# Orion stars distance from Earth

For a textbook I'm creating a figure depicting the distances of Orion constellation's stars from Earth.

However i wasn't able to found an Official Scientific catalog of most recent stars distance measurement and when looking on non-scientific websites (including Wikipedia) i found distances that varies most of the time from 50% to 300%............

Do someone know where i can found an official scientific catalog (database) with the latest measurements. Or confirm the following distances below:

• Bellatrix 244.6 ly
• Meissa 1,109 ly
• Betelgeuse 500-600 ly
• Mintaka 1,240 ly
• Alnilam 2,000 ly
• Alnitak 1,262 ly
• Saiph 650 ly
• Rigel 864.3 ly

• This isn't an answer, but this tool is pretty handy for visualising relative distances of objects in our galaxy: ourgalaxy.otherwise.com Sep 22, 2023 at 12:58

This is a real problem with star distances, and one that isn't well appreciated. We just don't know how far many large, bright, distant stars are.

The values you will find on Wikipedia, which are sourced from measurements of parallax (via Simbad (etc)) are "best estimates". We can tell the size of a star by measuring it's parallax: the apparent "wiggle" ad it moves around the sun. But this wiggle is exceedingly small, and for a star like Betelgeuse, might be smaller than the disc of the star.

So we can say that Bellatrix is "about 250 light years". Mintaka and Alnitak are probably about 1200-1300 light years (the Hippcaros measurement is generally agreed to be an under-estimate of the distance) but we don't actually know which one is closer. Betelgeuse is probably between 500 and 600 light years (but could be further) Alnilam is between 1500 and 2500 light years and so on.

In may parts of astronomy, we are used to being able to make exceedingly precise measurements: we can predict eclipses to the the second, and the distance to the moon in centimetres. But we simple don't know with any accuracy how far away many common stars are. The values in your list are good "best current guess".

• It was a discovery for me that it turns out to be quite difficult to determine the distances to stars
– dtn
Sep 25, 2023 at 7:07

I'm not sure if you can get the VERY latest measurements there, but Simbad is always good for finding stars by criteria and learning more about existing ones, though it's not the most intuitive site out there in how searching works if you want something more detailed than entering the name of an object. If ever a star's distance is unavailable, you can always calculate it from its parallax: Let $$d$$ be distance in parsecs, and $$p$$ the parallax value in milli arc seconds (thus the factor 1000 in this equation):

$$d = \frac{1}{p/1000}.$$

Therefore, going by the latest measurement on Simbad for Rigel, 1/(3.78/1000) = 264.55 parsecs = 862.44 light-years (rounded up), which seems to be corroborated by Wikipedia in this instance.

EDIT: As @ProfRob rightly says below, this is not an exact measurement. I included five figures just to help anyone else trying the formula, since I myself am not good with mathematics.

• Ok i didn't know what as SIMBAD. I will check that. Thanks a lot Sep 22, 2023 at 12:02
• @kazom +1. But don't be shy with linking these ressources... Sep 22, 2023 at 12:54
• Please don't quote 5 significant figures unless you have discussed the uncertainties. The approximation that the most probable distance is the reciprocal of the parallax will not be true to 5 significant figures. Sep 22, 2023 at 14:44
• @ProfRob That's a very good point. I hadn't considered that, sorry. Sep 22, 2023 at 16:52
• No. The formula follows from the definition in this case. I meant: You quote output from Sinbad. Thus link these, your sources, next time like I added them to your answer in this case :) When you quote a paper, link its archive entry etc. Sep 22, 2023 at 21:34

The database Augmented Tycho-HYG (v1.0) from http://www.astronexus.com/hyg uses parallax records from Hipparcos and uses updated Gaia DR3 distances where available. Luckily the records show "dist_src" to see where the value actually comes from. I went through the trouble (Oooh, such trouble!) of fetching them for you:

name pc ly (pc * 3.261598) dist_src
Bellatrix 77.3994 252.4457282 HIP
Meissa 336.7003 1098.181025 HIP
Betelgeuse 152.6718 497.9540375 HIP
Mintaka 212.3142 692.4835701 HIP
Alnilam 606.0606 1976.726041 HIP
Alnitak 225.7336 736.2522583 HIP
Saiph 198.4127 647.1424655 HIP
Rigel 264.5503 862.8567294 HIP

In case you or anyone else wants to check more distances, my method was importing the csv file from astronexus in a mongodb and then running:

    db.athyg.find({"proper":"Rigel"},{"dist":1,"dist_src":1,"proper":1})

• Far too many significant figures. The distance to Betelgeuse is uncertain by at least 10% and I wouldn't have thought Hipparcos parallaxes would be much better. Sep 22, 2023 at 22:11
• I have immediate access to the HYG dataset from astronexus, so that's where I pulled the numbers from. To know the significant figures, I would have to pull from the original Hipparcos dataset (they provide a Parallax in mas and a Parallax_Error field). The aim of my answer was mostly to provide the sources for said data: Hipparcos and Gaia DR3. Hipparcos is indeed inferior. Sep 24, 2023 at 3:15