Sentence:  ... I was thrilled at the prospect of seeing the waning crescent Moon swing over Venus in the predawn sky on Wednesday morning, April 22, 2009. While the <WSD>occultation</WSD> was visible from much of North America, it was only in Arizona and parts of other surrounding states, where Wendee and I live, that the ingress would take place in a completely dark sky. It would be a highlight of the International Year of Astronomy, which reached its peak during 2009. 
Meaning of the word marked with <WSD> tags:  An astronomical event that occurs when one celestial object is hidden by another celestial object that passes between it and the observer when the nearer object appears larger and completely hides the more distant object.