I've watched your tutorials on using Stellarium, I have had trouble setting it up to drop an image as an overlay and look for alignments that way, although I see it's possible, I can't figure it out. If you have time could you cover that in a future video? Thanks so much :)
I think you need to turn the image into a custom landscape file. There are tutorials for this, but the main points are: * It has to be a 360 panorama file, so if your image doesn't cover the full horizon you have to insert it into a transparent 360 panorama. * The resolution of the panorama must be an integer multiple of a power of two, or it might not work on some OpenGL implementations. E.g. 1024, 2048, 4096, 8192 etc pixels. * You need to create an INI file for the landscape so Stellarium knows how to use it. There is a Z rotation parameter, which rotates the panorama around the Zenith vertical, so you can align it properly with the cardinal directions.
Do you mean an actual photo or just a rendered horizon? I'm still working to learn how to do 360 photos, as the other commenter mentioned, it is quite involved. I might be able to post some tutorial links. As for rendered landscapes I use heywhatsthat.com for rough views from anywhere, or standingstones.org for nicely rendered views from specific sites. That site also has a tool you can use to render landscapes from locations of your choosing, but they are never as detailed as photos since they only use a limited number of elevation points (depending on the resolution) to draw the horizons (no specific details of rock formations, structures, etc.) although there are some that use LIDAR to get more detail. I will certainly do a video on what I know how to do as soon as I can. My list keeps growing!
An even more accurate way is to see when the solar disk is centered on the 0, 90, 180 and 270 degree markings in RA. To get the "official" value, we need to set the system to geocentric.
Interesting video! When I convert the proleptic Gregorian date 3000-06-21 BC to the Julian calendar I get 3000-07-15 BC, but the solstice seems to be early morning on 3000-07-18 BC. (I tied to fuzz by a few years and got the same result, so it is apparently not due to leap years and whether year -0 is counted or not.) Do you happen to know what accounts for this small difference?
Hi! How are you doing the calculation? My guess (though I'm not 100% sure) is that just projecting the Gregorian system backward will still not give you the exact solstice because changes in the orientation of the Earth's axis relative to the near/far (fast/slow) (perihelion/aphelion) points in its orbit over long periods of time change how many days there are from winter solstice to summer solstice and back again (the maximum difference can be up to around 9 days) so that the actual moment of the solstices is being shifted in actual day count spacing while the Gregorian system just keeps the the total number of days in a year adjusted to account for the fractional day up to a few decimal places. Does this make sense? I actually detailed these orbital changes in a previous video. Here is a link to that part of the video: ua-cam.com/video/roESGKhB3cY/v-deo.html
@@ArchaeoastronomyDatabase "How are you doing the calculation?" - Exactly the way you suspected. I had already watched that video (along with all your other ones), but it was apparently too long ago. I had forgotten about the interplay between obliquity and the peri-/ap-helions, so thanks for the reminder!
Hi, I wanted to post a quick question. I'm looking at first century solar eclipses in Jerusalem for the obvious reasons. NASA lists an April 3, 33 partial eclipse in Jerusalem. Which made no sense to me because there is a full moon on that day. NASA also claims to use Julian calendar pre 15 whatever. I did a bunch of back and forth scrolling like you do in the video. But my question is this actually: How could NASA and Stellarium be completely opposite phase of the moon if both are on Julian calendar? I presume NASA's eclipse database is correct. But I don't know what about Stellarium could be off by a full fifteen days on the phase of the moon. I know we lost eleven days in the Gregorian switchover. But that should not be showing up in Stellarium if it uses Julian by default before 15 whatever. (And of course, there's the two hundred years until England accepted Gregorian...). My concern is that Stellarium would be useless for archeoastronomy if I don't know why they are off by a half cycle of the moon without an explanation; because I don't know why, or how or which way to correct it. I was getting ready to do a review of NASA first century eclipses versus STellarium. I expect all of them to be wrong (and would be even more troubled if some of them are right). So I found your video and thought I'd ask first in case you've already encountered this. IOW, I know it's all math, so there is an answer that I can figure out eventually. But I assume that actual astronomers and people with more experience with Stellarium have encountered this already.
Hi, what NASA page are you using. I looked here: eclipse.gsfc.nasa.gov/SEhistory/SEhistory.html I'm not seeing 3 April 33 on there, but I tested a few around that time and they are showing in Stellarium correctly for me. Try also: xjubier.free.fr/en/site_pages/solar_eclipses/5MCSE/xSE_Five_Millennium_Canon.html The 24 November of 29 looks the most promising to me. Let me know if any of this helps.
@@ArchaeoastronomyDatabase Thanks. I pulled up NASA's lunar eclipse list by mistake. I'd better get on that Zeni eyewear site that Professor of Rock is always talking about .
Is there anyway using stellarium to project the form of a constellation on the ground? For example how someone can see the Orion belt been projected on the top of the three Egyptian pyramids?
For that sort of thing, I'll usually just find a rendering of a constellation elsewhere, reverse the image, and put it into Google Earth as a transparent overlay. You can take a screenshot from Stellarium and invert the colors, but you'd have to be very careful about the distortion depending on the projection and positioning on the screen.
thanks so much brother... much appreciated... the 1582 addition of the 10 days is a flaw in stellarium (awesome program) that needs to be addressed... we did a video of this "jump" / error... its only 2 mins long.. ua-cam.com/video/D-BQTW8Bnjo/v-deo.html
I just now added the archaeolines plugin (THANK YOU) and set the date to 1582 / 10 /04 and then move the year to 1583 / 10 / 04 and watch the jump... 🙏❤
@@iyoutome That jump is expected, but if you move it forward 364 or 365 days manually you'll get the sky at the same position (with only the regular fractional day shift). Same as just advancing 1 year and then the 10 days because the previous 'year' didn't have them. The dating system is of course a convention, but it would be nice if there was an option to display the Proleptic Gregorian date (projected into the past). This would keep the solstices around the same dates, but even then they would shift a bit due to other orbital parameters changing. Most of the time when I want to get a good idea of what time of year something is occurring in Stellarium in the distant past I just look at the sun's declination and which way it is heading, and either match that up with roughly the same declination/direction in the current year (doesn't quite work as the sun doesn't reach the same declination extremes) or I just turn on ArchaeoLines and select the sun and visually perceive the progress of the sun on the horizon between the solstice range and other subdivisions of the year. When I graph things like star visibility, I don't usually plot heliacal rising/setting etc. against modern calendar dates (and certainly not using the shifting Julian dates which would be meaningless) but simply start the graph at a solstice and mark the other solstice (not quite half a year most of the time) and then divide between those into into quarters (near the equinoxes but not quite usually) and then further into 8ths (cross-quarters) and 16ths as needed. That is mostly because I am concerned with the coherent pattern of the year. Where you are counting out intervals you are probably stuck with calculating Julian Dates or Modified Julian Dates (I haven't worked much with those systems), or using some of the shortcuts to advance time by sidereal years, and making manual day adjustments from there.
Thanks for this
You are most welcome! Lots more to come, there is so much to do!
I've watched your tutorials on using Stellarium, I have had trouble setting it up to drop an image as an overlay and look for alignments that way, although I see it's possible, I can't figure it out. If you have time could you cover that in a future video? Thanks so much :)
I think you need to turn the image into a custom landscape file. There are tutorials for this, but the main points are:
* It has to be a 360 panorama file, so if your image doesn't cover the full horizon you have to insert it into a transparent 360 panorama.
* The resolution of the panorama must be an integer multiple of a power of two, or it might not work on some OpenGL implementations. E.g. 1024, 2048, 4096, 8192 etc pixels.
* You need to create an INI file for the landscape so Stellarium knows how to use it. There is a Z rotation parameter, which rotates the panorama around the Zenith vertical, so you can align it properly with the cardinal directions.
Do you mean an actual photo or just a rendered horizon? I'm still working to learn how to do 360 photos, as the other commenter mentioned, it is quite involved. I might be able to post some tutorial links. As for rendered landscapes I use heywhatsthat.com for rough views from anywhere, or standingstones.org for nicely rendered views from specific sites. That site also has a tool you can use to render landscapes from locations of your choosing, but they are never as detailed as photos since they only use a limited number of elevation points (depending on the resolution) to draw the horizons (no specific details of rock formations, structures, etc.) although there are some that use LIDAR to get more detail. I will certainly do a video on what I know how to do as soon as I can. My list keeps growing!
@@ArchaeoastronomyDatabase Thanks so much! I'll see if either of those links will do the job I need them too. Looking forward to more of these!
An even more accurate way is to see when the solar disk is centered on the 0, 90, 180 and 270 degree markings in RA. To get the "official" value, we need to set the system to geocentric.
Yes indeed, but be sure to toggle Topocentric back on for any use at a specific site as that will best simulate what is seen from the ground.
Excellent videos! Where did you find this landscape zip file?
Thanks! I get many of the landscapes from standingstones.org
@@ArchaeoastronomyDatabase Thanks for the tip! I'll check it out.
Exactly what i needed, thnx
I'm glad you found it useful!
Interesting video! When I convert the proleptic Gregorian date 3000-06-21 BC to the Julian calendar I get 3000-07-15 BC, but the solstice seems to be early morning on 3000-07-18 BC. (I tied to fuzz by a few years and got the same result, so it is apparently not due to leap years and whether year -0 is counted or not.) Do you happen to know what accounts for this small difference?
Hi! How are you doing the calculation? My guess (though I'm not 100% sure) is that just projecting the Gregorian system backward will still not give you the exact solstice because changes in the orientation of the Earth's axis relative to the near/far (fast/slow) (perihelion/aphelion) points in its orbit over long periods of time change how many days there are from winter solstice to summer solstice and back again (the maximum difference can be up to around 9 days) so that the actual moment of the solstices is being shifted in actual day count spacing while the Gregorian system just keeps the the total number of days in a year adjusted to account for the fractional day up to a few decimal places. Does this make sense? I actually detailed these orbital changes in a previous video. Here is a link to that part of the video: ua-cam.com/video/roESGKhB3cY/v-deo.html
@@ArchaeoastronomyDatabase "How are you doing the calculation?" - Exactly the way you suspected. I had already watched that video (along with all your other ones), but it was apparently too long ago. I had forgotten about the interplay between obliquity and the peri-/ap-helions, so thanks for the reminder!
Hi, I wanted to post a quick question. I'm looking at first century solar eclipses in Jerusalem for the obvious reasons. NASA lists an April 3, 33 partial eclipse in Jerusalem. Which made no sense to me because there is a full moon on that day. NASA also claims to use Julian calendar pre 15 whatever. I did a bunch of back and forth scrolling like you do in the video. But my question is this actually:
How could NASA and Stellarium be completely opposite phase of the moon if both are on Julian calendar?
I presume NASA's eclipse database is correct. But I don't know what about Stellarium could be off by a full fifteen days on the phase of the moon. I know we lost eleven days in the Gregorian switchover. But that should not be showing up in Stellarium if it uses Julian by default before 15 whatever. (And of course, there's the two hundred years until England accepted Gregorian...).
My concern is that Stellarium would be useless for archeoastronomy if I don't know why they are off by a half cycle of the moon without an explanation; because I don't know why, or how or which way to correct it.
I was getting ready to do a review of NASA first century eclipses versus STellarium. I expect all of them to be wrong (and would be even more troubled if some of them are right). So I found your video and thought I'd ask first in case you've already encountered this. IOW, I know it's all math, so there is an answer that I can figure out eventually. But I assume that actual astronomers and people with more experience with Stellarium have encountered this already.
Hi, what NASA page are you using. I looked here: eclipse.gsfc.nasa.gov/SEhistory/SEhistory.html
I'm not seeing 3 April 33 on there, but I tested a few around that time and they are showing in Stellarium correctly for me.
Try also:
xjubier.free.fr/en/site_pages/solar_eclipses/5MCSE/xSE_Five_Millennium_Canon.html
The 24 November of 29 looks the most promising to me. Let me know if any of this helps.
@@ArchaeoastronomyDatabase Thanks. I pulled up NASA's lunar eclipse list by mistake. I'd better get on that Zeni eyewear site that Professor of Rock is always talking about
.
Is there anyway using stellarium to project the form of a constellation on the ground?
For example how someone can see the Orion belt been projected on the top of the three Egyptian pyramids?
For that sort of thing, I'll usually just find a rendering of a constellation elsewhere, reverse the image, and put it into Google Earth as a transparent overlay. You can take a screenshot from Stellarium and invert the colors, but you'd have to be very careful about the distortion depending on the projection and positioning on the screen.
thanks so much brother... much appreciated... the 1582 addition of the 10 days is a flaw in stellarium (awesome program) that needs to be addressed... we did a video of this "jump" / error... its only 2 mins long.. ua-cam.com/video/D-BQTW8Bnjo/v-deo.html
I just now added the archaeolines plugin (THANK YOU) and set the date to 1582 / 10 /04 and then move the year to 1583 / 10 / 04 and watch the jump... 🙏❤
@@iyoutome That jump is expected, but if you move it forward 364 or 365 days manually you'll get the sky at the same position (with only the regular fractional day shift). Same as just advancing 1 year and then the 10 days because the previous 'year' didn't have them. The dating system is of course a convention, but it would be nice if there was an option to display the Proleptic Gregorian date (projected into the past). This would keep the solstices around the same dates, but even then they would shift a bit due to other orbital parameters changing. Most of the time when I want to get a good idea of what time of year something is occurring in Stellarium in the distant past I just look at the sun's declination and which way it is heading, and either match that up with roughly the same declination/direction in the current year (doesn't quite work as the sun doesn't reach the same declination extremes) or I just turn on ArchaeoLines and select the sun and visually perceive the progress of the sun on the horizon between the solstice range and other subdivisions of the year. When I graph things like star visibility, I don't usually plot heliacal rising/setting etc. against modern calendar dates (and certainly not using the shifting Julian dates which would be meaningless) but simply start the graph at a solstice and mark the other solstice (not quite half a year most of the time) and then divide between those into into quarters (near the equinoxes but not quite usually) and then further into 8ths (cross-quarters) and 16ths as needed. That is mostly because I am concerned with the coherent pattern of the year. Where you are counting out intervals you are probably stuck with calculating Julian Dates or Modified Julian Dates (I haven't worked much with those systems), or using some of the shortcuts to advance time by sidereal years, and making manual day adjustments from there.