How to Use "perihelion" with Example Sentences

1. How much does the direction of perihelion change each orbit ?
2. According to marsden 's calculations , this comet reaches its closest point to the sun ( perihelion ) on march 18th .
3. Although predicting the brightness of comets with any degree of accuracy is very difficult , hale-bopp met or exceeded most predictions when it passed perihelion on april 1 , 1997 . The comet was dubbed the great comet of 1997 .