Simplify the following text for a Grade 9 native English-speaking person.
Original: The site that was decided upon was la Silla , a 7800 foot mountain bordering the southern extremity of the Atacama Desert , situated 100 miles north of La Serena , 17 miles south of Las Campanas Observatory , and 60 miles north of Cerro Tololo Observatory .
Simplified: La Silla is a 2,400 meter high mountain that is found in the far southern part of the Atacama Desert . It can be found about 160 kilometers north of La Serena , 27 kilometers south of the Las Campanas Observatory , and about 100 kilometers north of the Cerro Tololo Observatory .