All Questions
Tagged with astronomy homework-and-exercises
63
questions
3
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1
answer
193
views
Speed at which the Moon moves past a point on Earth's surface?
I'm trying to calculate how fast a point on the surface of the Moon is moving past a point on the surface of the Earth (I assume a point on the equator of each for simplicity).
I know the Earth is ...
- 31
0
votes
1
answer
100
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Estimate Saturn's mass [closed]
How can you estimate Saturn's mass using data from Cassini's final moments in September 2017 (apoapsis on September 12 at 1:27 a.m. EDT Saturn time at a distance of about $1.3*10^6$ km from Saturn, ...
1
vote
2
answers
155
views
Why is $G*M_{sun}=4\pi^2$ when using AU/year units?
So, when using AU/year units, it turns out that 3rd Kepler Law: $\frac{r^3}{T^2}=\frac{G*M_{sun}}{4\pi^2}=1$, meaning $G*M_{sun}=4\pi^2$, any easy explanation for this? Cheers.
- 152
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33
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How do you find the extinction coefficient for Gaia photometry?
I have Gaia photometry g, bp, and rp. My final goal is to find the photometric temperature but first I need to account for reddening by finding the extinction coefficient. I’m really stumped on how to ...
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0
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0
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26
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How can I find the expected value of the number of particles in a region?
The actual problem asks to find the expected value of number of molecular clouds between Earth and the gallactic center, these clouds are distributed through the gallactic disk approching it as a ...
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0
votes
3
answers
378
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Length of Lunar Month
The time it takes the Moon to return to a given position as seen against the background of fixed stars, $27.3$ days, is called sidereal month. The time interval between identical phases of the Moon is ...
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4
votes
1
answer
205
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Drawing night sky of planets other than Earth (invariable plane ambiguity)
I'm writing an application that draws maps of night sky that can be visible from other planets (ultimately they are to be exoplanets). Mostly I do it out of curiosity :).
I's thinking a lot where I ...
- 137
1
vote
1
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177
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How to calculate change in absolute magnitude due to a change in stellar radius?
Suppose that the radius of a star increases by some factor, how does this affect the absolute magntiude of the star?
I know that $M_1 - M_2 = \Delta M = 2.5 \log \frac{L_1}{L_2}$, so if I knew the ...
- 169
1
vote
1
answer
710
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How to calculate the maximum Elongation of Mercury seeing from the Earth? [closed]
I want to calculate the maximum Elongation of mercury seeing from the Earth but not by this assumption that its orbit is circle but it is an ellipse with semimajor axis a = 0.387 AU and e = 0.2 and ...
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votes
2
answers
386
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How does a proper motion displacement of $x$ arcseconds/year mean a star is moving at $x$ AU/year?
I trying to understand the author's answer to this question:
I don't understand the part underlined red. How does 3.6pc mean 3.6AU? It says a "distance of 3.6AU", but doesn't say what is ...
- 156
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2
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244
views
How to calculate the brightness of an object in space dependent on its distance from earth?
If a comet appears increasingly brighter as it approaches the earth, how many times brighter will it appear as it moves from $25AU$ to $5AU$ from us?
2
votes
2
answers
349
views
Calculating apparent density of stars in sky, given an area and distance away from my viewpoint
According to this source, there are $5077$ visible stars in the night sky, and a full sky area of $41253$ square degrees of sky. This makes for a density of $0.12$ stars per square degree of the sky. ...
- 123
2
votes
1
answer
124
views
What is the derivation of this formula for eclipsed flux?
From my lecture notes:
Planetary Transit Searches
If a planetary system’s orbital plane lies along our line of sight, planets will from time to time pass in front of their star, absorbing some of the ...
- 295
0
votes
1
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263
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Apparent magnitude vs. absolute magnitude
Star Zeta Puppis lies at a distance $460$ pc from Earth. Its apparent visual magnitude $m_V$ is $2.25$,
its absolute bolometric magnitude $M_{\mathrm{bol}}$ is $-9.9$, and its angular diameter is $4....
- 295
0
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1
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68
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Are there any patterns in the locations of pulsars in our universe?
Are there any particular places pulsars are distributed? If so, why? Any information to links and articles will also be appreciated. I just want to understand more about pulsars and if there are any ...
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