Skywatchers across Pennsylvania could be treated to one of the year’s most unusual astronomical displays early Tuesday — if clouds and rain hold off.
A total lunar eclipse is set to begin around 6:04 a.m. March 3 and conclude at approximately 7:03 a.m., just as the sun rises in the eastern sky. During that overlap, the moon will be setting in the west while still fully eclipsed, turning a deep, rusty red.
The rare alignment is known as a selenelion, sometimes called a horizontal eclipse. The event occurs when both the rising sun and the eclipsed moon are visible in the sky at the same time — a phenomenon that appears to defy the basic geometry of a lunar eclipse.
Under normal circumstances, a total lunar eclipse happens when the Earth passes directly between the sun and the moon, placing the two celestial bodies on opposite sides of the planet. In theory, that positioning should make it impossible to see both at once.
However, the Earth’s atmosphere bends, or refracts, light from the sun and moon. This atmospheric effect allows observers near the horizon to glimpse the eclipsed moon in the west while the sun peeks above the eastern horizon. The same bending of light also filters out shorter blue wavelengths, leaving the moon glowing in shades of red and copper — the source of the term “blood moon.”
While total lunar eclipses occur periodically, selenelions are far less common because they require precise timing at sunrise or sunset, along with clear sightlines to both horizons.
For the best view, observers should seek locations with unobstructed eastern and western horizons, such as hilltops or open fields. Buildings, trees or terrain features could easily block the low-hanging moon or the rising sun during the brief window of visibility.
Whether central Pennsylvania residents will see the spectacle remains uncertain. Forecasts currently call for cloudy skies and possible rain through much of Monday into early Tuesday morning. If cloud cover lingers at dawn, the rare alignment may be hidden from view.
If skies clear at the right moment, though, early risers could witness a striking celestial pairing: a red-hued moon sinking into the western horizon as daylight breaks in the east — a fleeting astronomical illusion that blends orbital mechanics with atmospheric science.
Source: The Weather Channel, CBS 21