<p>In the night sky in 10,000 years, two things will have changed in relation to the stars. The first, the rotational axis of the Earth will have changed, shifting the celestial sphere. The second, the stars themselves will have moved a bit relative to each other due to proper motion. So, the night sky will be quite different in 10,000 years, but still recognizable, particularly the constellations which will have changed somewhat but will still be identifiable. I would posit that as long as the person or persons were at least casual star gazers or astronomy enthusiasts (not even necessarily professionals) they could estimate how much time has passed in the course of their slumber, I'd say with a margin of error of about +/-2000 years. Should they be trained astronomers that margin of error should fall. </p>

CC BY-SA 3.0
2015-04-02T00:06:31.823Z
2015-04-02T03:30:55.043Z
2015-04-02T03:30:55.043Z
PJS1987
<p>I'm writing a science fiction short story which involves a group of people being in suspended animation for a very long period of time, on the order of thousands of years.</p>

<p>My question is, would an astronomer on waking be able to determine that a significant period of time has passed purely by making observations in the night sky? How accurate would they be?</p>

<p>For the purposes of the story, I'm more interested in what an astronomer could observe unaided or with a primitive telescope of the sort Galileo might have had early in his career (around 3X magnification).</p>

<p>Thanks!</p>

CC BY-SA 3.0
2015-03-31T02:48:41.083Z
There are a lot of methods in which someone might try to accomplish this.  What method they employ would depend highly upon what they knew *before* going into their suspended animation.  Presumably, as you mention that they are an astronomer, they would have been well versed in astronomy before going to sleep? Would they have a modern understanding of Astronomy but rudimentary tools? Or rather primitive understanding?
Mitch Goshorn
CC BY-SA 3.0
2015-03-31T03:02:05.353Z
@Mitch Please assume that they are a modern astronomer working at professional level before going into suspension. Afterwards, they would only have access to primitive technology.
Mark Micallef
CC BY-SA 3.0
2015-03-31T03:03:53.407Z
Okay, great. Also would they have access to modern data (physical or digital), or be working with only what they might reasonably remember? Ahh, one last thing. Are we to assume that they are on Earth?
Mitch Goshorn
CC BY-SA 3.0
2015-03-31T03:11:36.823Z
Yes, they're on Earth. Around 10,000 years has passed (but they don't know it). They only have what they remember and what they had on their person at the time of the event (i.e. clothes, keys, wallet, maybe a phone, that kind of stuff). All civilisation has decayed from lack of maintenance in the meantime, so buildings, roads, vehicles, industrial facilities, and of course, observatories, libraries, etc, are all buried rubble and rust. Civilisation is restarting, so primitive industry only is available, mostly rebuilt from memory.
Mark Micallef
CC BY-SA 3.0
2015-03-31T19:04:46.250Z
I would guess that, after 10,000 years, most constellations would still be recognizable, if slightly distorted. So that would give a quick upper limit on the passage of time. In addition, you could also use the [precession of the Earth's rotation axis](https://en.wikipedia.org/wiki/Axial_precession) by observing which star is the present pole star (or where a present pole star has moved to).
Warrick
CC BY-SA 3.0
2015-03-31T23:13:39.187Z
Thanks guys. That gives me a good starting point for my research.
Mark Micallef
<telescope><observational-astronomy><star-gazing>
Is it possible to use the stars to determine the passage of time?
Mark Micallef
# Is it possible to use the stars to determine the passage of time?

(Asked by: username_0 on 2015-03-31)

I'm writing a science fiction short story which involves a group of people being in suspended animation for a very long period of time, on the order of thousands of years.

My question is, would an astronomer on waking be able to determine that a significant period of time has passed purely by making observations in the night sky? How accurate would they be?

For the purposes of the story, I'm more interested in what an astronomer could observe unaided or with a primitive telescope of the sort Galileo might have had early in his career (around 3X magnification).

Thanks!

**Tags:** telescope, observational-astronomy, star-gazing
> **Comments:**
> **username_1**: There are a lot of methods in which someone might try to accomplish this.  What method they employ would depend highly upon what they knew *before* going into their suspended animation.  Presumably, as you mention that they are an astronomer, they would have been well versed in astronomy before going to sleep? Would they have a modern understanding of Astronomy but rudimentary tools? Or rather primitive understanding?  
> **username_0**: @Mitch Please assume that they are a modern astronomer working at professional level before going into suspension. Afterwards, they would only have access to primitive technology.  
> **username_1**: Okay, great. Also would they have access to modern data (physical or digital), or be working with only what they might reasonably remember? Ahh, one last thing. Are we to assume that they are on Earth?  
> **username_0**: Yes, they're on Earth. Around 10,000 years has passed (but they don't know it). They only have what they remember and what they had on their person at the time of the event (i.e. clothes, keys, wallet, maybe a phone, that kind of stuff). All civilisation has decayed from lack of maintenance in the meantime, so buildings, roads, vehicles, industrial facilities, and of course, observatories, libraries, etc, are all buried rubble and rust. Civilisation is restarting, so primitive industry only is available, mostly rebuilt from memory.  
> **username_2**: I would guess that, after 10,000 years, most constellations would still be recognizable, if slightly distorted. So that would give a quick upper limit on the passage of time. In addition, you could also use the [precession of the Earth's rotation axis](https://en.wikipedia.org/wiki/Axial_precession) by observing which star is the present pole star (or where a present pole star has moved to).  
> **username_0**: Thanks guys. That gives me a good starting point for my research.  

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## 1 answers

### Answer by username_3 on 2015-04-02. Score: 1 | Accepted answer

In the night sky in 10,000 years, two things will have changed in relation to the stars. The first, the rotational axis of the Earth will have changed, shifting the celestial sphere. The second, the stars themselves will have moved a bit relative to each other due to proper motion. So, the night sky will be quite different in 10,000 years, but still recognizable, particularly the constellations which will have changed somewhat but will still be identifiable. I would posit that as long as the person or persons were at least casual star gazers or astronomy enthusiasts (not even necessarily professionals) they could estimate how much time has passed in the course of their slumber, I'd say with a margin of error of about +/-2000 years. Should they be trained astronomers that margin of error should fall.


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