微信是腾讯公司于2011年推出的一款为智能终端提供即时通讯服务的免费应用程序。截至2015年底,微信的活跃用户超过6亿,每天都有数十亿人次登录。图1为微信启动界面,图示一个人站在巨大的地球(常被一部分微信用户误认为是月球)面前。图中的地球引用的是地球的真实照片——“蓝色弹珠”(见图2)。该照片是在1972年由阿波罗17号太空船船员在距地球 WeChat is a free application that Tencent launched in 2011 to provide instant messaging services for smart terminals. As of the end of 2015, WeChat had more than 600 million active users and had several billion logins every day. Figure 1 shows the WeChat activation interface, which shows a person standing in front of a huge Earth (often mistakenly considered by the WeChat user as the Moon). The earth in the picture refers to the real photo of the earth—“blue marbles” (see Figure 2). The photo was taken in 1972 by Apollo 17 spacecraft crew at a distance from Earth