As a girl in Michigan, Gabriela Aguilar sometimes went looking for the northern lights in the state’s Upper Peninsula. But it wasn’t until Thursday night, when she climbed to the roof of her apartment building in Harlem, that she finally saw them.

“I’m just shocked that it took my entire life to be able to see it,” said Dr. Aguilar, 37, who stood with her dog, Gomez, and watched the sky turn pink, purple and green until the autumn chill drove her back inside. “And — of all places — seeing it in New York City!”