As noted by @Halfak (many thanks !):
https://tools.wmflabs.org/pageviews/?project=en.wikipedia.org&platform=all-access&agent=user&range=all-time&pages=Earth
Top 1 user agent for "Earth" pageview for an our is:
Mozilla/5.0 (Windows NT 6.2; WOW64) AppleWebKit/534.34 (KHTML, like Gecko) PhantomJS/1.9.1 Safari/534.34 {"browser_major":"1","os_family":"Windows 8","device_family":"Other","os_major":"-","browser_family":"PhantomJS","wmf_app_version":"-","os_minor":"-"} 1673
See https://en.wikipedia.org/wiki/PhantomJS - I think we want to add this to the list of known bots.