冰川点上的银河

优胜美地的夜空是许多美国游客见过的最黑暗的。Polly 是从 Tomas 那里听说的，她想亲眼看看。

Yosemite has the darkest sky most American visitors ever see. Polly had heard this from Tomas. She wanted to see for herself.

她在冰川点度过了整个下午，这里是一个海拔970米的观景台。小小的人群聚集在这里等待日落。Polly 坐在栏杆上。

She waited out the afternoon at Glacier Point, an overlook 970 metres above the valley floor. A small crowd was there for the sunset. Polly perched on the railing.

太阳在内华达山脉的山脊后面落下。对面的半圆顶山峰在脸上捕捉到了最后的红光，持续了二十秒。然后，红光消失了。人群轻轻地鼓掌。

The sun went down behind the Sierra ridge. Half Dome, across the valley, caught the last red light on its face and held it for twenty seconds. Then the red was gone. The crowd clapped softly.

一位穿着棕色背心的公园天文学家架起了一台小型望远镜。他在天色渐暗时开始讲解。他解释说，大多数美国城市因为路灯而失去了银河。但在优胜美地，在晴朗的夜晚，你仍然可以看到人类几千年来在这里看到的景象。

A park astronomer in a brown vest set up a small telescope. He gave a talk while the sky grew darker. He explained that most American cities have lost the Milky Way to streetlights. But in Yosemite, on a clear night, you can still see what humans have seen here for thousands of years.

第一颗星星一颗接一颗地出现。天完全黑下来时，银河像一条淡淡的光带横跨天空。它被黑暗的斑块打断，那是尘云挡住了后面的星星。最大的黑暗斑块被称为大裂缝。Polly 看得很清楚。

The first stars came out one at a time. By full dark, the Milky Way was a band of pale light running across the sky. It was broken by dark patches where dust clouds blocked the stars behind them. The biggest dark patch was called the Great Rift. Polly could see it clearly.

天文学家把望远镜指向射手座附近的一个小斑点。“这是我们银河系的中心，”他说。“它中心的超大质量黑洞距离我们两万六千光年。”

The astronomer pointed the telescope at a small smudge near Sagittarius. "This is the centre of our galaxy," he said. "The supermassive black hole at its heart is twenty-six thousand light years away."

一位游客透过目镜看了一眼，然后退后一步。天文学家调整了望远镜，让 Polly 也能看到。透过目镜可以看到密集的星星和尘埃。

A visitor looked through the eyepiece, then stepped back. The astronomer tilted the telescope so Polly could see in too. Through the eyepiece was a dense cluster of stars and dust.

两万六千年前，从那个星团发出的光开始了它到这台望远镜的旅程。Polly 看了很长时间。

Twenty-six thousand years ago, the light leaving that cluster had started its trip to this telescope. Polly looked for a long time.