Questions tagged [apparent-magnitude]
Questions regarding how bright an object appears to be.
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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 ...
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Would one have to be more than halfway to the Oort Cloud for the Sun to appear as bright as the full moon?
Is this correct? If the Sun is 400,000 times brighter than the full moon am I correct in figuring that one would have to be about 632AU from the Sun for it to appear as bright as the full moon. If ...
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Galactic mass estimation from apparent magnitude and distance
Can we estimate the order of the total mass of any galaxy from the apparent magnitude and its distance to us? Just like
\begin{equation}
M_{galaxy}=c\times 10^{8}M_{\odot },
\end{equation}
where $c$ ...
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1answer
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Light pollution and apparent magnitude of objects in solar system
Dust along the ecliptic scatters light, causing “light pollution” throughout the orbital plane of the solar system. If an object like, say, the sun's corona, had its brightness measured from above the ...
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What is the planet relative to earth that shows the greatest change in apparent brightness?
What is the planet relative to earth that shows the greatest change in apparent brightness?
I think the answer is Mars, and a quick google search reveals it is Mars.
I have my reasoning here, but I ...
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“Pluto Time” for any solar system body
A while back NASA made a site called Pluto Time, where you can enter your address and find that "...moment near dawn and dusk each day, where the illumination on Earth matches that of high noon on ...
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1answer
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How would a flat mirror on the Moon reflect sunlight
I was solving a task that said (paraphrasing):
There is a flat mirror on the Moon, whose reflection coefficient is 100%, and observers on the Earth observe it as a star whose apparent magnitude is $...
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1answer
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What are the apparent visual magnitudes of Spica A and Spica B?
What would be the (theoretical) apparent visual magnitudes of Spica A and Spica B (since they are too close together to be resolved telescopically)? The Spica System is 77 parsecs away, and the ...
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1answer
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How to get the zeropoint magnitude?
I'm working with some data and I have some values named fluxmag0 and fluxmag0err that should correspond to the zero point values ...
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total energy and apparent bolometric magnitude
So I have been given this question:
A typical Type Ia Supernova emits $10^{44}\ \mathrm{J}$. All nuclear weapons
tested by humans have released a total of about $2\times10^{6}\ \mathrm{TJ}$ of ...
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1answer
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Are stars beyond the asteroid belt less constant?
If we graph the variability of a small bright star which is lined up with the asteroid belt, is it less constant than stars that are far away from the asteroid belt? To what degree does variability ...
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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 ...
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How bright would Alpha Centauri appear (in apparent Magnitude) if it were 1 light year away?
I'm trying to determine what a star of comparable mass and luminosity to the Sun would look like from the surface of the Earth if it were 1 light year away - I chose Alpha Centauri since it is close ...
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Why are nearby stars like Proxima Centauri and Barnard's star not visible to the naked eye?
Proxima Centauri is the closest star to the earth other than the sun yet it isn't visible to the naked eye, but stars that are further away are easily found in the night sky. Why is that?
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Asteroid visible during the day?
In a story I'm working on, a huge, 20 by 14 kilometer, Ni-Fe asteroid attains a 1760 km. orbit around earth (why/how? Long story). I figure it has an H magnitude of ~12. Would this body be visible ...
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How much has the apparent magnitude of the Sun changed?
Did the apparent magnitude of the Sun change in the past 1000 years or so? If so, for what reasons?
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compute magnitude in vega system from fluxes in the unit of photons per unit area
I downloaded a catalogue of fluxes in the unit of photons per unit area from here. I don't know how to convert these fluxes to magnitudes ($m$) in the vega system. I use following equations for ...
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What apparent sizes of the sun an Earth like planet can have?
What is the smallest and largest sun an Earth like planet could have in its sky? What kinds of stars are those?
I saw this video and thought, yeah, some of those stars are really big in absolute ...
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Formula for translating view brightness to pixel values on a monitor?
I want to build a telescope/eyepiece simulator that roughly shows a brightness comparison between different apertures at constant magnification.
For example, an 8" F10 @ 100x will produce a 2mm exit ...
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1answer
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Problem about finding distance with magnitude given
A star in Pleiades cluster has apparent magnitude of +12 ($m_{star} = +12$) determine it's distance from the sun? (We know the Sun properties such apparent and absolute magnitudes, distance from earth,...
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Sun's apparent magnitude at 2.5 AU?
Imagine an astronaut standing on an asteroid 2.5 A.U. distant from the Sun. He is gazing, naked-eye, towards the Sun.
What is the apparent magnitude of the Sun at that distance, and is that bright ...
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1answer
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Why do different instrumental filters use different magnitude systems (Vega vs AB)?
Suppose I wanted to construct the spectral energy distribution (SED) of an object. Further suppose I observe this object through the 9 broad-band filters using the Subaru Suprimecam (just for an ...
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Asteroid apparent magnitude
I'm writing an SF story in which a main belt asteroid is diverted into a collision course trajectory with earth (long story), and unknown to us here on earth.
Its H magnitude is 12. As it nears ...
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1answer
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How bright could Gliese 710 appear in 1.35 million years?
I read this article on Gliese 710 that stated it would come within about 1.1 ly (+/- 0.577 ly) of earth in 1.35 million years. Wikipedia states it would have an apparent magnitude of 0.5, and the ...
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1answer
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What's the difference between apparent brightness and apparent magnitude? Are they the same?
I know that the equation for the difference in apparent magnitudes can be represented as:
$\Delta m=-2.5\log\left(\dfrac{I_{1}}{I_{2}}\right)$
and the apparent brightness of a celestial object is ...
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Is the Sun visible from Proxima Centauri to human eyes?
I know that the light coming from Proxima Centauri is not bright enough to make it naked-eye visible from the Earth. Is the Sun naked-eye visible from Proxima Centauri?
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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 ...
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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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1answer
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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 ...
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1answer
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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 ...
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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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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 ...
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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?
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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 ...
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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.
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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 ...
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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 ...
