<p>There are a number of misconceptions here.</p>

<p>First, most of the visible stars that we see are much closer than you think. Most are within a few hundred light-years. With telescopes you can see more distant stars, but also lots of dim nearby ones. So the "3 million" value is wrong. "3 hundred" would be better.</p>

<p>Secondly stars formed at different times. If the star formed before the sun, the planet would have had more time to develop. </p>

<p>Finally, there is no reason to think that life on all planets develops at the same rate or in the same way.  For 3 billion years, life on Earth was mostly "slime" then suddenly complex animals evolved.  Perhaps on another planet the "slime" period took longer, or shorter, or the complex life never happened at all.</p>

<p>There is something of a mystery on why we don't see other intelligent life, and your notion of "we see their past" doesn't explain it.</p>

CC BY-SA 4.0
2018-06-09T07:24:58.377Z
2018-06-09T07:24:58.377Z
James K
<p>In addition to James K's answer, you might find the following interesting and of relevance to your question about observing distant planets.</p>

<p>We can't normally detect exoplanets (i.e. planets beyond our own solar system) if they're very far away. It's hard enough to detect dim stars at a distance, and planets capable of supporting intelligent life are <em>much</em> smaller than stars and emit extremely little light of their own (mostly as infrared, i.e. heat), so this makes it almost impossible to see far-distant planets. The most distant exoplanet we've observed <em>directly</em> is <a href="https://en.wikipedia.org/wiki/CVSO_30" rel="nofollow noreferrer">CVSO 30 c</a>, a gas giant 4.7 times the mass of Jupiter and located 1,200 light years from Earth, in the constellation of Orion.</p>

<p>We mainly detect exoplanets <em>indirectly</em>, by observing either a pattern of wobbles in a star's position (the <a href="https://en.wikipedia.org/wiki/Doppler_spectroscopy" rel="nofollow noreferrer">"radial-velocity method"</a>), or a pattern of changes in a star's light due to an exoplanet passing in front of the star (the <a href="https://en.wikipedia.org/wiki/Methods_of_detecting_exoplanets#Transit_photometry" rel="nofollow noreferrer">"transit method"</a>).</p>

<p>The most distant <em>potentially habitable</em> planet so far confirmed is <a href="https://en.wikipedia.org/wiki/Kepler-443b" rel="nofollow noreferrer">Kepler-443b</a> in the constellation Cygnus, at 2,540 light years from Earth.</p>

<p>The most distant of all exoplanets discovered (as at June 2018) is <a href="https://en.wikipedia.org/wiki/SWEEPS-11" rel="nofollow noreferrer">SWEEPS-11</a>, a <a href="https://en.wikipedia.org/wiki/Hot_Jupiter" rel="nofollow noreferrer">"hot Jupiter"</a> with a mass 9.7 times that of Jupiter and orbiting so close to its parent star that its "year" is only 43 hours. It's around 27,700 light years away.</p>

<p>All these exoplanets are within our own Milky Way galaxy. To give you an idea of distance, the centre of the Milky Way is about 26,000 light years from Earth, and from the centre to the outer edge of the galactic disk is up to 90,000 light years.</p>

<p>You mention a distance of 3 million light years away. This is well beyond the <a href="https://en.wikipedia.org/wiki/Andromeda_Galaxy" rel="nofollow noreferrer">Andromeda Galaxy</a>, the nearest major galaxy to our own, at around 2.5 million light years. Detection of exoplanets at that distance isn't currently possible with the transit or radial-velocity methods, but <a href="https://en.wikipedia.org/wiki/Gravitational_microlensing" rel="nofollow noreferrer">gravitational microlensing</a> provides a method of detecting extremely distant objects. Analysis of the 1999 microlensing event <a href="https://en.wikipedia.org/wiki/PA-99-N2" rel="nofollow noreferrer">PA-99-N2</a> <em>suggests</em> the presence of a planet orbiting a star in the Andromeda Galaxy. However, intelligent aliens would have to be able to send signals of inconceivable strength for us to be able to detect them at that distance.</p>

<p>Even more interesting is the claim, <a href="https://news.nationalgeographic.com/2018/02/exoplanets-discovery-milky-way-galaxy-spd/" rel="nofollow noreferrer">published in February this year</a>, of the microlens discovery of a collection of about 2,000 <a href="https://en.wikipedia.org/wiki/Rogue_planet" rel="nofollow noreferrer">rogue planets</a> in the amazing quasar <a href="https://en.wikipedia.org/wiki/RX_J1131-1231" rel="nofollow noreferrer">RX J1131-1231</a>, which is 3.8 <em>billion</em> light-years distant.</p>

CC BY-SA 4.0
2018-06-11T01:36:12.933Z
2018-06-11T01:36:12.933Z
Chappo Hasn't Forgotten
<p>I've heard somewhere that when we observe distant galaxies, we actually look into the past. For example, if a planet is 3 million light years away from us, it means that we observe its state as it was 3 million years ago, am I right?</p>

<p>So, I think this explains why we haven't encountered any aliens yet. Because we see their planets in their ancient times, their civilizations haven't formed yet. So we think that nobody's around us. But instead we can actually be surrounded by alien civilizations.</p>

<p>Is this idea plausible?</p>

CC BY-SA 4.0
2018-06-09T08:49:06.507Z
If you are interested in serious discussion of this then do a web search for "The Fermi Paradox".  I'd suggest [this video from the PBS Spacetime channel](https://www.youtube.com/watch?v=cJONS7sqi0o) on You tube as well.
StephenG - Help Ukraine
<exoplanet><life>
Can aliens possibly be around us?
saintcrawler
# Can aliens possibly be around us?

(Asked by: username_0 on 2018-06-09)

I've heard somewhere that when we observe distant galaxies, we actually look into the past. For example, if a planet is 3 million light years away from us, it means that we observe its state as it was 3 million years ago, am I right?

So, I think this explains why we haven't encountered any aliens yet. Because we see their planets in their ancient times, their civilizations haven't formed yet. So we think that nobody's around us. But instead we can actually be surrounded by alien civilizations.

Is this idea plausible?

**Tags:** exoplanet, life

> **Comments:**
> **username_1**: If you are interested in serious discussion of this then do a web search for "The Fermi Paradox".  I'd suggest [this video from the PBS Spacetime channel](https://www.youtube.com/watch?v=cJONS7sqi0o) on You tube as well.  

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## 2 answers

### Answer by username_2 on 2018-06-09. Score: 6

There are a number of misconceptions here.

First, most of the visible stars that we see are much closer than you think. Most are within a few hundred light-years. With telescopes you can see more distant stars, but also lots of dim nearby ones. So the "3 million" value is wrong. "3 hundred" would be better.

Secondly stars formed at different times. If the star formed before the sun, the planet would have had more time to develop.

Finally, there is no reason to think that life on all planets develops at the same rate or in the same way. For 3 billion years, life on Earth was mostly "slime" then suddenly complex animals evolved. Perhaps on another planet the "slime" period took longer, or shorter, or the complex life never happened at all.

There is something of a mystery on why we don't see other intelligent life, and your notion of "we see their past" doesn't explain it.


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### Answer by username_3 on 2018-06-11. Score: 1

In addition to username_2's answer, you might find the following interesting and of relevance to your question about observing distant planets.

We can't normally detect exoplanets (i.e. planets beyond our own solar system) if they're very far away. It's hard enough to detect dim stars at a distance, and planets capable of supporting intelligent life are *much* smaller than stars and emit extremely little light of their own (mostly as infrared, i.e. heat), so this makes it almost impossible to see far-distant planets. The most distant exoplanet we've observed *directly* is [CVSO 30 c](https://en.wikipedia.org/wiki/CVSO_30), a gas giant 4.7 times the mass of Jupiter and located 1,200 light years from Earth, in the constellation of Orion.

We mainly detect exoplanets *indirectly*, by observing either a pattern of wobbles in a star's position (the ["radial-velocity method"](https://en.wikipedia.org/wiki/Doppler_spectroscopy)), or a pattern of changes in a star's light due to an exoplanet passing in front of the star (the ["transit method"](https://en.wikipedia.org/wiki/Methods_of_detecting_exoplanets#Transit_photometry)).

The most distant *potentially habitable* planet so far confirmed is [Kepler-443b](https://en.wikipedia.org/wiki/Kepler-443b) in the constellation Cygnus, at 2,540 light years from Earth.

The most distant of all exoplanets discovered (as at June 2018) is [SWEEPS-11](https://en.wikipedia.org/wiki/SWEEPS-11), a ["hot Jupiter"](https://en.wikipedia.org/wiki/Hot_Jupiter) with a mass 9.7 times that of Jupiter and orbiting so close to its parent star that its "year" is only 43 hours. It's around 27,700 light years away.

All these exoplanets are within our own Milky Way galaxy. To give you an idea of distance, the centre of the Milky Way is about 26,000 light years from Earth, and from the centre to the outer edge of the galactic disk is up to 90,000 light years.

You mention a distance of 3 million light years away. This is well beyond the [Andromeda Galaxy](https://en.wikipedia.org/wiki/Andromeda_Galaxy), the nearest major galaxy to our own, at around 2.5 million light years. Detection of exoplanets at that distance isn't currently possible with the transit or radial-velocity methods, but [gravitational microlensing](https://en.wikipedia.org/wiki/Gravitational_microlensing) provides a method of detecting extremely distant objects. Analysis of the 1999 microlensing event [PA-99-N2](https://en.wikipedia.org/wiki/PA-99-N2) *suggests* the presence of a planet orbiting a star in the Andromeda Galaxy. However, intelligent aliens would have to be able to send signals of inconceivable strength for us to be able to detect them at that distance.

Even more interesting is the claim, [published in February this year](https://news.nationalgeographic.com/2018/02/exoplanets-discovery-milky-way-galaxy-spd/), of the microlens discovery of a collection of about 2,000 [rogue planets](https://en.wikipedia.org/wiki/Rogue_planet) in the amazing quasar [RX J1131-1231](https://en.wikipedia.org/wiki/RX_J1131-1231), which is 3.8 *billion* light-years distant.


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