Project Hail Mary – Stellar Navigation Chart
93 points by speleo 2 hours ago | 24 comments

ggreer 28 minutes ago
Just FYI the sizes of the planets, stars, and their orbits are not to scale at all. To get an idea of how empty space is, there are 63,360 inches in a mile, and 63,239 astronomical units in a light-year. So if you scaled everything down such that Earth was 1 inch from the Sun, Neptune would be 30 inches away and Alpha Centauri would be 4 miles away.

If you were using a 4k display and had the Sun and Alpha Centauri visible at opposite sides of the display, the orbit of Neptune would be in the same pixel as the Sun.

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hnuser123456 12 minutes ago
Mercury is orbiting partially inside the Sun, and Jupiter is nearly as wide as the Sun when it should be 1/10 as much, so the planet nodes should be scaled down 10x relative to the Sun.

Also, I did a top-down pixel measurement, where I could see the distance to Tau Ceti as well as the orbit of Neptune. The radius of Neptune's orbit was 32px, while the distance to Tau Ceti was 1152px, for a ratio of 36, when in reality, Tau Ceti is 11.9 ly away, while Neptune has an orbit radius of 30 AU, which means Tau Ceti is around 25,000 Neptune orbits away, so the planet orbit scale is too big (or distance to other stars too small) by a factor of ~694 (25000/36)

Edit: Since this was top-down, the vertical displacement didn't factor into the distance, which also contributed to Tau Ceti appearing too close on screen, so the error is slightly better than that, maybe a factor of 600.

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rdtsc 39 minutes ago
I can also recommend https://www.youtube.com/watch?v=8FT-oz9aZU4 Time Dilation Visualized (by The Overview Effekt).

It talks about the distances and times involved and how time compression and astrophage infection rates work out. As a fan of the book and the movie it was nice to see the actual 3D star chart of everything. (warning: there may be spoilers there)

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ge96 48 minutes ago
I am so happy this movie did great, the book was great

Similar to me books: Bobiverse, Long Way To A Small Angry Planet

I'm not a heavy reader

This site is cool, I want to get to know stellar navigation stuff for astrophotography watching a video like this where they pull up star charts to point the telescope at it pretty cool https://www.youtube.com/live/TexqPMQMyZg?si=oEnvrxW21-D0VXGV...

Tangent I'll throw in here, I never get the fabric folding gravity well diagrams as it seems to have a "down" direction, I guess it looks like it's down since it's a slice but the effect is an inward sphere?

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imglorp 8 minutes ago
> I guess it looks like it's down since it's a slice but the effect is an inward sphere?

Yes, gravity is a vector field: every point in space near a heavy body has a vector pointed at the center of the body with a magnitude of the field strength. https://en.wikipedia.org/wiki/Gravitational_field

Whenever someone uses fabric sheet analogy, they need to shout that the X-Y of the sheet is a 2 dimensional analog of X-Y-Z space, and the Z direction of the sheet is the field magnitude, with the slope indicating direction.

All models are wrong, but some are useful (for understanding).

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ge96 2 minutes ago
Other thing is I believe they say gravity is strongest at the center of the sphere/core but I would think the mass is split evenly away from the core eg. maybe 2/3 radius from the center where it's equal mass on each side. But probably doesn't make sense wouldn't be a ball.
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stevenwoo 17 minutes ago
Just a question - why do you classify Long Way with PHM - because there are aliens working with humans? I don’t see any other similarities. The technology IIRC (haven’t read in years) in the Becky Chambers book is closer to Star Trek than reality, and there’s not that much of an overarching plot - which is not to say a book cannot be good without one but it’s a big difference.
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ge96 14 minutes ago
True less technical and space themed so maybe not fitting just a fun easy read

Oh yeah another series would be Nick Webb Constitution (Legacy Fleet), I think I got farther into that series but didn't finish it unlike Bobiverse, maybe I did finish this trilogy, I haven't read books in a while honestly

Trying to be better at being in the moment vs. watching youtube/scrolling a website at the same time kind of thing

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lstodd 19 minutes ago
it's like an inverse gas bubble underwater, or a liquid blob in gas in microgravity, but without phase border.

see, it's not that easy to explain or visualise.

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ge96 16 minutes ago
Yeah I watched this video recently about slingshotting I can see how it works but yeah https://youtu.be/-CqBP-CtM0c?si=BdCiZwWgpAp07mgs&t=15

It's not like there is a "down" it's just you're looking at it from a top view?

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dkobia 42 minutes ago
Thank you for making this whoever you are. There is a wonderful video at https://www.youtube.com/watch?v=8FT-oz9aZU4 that visualizes space travel and time dilation in Hail Mary. What I wished I had immediately after watching it was an interactive stellar chart.
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TeaVMFan 20 minutes ago
For other software engineers thinking of following in Andy Weir's footsteps and writing a novel, I put together my guide to self-publishing using software tools and techniques here: https://frequal.com/forwriters/
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V__ 17 minutes ago
"Thumbs" down
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waynecochran 34 minutes ago
Very cool. On Voyager 2 we placed a map on the side of the probe that places the position of our sun based on an array of Pulsar stars (the map was designed by Carl Sagan). I noted in the PHM movie Rocky and Dr Grace made similar 3D maps (I think they were pulsars(?)). I guess pulsars form natural beacons that can be detected at large distances.
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Deprogrammer9 32 minutes ago
Movie was awesome & will be watching again.
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sigmar 40 minutes ago
this is cool. My nit pick- aren't the petrova lines curving along the wrong plane? For example, in our solar system the line should start at the sun and should be pointed at where Venus used to be, but then curve towards where Venus is now (until gets to venus). Since the astrophage will course-correct over their journey and stay in the same plane as Venus' orbit.
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slg 16 minutes ago
It has been a little while since I read the book, but I think you have the cause of the curve wrong. These things are moving at such a high percentage of the speed of light that there isn't much visible curve from the movement of the planet. The curve is instead caused by them leaving the star at the pole (which leads to a different nitpick of the visualization since the curve isn't shaped to represent that). It's theorized that the Astrophage do this to make is easier to find their way as exiting the plane of the solar system reduces the chances of there being any occultation blocking their view of their destination.
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retrocryptid 19 minutes ago
NICE!
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Lapsa 3 minutes ago
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nekusar 23 minutes ago
It can be summed up as "Ken Meets Jesus", "Ken Goes to Space", "Ken is a bumbling moron", "Ken's first friend". "Ken's White Savior moment"

This appears to be the norm for US based scifi now. Glad I'm watching movies like The Wandering Earth and Alienoid instead.

It had a good premise. But it also fell apart immediately. Like, they only sent 3 people, 2 whom died on this UBER CRITICAL SAVE THE PLANET idea?

And Ryan Gosling's character is a fucking moron. You're supposed to be a molecular biologist, and you're basically a reddit-gag line?

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tantalor 14 minutes ago
> White Savior moment

???

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rpmisms 8 minutes ago
White people doing anything good is actually bad. Duh.

/s, but I think I'm accurately describing the viewpoint you're responding to.

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lstodd 15 minutes ago
As a european arthouse cinema snob I must say Gosling would have made a nice stand-in for Rocco Siffredi. Maybe.
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TwoNineA 18 minutes ago
You must be fun at parties.
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Bud 4 minutes ago
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makach 45 minutes ago
Elite Dangerous does it better. Pretty but idk.. get the AI generated feeling.
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