Neil Armstrong on the moon next to an American flag. Laika the dog sitting in a space capsule, shortly before becoming the first animal to orbit the Earth. Buzz Aldrin taking a selfie, our planet a blue curve behind him, in the first-ever self portrait produced in space.

尼尔·阿姆斯特朗在月球上与美国国旗的合影。第一只绕地球飞行的太空狗莱卡发射前坐在太空舱中的照片。巴兹·奥尔德林以蓝色地球弧线为背景的史上第一张太空自拍照。

These are just three of the 2,400 rare NASA photos now up for sale in an online auction hosted by the Christie's. The images capture "the golden age of space exploration," the auction house said in a press release.

这些只是佳士得主办的在线拍卖会上展售的2400张美国宇航局罕见照片的其中三张。佳士得在新闻稿中指出，这套照片集涵盖了“太空探索的黄金时期”。

The collection of original photographs spans a number of historic missions, from the Mercury and Gemini spaceflight programs to the Apollo moon missions. Some of the images are now iconic, like the "Blue Marble" picture taken by the crew of the Apollo 17 -- the first fully illuminated photo of Earth taken by a human in space.

这套原始照片集囊括水星计划、双子星计划以及阿波罗登月计划等一系列历史性任务，比如，阿波罗17号任务中，宇航员拍到的“蓝色弹珠”照片，现在都极具代表性意义。“蓝色弹珠”是宇航员首度拍到整个地球完全被照亮的照片。

Others, however, were not released by NASA at the time they were taken, and are new to the general public.

不过，其他照片被拍下时美国宇航局没有发布出来，所以公众还是初次看到。

The most expensive item on offer is the only photo showing Armstrong on the Moon, taken by Aldrin during the Apollo 11 mission in 1969. It's estimated to be worth between £30,000 and £50,000, according to the auction house.

拍卖会上最昂贵的拍品是1969年阿波罗11号任务期间，宇航员奥尔德林拍下的唯一一张阿姆斯特朗在月球上的照片。据佳士得估计，这张照片价格应在3万至5万英镑（约合人民币26万至44万元）之间。

Other high-value images include "Blue Marble," which is estimated to sell for up to £25,000, and a photo of the first "Earthrise" seen by humans in space, dated 1968 and worth up to £30,000.

其他高价照片中，“蓝色弹珠”估价高达2.5万英镑，人类上太空后首度目睹“地出”的1968年照片估价也高达3万英镑。

The astronauts were instructed on how to take photos in space by NASA, alongside specialists from the likes of Kodak and National Geographic.

当时除美国宇航局外，柯达与国家地理等公司机构也都派出专家，指导宇航员如何在太空拍照。

"Through their cameras, the astronauts-turned-artists were able to convey to mankind the beauty and profundity of their experience into space, forever changing the way we see ourselves and our place in the universe," said the release.

新闻稿称：“变身艺术家的宇航员通过相机将他们在太空体验到的美与深度传达给人们，永远改变了我们看待自己与我们在宇宙中地位的方式”。

For decades, the unreleased photos were kept in the archives of the Manned Spacecraft Center in Houston, Texas, and could only be accessed by accredited researchers. The items, assembled over the course of 15 years by private collector Victor Martin-Malburet, have been exhibited in museums around the world including the Grand Palais in Paris and the Kunsthaus in Zurich.

几十年来，这些未被公开的照片一直保存在得克萨斯州休斯敦载人航天中心档案室，只限官方认可的研究人员才能观看。这些照片由收藏家维克多·马丁-马尔雷特耗费15年的时间搜罗，曾在世界各地博物馆展出，包括巴黎大皇宫和苏黎世美术馆。

The online sale, named "Voyage To Another World: The Victor Martin-Malburet Photograph Collection," runs through November 19.

这场名为“前往另一个世界的航行：维克多·马丁-马尔雷特照片收藏集”的在线拍卖会将持续到11月19日。