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Total Eclipse of the Plot for unrealistic eclipses in general. As Laconic.Total Eclipse Of The Plot says: "Eclipses behave like they shouldn't, but who cares?"
Honestly the description for Total Eclipse of the Plot is unclear whether it refers to an unrealistic eclipse or any plot relevant or supernatural eclipse (which is what I thought it was). I feel like it should probably be separated into two tropes, might want to take this up on trope talk...
I think the laconic page is so broad as to be inaccurate; Total Eclipse of the Plot is more about the narrative drama surrounding eclipses. That would cover "extreme sky darkening for more visual panache" and "magical eclipse" both. If it's just the astronomical inaccuracy with no increased spectacle, there's always Artistic License – Space
Edited by Synchronicity
Total Eclipse of the Plot: Also, solar eclipses only completely block out the light in one relatively small area and the light reduction gets less pronounced the further away from the center of the eclipse, but in fiction tend to block out the sun completely wherever they happen to be. So this situation is covered by the trope.
But it seems weird to use the same trope for "eclipses are supernatural", "eclipses are plot-relevant and dramatic", "eclipses fully darken the sky", and "total eclipses last hours and partial eclipses last minutes" those seem like completely different concepts that shouldn't be pushed into the same trope just because they all involve eclipses.
Perhaps, but that's how things are right now.
Current Project: Incorruptible Pure Pureness
Well this is inspired by seeing the total eclipse last week - in media, I've noticed a total solar eclipse is usually portrayed with an entirely black sky like it's the middle of the night, when in reality it is dark but more like dusk/the sun just set. Is this a trope we have?