Collections like this are not necessarily complete.
http://www.oldversion.com/windows/google-earth/
There is a timeline here of versions, for comparison.
It might not be complete either.
https://en.wikipedia.org/wiki/Google_earth
And Google may have stopped work on separate
applications. It's really hard to tell. As there
is a plugin for Chrome (and of course Chrome is
not supported on WinXP any more, and might only
be available in a 64-bit version anyway).
There are a couple possibilities for compatibility:
1) The Google site still lists WinXP as supported.
Like WinXP, Vista, Win7. No mention of Win8/Win10.
This suggests the OS support listed on the page
is just bullshit.
2) Does it use .NET on Windows ? If so, it might use
a version of .NET not available on WinXP.
3) The graphics are also a sticking point. Google Earth
uses DirectX or OpenGL for rendering. They couldn't
just be happy drawing a picture into a bitmap buffer
directly as a perfectly adequate display mechanism.
Hitching your wagon to hardware acceleration, carries
risks. For users, for which the application complains
there is no DirectX (a bullshit claim), they should attempt
to use the preferences and switch to OpenGL. Even OpenGL
has versions, and if Google pushes their code to using
the newest OpenGL features (why?), then it could be
busted because of that.
4) Google feels a need to install GoogleUpdater, hide it in
a svchost or whatever. Could you be denied service because
that bit of trickery didn't work ? Dunno.
You're just going to have to test versions, and take your
best guess as to the reason they don't work.
I was not able to find any knowledgeable analysis of why
it might fail. But the ingredients are there for trouble.
They can pretend it's compatible in the sense that they
delivered a PE32 EXE to your desk, but that doesn't mean
the subsystems are actually compatible.
Paul