The simplest explanation is exposure time.

最简单的解释是曝光时间。

The longer the exposure, the longer the streaks as the stars rise and set, making their circular arcs in the sky.

曝光时间越长，星星天空中形成圆弧的起落轨迹也就越长。

On film, even with long exposures, they can appear to be little more than disks.

即使是经过了长时间曝光，上它们看起来也不过是磁盘。

You will need a tripod for this type of long exposure photography!

此类长时间曝光摄影需要三脚架！

Often he included himself in the scenes, eyes closed because of the long exposure time his process required.

他经常把自己包括场景中，闭着眼睛，因为需要长时间的曝光。

But by using a telescope as a camera, long time exposures can be made.

但是通过使用望远镜作为相机，可以进行长时间曝光。

So in order to study distant places in the universe, astronomers take long exposure images of the night sky.

因此，为了研究宇宙中遥远的地方，天文学家拍摄了夜空的长时间曝光图像。

We didn't try it, but somebody recommended this app as a way to take long exposure pictures with your phone.

我们没有尝试， 但有人推荐这个应用程序作为用手机拍摄长时间曝光照的一种方式。

Being able to hook a camera up to a telescope and take long exposures meant being able to see fainter objects, revealing previously hidden details.

它能够将相机与望远镜连接起来，且进行长时间曝光意味着能够看到更模糊的物体，揭示前隐藏的细节。

It looks like a star by eye, but even binoculars reveal it to be fuzzy, and through a telescope, or with long exposure images, you get unmitigated majesty.

肉眼看它就像一颗恒星，但即使是双筒望远镜也显示出它很模糊，而通过望远镜，或长时间曝光的照，你会得到无与伦比的庄严景象。

But exposure times were much quicker by the 1880s, and the introduction of the Box Brownie and other portable cameras meant that, though slow by today's digital standards, the exposure was almost instantaneous.

但到了 19 世纪 80 年代，曝光时间已经快得多了，盒子布朗尼和其他便携式相机的问世意味着，尽管以今天的数字标准来看很慢，但曝光几乎是瞬时完成的。

Instead of looking at previously-known galaxies observed from ground-based telescopes, they pointed Hubble at a relatively empty part of the sky and took hundreds of long exposures over a 10-day period, then combined them.

他们没有观察从地面望远镜观察到的先前已知的星系，而是将哈勃望远镜指向天空中相对空旷的部分，并 10 天内进行了数百次长时间曝光，然后将它们组合一起。

Now, many of the beautiful shots of the night sky you've seen in this video are time lapses, made with long-exposure photos that show you a bit more than you can see with your own eyes.

现，您本视频中看到的许多美丽的夜空照都是延时拍摄的，这些照是用长时间曝光的照拍摄的， 向您展示的比您亲眼看到的要多一些。