Through a telescope, Mercury will appear as a tiny black dot moving across the face of the sun for about 5 1/2 hours Monday.
It will be the last “transit of Mercury” visible from Maryland until 2049.
NASA calls planetary transits “a special kind of eclipse.” They are similar to when the moon blocks out the sun in a full solar eclipse, though more rare but also harder to see. Mercury blocks just about 0.5% of the sun’s face.
From Earth, only Mercury and Venus can transit the sun because they’re closer to the center of the solar system. According to NASA, transits of Mercury occur once every seven or eight years, on average; Venus transits come in pairs separated by eight years, but more than a century passes between each of those transit pairs.
This transit of Mercury will occur from about 7:30 a.m. to 1 p.m. Monday.