Earth may not be the "Metric" ...

[Stryder50]

As a general rule, Earth is used as the example of what to look for in a planet(world) where life could exist, especially intelligent and advanced (with tech and industry) Life. While most of the conditions connected to Earth could apply as guidelines, there are a couple of quirks~exceptions. Plate tectonics would be one, and having a relatively close and massive/weighty satellite~Luna/Moon another. I'll address these two in more detail in a later post here.

Meanwhile, here's a few other items to chew on ...

Earth Holds Some Strange Secrets, and We’re Reminding You About 20 of Them​

MSN

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[watchingfromafar]

At night, what does a satellite picture of earth look like?

Looking from the moon towards earth, can the lights emitted by civilization be detected?
any guesses
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[Stryder50]

At night, what does a satellite picture of earth look like?

Looking from the moon towards earth, can the lights emitted by civilization be detected?
any guesses
-

If not covered by clouds, short answer is yes.
However distance is such you may need a telescope to make them out.

 

[Fort Fun Indiana]

At night, what does a satellite picture of earth look like?

Looking from the moon towards earth, can the lights emitted by civilization be detected?
any guesses
-

Nope.

Because, if you can see the night side of Earth from the Moon, you can also see the sun. And it is too bright.

 

[watchingfromafar]

Because, if you can see the night side of Earth from the Moon, you can also see the sun. And it is too bright.

If you are on the moon and you are looking at our planet which is between you and the sun, earth will block out the sun as it passes. This is the same technique used to discover planets circling other suns.
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[Fort Fun Indiana]

If you are on the moon and you are looking at our planet which is between you and the sun, earth will block out the sun as it passes.

Only a tiny fraction of the time. Else we would have a total solar eclipse on Earth every single month.

And even when the earth is directly between, the visible Corona is still relatively very bright. This is what you would see from the Moon. The Corona would still be far brighter than the electric lights from earth. You would see only a black disk and the Corona around it:

 

[watchingfromafar]

The Corona would still be far brighter than the electric lights from earth. You would see only a black disk and the Corona around it:

I disagree, there are many properties to light. Light emitted from cities or cars have a different wavelength than light coming from the sun.

An optical spectrometer (spectrophotometer, spectrograph or spectroscope) is an instrument used to measure properties of light over a specific portion of the electromagnetic spectrum, typically used in spectroscopic analysis to identify materials. The variable measured is most often the light's intensity but could also, for instance, be the polarization state. The independent variable is usually the wavelength of the light or a unit directly proportional to the photon energy, such as reciprocal centimeters or electron volts, which has a reciprocal relationship to wavelength.
Optical spectrometer - Wikipedia
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[Fort Fun Indiana]

I disagree, there are many properties to light. Light emitted from cities or cars have a different wavelength than light coming from the sun.

An optical spectrometer (spectrophotometer, spectrograph or spectroscope) is an instrument used to measure properties of light over a specific portion of the electromagnetic spectrum, typically used in spectroscopic analysis to identify materials. The variable measured is most often the light's intensity but could also, for instance, be the polarization state. The independent variable is usually the wavelength of the light or a unit directly proportional to the photon energy, such as reciprocal centimeters or electron volts, which has a reciprocal relationship to wavelength.
Optical spectrometer - Wikipedia
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That doesn't matter to the brightness, though.

Try it yourself.

Look at some artificial light.

Now stare at the sun's Corona during an eclipse.

Don't do that, actually. It is so bright, it will permanently damage your eyes.

 

[watchingfromafar]

That doesn't matter to the brightness, though.

I am not looking for brightness, I am looking for the wavelength of the light being emitted.

Look at some artificial light.

I do not look at the "light", what I see is the reflection of the light as it reflects off a surface. You cannot see "light".

Now stare at the sun's Corona during an eclipse.
Don't do that, actually. It is so bright, it will permanently damage your eyes.

What if I was wearing sunglasses?
But again, it is the wavelength, not its brightness.
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[watchingfromafar]

Only a tiny fraction of the time. Else we would have a total solar eclipse on Earth every single month.

It has been a real tit for tat with you. Unfortunately, I have to go. Hopefully we can pick this up where we left it.

Then I will crush you into submission

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[Fort Fun Indiana]

am not looking for brightness, I am looking for the wavelength of the light being emitted.

Which does not really matter, here. But okay.

 

[Stryder50]

Yeah, a slide show ("click bait"), but underscores how unique our world and life existence really are;

What would happen if we didn't have the moon?​

MSN

www.msn.com

 

[Fort Fun Indiana]

Yeah, a slide show ("click bait"), but underscores how unique our world and life existence really are;

What would happen if we didn't have the moon?​

MSN

www.msn.com

Of course it is "unique". If conditions were different, it would be different.

 

[Stryder50]

Of course it is "unique". If conditions were different, it would be different.

I think you miss the point of this thread and that post. (and there is more than semantics involved here.)

Many exo-biologists look to Earth as an example of the sort of planet that would support life in other star-planet systems. However, while many conditions here on Earth could exist and support life on other worlds, those worlds being "similar" to Earth, our Moon/Luna adds a layer of exceptional conditions and factors.

Moon/Luna appears to be a major factor in the plate tectonics phenomena on Earth and also the "unique" role of ocean tidal effects which create a special niche for life forms. These are conditions we don't see on the other "rocky worlds" in our Solar System such as Venus and Mars, and which may be rare on other "rocky worlds" in other stellar systems.

Hence my jest at times that geoducks are a hot export gourmet food item to Rigel Five and Alpha Centauri B 3.

 

[Fort Fun Indiana]

I think you miss the point of this thread and that post. (and there is more than semantics involved here.)

Many exo-biologists look to Earth as an example of the sort of planet that would support life in other star-planet systems. However, while many conditions here on Earth could exist and support life on other worlds, those worlds being "similar" to Earth, our Moon/Luna adds a layer of exceptional conditions and factors.

Moon/Luna appears to be a major factor in the plate tectonics phenomena on Earth and also the "unique" role of ocean tidal effects which create a special niche for life forms. These are conditions we don't see on the other "rocky worlds" in our Solar System such as Venus and Mars, and which may be rare on other "rocky worlds" in other stellar systems.

Hence my jest at times that geoducks are a hot export gourmet food item to Rigel Five and Alpha Centauri B 3.

Okay, but I think you miss the point the scientists are making. They arent restricting their search when it comes to form. They are basically looking for function. The by-products of metabolism of carbon-based life. That ways that carbon based life can gain energy are quite finite.

 

[Stryder50]

Not sure I'd call it "Big", but significant and helpful. If there was a collision between the early Earth and what would become Luna/Moon, than it's likely that impact event is what broke the original crust of Earth and produced the two major types of crust that generated "plate tectonics".

Scientists Just Made A Big Discovery About The Earth's Crust​

...
According to SpaceRef, "Earth's outer shell consists of about 15 shifting blocks of crust," that have been moving over millions of years to form the continents and unique landforms that currently exist. The tectonic plate theory is widely accepted, but what has remained a topic of hot debate is when exactly the movement of these gigantic plates first began, transforming Earth from a sphere of rocks and lava into the habitable planet that it is today. New research suggests the movements first began roughly 3.8 billion years ago.
...

Scientists Just Made A Big Discovery About The Earth's Crust

 

[Stryder50]

Okay, but I think you miss the point the scientists are making. They arent restricting their search when it comes to form. They are basically looking for function. The by-products of metabolism of carbon-based life. That ways that carbon based life can gain energy are quite finite.

True, but ...
My point is that most exo-biology and exo-planet work can barely detect Earth like and sized worlds orbiting other stars in their "goldlocks zones". But detecting orbiting moons isn't in the skill set much, yet.

Also, looking at the two other could have beens in our Solar System, Venus has no orbiting moon and Mars has two very small, in range of 5-10 mile diameter. One of my points is that of size of an orbiting moon to the size of the planet it orbits. Earth/Luna is a very high ratio.