Splitting of string at an interval

[subhabangalore at gmail.com]

Dear Group,

I was looking to split a string in a particular interval, like,

If I have a string, 
string="The Sun rises in the east of  our earth"

I like to see it as, 
words=["The Sun","rises in","in the","east of","our earth"]

If any one of the learned members can kindly suggest.

Regards,
Subhabrata.