Lunar eclipse of July 2018

Anybody watch it? How bright did the moon appear compared to Mars?

Please don’t tell me that e-mail comparing the brightness of the Moon and Mars is still alive.

And why the focus on the July 2018 one? Lunar eclipses happen twice a year, and are visible by half the planet whenever they happen.

I never got any e-mail; is there a story here? Lunar eclipses do vary in brightness, though.

With the Moon right next to Mars (within a few degrees, anyway) it should make for a nice spectacle (there is no way that happens twice a year, especially with Mars at opposition). You can see various photos, but the camera doesn’t respond to light the same way your eyes do, not to mention the difference in diameter of the two objects should affect one’s perception.

Oh, OK, I was missing that context. About a decade ago, the Earth and Mars came unusually close (like, a few percent closer than they do when they’re ordinarily at their closest), and some source made the unhelpful observation that Mars would look as big as the Moon, if you looked at it through a telescope. But then a chain e-mail got started saying “This August, Mars is going to look as big as the Moon!”, leaving off the bit about the telescope. And since the e-mail never said what year “this August” was, it was still circulating at least five years later. You can see how your question might look like a mutation of that.

As to seeing them side-by-side in the sky, it’s still going to be hard to make a comparison by eye, because the Moon will cover so much more area. Certainly, Mars would be brighter than a Mars-sized patch of the eclipsed Moon, but the entirety of the Moon would likely still be brighter. Heck, in a light-polluted area, a Moon-sized patch of “empty” sky might well be brighter than Mars.


The “especially” doesn’t fit there. If the eclipsed Moon is right next to Mars, then Mars must be at opposition, and vice-versa. But you’re right; Mars isn’t usually at opposition during a lunar eclipse.