Is Google Earth Pro a real program? It installed itself overnight, without my permission
[Update 02/08/2017]
It seems this is a genuine update to Google Earth that the Big G have pushed out through the Google Update service. They announced the change in their product forum:
Beginning with this version, Google Earth "Free" and Earth Pro have been combined into a single product, Earth Pro...In the weeks to come, Earth "Free" users will be automatically upgraded to Earth Pro. We encourage Earth users not requiring any Pro features to check out the new Google Earth for web browsers.
[Original Answer - applies to any unknown software that mysteriously appeared]
Until you are sure, DO NOT RUN IT.
If this is a work computer, you may want to check with your corporate IT department if they pushed it out themselves.
You may have accidentally agreed to a prompt to install it if you have been recently using Google Earth (have you?).
If you right-click on the shortcut and select Properties, what is the file path? You may want to browse to the target and upload it to Virus Total for analysis.
Other sources of it being installed are a previously aborted or partial install that has been corrected by a new version being installed by Google Updater - do you have that installed? - or it was installed as shovel-ware by another application installer.