to form. All was darkness. It took another few hundred million years before stars and galaxies lit up the universe, ending the cosmic "Dark Age". In this talk, I will review what we know about the first stars, galaxies and supermassive black holes and how new and future facilities will enable us to witness the epoch of "Cosmic Dawn".