Re-measuring Safehold

This is my first post to this forum, so bear with me. I’ve been a Weber fan for a long time, and a Safehold series fan since the series started. The one thing I’ve been a bit disappointed about has been the lack of detailed technical data about the planet itself and its solar system. What I have so far (mostly from OAR):

• Local Sun: G6 class star (presumably type V) named Kau-zhi.
• Local day: 26 hours, 31 minutes Terran Standard time.
• Local year: 301.32 local days, 0.91 Terran years.
• Lunar Month: 27.6 local days (Langhorne).
• Diameter of planet: 25390.9 miles or 40892.7 km based on a downloaded map width of 9555 pixels and a scale bar length of 715 pixels (1900 mile/3060 km).

What I would like to know:

• Axial Tilt: slightly greater than Earth’s.
• Gravity (Gs): from that I could get the planet’s density.
• Any hard data on the planet’s moon and the star’s other planets. (Stuff about comets and asteroids would be nice too.)

Data from DW would be perfect, but anything even vaguely canonical would be appreciated.

Dalton “who likes the science in sci-fi” Spence

Hello, Dalton! Glad to meet another hard sci-fi fan!

Welcome Dalton!

Not that it's particularly scientific, but I offer the following from OAR (almost at the beginning):

"The world they’d named Safehold was a bit smaller than Old Earth. Kau-zhi was considerably cooler than Sol, and although Safehold orbited closer to it, the planet had a noticeably lower average temperature than Old Earth. Its axial tilt was a bit more pronounced, as well, which gave it somewhat greater seasonal shifts as a result. It also had a higher proportion of land area, but that land was broken up into numerous smallish, mountainous continents and large islands, and that helped to moderate the planetary climate at least a little.

Despite its marginally smaller size, Safehold was also a bit more dense than mankind’s original home world. As a result, its gravity was very nearly the same as the one in which the human race had initially evolved. Its days were longer, but its years were shorter—only a bit more than three hundred and one local days each—and the colonists had divided it into only ten months, each of six five-day weeks. The local calendar still felt odd to Kau-yung (he supposed it made sense, but he missed January and December, damn it!), and he’d had more trouble than he expected adjusting to the long days, but overall, it was one of the more pleasant planets mankind had settled upon."

Cheers!

Think you mean

• Circumference of planet: 25390.9 miles or 40892.7 km based on a downloaded map width of 9555 pixels and a scale bar length of 715 pixels (1900 mile/3060 km).
• Diameter of planet: 8,082.2 miles or 13,007 km based on circumference above.

DaltonSpence wrote:.......

• Diameter of planet: 25390.9 miles or 40892.7 km based on a downloaded map width of 9555 pixels and a scale bar length of 715 pixels (1900 mile/3060 km).

..........

Also, you may want to look at this page - it's using an out-dated map, but you can see Safehold as a globe (interactive if you download the Celestia application)

Illustrating David Weber's Books http://www.lepp.cornell.edu/~seb/celestia/weber/#3.1

dobriennm wrote:Also, you may want to look at this page - it's using an out-dated map, but you can see Safehold as a globe (interactive if you download the Celestia application)

Illustrating David Weber's Books http://www.lepp.cornell.edu/~seb/celestia/weber/#3.1

ABSOLUTELY REMARKABLE!!! Technology can truly be a cool, cool thing!

Two major issues with this calculation, which lead to the suggestion that a planet 'slightly smaller than Old Earth' could have a radius that is _larger_ than Earth's [admittedly, I'm ignoring the possibility that we don't live on Old Earth either, but that's really unlikely]:

First, that red & white scale bar in the lower right corner isn't. To scale, that is. The bar Himself inserted in the middle of the Markovian Sea is, but unfortunately we don't know if the scale is correct for the equator or for the latitude where it's drawn. Since the map is essentially a Mercator projection, that matters - a lot.

Second, if you inspect the edges carefully, it turns out that that map is incomplete: the east and west edges don't meet and the equator isn't centered north/south. So not only do we not know which latitude the scale bar is drawn for, we don't actually know what it's latitude is. Nor do we know the projected length of the equator of Safehold.

I ran a guestimate a while back that makes me think that the top edge could be the Safehold Arctic Circle, although the bottom would be well south of the Antarctic Circle. Unfortunately, I no longer recall what my input assumptions were, so that doesn't even count as informed speculation.

BTW, the suggestion that Kau-zhi must be a G6V is easy to prove: a G6 star in any of the higher luminosity classes would render any planet in a 300-day orbit uninhabitable.

dobriennm wrote:Think you mean

• Circumference of planet: 25390.9 miles or 40892.7 km based on a downloaded map width of 9555 pixels and a scale bar length of 715 pixels (1900 mile/3060 km).
• Diameter of planet: 8,082.2 miles or 13,007 km based on circumference above.

DaltonSpence wrote:.......

• Diameter of planet: 25390.9 miles or 40892.7 km based on a downloaded map width of 9555 pixels and a scale bar length of 715 pixels (1900 mile/3060 km).

..........

Louis R wrote:
First, that red & white scale bar in the lower right corner isn't. To scale, that is. The bar Himself inserted in the middle of the Markovian Sea is, but unfortunately we don't know if the scale is correct for the equator or for the latitude where it's drawn. Since the map is essentially a Mercator projection, that matters - a lot.

Actually, I seem to remember a long-ago post where Himself said that, for simplicity, he tends to treat the map as the terrain, and measure distances off on it regardless of latitude, despite the problems you mention. I suppose the alternative would be some kind of software that projects the map back onto a globe for measurement, especially for long journeys and having to use that every time could get old quite quickly.

Not all sci-fi writers set out to be as complete and accurate as possible in describing their worlds. David's description of Safehold is certainly as complete as necessary to support the plot and action, and I guess he didn't want to spend a lot of time dotting the i's and crossing the t's of minor technical details. He does, after all, have a lot of balls in the air at the same time.
If you want scientifically accurate and complete world descriptions, read Hal Clement or Robert L. Forward. They really took the time to fully develop complete, consistent worlds to background their stories.

Philip Stanley
"Coincidence means that you weren't paying attention to the other half of what was happening"

Philip Stanley wrote:Not all sci-fi writers set out to be as complete and accurate as possible in describing their worlds. David's description of Safehold is certainly as complete as necessary to support the plot and action, and I guess he didn't want to spend a lot of time dotting the i's and crossing the t's of minor technical details. He does, after all, have a lot of balls in the air at the same time.
If you want scientifically accurate and complete world descriptions, read Hal Clement or Robert L. Forward. They really took the time to fully develop complete, consistent worlds to background their stories.

Philip Stanley
"Coincidence means that you weren't paying attention to the other half of what was happening"

I remember reading once (a long time ago) that David uses an application to "build his worlds" then - over time - adds more and more detail to them as the narrative grows to different areas of the world. Perhaps that's why there's a lot more detail on some of the maps than there is on others. Of course someone will remember where David's comments were, and what the application was - it really doesn't matter here.

My point is that I'm pretty sure David has spent a lot of time and effort (similar to the authors cited above) to make sure Safehold is "right." My opinion is that his level of detail and commentary about Safehold, its geography, geology, climatology, et.al. really adds depth and context to the narrative and (for me at least) makes the reading much more enjoyable, vivid, and "real"...