Simplify the following text for a Grade 15 native English-speaking person.
Original: The European Southern Observatory ( ESO ; formally the European Organization for Astronomical Research in the Southern Hemisphere ) is an intergovernmental research organization for astronomy , composed and supported by fifteen countries .
Simplified: The European Southern Observatory ( ESO , officially called the European Organization for Astronomical Research in the Southern Hemisphere ) , is a research group for astronomy , made up of fourteen countries from Europe .