# All Questions

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### Eclipse — Solar and Lunar

Q. Why are solar and lunar eclipses not seen from all parts of the Earth at the same time? I think it is because of the revolution of the Earth but I am not sure. I am looking for a more reliable ...
103 views

### Are there other planetary systems where gas giants are on the inside to rocky planet orbits?

I understand that formation theories for gas giants suggest they should be born further away where there is more gas for them to monopolize vs the sun, and then to form Hot Jupiters they need to ...
66 views

### Stellar age determination - code

I'm trying to determine the age of some stars. I have many parameters that characterize these stars: $T_{eff}$ ,log ${g}$ ,$[Fe/H]$, $V$... I've tried to use the isochrones package but so far no ...
54 views

### Convert dates to julian day number in astropy?

I'm using astropy and I need to convert dates like this: 2012.06.22_17:56:15_TAI into julian day number. I tried: ...
60 views

### Bounded Observable Universe and General Relativity

The book General Relativity for Mathematicians by Sachs and Wu defines a "spacetime" as a connected 4-dimensional, oriented and time oriented Lorentzian manifold. I emphasize the word "connected." ...
54 views

### Bounded Observable Universe; is there an object we once could see but can no longer? [duplicate]

If the universe is expanding faster than the speed of light, then there will be objects (matter or energy or whatever) that previously could be seen, but no longer can be seen, precisely because the ...
2k views

### Why do gas giants have clearly delineated surfaces, whereas the Earth's atmosphere fades into space?

I've just seen this Forbes article. Why do gas giants appear to have clearly delineated surfaces, whereas the Earth's atmosphere fades into space? Is it just a matter of scale? Or is there some ...
2k views

### Are there accurate equinox and solstice predictions for the distant past?

I am trying to find information on the equinox/solstice dates before 1600, more exactly referring up to 10,000 BCE so as to create a sort of calculator on an Excel spreadsheet. I have read about the ...
1k views

### How fast would Earth need to rotate to fling someone off due to centrifugal force?

If Earth started spinning fast enough, would the centrifugal force eventually overcome Earth's gravity enough enough to fling someone (let's assume 75 kg) into orbit or into space? If so, how fast ...
60 views

### Detecting anomalies from the sun from home

I was wondering if there are any ways for some amateur to detect let's say solar flares or CMEs from home. What kind of hardware would you need in order to have chance of seeing/measuring those? I ...
309 views

I recently inherited some Fortran 77 code that calls the IMFORT interface to write data out to an imh and pix files. I could not get this to compile on a modern compiler and it is not supported. So I ...
5k views

### Fate of Jupiter when our sun dies

Five billion years from now, the sun will have grown into a red giant star, more than a hundred times larger than its current size. While this metamorphosis into the giant star will change the solar ...
773 views

### Why has there been no moon for 2 nights straight

I have been watching the sky all night for a week now I see flying stars everywhere well things that look like stars, what are they? And the moon has been gone for two nights now? Why?
44 views

### Where do stellar classes names come from?

Under Morgan-Keenan classification stellar classes are called O, B, A, F, G, K, M, but what is the logic behind these letters? I can't see any pattern and I doubt they have just been chosen randomly. ...
2k views

### Where can I find a set of data of the initial conditions of our solar system?

As the title suggests, I'm in need of a set of data of our solar system. Similar to this http://bima.astro.umd.edu/nemo/archive/#iau25, but more specifically, the Dubinsky Milky Way-Andromeda data. I'...
36 views

### Keplerian Elements for the Moon and Earth around their Barycenter

So I'm looking to replicate the inner Solar System to a decent degree of accuracy. So far I've been utilizing the Keplerian Elements and Equations for the planets, as shown here. There is one issue ...
24 views

### How to generate times of sunset along a line that crosses a continent?

Would like to avoid using single location iteration of a website that gives time of sunset each date for locations. I want to be able to produce a chart or info-graphic for publishing on a website as ...
82 views

### Best response to shut down the fake Moon landing conspiracy [closed]

This Question was closed for various reasons. For people looking for the answer to similar question, please see this link. I believe this is a solid answer to my question. As the designated Space ...
19 views

### Why do exoplanets a little more massive than Earth, often appear to have lower densities than Earth from transit measurements?

Why do exoplanets a little more massive than Earth, often appear to have lower densities than Earth from transit measurements? Assuming that that they are terrestrial planets, what four(I am also nore ...
233 views

### Different times of sunset at the same location due to elevation

Me and my friend were watching the sunset on the same location (at my country the latitude is approximately 40 degrees). I am at sea level and my friend is at an elevation. He observed the sunset with ...
10 views

### Question about mass growth rate for individual planetesimals

In one stage of classic accretion, the mass growth rate with time (dm/dt) for individual planetesimals is proportional to $m^{2/3}$ and in another stage it is proportional to $m^{4/3}$. My question is ...
91 views

### How can the IAU 2000A vs IAU 2000B nutation comparison be reproduced?

I am attempting to plot how the IAU 2000A nutation model degrades as its terms are omitted. As a spot-check, I decided to compare it to IAU 2000B, which includes only the 77 most important lunisolar ...
38 views

### Calculate depth and duration of exoplanet's transit using Python, astropy or lightkurve

I am creating a program for the analysis of exoplanets in Python using Astropy and Lightkurve libraries. I have light curve of specified star and I would like to calculate depth and duration of planet ...
77 views

### Is there a relation between mass, radius, and luminosity in deuterium-burning brown dwarfs?

I'm a worldbuilder and my setting has a lot of brown dwarfs. While I'm trying to keep my setting as science-compliant as possible, I can't seem to find any resources for brown dwarfs like there are ...
56 views

### Can a single location on earth witness solar eclipse totality 2 times during a single eclipse event?

The question came to my mind when I saw a visualisation of the path of the moon (relative to the sun - the sun is kept centered in the graphic, and only the moon moves) as its seen from a particular ...
6k views

### Is Venus in some way tidally locked to… Earth?

The video here demonstrates how Earth sees the same face of Venus every inferior conjunction (i.e., two planets are the closest to each other): https://www.youtube.com/watch?v=4m_ouMC61-w (or https://...
64 views

### Map planetary eccentricity on a perfect circle? [closed]

What is the formula to plot an eccentric orbit on a perfect circle? I have estimated the full degrees each planet would occupy on a 360 degree wheel (natal chart) but how do I take into account a ...
636 views

### How much mass per year may the black hole at the center of the Milky Way gain by capturing neutrinos?

If we are immersed in a sea of neutrino, then a black hole should be constantly capturing the ones crossing its event horizon, and gaining mass. How much neutrino mass falls inside a black hole per ...
37 views

### How many judges sat on Galileo's trial and who were they exactly? [duplicate]

I saw several chronologies of the trial online but most of them only mention the name of Urban 8 as involved in the actual court proceedings. How many judges were involved and who were they exactly? ...
582 views

### How Are Radioactive Decay Rates Influenced by Neutrinos - On Earth and Other Dense Planets

I read a science report recently that mentioned an accidental discovery where radioactive decay rates shifted slightly slower in advance ( about a day and a half) of solar storms or in sync with sun's ...
27 views

### Emission Line Galaxies(ELGs) selection using narrow band

I selected ELGs using the z BroadBand and NB921 narrow band according to the condition of Hayashi+11 Then I plot the transmission curve of the filters used, I got this As we can see NB921 and NB926 ...
112 views

### problems finding rise set and transit times at high latitudes using Meeus' algorithms

I am implementing Jean Meeus' algorithm from his book "Astronomical Algorithms", 2nd ed. for rise, set and transit times in Swift. It seems to provide very good results (no more than 1 minute ...
32 views

### Do space organisations take the positions of space junk and satellites into account when launching? [migrated]

There are so many satellites orbiting Earth now at various altitudes and there is quite a lot of space junk floating around as well. Now although there are so many satellites and so much junk up ...
120 views

### What is the gravitational lensing focal distance of a white dwarf star?

I tried looking this up, but I couldn't find any formula on gravitational lensing distance. I know that our Sun's is about 550 AU, though further distances work too, as it's not a single focus due ...
1k views

### How can the Sun block an X-ray telescope from observing a QPO galaxy “for several years”?

Phys.org's Black hole's heart still beating says: X-ray satellite observations spotted the repeated beat after its signal had been blocked by our Sun for a number of years. and links to the Open ...
59 views

### Was the solar system flat before the planets formed? Or does the Kozai-Lidov mechanism flatten orbits after the gas giants form?

An astronomer living on Jupiter measures the orbits of the inner planets against Jupiter's ecliptic. Their inclinations are; Mercury 5.7 deg. Venus 2.1 deg. Earth 1.3 deg. Mars 0.6 deg. It looks ...
946 views

### Solar / lunar positions in ECEF using SOFA C libraries

I'd like to calculate the positions of the sun and moon in the ECEF coordinate system using the SOFA (http://www.iausofa.org/current_C.html) libraries given a Julian day input. So far, I've got this ...
43 views

### Why does Hellas Basin look white on some maps?

One map of Mars I see a lot is this colourized map: the Viking colourized global mosaic: (Source) But one thing which strikes me as odd is just how white the Hellas Basin is (the white patch which ...
213 views

### Understanding the JPL Ephemerides

I'm working on an animation that replicates our Solar System. I know this has been done before, but I'm working on something that requires me to make one myself. With that being said, I'm having a ...
106 views

### Is there a recent update on the mysterious M82 radio source reported in 2010?

The Wikipedia page on the "Cigar Galaxy" (M82) has the following summary about an "unknown object": In April 2010, radio astronomers working at the Jodrell Bank Observatory of the University of ...
65 views

### What is the definition of the “solar mixing ratio”?

What is the definition of the "solar mixing ratio"? Specifically, I'd like to know why the ratio of H2 and He is 0.84 and 0.16 at the "solar mixing ratio" as shown in Table I in The Galileo Mission.
91 views

### Food in outer space [closed]

Considering that soon (or maybe in the next 100 years or so) people will be going on long voyages in space, is there something to eat in space (as an analogy, consider fish in seas) that they may ...
108 views

### How do we know that comets definitely mase and not just fluoresce?

Wikipedia's Astrophysical_maser#; comets mentions some anecdotes of notable masers associated with comets, and Maser emissions from comets begins: The 18-cm lines of the OH radical are the only ...
101 views

### A Noob's question on declination

The Sun's position at noon is perpendicular to the local x-y plane on the equator during equinox. So the declination of Sun on that day is 0. Today the declination of Sun is close to 23, can this be ...
49 views

### Which Barlow lens should I choose, 2x or 3x?

I recently bought a 6-inch reflector, 750 mm focal length and I want to get a Barlow lens to get better observations. I have 2 eyepieces, one 9mm and one 25mm. My question is: Should I go for a ...
88 views

### What are the things, the hobby astronomers observe? [closed]

I was thinking: What are the things, that hobby astronomers observe? (Things, that are in the domain of astronomy and hobby.) I tried some googling, and I found just what do professional ...
18 views

### To find the mass and radii of hill sphere of a planet after passing through a region of planetary nebula

Consider a planet with initial mass m* kg and radii of hill sphere as r*. The planet it traveling (assume) perpendicular to the nebula at a speed of 13km/s and the nebula is approaching the planet ...
324 views

### What does “additive fringing from the (multiplicative) twilights” mean?

The question How can I make the fringing pattern visible in my flat (twilight) images for filter i? includes: I have a bunch of twilight flats that have been preprocessed (dark, bias, overscan etc.)...