<p>There are two main things we should look at here, because there are two main ways these distant stars can affect us: light and gravity.</p>

<p><strong>Light</strong></p>

<p>If all the stars in the universe disappeared (besides the Sun), the most of the luminous objects in the universe would simply vanish. There would still be objects emitting radiation - stellar remnants, accretion disks, etc. - but the notable sources of light would be gone.</p>

<p>Would this be an issue? I can't give you any numbers, but I would assume that there wouldn't be much of a difference. Night/day cycles would continue as normal, because the rotation of the Earth also would not be affected. The behavior of <a href="https://en.wikipedia.org/wiki/Stoma" rel="nofollow">stoma</a> in plants should remain the same, as should all the other natural rituals of life.</p>

<p><strong>Gravity</strong></p>

<p>This is where I'm slightly more concerned. Stars have mass, and so they influence other objects with gravity. There are varying estimates of how much of the Milky Way is made up of stars. For example, <a href="http://mnras.oxfordjournals.org/content/414/3/2446.full.pdf" rel="nofollow">McMillan (2011)</a> estimated the stellar mass of the Milky Way to be about 6.43$\times$10<sup>10</sup> solar masses, while the virial (total) mass was estimated to be about 1.26$\times$10<sup>12</sup> solar masses.</p>

<p>The extra matter consists of gas, dust, planets, stellar remnants, and, of course, dark matter (a lot of it). The mass of the Milky Way would be reduced by about 5% - not a terrible amount, but certainly non-negligible. I don't know how this would impact the motion of the Solar System; detailed simulations based on density models would be needed.</p>

<p>However, any effects from stars wouldn't reach us any time soon. Light and gravity both travel at the speed of light, so we'd have at least four years before we started seeing the effects (4 light-years is the distance to the nearest star, Proxima Centauri). We wouldn't feel the effects from the rest of the galaxy for many more years.</p>

CC BY-SA 3.0
2015-11-14T16:36:17.127Z
2015-11-14T18:14:54.507Z
2015-11-14T18:14:54.507Z
HDE 226868
<p>One example: there might be some effects on animal migration, as migrating species have been shown to respond to star patterns in a planetarium in various experiments over the years.</p>

<p>Even dung beetles were found to respond to the "stripe" of the milky way across the sky, in an experiment publicised a few years ago.  This was not for long distance migration by the way, but for moving in a straight line for a short distance when a food source is found.</p>

<p><a href="http://www.bbc.co.uk/news/science-environment-21150721" rel="nofollow">BBC news story about dung beetles</a></p>

<p><a href="http://web.mnstate.edu/wisenden/AnBeh13%20Paper%205%20Dacke%20et%20al%202013.pdf" rel="nofollow">Paper about dung beetles</a></p>

CC BY-SA 3.0
2015-11-16T12:10:28.897Z
2015-11-16T12:10:28.897Z
Andy
<p>Do you mean if they disappeared now, or disappeared at some arbitrary time?</p>

<p>If the latter, then I would say that if they had disappeared more than a few thousand years ago, we might still be living in mud huts. The movement of stars and planets in the heavens motivated many of the ancient scholars and led directly to things like Newton's laws and a theory of gravity.</p>

<p>If the former, no immediate physical consequences, but - I would say a worldwide panic and financial meltdown for starters.</p>

CC BY-SA 3.0
2015-11-15T11:42:55.760Z
And if they'd disappeared billions of years ago, maybe Earth would be lifeless. Not that I'm a fan of "panspermia", but you never know.
John Duffield
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2015-11-14T21:32:20.713Z
2015-11-14T21:32:20.713Z
ProfRob
<p>I am not an astronomy expert, but as of today, all other stars than the Sun have little to no effect on life on Earth. So I was thinking, would there be any differences for the Earth <strong>at all</strong> if all stars would disappear except the Sun?</p>

CC BY-SA 3.0
2015-11-14T21:27:47.080Z
You wouldn't be able to tell which way is north at night.
ProfRob
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2015-11-14T21:29:33.353Z
Well it's 2015, a compass will do the  job
Thomas Wagenaar
CC BY-SA 3.0
2015-11-14T21:33:53.167Z
Oh yeah, I hadn't thought of that... not.
ProfRob
CC BY-SA 3.0
2015-11-15T00:23:56.150Z
Pictures of the aurora would be less interesting. The internet would no longer be infested with shots of the milky way over eg Baffin bay. The planets, and a few asterods, would stand out a lot clearer. We'd actually be able to see a goodly number of the vast number of satellites and bits of space junk that orbit the earth. It'd be easier to set a camera to take a pic whenever a meteor flashes in.
Wayfaring Stranger
<star><life><habitable-zone>
Notable differences if all stars would disappear except the Sun
Thomas Wagenaar
# Notable differences if all stars would disappear except the Sun

(Asked by: username_0 on 2015-11-14)

I am not an astronomy expert, but as of today, all other stars than the Sun have little to no effect on life on Earth. So I was thinking, would there be any differences for the Earth **at all** if all stars would disappear except the Sun?

**Tags:** star, life, habitable-zone
> **Comments:**
> **username_1**: You wouldn't be able to tell which way is north at night.  
> **username_0**: Well it's 2015, a compass will do the  job  
> **username_1**: Oh yeah, I hadn't thought of that... not.  
> **username_2**: Pictures of the aurora would be less interesting. The internet would no longer be infested with shots of the milky way over eg Baffin bay. The planets, and a few asterods, would stand out a lot clearer. We'd actually be able to see a goodly number of the vast number of satellites and bits of space junk that orbit the earth. It'd be easier to set a camera to take a pic whenever a meteor flashes in.  

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## 3 answers

### Answer by username_3 on 2015-11-14. Score: 1 | Accepted answer

There are two main things we should look at here, because there are two main ways these distant stars can affect us: light and gravity.

**Light**

If all the stars in the universe disappeared (besides the Sun), the most of the luminous objects in the universe would simply vanish. There would still be objects emitting radiation - stellar remnants, accretion disks, etc. - but the notable sources of light would be gone.

Would this be an issue? I can't give you any numbers, but I would assume that there wouldn't be much of a difference. Night/day cycles would continue as normal, because the rotation of the Earth also would not be affected. The behavior of [stoma](https://en.wikipedia.org/wiki/Stoma) in plants should remain the same, as should all the other natural rituals of life.

**Gravity**

This is where I'm slightly more concerned. Stars have mass, and so they influence other objects with gravity. There are varying estimates of how much of the Milky Way is made up of stars. For example, [McMillan (2011)](http://mnras.oxfordjournals.org/content/414/3/2446.full.pdf) estimated the stellar mass of the Milky Way to be about 6.43$\times$1010 solar masses, while the virial (total) mass was estimated to be about 1.26$\times$1012 solar masses.

The extra matter consists of gas, dust, planets, stellar remnants, and, of course, dark matter (a lot of it). The mass of the Milky Way would be reduced by about 5% - not a terrible amount, but certainly non-negligible. I don't know how this would impact the motion of the Solar System; detailed simulations based on density models would be needed.

However, any effects from stars wouldn't reach us any time soon. Light and gravity both travel at the speed of light, so we'd have at least four years before we started seeing the effects (4 light-years is the distance to the nearest star, Proxima Centauri). We wouldn't feel the effects from the rest of the galaxy for many more years.


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### Answer by username_4 on 2015-11-16. Score: 1

One example: there might be some effects on animal migration, as migrating species have been shown to respond to star patterns in a planetarium in various experiments over the years.

Even dung beetles were found to respond to the "stripe" of the milky way across the sky, in an experiment publicised a few years ago. This was not for long distance migration by the way, but for moving in a straight line for a short distance when a food source is found.

[BBC news story about dung beetles](http://www.bbc.co.uk/news/science-environment-21150721)

[Paper about dung beetles](http://web.mnstate.edu/wisenden/AnBeh13%20Paper%205%20Dacke%20et%20al%202013.pdf)


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### Answer by username_1 on 2015-11-14. Score: 1

Do you mean if they disappeared now, or disappeared at some arbitrary time?

If the latter, then I would say that if they had disappeared more than a few thousand years ago, we might still be living in mud huts. The movement of stars and planets in the heavens motivated many of the ancient scholars and led directly to things like Newton's laws and a theory of gravity.

If the former, no immediate physical consequences, but - I would say a worldwide panic and financial meltdown for starters.

> **Comments:**
> **username_5**: And if they'd disappeared billions of years ago, maybe Earth would be lifeless. Not that I'm a fan of "panspermia", but you never know.  

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