Simplify the following text for a Grade 9 native English-speaking person.
Original: It was discovered on June 4 , 2002 by astronomers Chad Trujillo and Michael Brown at the California Institute of Technology from images acquired at the Samuel Oschin Telescope at Palomar Observatory .
Simplified: It was found on June 4 , 2002 by Chad Trujillo and Michael Brown at the California Institute of Technology .