<a href="https://en.wikipedia.org/wiki/Venus" id="mw1g" rel="mw:WikiLink" title="Venus">Venus</a> <a href="https://en.wikipedia.org/wiki/Occultation" id="mw1w" rel="mw:WikiLink" title="Occultation">occults</a> the star <a href="https://en.wikipedia.org/wiki/Regulus" id="mw2A" rel="mw:WikiLink" title="Regulus">Regulus</a>. This rare event is used to determine the diameter of Venus and the structure of the Venusian atmosphere.