How many Earths in the Milky Way?

https://phys.org/news/2018-06-clues-earth-like-exoplanets.html

So if that holds up, an Earthlike planet 400 ly away, it seems there may be over a half million Earth like planets just in our galaxy alone.
They say there is another one about 1200 ly away so maybe that half million number isn't so far off.
What do you think?

Also, if there a half million Earthlike planets in our galaxy and there are literally trillions of galaxies, that would seem to suggest life in our universe will form anywhere there is sufficient radiant energy, water and minerals like phosphorus and solfur and the like.

So the universe may be awash with life and I will not be in the least surprised if they find even microbic life on Mars or Enceladus and the like right here in our own solar system.

That would clearly suggest this universe is compatible with life forms anywhere there is energy, liquid water and proper minerals.

Compare that to this estimate of life elsewhere in the universe:

https://www.extremetech.com/extreme/272357-researchers-maybe-were-alone-in-the-universe-after-all

They talk about technological advanced life but we have lived with nukes for 70 odd years now and only used 2X in war. We might survive the next 100 years without another nuke going off in anger.

If so, their argument may be a bit overblown. Especially if we humans get out into space and get even as close as Alpha Centauri, only 4 and change light years from Earth.

Even there, no matter what happens to Earth, devastating nuclear war, asteroid strike, world wide mutant virus, whatever, even if Earth literally explodes by getting hit by a rogue planet, humans still go on elsewhere.

That is what we need to do if we are to survive in this hostile universe.
Like a supernova going of a few hundred light years away, that alone could kill us all or run us back into cave man times.
There have to be a hundred ways human and maybe ALL life on Earth can get destroyed.

Getting the hell away from Earth and getting colonies going around planets orbiting other stars is a great way to beat the hostility odds.

Originally posted by @sonhouse
https://phys.org/news/2018-06-clues-earth-like-exoplanets.html

So if that holds up, an Earthlike planet 400 ly away, it seems there may be over a half million Earth like planets just in our galaxy alone.
They say there is another one about 1200 ly away so maybe that half million number isn't so far off.
What do you think?

Also, if there a half mill ...[text shortened]... ng colonies going around planets orbiting other stars is a great way to beat the hostility odds.

Terrestrial water came from comets right? Seems like lots and lots of comets. If these are Earth-like planets, as they suggest, wouldn't they all (or at least most of them) similarly have comet water?

Originally posted by @wildgrass
Terrestrial water came from comets right? Seems like lots and lots of comets. If these are Earth-like planets, as they suggest, wouldn't they all (or at least most of them) similarly have comet water?

However water arrived, sure, to be Earthlike, those planets BETTER have a lot of liquid water, not steam in the atmosphere or miles of ice all over the planet.

Originally posted by @wildgrass
Terrestrial water came from comets right?

That's one theory.
Water would have been present when the Earth formed.
Water would have been produced by chemical reactions.
Water would have been produced by biological action.
Plus some water from comets and asteroids.
Oh and don't forget god did it.

Originally posted by @wolfgang59
That's one theory.
Water would have been present when the Earth formed.
Water would have been produced by chemical reactions.
Water would have been produced by biological action.
Plus some water from comets and asteroids.
Oh and don't forget god did it.

Since life depends on the presence of water, it's difficult to see how primordial life could be the origin of the bulk of water on the planet.

The difficulty with theories involving water being present during formation is that it was collisional, so the objects from which the Earth formed will have spent time molten. They will not have been massive enough to hold onto the vapourized water. So the very early Earth will have been dry.

This isn't my field, but I think the consensus of astrophysicists is that the best explanation for the presence of water on Earth is cometary impacts during the Late Heavy Bombardment Period.

Originally posted by @deepthought
Since life depends on the presence of water, it's difficult to see how primordial life could be the origin of the bulk of water on the planet.

The difficulty with theories involving water being present during formation is that it was collisional, so the objects from which the Earth formed will have spent time molten. They will not have been massive ...[text shortened]... for the presence of water on Earth is cometary impacts during the Late Heavy Bombardment Period.

Besides, Earth even early on was too hot to have liquid water if I have it right. That whole protoplanet buildup thing takes massive impacts.

Originally posted by @deepthought
Since life depends on the presence of water, it's difficult to see how primordial life could be the origin of the bulk of water on the planet.

The difficulty with theories involving water being present during formation is that it was collisional, so the objects from which the Earth formed will have spent time molten. They will not have been massive ...[text shortened]... for the presence of water on Earth is cometary impacts during the Late Heavy Bombardment Period.

So, what of the probability that the millions of other earth-like planets (based on size, composition, proximity to sun, and presence of a moon I think) also "received" a comet in the last 5 billion years? I'd imagine it's pretty high, therefore lots of these have water.

Originally posted by @sonhouse
https://phys.org/news/2018-06-clues-earth-like-exoplanets.html

So if that holds up, an Earthlike planet 400 ly away, it seems there may be over a half million Earth like planets just in our galaxy alone.
They say there is another one about 1200 ly away so maybe that half million number isn't so far off.
What do you think?

Also, if there a half mill ...[text shortened]... ng colonies going around planets orbiting other stars is a great way to beat the hostility odds.

what do you think of Drake's equation?
if none of the factors equal zero then there must be millions of life forming planets

Originally posted by @lemondrop
what do you think of Drake's equation?
if none of the factors equal zero then there must be millions of life forming planets

Just thinking about it from a statistical POV, there are literally trillions of stars very similar to Sol and just about every one of them will have planets and there has to be a non-zero chance of Earthlike ones out there, even if it is say is proven there is only one like Earth per galaxy, there are literally hundreds of billions of galaxies.

Even if there was only one Earth in a million galaxies there would still be millions of Earths out there.

However, finding 2 planets within a thousand light years or so really bumps up the probability of there being many many more than one Earth in our galaxy alone. So I am confident there are more like thousands of Earth's in our galaxy alone.

Originally posted by @wildgrass
So, what of the probability that the millions of other earth-like planets (based on size, composition, proximity to sun, and presence of a moon I think) also "received" a comet in the last 5 billion years? I'd imagine it's pretty high, therefore lots of these have water.

I don't see any reason why not. When a carbon star undergoes Type Ia supernova one of the major products is oxygen and there is hardly a shortage of hydrogen. So water seems likely to be abundant. We've no reason to believe there is anything unusual about the initial composition of the Solar System. The presence of life here depends on the Earth's orbit being more or less circular, which I think depends on what are basically coincidences in the early evolution of the solar system. The question isn't so much "Is there life elsewhere?", but "How close?".

Originally posted by @deepthought
I don't see any reason why not. When a carbon star undergoes Type Ia supernova one of the major products is oxygen and there is hardly a shortage of hydrogen. So water seems likely to be abundant. We've no reason to believe there is anything unusual about the initial composition of the Solar System. The presence of life here depends on the Earth's or ...[text shortened]... n of the solar system. The question isn't so much "Is there life elsewhere?", but "How close?".

I agree. It seems like every time they release another "bunch of new Earth-like planets found" there is always a discussion of whether or not water is there. But that probability seems very high, given the other Earth-like criteria are met.

Originally posted by @sonhouse
https://phys.org/news/2018-06-clues-earth-like-exoplanets.html

So if that holds up, an Earthlike planet 400 ly away, it seems there may be over a half million Earth like planets just in our galaxy alone.
They say there is another one about 1200 ly away so maybe that half million number isn't so far off.
What do you think?

Also, if there a half mill ...[text shortened]... ng colonies going around planets orbiting other stars is a great way to beat the hostility odds.

Like a supernova going of[f] a few hundred light years away, that alone could kill us all or run us back into cave man times.

The closest supernova candidate is IK Pegasi, 150 lightyears away, which would be a problem as a type Ia candidate. The system has a variable primary of 1.6 solar masses in the main sequence. The secondary is a white dwarf around 1.15 solar masses and an orbit tighter than Mercury's. When the primary goes off the main sequence the secondary will start accreting mass and if it's a carbon star will undergo type Ia supernova. The system is moving away from us and will probably be far enough away by the time anything can happen for the Earth to be safe.

All other close supernova candidates are core collapse candidates and outside minimum safe distance. To be a real problem it would have to be within about 30 lightyears. Although I have seen different figures for this, I think for type Ia the largest minimum safe distance estimate I've seen is 1,500 lightyears and for core collapse supernovae about 150 lightyears. Supernovae simply aren't a threat for the next ten million years or so.

Originally posted by @deepthought

Like a supernova going of[f] a few hundred light years away, that alone could kill us all or run us back into cave man times.

The closest supernova candidate is IK Pegasi, 150 lightyears away, which would be a problem as a type Ia candidate. The system has a variable primary of 1.6 solar masses in the main sequence. The secondary is a whi ...[text shortened]... e about 150 lightyears. Supernovae simply aren't a threat for the next ten million years or so.

When the dwarf sucks off enough material from the larger star and goes nova, does the larger star disappear?