Examples from literature

• Analysis of their atmosphere might show a great hazard to earthlings, one making it impossible to land or requiring years of research to overcome. 
• How can we know the actual number of earthlings that are sceptics? 
• If the God of these earthlings bothers not about them, why should they trouble about God? 
• It is a bright day, and the Martian is aware of a head-ache brought on by the effort to understand the ways of earthlings, and therefore decides to drive through the city streets. 
• Later analysis would tell whether earthlings would need oxygen-helmet suits such as we plan to use on the moon.