It was almost as if the universe had decided the time was right to reveal this particular secret. At some sites, the weather could hardly have been better. The skies were clear in all the right places.

That night-the first of five opportunities in a ten-night window-the decision was straightforward. They had until 4 pm local time to make the go/no-go decision.

Astronomers in the field checked in via phone, Slack, and Webex. A prime target is Sagittarius A*, the 4 million-solar-mass giant at the center of the Milky Way.Įarlier in the day, Shep Doeleman, the director of the EHT, gathered with a handful of colleagues to oversee the global effort here at the project’s command center, a modified faculty office at Harvard University’s Black Hole Initiative. Using a technique called Very Long Baseline Interferometry, the astronomers would unite these geographically distant stations into a virtual Earth-size telescope capable of imaging the “shadow” that certain supermassive black holes cast against the glow of surrounding, superheated matter. A crew wintering over in Antarctica, whom EHT astronomers trained months earlier, would operate the South Pole Telescope. Was the weather good in all those places simultaneously? If so, they had a shot at imaging a black hole.įor this experiment, some 50 astronomers from around the world had traveled to high-frequency radio telescopes on four continents: ALMA and the Atacama Pathfinder Experiment in Chile the Large Millimeter Telescope in Mexico the Submillimeter Telescope in Arizona the Submillimeter Array and the James Clerk Maxwell Telescope in Hawaii the IRAM 30-meter telescope on Pico Veleta in Spain. What mattered were the conditions in Hawaii, Arizona, Spain, central Mexico, northern Chile, and at the South Pole. Last Tuesday, the weather at the Event Horizon Telescope (EHT) command center in Cambridge, Massachusetts couldn’t have been much worse: it was rainy and barely 40 degrees F.

Clear the skies world quest