As a novel coronavirus known as 2019-nCoV continues to spread throughout China and to countries across the world , the big question is: How long will the outbreak last—and how bad will it get? While some doctors have made predictions and outbreaks of similar coronaviruses like severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS) provide clues , the short, if unsatisfying, answer is that no one is exactly sure. “There is no scientist nor sage on the planet that will tell you when the peak of this epidemic will occur,” said Dr. Michael Ryan, executive director of the World Health Organization’s health emergencies program, at a press conference Wednesday. “The peak will occur when the peak occurs.” Nonetheless, research is moving forward. Here’s what scientists know so far. How does 2019-nCoV compare to other coronaviruses? The novel coronavirus, which was first found in Wuhan, China, is not identical to either SARS or MERS, but the virus