Simplify the following text for a Grade 7 native English-speaking person.
Original: Four principal stars , Î , Î , Î , and Î Crv , form an asterism known as `` the Spica 's Spanker '' or `` the Sail '' .
Simplified: Four principal stars , Î , Î , Î , and Î Crv , make a group of stars called as `` the Spica 's Spanker '' or `` the Sail '' .