Top
Best
New

Posted by speleo 3 hours ago

Project Hail Mary – Stellar Navigation Chart(valhovey.github.io)
221 points | 66 comments
speleo 27 minutes ago|
Hi there! This is Val, I made the star chart. There's a little "about" blurb you can open in a modal on the site, but I wanted to mention that this demo uses the amazing GAIA DR3 dataset from ESA. I have a Python script that renders all 1.8+ billion stars into custom images, which is what I used for the skybox. The star positions and colors all use the GAIA data (save for a few bright stars not in the set). The data is amazing, and if you have any interest in doing some fun projects with open data I recommend checking it out: https://www.cosmos.esa.int/web/gaia/dr3
asabla 11 minutes ago|
Super cool! how long did it take to generate all those custom images?
ggreer 2 hours 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.

Mogzol 32 minutes ago||
Another comparison: if you count the "solar system" as ending at Neptune's orbit (obviously it extends much further, but just for the sake of comparison), then you could fit ~4465 "solar systems" in between our sun and the closest star, Proxima Centauri.
hnuser123456 1 hour 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.

Edit 2: Tau Ceti is rendered at 3.652 pc × 3 world units/pc = 10.956 world units

Neptune’s orbit radius is rendered as 30.05 AU × 0.0065 world units/AU = 0.195325 world units

The rendered ratio is 10.956 / 0.195325 = 56.09 Neptune-orbit radii

The real ratio should be 25,067.5 Neptune-orbit radii

The scale error = 25,067.5 / 56.09 = 446.9×

dylan604 48 minutes ago|||
Sure, but why does this need to be to scale. Isn't the point more to get the humans a way of understanding where things are relatively? Navigating the map makes it interesting in being able to interactively see where some of the stars are relative to each other. Seeing Regulus and Castor/Pollux from this perspective is much different than on terra firma.
api 1 hour ago||
Even sci-fi writers that try to get this right have a hard time wrapping their heads around it.

"It's called space for a reason."

When I saw the series adaptation of The Expanse, it was really obvious they played a lot of artistic license to make it exciting. A real space battle would be dots firing invisible dots at each other. "Close quarter battle" would be within something like 2000 kilometers, maybe more. That is close.

loeg 3 minutes ago|||
I don't think the Expanse authors were going for "hard sci-fi." There's, you know, fiction elements -- gates, aliens, magic. And the TV series is itself an adaptation of the books for a visual medium. Showing almost nothing would make for kind of boring TV combat.
QuercusMax 8 minutes ago||||
I recently read The Mote in God's Eye and its (much later) sequel The Gripping Hand, which had very interesting long-distance space combat scenes with high powered lasers - which only move at the speed of light. There's a very real "fog of war" element where you might be VERY out of date with what's happening just due to radio transmission speeds / direct observation.
the_af 59 minutes ago|||
> When I saw the series adaptation of The Expanse, it was really obvious they played a lot of artistic license to make it exciting. A real space battle would be dots firing invisible dots at each other. "Close quarter battle" would be within something like 2000 kilometers, maybe more. That is close.

This is noteworthy because The Expanse tried to get this better than other scifi, say Star Trek, Battlestar Galactica, or Star Wars (ok, space opera), where engagements take place at absurdly short ranges. In The Expanse you see the spaceships are really far apart, mostly dots to each other, and the engagements are (mostly) at really long torpedo ranges, with the exception of those cool scenes using PDCs. You get all those awesome shots where one spaceship sees the other as a tiny dot, then the camera zooms in dramatically to the other point of view. Cool!

And still, engagements are far too close range. But they "feel" long range in The Expanse, I think they got that visually right. I cannot blame them because I haven't seen anything any space combat in shows or movies that is even half as exciting and well done.

manmal 16 minutes ago||
The Expanse also was (for me) the first to introduce the concept of a braking burn. Star Wars ships just stop without turning around - can’t unsee it. I think the way X-wing fighters “fly” also wouldn’t work at all, I don’t see any reaction mass coming out the sides.
QuercusMax 11 minutes ago||
Babylon 5 was the only show in the 90s that actually had any sort of physics based space combat (as opposed to Star Wars-style "they're really just airplanes but we're pretending it's space").
ge96 2 hours 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?

imglorp 1 hour 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).

ge96 1 hour 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.
recursivecaveat 1 hour ago||
Since the strength is represented by the slope of the sheet (not the depth), it should still line up. Underneath the ball at the very center the sheet will be level, to match as you say, that the field strength is 0 there. The exact shape will probably be wrong though since it's mostly determined by the shape of the bottom of the object.
stevenwoo 2 hours 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.
ge96 2 hours 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. That was a good series though I remember the depiction of the space battles.

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

Hikikomori 1 hour ago|||
In the vein of popcorn scifi, expeditionary force books are fun.
ge96 1 hour ago||
Added to my kindle list, funny I tried to read Gravity's Rainbow as I heard it in a song, I did not get far, on the topic of reading, it is related to rockets but yeah
lstodd 2 hours 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.

ge96 2 hours 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?

lstodd 1 hour ago||
There is no down, yes. There is no looking at it from a top view either, since there is no bottom. 3d models like this video are helpful, but one must keep in mind that they are but a slice.
godzillabrennus 1 hour ago||
I doubt my opinion will be well-received by all, but I hope that creators like the author of the Bobiverse will be able to, affordably and within their own capabilities, create new forms of content, such as AI-generated long-form content, like entire TV seasons, as the technology matures. That series is fantastic.
rdtsc 2 hours 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)

hotsalad 8 minutes ago||
Looks nice, but is it finished? I don't see a skybox or any of the more detailed information mentioned in the "about" dialog, and I don't see any effect from clicking the buttons along the top.

I allowed WebGL and disabled Enhanced Tracking Protection and my adblocker, and still only the star labels appear.

arkaic 13 minutes ago||
Anyone with a gaming rig and an interest in scale of a galaxy should check out elite dangerous.
ge96 7 minutes ago|
Space engine too
TeaVMFan 2 hours 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/
Esophagus4 1 hour ago|
Didn’t know he was a programmer!
jimnotgym 47 minutes ago||
I had sudden memories of playing Frontier: Elite 2.

I wanted to go to Sol, buy luxury goods...and take them to Barnards Star

maniacalrobot 14 minutes ago|
Yep, quick trip in your panther clipper to ross 154, park up and buy everything on the planet.
dkobia 2 hours 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.
speleo 36 minutes ago|
You're welcome! I love that channel so much. Their videos and the blog post I link in the about section/citations on the starmap were inspirations for making this.
V__ 2 hours ago|
"Thumbs" down
elteto 22 minutes ago||
You mean up. Question.
IdiotSavage 1 hour ago|||
Amaze!
staindk 1 hour ago||
Fist my bump
More comments...