top of page

Anticipating Partial Solar Eclipse

Not everyone will experience totality. For the rest of us anticipating April 8, 2024, what will our fraction of the sun look like? Fortunately, nature gives us a stunt double with the moon.

On some given day, you can anticipate seeing the moon in the same phase as the solar phase you will see from your site on April 8, 2024. Look on Michael Zeiler's map to find the degree (or percentage) of the partial eclipse for your observing site. Or subtract from 90 the percent of obscuration given for any location on Xavier Jubier's interactive Google map.

Map courtesy of Michael Zeiler,; used with permission.

Then find the calendar day when the moon is of an equivalent illumination. Observe the moon on that day to anticipate the appearance of the eclipsed sun.

For example, at Four Corners National Monument the obscuration is about 63%, so 27% of the moon is illuminated, which occurs around the First Quarter phase. The evening of March 14, the moon is illuminated 27%. For eclipse observers in Four Corners, the size of that March 14 moon will compare with the April 8 sun.

What does a four percent sun look like at maximum eclipse in South Bend, IN (timeanddate) ?

Thin crescent moon with earthshine above treeline.
When earthshine is present the moon looks three dimensional, seemingly obscuring the "sun" behind it.

On March 11 when the waxing moon was about four percent illuminated, I watched it settle in the west shortly after sunset. I was viewing the crescent when a string of Starlink satellites rose, passed under Jupiter, passed over Rigel, and disappeared into the moon's shadow.

Crescent moon above parking lot; bright Jupiter above; and Starlink rising right center.

Are there any Starlink passes predicted during totality? It'd be a visceral introduction to Starlink. This pass the Starlink chain was magnitude=3.3, so any pass during totality would likely be too faint against twilight sky.

And that's just what I expect of Eclipse Day. I was anticipating a solar eclipse but experienced more.


Commenting has been turned off.
Featured Posts
Recent Posts
Search By Tags
bottom of page