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Loading contentWhen a target crosses the meridian — its highest, sharpest point in the sky — the ideal moment to observe or image it. Computed from its right ascension and the local sidereal time.
Facts on this topic will be cited from these primary and reference sources.
Mission data, planetary science, space telescopes, and public-domain imagery.
Most NASA-produced imagery is in the public domain; individual items are checked for usage terms before publication.