Seeing a Galaxy

On the sixth night, Camila was observing a distant galaxy. Its catalogue name was NGC 1068. To astronomers, it was one of the brightest and closest active galactic nuclei in the sky.

An active galactic nucleus is a region at the centre of a galaxy where a supermassive black hole is actively feeding on gas. The gas spirals in, heats up to millions of degrees, and emits radiation before it crosses the event horizon. NGC 1068's central black hole is about ten million times the mass of the Sun. It is forty-seven million light years from Earth.

"Look," Camila said. She pulled up a false-colour image of a small bright blob with two larger fainter lobes. "The blob is the galaxy's nucleus. The lobes are jets of plasma being thrown out by the black hole. They are travelling at perhaps a tenth of the speed of light."

Polly tilted her glasses.

"And we are looking at it from forty-seven million years ago," Camila said. "The light we are recording right now left this galaxy when life on Earth was still in the late Eocene. There were no humans. There were no chimpanzees. Antarctica still had forests."

The telescope made a small hum.

"Sometimes I think," Camila said quietly, "that astronomy is mostly about getting comfortable with the fact that you are very small and very late, and then finding that comforting."

Polly tilted her red head.

"I think," she said slowly, "that I do not mind being small. I mind, sometimes, being late."

Camila smiled. "You are not so late. The light has been travelling for forty-seven million years to get to us. In some sense the galaxy is happening tonight."

The observation continued for two hours. The Magellanic Clouds were visible to the south. They are only visible from the southern hemisphere, which is why so much astronomy of the past century has been done from the southern hemisphere. The Magellanic Clouds are between one hundred sixty thousand and two hundred thousand light years away. The light Polly was watching had been older than her species.