"Per aspera ad astra" or "Ad astra per aspera" is a Latin phrase which means roughly "Through hardships to the stars", "A rough road leads to the stars" or "To the stars through difficulties."

"To excellence through effort” is a correct way to translate this phrase. The noun "astra" (lit.,‘stars’) denotes exactly the excellence we can achieve through our efforts; therfore, “ad astra" connotes 'pursuing excellence.'