<p>I note that in old style space opera type stories, such as <em>Star Trek</em>, it is common to mention and visit habitable planets orbiting around types of stars which should not have habitable planets for various reasons.  Thus one could assumed that in such stories hypothetical super advanced aliens have moved habitable planets into orbit around those stars, or have terraformed planets orbiting those stars to make them habitable.</p>
<p>Assuming that the Earth could be moved into orbit around a hypergiant, such as by creating an artificial wormhole in front of the orbiting Earth so that Earth enters the mouth of the wormhole in our solar system and emerges from the other mouth near the hypergiant star, it is fairly simple to calculate the proper orbital distance.</p>
<p>Simply multiply the distances of the inner and outer edges of the Sun's circumstellar habitable zone, by the luminosity of the new star relative to the Sun, to find out how close or far from that new star the inner and outer edges of the star's circumstellar habitable zone are.</p>
<p>it's very, very simple.</p>
<p>Except that I have seen a list of about a dozen estimates and calculations of the inner or  outer edges, or both, of the Sun's circumstellar habitable zone, and some of them differ a lot from others.</p>
<p><a href="https://en.wikipedia.org/wiki/Circumstellar_habitable_zone#Solar_System_estimates%5B1%5D" rel="nofollow noreferrer">https://en.wikipedia.org/wiki/Circumstellar_habitable_zone#Solar_System_estimates[1]</a></p>
<p>As I point out in my answer to this question:</p>
<p><a href="https://worldbuilding.stackexchange.com/questions/186020/how-big-can-the-habitable-zone-be-in-a-g-type-binary-system/186104#186104%5B2%5D">https://worldbuilding.stackexchange.com/questions/186020/how-big-can-the-habitable-zone-be-in-a-g-type-binary-system/186104#186104[2]</a></p>
<blockquote>
<p>The broadest possible range (combining different estimates) for the Sun's circumstellar habitable zone is about 481 times as wide, and about 1,436,139,559 kilometers wider, than the narrowest possible range (combining different estimates) for the Sun's circumstellar habitable zone.</p>
</blockquote>
<p>So instead of calculating the extent of a hypergiant's hypothetical circum stellar habitable zone, we can assume that the Earth could orbit the hypergiant at Earth's exact distance from the Sun, one Astronomical Unit, or AU, multiplied by the Hypergiant's luminosity relative to the Sun.</p>
<p>Because of the inverse square law, if an object is moved to twice as far away from a source of light, it will receive only a quarter of the light it once received, and if the object is moved to half the distance from the light source it will recieve four times the light it once received.</p>
<p>If a star is twice as  luminous as the Sun, a planet at a distance of 1.41 AU will receive as much light from it as Earth gets from the Sun.</p>
<p>If a star is 64 times as luminous as the Sun, a planet at a distance of 8 AU will receive as much light from it as Earth gets from the Sun.</p>
<p>If a star is 100 times as luminous as the Sun, a planet at a distance of 10 AU will receive as much light from it as Earth gets from the Sun.</p>
<p>If a star is 1,000 times as luminous as the Sun, a planet at a distance of 31.622 AU will receive as much light from it as Earth gets from the Sun.</p>
<p>If a star is 10,000 times as luminous as the Sun, a planet at a distance of 100 AU will receive as much light from it as Earth gets from the Sun.</p>
<p>Since the list of the few dozen most luminous stars known includes luminosities between  1,000,000 times that of the Sun and at least 6,400,000 times that of the Sun, a planet in orbit around such stars woudl have to orbit at least 1,000 AU from the star, and up to at least 2,529.822128 AU from the star, to recieve exactly as much radation from those stars as Earth receives from the Sun.</p>
<p><a href="https://en.wikipedia.org/wiki/List_of_most_luminous_stars%5B3%5D" rel="nofollow noreferrer">https://en.wikipedia.org/wiki/List_of_most_luminous_stars[3]</a></p>
<p>Of course, because those stars have different spectral types than they Sun, different percentages of their radiation will be in the visual spectrum as compared to infra read and ultra violent parts of the spectrum.  So that will have some effect on the planetary temperatures which I have not calculated.</p>
<p>And if you want to learn more about what type of stars would be suitable for having habitable planets, you might want to read <em>Habitable Planets for Man</em> by stephen H. Dole, 1964:</p>
<p><a href="https://www.rand.org/content/dam/rand/pubs/commercial_books/2007/RAND_CB179-1.pdf%5B4%5D" rel="nofollow noreferrer">https://www.rand.org/content/dam/rand/pubs/commercial_books/2007/RAND_CB179-1.pdf[4]</a></p>
<p>And this article and its sources for more recent research:</p>
<p><a href="https://en.wikipedia.org/wiki/Planetary_habitability#Suitable_star_systems%5B5%5D" rel="nofollow noreferrer">https://en.wikipedia.org/wiki/Planetary_habitability#Suitable_star_systems[5]</a></p>
<p>Ir you are wondering how many habitable planets could orbit within the circumstellar habitable zone of a star, you might want to go to the PlanetPlanet site and check the Ultimate Solar System section.  The Ultimate Solar System is dedicated to designing solar systems with the most possible habitable planets.  And some of them are very impressive and correspondingly improbable in the number of habitable planets they have:</p>
<p><a href="https://planetplanet.net/the-ultimate-solar-system/%5B6%5D" rel="nofollow noreferrer">https://planetplanet.net/the-ultimate-solar-system/[6]</a></p>

CC BY-SA 4.0
2020-10-01T10:42:41.903Z
So, (if I am doing my maths right) Eta Carine, the star that is about 4,000,000 times the mass of our Sun (more on that [here](https://starchild.gsfc.nasa.gov/docs/StarChild/questions/question21.html#:~:text=It%20has%20a%20size%20about,times%20brighter%20than%20our%20Sun.&text=It%20is%20in%20a%20stage,temperature%20compared%20to%20our%20Sun.)), then Earth will have to be about 2000 AU away from it to receive as much light from it as it gets from our Sun.
Infinity Milestone
CC BY-SA 4.0
2020-10-01T16:08:04.930Z
@AyushBhatt  Eta Carinae A has a mass of about 100 times that of the Sun, and Eta Carinae B has a mass of about 30 to 80 times the mass of the Sun.  Together they have a luminosity about 6,000,000 times that of the Sun, and so Earth would have to orbit about 2,449.48 AU from them to have the same temperature as it actually does 1 AU from the Sun.   https://en.wikipedia.org/wiki/Eta_Carinae
M. A. Golding
CC BY-SA 4.0
2020-09-29T16:32:40.607Z
2020-09-29T16:32:40.607Z
M. A. Golding
<ul>
<li>Where would an Earthlike planet need to be so it's still in the 'Habitable Zone' of a hypergiant Star, compared to the distance of the Earth from the sun?</li>
<li>Could complex life develop or survive on such a planet?</li>
</ul>
<p>It's not necessary to answer the second question, as it is not really related to Astronomy much. But if someone <em>could</em> really answer that, I would be grateful.</p>
<h2>Some background</h2>
<p>I was watching <a href="https://www.youtube.com/watch?v=3mnSDifDSxQ" rel="nofollow noreferrer">this</a> video of Kurzgesagt ( that's a YouTube channel.) which was released only some days ago, and the video spoke about the comparison of the Sun to some of the largest types of stars out there. The video also mentions Giants and of course, Hypergiants.</p>
<p>This made me think about what would happen if our very own Sun, turned into a Hypergiant.</p>

CC BY-SA 4.0
2020-09-29T05:24:59.993Z
I've edited quite radically, to make the about real stars and not about the sun (which can't change to a hypergiant)  This is to make the question on topic and answerable.  I've removed the third question, which was probably unanswerable.
James K
CC BY-SA 4.0
2020-09-29T05:38:02.310Z
This is relvant, if not an actual duplicate https://astronomy.stackexchange.com/questions/20610/do-blue-giants-have-a-habitable-zone?rq=1
James K
<habitable-zone><hypergiants>
Where is the habitable zone of a Hypergiant?
Infinity Milestone
# Where is the habitable zone of a Hypergiant?

(Asked by: username_0 on 2020-09-29)

* Where would an Earthlike planet need to be so it's still in the 'Habitable Zone' of a hypergiant Star, compared to the distance of the Earth from the sun?
* Could complex life develop or survive on such a planet?

It's not necessary to answer the second question, as it is not really related to Astronomy much. But if someone *could* really answer that, I would be grateful.

## Some background

I was watching [this](https://www.youtube.com/watch?v=3mnSDifDSxQ) video of Kurzgesagt ( that's a YouTube channel.) which was released only some days ago, and the video spoke about the comparison of the Sun to some of the largest types of stars out there. The video also mentions Giants and of course, Hypergiants.

This made me think about what would happen if our very own Sun, turned into a Hypergiant.

**Tags:** habitable-zone, hypergiants

> **Comments:**
> **username_1**: I've edited quite radically, to make the about real stars and not about the sun (which can't change to a hypergiant)  This is to make the question on topic and answerable.  I've removed the third question, which was probably unanswerable.  
> **username_1**: This is relvant, if not an actual duplicate https://astronomy.stackexchange.com/questions/20610/do-blue-giants-have-a-habitable-zone?rq=1  

---

## 1 answers

### Answer by username_2 on 2020-09-29. Score: 2 | Accepted answer

I note that in old style space opera type stories, such as *Star Trek*, it is common to mention and visit habitable planets orbiting around types of stars which should not have habitable planets for various reasons. Thus one could assumed that in such stories hypothetical super advanced aliens have moved habitable planets into orbit around those stars, or have terraformed planets orbiting those stars to make them habitable.

Assuming that the Earth could be moved into orbit around a hypergiant, such as by creating an artificial wormhole in front of the orbiting Earth so that Earth enters the mouth of the wormhole in our solar system and emerges from the other mouth near the hypergiant star, it is fairly simple to calculate the proper orbital distance.

Simply multiply the distances of the inner and outer edges of the Sun's circumstellar habitable zone, by the luminosity of the new star relative to the Sun, to find out how close or far from that new star the inner and outer edges of the star's circumstellar habitable zone are.

it's very, very simple.

Except that I have seen a list of about a dozen estimates and calculations of the inner or outer edges, or both, of the Sun's circumstellar habitable zone, and some of them differ a lot from others.

[https://en.wikipedia.org/wiki/Circumstellar\_habitable\_zone#Solar\_System\_estimates[1]](https://en.wikipedia.org/wiki/Circumstellar_habitable_zone#Solar_System_estimates%5B1%5D)

As I point out in my answer to this question:

[https://worldbuilding.stackexchange.com/questions/186020/how-big-can-the-habitable-zone-be-in-a-g-type-binary-system/186104#186104[2]](https://worldbuilding.stackexchange.com/questions/186020/how-big-can-the-habitable-zone-be-in-a-g-type-binary-system/186104#186104%5B2%5D)

> The broadest possible range (combining different estimates) for the Sun's circumstellar habitable zone is about 481 times as wide, and about 1,436,139,559 kilometers wider, than the narrowest possible range (combining different estimates) for the Sun's circumstellar habitable zone.

So instead of calculating the extent of a hypergiant's hypothetical circum stellar habitable zone, we can assume that the Earth could orbit the hypergiant at Earth's exact distance from the Sun, one Astronomical Unit, or AU, multiplied by the Hypergiant's luminosity relative to the Sun.

Because of the inverse square law, if an object is moved to twice as far away from a source of light, it will receive only a quarter of the light it once received, and if the object is moved to half the distance from the light source it will recieve four times the light it once received.

If a star is twice as luminous as the Sun, a planet at a distance of 1.41 AU will receive as much light from it as Earth gets from the Sun.

If a star is 64 times as luminous as the Sun, a planet at a distance of 8 AU will receive as much light from it as Earth gets from the Sun.

If a star is 100 times as luminous as the Sun, a planet at a distance of 10 AU will receive as much light from it as Earth gets from the Sun.

If a star is 1,000 times as luminous as the Sun, a planet at a distance of 31.622 AU will receive as much light from it as Earth gets from the Sun.

If a star is 10,000 times as luminous as the Sun, a planet at a distance of 100 AU will receive as much light from it as Earth gets from the Sun.

Since the list of the few dozen most luminous stars known includes luminosities between 1,000,000 times that of the Sun and at least 6,400,000 times that of the Sun, a planet in orbit around such stars woudl have to orbit at least 1,000 AU from the star, and up to at least 2,529.822128 AU from the star, to recieve exactly as much radation from those stars as Earth receives from the Sun.

[https://en.wikipedia.org/wiki/List\_of\_most\_luminous\_stars[3]](https://en.wikipedia.org/wiki/List_of_most_luminous_stars%5B3%5D)

Of course, because those stars have different spectral types than they Sun, different percentages of their radiation will be in the visual spectrum as compared to infra read and ultra violent parts of the spectrum. So that will have some effect on the planetary temperatures which I have not calculated.

And if you want to learn more about what type of stars would be suitable for having habitable planets, you might want to read *Habitable Planets for Man* by stephen H. Dole, 1964:

[https://www.rand.org/content/dam/rand/pubs/commercial\_books/2007/RAND\_CB179-1.pdf[4]](https://www.rand.org/content/dam/rand/pubs/commercial_books/2007/RAND_CB179-1.pdf%5B4%5D)

And this article and its sources for more recent research:

[https://en.wikipedia.org/wiki/Planetary\_habitability#Suitable\_star\_systems[5]](https://en.wikipedia.org/wiki/Planetary_habitability#Suitable_star_systems%5B5%5D)

Ir you are wondering how many habitable planets could orbit within the circumstellar habitable zone of a star, you might want to go to the PlanetPlanet site and check the Ultimate Solar System section. The Ultimate Solar System is dedicated to designing solar systems with the most possible habitable planets. And some of them are very impressive and correspondingly improbable in the number of habitable planets they have:

[https://planetplanet.net/the-ultimate-solar-system/[6]](https://planetplanet.net/the-ultimate-solar-system/%5B6%5D)

> **Comments:**
> **username_0**: So, (if I am doing my maths right) Eta Carine, the star that is about 4,000,000 times the mass of our Sun (more on that [here](https://starchild.gsfc.nasa.gov/docs/StarChild/questions/question21.html#:~:text=It%20has%20a%20size%20about,times%20brighter%20than%20our%20Sun.&text=It%20is%20in%20a%20stage,temperature%20compared%20to%20our%20Sun.)), then Earth will have to be about 2000 AU away from it to receive as much light from it as it gets from our Sun.  
> **username_2**: @AyushBhatt  Eta Carinae A has a mass of about 100 times that of the Sun, and Eta Carinae B has a mass of about 30 to 80 times the mass of the Sun.  Together they have a luminosity about 6,000,000 times that of the Sun, and so Earth would have to orbit about 2,449.48 AU from them to have the same temperature as it actually does 1 AU from the Sun.   https://en.wikipedia.org/wiki/Eta_Carinae  

---

