“Mercury will pass very close to the Sun in the sky as its orbit carries it around the far side of the solar system from the Earth.
This occurs once in every synodic cycle of the planet (116 days), and marks the end of Mercury’s apparition in the morning sky and its transition to become an evening object over the next few weeks.
At closest approach, Mercury will appear at a separation of only 0°34′ from the Sun, making it totally unobservable for several weeks while it is lost in the Sun’s glare.” – in-the-sky.org