Questions tagged [apparent-magnitude]

Questions regarding how bright an object appears to be.

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13 votes
4 answers
4k views

Could Neptune be viewed with the naked eye from Uranus?

Which star or planet in our night sky can match what Neptune would look like when viewed from Uranus, or one of its moons? The answer would be for the most favourable condition, which is when Neptune ...
Constantthin's user avatar
4 votes
2 answers
1k views

How bright are geostationary satellites due to reflected sunlight?

We are all familiar with seeing low-Earth orbit satellites scooting across the sky in a couple of minutes. Many of them are bright and readily identifiable with the naked eye. Geostationary satellites ...
ProfRob's user avatar
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3 votes
2 answers
298 views

Best way to simulate star sizes to scale in celestial sphere

Using the Hipparcos catalogue, I am trying to create a celestial sphere. As all the stars are a fixed distance from the centre of this sphere, the only way to differentiate the distances and magnitude ...
SidS's user avatar
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34 votes
2 answers
2k views

How could a hobbyist astronomer determine apparent magnitude of a star?

Apparent magnitude is a rather complex way to determine the brightness of a star. Quoting the introduction text from the linked to Wikipedia page: The apparent magnitude (m) of a celestial body is ...
TildalWave's user avatar
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28 votes
4 answers
6k views

Which is brighter, Mars as seen from Earth, or Earth as seen from Mars?

At their closest flyby, Earth is ‘new’ and dim from Mars, and Mars is ‘full’ from Earth and brightest as seen from Earth. When Earth is 39 degrees from the Sun then Earth is brightest as seen from ...
Mark Besser's user avatar
15 votes
2 answers
5k 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 ...
Emilio Pisanty's user avatar
7 votes
3 answers
2k views

Apparent magnitude of Milky Way?

We have apparent magnitude of stars, planets, DSOs. What about the apparent magnitude of Milky Way? Can it be estimated?
Mathematicie's user avatar
7 votes
1 answer
2k views

Is Uranus the farthest object in Solar System that you can see with naked eyes?

The following text is from this article: The fact is, even at its brightest, Uranus is still quite faint. It’s barely perceptible as a dim speck of light to the unaided eye, even under dark skies. At ...
Nilay Ghosh's user avatar
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5 votes
1 answer
263 views

How long does lunar opposition surge last? Are there measurements of the full Moon getting suddenly brighter?

Wikipedia's opposition surge is a short article and forwards shadow hiding and coherent backscattering as proposed mechanisms, but it doesn't really explain how much the brightness of the Moon ...
uhoh's user avatar
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2 votes
0 answers
184 views

Can JWST be damaged by looking at a bright star?

Can JWST be damaged by looking at a bright star? The Sun as well as particularily bright solar-system objects like Jupiter, Venus or the Moon not meant with this question.
sno's user avatar
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0 votes
0 answers
65 views

Is albedo ever greater than unity? How is it calculated for various surface diffusivities and specular reflection? [duplicate]

I'm trying to understand how albedo would be calculated for a body with well-characterized surface reflectance properties, so that it's absolute magnitude could be defined. One could argue that this ...
uhoh's user avatar
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23 votes
2 answers
4k views

At what distance from Earth would our Sun be the same apparent magnitude as the next brightest star in the sky?

When I stand outside looking at the night sky, to my untrained eye, everything except the moon looks like a star. I know intellectually that some are planets circling our sun, and some are entire ...
James Jenkins's user avatar
9 votes
1 answer
512 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).
NeutronStar's user avatar
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7 votes
1 answer
1k views

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 ...
DrZ214's user avatar
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7 votes
1 answer
3k views

Have there been successful attempts at spotting Neptune with the naked eye?

As pointed out here, the limit of naked eye visibility for people with extremely good night vision is about magnitude 8.5. Neptune at opposition is much brighter at magnitude 7.7, so it should be ...
Count Iblis's user avatar
6 votes
1 answer
218 views

Sky surface brightness vs magnitude limit visibility

I am wondering how we can calculate the magnitude limit of the celestial object, which could be visible at the given sky surface brightness conditions. We already know that Venus and Jupiter are ...
Geographos's user avatar
3 votes
2 answers
110 views

Can we measure comets in a similar way to exoplanets?

A 2km comet at 40AU's can dim a sun sized star at 100 light years by 3%, and a 10km comet can cause an eclipse (is that right?) So would 2,3,10 km objects be easy to measure via star dimming if we had ...
bandybabboon's user avatar
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1 vote
0 answers
73 views

How many streetlights should we turn off to decrease light on the ground by about 2.512 times?

I am looking for some guidance for a back-of-the-envelope-calculation to show that turning off street lights can make a difference for light pollution in the style of a Fermi problem. My first step is ...
B--rian's user avatar
  • 5,616
1 vote
2 answers
381 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?
Louis Waweru's user avatar
1 vote
1 answer
91 views

Has lunar opposition surge ever been observed from Earth? From Earth orbit?

This thorough answer to How long does lunar opposition surge last? Are there measurements of the full Moon getting suddenly brighter? details observations of lunar opposition surge by the Clementine ...
uhoh's user avatar
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1 vote
1 answer
83 views

How is Comet SWAN C/2020 F8 doing? Will it become easily visible by eye?

The New York Times article How to See Comet SWAN in Night Skies says: Astronomers have their fingers crossed that the comet will keep brightening in the coming weeks as it heads north, passing 52 ...
uhoh's user avatar
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-2 votes
1 answer
393 views

What is Saturn’s apparent magnitude at its brightest when viewed from Uranus?

Considering that the apparent magnitude scale is an inverted scale; what is the lowest apparent magnitude of Saturn that can be seen from Uranus. We are of course talking about when Saturn is viewed ...
Constantthin's user avatar