# Tagged Questions

Questions regarding how bright an object appears to be.

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### How can apparent magnitude be negative?

What is the reason for that scale? Is it because otherwise defining an maximum would be too hard(?). Why do objects that are (apparently) brighter get assigned a smaller number (and down to negative)?
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### As viewed from Mars, what are Jupiter's and Saturn's maximum brightness in apparent magnitude?

From Earth, Jupiter's maximum brightness is -2.94 and Saturn's is -0.24. But what about from Mars? They should be brighter, but by how much? There are equations at the obvious wiki entry but I'm not ...
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### Absolute/apparent magnitude and distance for HIP31978 inconsistent?

EDIT: I am still following up, but here's the latest response from Wolfram: Paclet servers are updated and optimized for each version of Mathematica, so I suspect you may be working on an older ...
51 views

### What is the share of stars in total radiation input of Earth?

Earth gets its radiation input primarily from Sun, then from reflected sunlight from Moon, and stars. Among these, what is the share of stars (or sources outside solar system) to this total radiation ...
106 views

### What is the brightest star (relative magnitude) in M31?

I am wondering what the brightest individual star is in M31, the Andromeda Galaxy. Specifically, brightest as seen from Earth (so relative magnitude).
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### Why do dark objects look white from a distance? (Moon, Ceres, but not Earth!)

What makes the Moon shine white in the sky, although it seems to be as dark as asphalt? Earth's average albedo is 3 and 4 times that of the Moon and Ceres respectively (0.37 vs 0.12 and 0.09). But ...
292 views

### How to calculate magnitude of a star in a triple star system?

I want to find a star's magnitude in a triple star. I already knew the the magnitude of the triple star and the other two star, but I don't quit know how to solve it. Is there a way to find it?
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### Galactic extinction as a function of distance

I am looking at several galactic sources in the $I$, $R$ and $V$ bands and I want to calculate their absolute magnitudes. I can get the apparent magnitude and I know the distance so I just need to ...
43 views

### Around what apparent magnitude can the naked eye observe an object during full moon

For a very rough guideline using healthy/corrected eyes adjusted to the dark, around how bright should an object be to expect it to be visible?
2k views

### How bright is the full Earth during the lunar midnight?

At lunar midnight (i.e. the new moon as seen from Earth), the Earth is in its full phase with its entire disk in sunlight, and it is the brightest object in the lunar sky. How bright is it, and how ...
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### need data-point: actual counts per second with APD (avalanche photodiode) detector

I'm designing a sensor system to perform specialized [astronomy and space-sciences] experiments, and need a "reality check" to support or adjust my theoretical calculations. What I need is the "...
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### How is the magnitude of a star measured?

How does one measure the brightness of a star?, I did not find anything on the internet.