Exoplanet discoveries

[Strange]

I haven't been keeping up with progress in discovering exoplanets so was surprised (amazed) by this graph summarising the number and range of sizes found so far, mainly by Kepler.

From this article (which is mainly about why Kepler is not going to find much more): https://medium.com/starts-with-a-bang/why-nasas-kepler-mission-is-toast-9f2c484abd01

 

[beecee]

Nice stuff, thanks Strange....

An excerpt from your article worth noting.....

Quote

It’s very likely that there are solar systems out their like ours, and that where the alignment has been good, NASA’s Kepler would have detected perhaps the Venus-like and Earth-like worlds, with Mercury being too small and all the other worlds being too distant. The idea that a solar system would simply “end” where Earth’s orbit exists is absurd; there are certainly additional worlds beyond the ones Kepler was sensitive to. In order to see them, we’ll either need longer observing periods or the technology to do direct imaging, both of which are quite far off given the current funding situation. Based on what we’ve seen so far, it’s likely that Kepler-90 is

 

[T. McGrath]

The number of confirmed exoplanets appears to depend on who you reference:

• According to NASA's Exoplanet Archive (which is where I suspect the graph the OP presented originates) there were 3,572 confirmed exoplanets as of December 21, 2017.  With 592 multi-planetary systems.
• While the Extrasolar Planet Enclyclopedia, maintained by the Observatoire de Paris, shows 3,726 confirmed exoplanets in 2,792 planetary systems with 622 of those systems having multiple confirmed exoplanets.  They include the year of the discovery, but not by whom.
• Then there is the Open Exoplanet Catalogue which shows 3,504 confirmed exoplanets as of November 28, 2017, being maintained by MIT.  They also do not list who made the discovery.
• Finally we have the Exoplanet.Org website, which is supposedly being maintained by Berkley, Penn. State, the National Science Foundation, and NASA.  They show 2,950 confirmed exoplanets.  I could not find a date when this website was last updated, but it would appear to have been awhile.

In this particular case, I would probably lean toward NASA's figures, but I would want to know why there is a discrepancy of 154 confirmed exoplanets in 30 multi-planetary systems.  NASA's database includes more than just Kepler's discoveries.  What exoplanets has the Paris Observatory confirmed that we don't know about yet?
 

On 12/27/2017 at 2:34 PM, beecee said:

Nice stuff, thanks Strange....

An excerpt from your article worth noting.....

 

Wait until the James Webb Space Telescope gets launched in 2019.  We may be able to directly image an exoplanet.  That will certainly be a milestone in the annals of astronomy. 

[Airbrush]

Before the Jack Webb Telescope we should be watching TESS (Transiting Exoplanet Survey Satellite).

"TESS will monitor the brightness of more than 500,000 stars during a two year mission.

The TESS launch date is NLT June 2018 (the current working launch date is March 2018).

TESS stars will be 30-100 times brighter than those surveyed by the Kepler satellite; thus,TESS planets should be far easier to characterize with follow-up observations. These follow-up observations will provide refined measurements of the planet masses, sizes, densities, and atmospheric properties.

TESS will provide prime targets for further, more detailed characterization with the James Webb Space Telescope (JWST), as well as other large ground-based and space-based telescopes of the future. TESS's legacy will be a catalog of the nearest and brightest stars hosting transiting exoplanets, which will comprise the most favorable targets for detailed investigations in the coming decades.

The Kepler project has provided ground-breaking new insights into the population of exoplanets in our galaxies; among the discoveries made using data from Kepler is the fact that the most common members of the exoplanet family are Earths and Super-Earths. However, the majority of exoplanets found by Kepler orbit faraway, faint stars. This, combined with the relatively small size of Earths and Super-Earths, means that there is currently a dearth of such planets that can be characterized with follow-up observations."

https://tess.gsfc.nasa.gov/overview.html

Does anyone know what NLT means?  As in "TESS lunch date is NLT June 2018."

T

Edited December 30, 2017 by Airbrush

[Outrider]

10 hours ago, T. McGrath said:

In this particular case, I would probably lean toward NASA's figures, but I would want to know why there is a discrepancy of 154 confirmed exoplanets in 30 multi-planetary systems.  NASA's database includes more than just Kepler's discoveries.  What exoplanets has the Paris Observatory confirmed that we don't know about yet?
 

The Paris catalog adds an exoplanet as soon as an announcement is made. NASA only lists them after they have been published in a scientific journal. 

6 hours ago, Airbrush said:

The TESS launch date is NLT June 2018 (the current working launch date is March 2018).

"No later than" launch date as opposed to the working launch date of March.

I too am very excited to see these missions inching closer. A bit miffed as well the JWST original launch date was 2013 and just last spring it was slated for October of this year. TESS has suffered similar setbacks but appears to be on track for now. I know. These are big one shot missions and its important they get everything right.

If JWST lives up to its potential it should go a long ways in telling us how empty or how crowded our galaxy is. JWST is expected to give us spectroscopy of exoplanets. 

[T. McGrath]

44 minutes ago, Outrider said:

The Paris catalog adds an exoplanet as soon as an announcement is made. NASA only lists them after they have been published in a scientific journal.

Except that isn't true.  They are listing confirmed exoplanets, just as NASA (and to be fair, it is really JPL at CalTech who is maintaining the database on behalf of NASA) does.  Which means that the exoplanets have already been discovered, announced/published, and confirmed.  There are still several thousand exoplanets waiting to be confirmed, but these 3,726 exoplanets the Paris Observatory says have already been confirmed.  Which is 154 more than NASA says have been confirmed.
 

Edited December 30, 2017 by T. McGrath

[Outrider]

4 hours ago, T. McGrath said:

Except that isn't true. 

Except that it is. 

https://www.seeker.com/exoplanet-count-blasts-through-the-1000-barrier-1767964789.html

Quote

One reason, according to New Scientist, is that the Extrasolar Planets Encyclopaedia lists exoplanets as soon as their confirmation is announced at conferences. The NASA list, however, only lists them once they've been published in a scientific journal. The NASA list will therefore always lag its European counterpart.

 

[T. McGrath]

20 minutes ago, Outrider said:

Except that it is. 

https://www.seeker.com/exoplanet-count-blasts-through-the-1000-barrier-1767964789.html

 

Then NASA is the one who is in error.  The Paris Observatory listing is the actual number of exoplanets that have been confirmed.  NASA's listing are the number of exoplanets that have been confirmed AND published in a scientific journal.  Even if the exoplanet has been confirmed, if the discoverer never publishes their findings in a scientific journal NASA will not count it as a confirmed exoplanet.  Which is just stupid, but not unexpected from a government agency.  Government agencies excel at stupidity.

[StringJunky]

39 minutes ago, T. McGrath said:

Then NASA is the one who is in error.  The Paris Observatory listing is the actual number of exoplanets that have been confirmed.  NASA's listing are the number of exoplanets that have been confirmed AND published in a scientific journal.  Even if the exoplanet has been confirmed, if the discoverer never publishes their findings in a scientific journal NASA will not count it as a confirmed exoplanet.  Which is just stupid, but not unexpected from a government agency.  Government agencies excel at stupidity.

Maybe they require another layer of oversight.

[MarkE]

There are more confirmed exoplanets than I'd expected, thanks @Strange!

How will we ever develop the technology to get more information about these exoplanets, such as their composition, their heat emission, and so on? What kind of technological innovations would that involve?

Edited December 31, 2017 by MarkE

[T. McGrath]

10 hours ago, StringJunky said:

Maybe they require another layer of oversight.

The layer of oversight is the confirmation.  There are still more than 3,000 potential exoplanets waiting to be confirmed.  However, once they are confirmed then they should go into a database for confirmed exoplanets.  Now if NASA wants to create an additional criteria, like it must be confirmed and published, then they should create a database and specify it as such.  Instead they come up with a list of exoplanets and say they have been confirmed and nothing else.  Why are they being deceptive with their data?  Are they afraid that if it hasn't been published the exoplanet might not exist, even though it has already been confirmed?  Like I said, government stupidity.  It also makes me wonder if NASA has a political motivation for keeping certain exoplanets off their list.

Edited December 31, 2017 by T. McGrath

[Airbrush]

8 hours ago, MarkE said:

....How will we ever develop the technology to get more information about these exoplanets, such as their composition, their heat emission, and so on? What kind of technological innovations would that involve?

The James Webb telescope should do much of that.  There must be a next generation after the James Webb, larger scale like maybe 10 times as large as the Webb?  Eventually propulsion methods may allow us to send probes at such high speeds, like about 1/10 light speed.  These probes could flyby nearby stars with Earth-like planets in habitable zones, and send info back to Earth which would take decades for us to receive their transmissions.

The question is will there be anyone listening for the transmission from the probes?  Stephen Hawking thinks the human race has about 100 years before our expiration date, due to any number of disasters that can befall us.

Edited December 31, 2017 by Airbrush

[Outrider]

7 hours ago, T. McGrath said:

The layer of oversight is the confirmation.  There are still more than 3,000 potential exoplanets waiting to be confirmed.  However, once they are confirmed then they should go into a database for confirmed exoplanets.  Now if NASA wants to create an additional criteria, like it must be confirmed and published, then they should create a database and specify it as such.  Instead they come up with a list of exoplanets and say they have been confirmed and nothing else.  Why are they being deceptive with their data?  Are they afraid that if it hasn't been published the exoplanet might not exist, even though it has already been confirmed?  Like I said, government stupidity.  It also makes me wonder if NASA has a political motivation for keeping certain exoplanets off their list.

They are not being deceptive. They have different criteria. As it turns out my explanation was deficient. 

https://exoplanetarchive.ipac.caltech.edu/docs/exoplanet_criteria.html

Quote

 

The NASA Exoplanet Archive has adopted a policy of including and classifying all objects as planetary that meet the following criteria:

• The mass (or minimum mass) is equal to or less than 30 Jupiter masses.
• The planet is associated with a host star (i.e. not free floating)
• Sufficient follow-up observations and validation have been undertaken to deem the possibility of the object being a false positive unlikely.
• The above information along with further orbital and/or physical properties are available in peer-reviewed publications.

An example of an object that has not been included is the companion to SCR 1845. This object was detected via imaging and has an estimated mass larger than the 30 Jupiter mass criteria stated above.

 

Maybe thats stupid to you but I really don't see it that way.

[T. McGrath]

1 hour ago, Outrider said:

They are not being deceptive. They have different criteria. As it turns out my explanation was deficient. 

https://exoplanetarchive.ipac.caltech.edu/docs/exoplanet_criteria.html

Maybe thats stupid to you but I really don't see it that way.

The stupid part is when NASA says they have a list of confirmed exoplanets, when in reality they have a list of confirmed exoplanets that have also been published in a peer-reviewed journal.  But they just tell people that the exoplanets have been confirmed, and nothing else.  That is also the deceptive part.  Deliberately misrepresenting their subset of exoplanets by excluding the additional criteria that they impose.

SCR 1845 is not in the Paris database either.  Apparently NASA didn't get the message that we were interested in tracking exoplanets in our exoplanet database, and not brown dwarfs.  Any planetary body that is massive enough to begin deuterium fusion has ceased to be a planet and has become a brown dwarf.  This occurs somewhere between 13 and 14 Jupiter masses, not 30.

I have far less confidence in NASA's data now than I did when I started this thread.  Apparently NASA is off in never-never-land doing their own thing that doesn't match what anyone else on the planet is doing.  I wish I could say I was surprised.

 

[Outrider]

6 hours ago, Airbrush said:

There must be a next generation after the James Webb, larger scale like maybe 10 times as large as the Webb? 

Yeah, there are plans on the table but nothing AFAIK green lighted so far.

http://www.space.com/37952-hunting-second-earth-next-generation-telescopes.html

Quote

One of the strongest contenders in the fight to follow JWST is the Large UV/Optical/Infrared Survey (LUVOIR). LUVOIR is a proposed multi-wavelength observatory with the ability to characterize exoplanets, study galaxy formation and evolution, and examine the early universe. With a primary mirror of 30 to 45 feet (9 to 14 meters), LUVOIR can reach the size Grunsfeld is calling for.

 Hubble's primary mirror is 2.4 meters in diameter and JWST's is 6.5 meters. So not quite 10 times as big but still a big step up. I wonder will I still be around to see it.

6 hours ago, Airbrush said:

Eventually propulsion methods may allow us to send probes at such high speeds, like about 1/10 light speed.  These probes could flyby nearby stars with Earth-like planets in habitable zones, and send info back to Earth which would take decades for us to receive their transmissions.

Well the Breakthrough Starshot team is looking for one fifth the speed of light using nanoprobes called Sprites. Funded by billionaire Yuri Milner and guided by Facebook guru Marc Zuckerberg and Stephen Hawking. The team have 5 or 6 sprites in orbit right now testing the telemetry and electronics.

At 1/5 the speed of light they could reach Proxima Centauri in 20 years. We could start receiving data in 24 years. Not bad!

The Sprites will utilize solar sails driven by a high power laser. This is the biggest problem. How do you power this laser for 20+ years? One of the other big problems is the Sprites have no brakes. How do you image planets as you fly by at 100 million MPH?

https://breakthroughinitiatives.org/initiative/3

 

Quote

In the last decade and a half, rapid technological advances have opened up the possibility of light-powered space travel at a significant fraction of light speed. This involves a ground-based light beamerpushing ultra-light nanocrafts – miniature space probes attached to lightsails – to speeds of up to 100 million miles an hour. Such a system would allow a flyby mission to reach Alpha Centauri in just over 20 years from launch, beaming home images of its recently-discovered planet Proxima b, and any other planets that may lie in the system, as well as collecting other scientific data such as analysis of magnetic fields.

 

[Airbrush]

On ‎12‎/‎31‎/‎2017 at 8:23 PM, Outrider said:

The Sprites will utilize solar sails driven by a high power laser. This is the biggest problem. How do you power this laser for 20+ years? One of the other big problems is the Sprites have no brakes. How do you image planets as you fly by at 100 million MPH?

https://breakthroughinitiatives.org/initiative/3

Maybe you don't need to use the laser for 20+ years because I suspect the author proposes that from Earth, a laser could push the Sprite to a speed of 0.2c, and maybe that speed can be reached in just a few years or even months from Earth?

Within a decade we should have a long list of nearest Earth-like candidates, prospects for future flybys.

How small is a Sprite?  How capable of a payload?  That is the trade off, better technology for imaging and sensors, which are heavier, and therefore more mass to accelerate.  How much info can it send from a tiny transmitter?

Eventually we can put Kepler-like, or TESS-like, satellites around nearby stars and therefore reveal other plants not currently visible from Earth.

[Raider5678]

16 minutes ago, Airbrush said:

How small is a Sprite?  How capable of a payload?  That is the trade off, better technology for imaging and sensors, which are heavier, and therefore more mass to accelerate.  How much info can it send from a tiny transmitter?

Eventually we can put Kepler-like, or TESS-like, satellites around nearby stars and therefore reveal other plants not currently visible from Earth.

2

Better question, what's its battery life?

This is an important question in my opinion.

Solar Panels are heavy, additionally, we can't guarantee how much power they'll generate around another planet.

We only have so much plutonium. 

[mistermack]

I do share the hunger and enthusiasm of others for more knowledge of exoplanets. But I also have a feeling that as time goes on, it's going to feel like a child being shown pictures of ice-cream. The pictures will get more and more vivid, but you will never get to taste it.

I think the future of human/space interaction is space stations, not planets. I think space stations will get bigger and bigger, once we get the hang of mining the Moon and smaller bodies of the solar system for raw materials. Eventually, they will be so good, that the craving for a new Earth will be eclipsed. There is room around the Sun for millions, if not billions of gigantic space stations, that can be designed to harvest free solar energy, and produce exactly 1g of artificial gravity by rotating. It will be much much better than starting again on a "new" Earth. 

A trillion people could easily live in space stations circulating the Sun without any overcrowding. We will just need the source for raw materials, without the problem of the huge cost of getting them into space, from the Earth. 

The Moon is the obvious place to start, as well as any other solar body as small, or smaller.

[beecee]

On 1/1/2018 at 1:03 AM, T. McGrath said:

The layer of oversight is the confirmation.  There are still more than 3,000 potential exoplanets waiting to be confirmed.  However, once they are confirmed then they should go into a database for confirmed exoplanets.  Now if NASA wants to create an additional criteria, like it must be confirmed and published, then they should create a database and specify it as such.  Instead they come up with a list of exoplanets and say they have been confirmed and nothing else.  Why are they being deceptive with their data?  Are they afraid that if it hasn't been published the exoplanet might not exist, even though it has already been confirmed?  Like I said, government stupidity.  It also makes me wonder if NASA has a political motivation for keeping certain exoplanets off their list.

I haven't been around much of late, but I'm really interested in why and what this supposed political motivation is. I really can't see how any small under-estimation of confirmed exo-planets could lead to any thought/s of any political agenda.....other then of course, that the few left off their list, may also have confirmation/s of being far more then just another common garden variety exo-planet...like for instance, having a detectable oxygen atmosphere. 

As you rightly said earlier, the JWST will be able to  give even more confirmed and accurate results re exo-planets discoveries.

39 minutes ago, mistermack said:

I do share the hunger and enthusiasm of others for more knowledge of exoplanets. But I also have a feeling that as time goes on, it's going to feel like a child being shown pictures of ice-cream. The pictures will get more and more vivid, but you will never get to taste it.

I think the future of human/space interaction is space stations, not planets. I think space stations will get bigger and bigger, once we get the hang of mining the Moon and smaller bodies of the solar system for raw materials. Eventually, they will be so good, that the craving for a new Earth will be eclipsed. There is room around the Sun for millions, if not billions of gigantic space stations, that can be designed to harvest free solar energy, and produce exactly 1g of artificial gravity by rotating. It will be much much better than starting again on a "new" Earth. 

A trillion people could easily live in space stations circulating the Sun without any overcrowding. We will just need the source for raw materials, without the problem of the huge cost of getting them into space, from the Earth. 

The Moon is the obvious place to start, as well as any other solar body as small, or smaller.

I actually like your thinking re space stations, but I don't agree with "never getting to taste it"  remark. Given the time of course. I see it as inevitable that given the time, [that is in a time frame in excess of your space stations idea] all options and achievements will be undertaken. Generation type space ships to these suitable type exo-planets, should be viable to any civilisation that is able to undertake your space stations idea.

[HB of CJ]

Lots of exo planets found but they are ALL dead'uns.  Let them go.  We can not live there.  Look for Earth like planets.  Perhaps in the near future we can focus, (pun intended) on "G" type stars closer to earth?  Maybe include the early "K" type also but that should be it.  Perhaps also focus on "G" and hotter "K" type stars less than 100 p.c. from Earth?  Restricting the playing field of observation might give us some results that might be meaningful for even closer future looks?

Perhaps the next generation of space telescopes can do this?  That would be nice.  But ... will we ever find an Earth like exo planet?  No.  Our Earth is unique.  We MIGHT find a few exo planets were it might be POSSIBLE for mankind to live upon.  I find it interesting that so many different fields of scientific study and advance coincide with each other.   You gotta have that to have that to have that and so on.    Perhaps it will all come together some day.  We need to take a long view.

"Break us out of Orbit Mr. Sulu.  Get a move on, 1000 gees impulse to the outer marker, then full impulse to the System Warp Limit ... then Warp 5 when she can take it"

But even at Warp 5, 100 p.c. still will take about 40 days. 

[beecee]

23 minutes ago, HB of CJ said:

Lots of exo planets found but they are ALL dead'uns.  Let them go.  We can not live there.  Look for Earth like planets. 

Earth like planets, within habitable/Goldilocks zones, are always the hardest to detect for obvious reasons.

Quote

Perhaps in the near future we can focus, (pun intended) on "G" type stars closer to earth?  Maybe include the early "K" type also but that should be it.  Perhaps also focus on "G" and hotter "K" type stars less than 100 p.c. from Earth?  Restricting the playing field of observation might give us some results that might be meaningful for even closer future looks?

Any star will have a potential habitable zone.

 

Quote

Perhaps the next generation of space telescopes can do this?  That would be nice.  But ... will we ever find an Earth like exo planet?  No.  Our Earth is unique.  We MIGHT find a few exo planets were it might be POSSIBLE for mankind to live upon.  I find it interesting that so many different fields of scientific study and advance coincide with each other.   You gotta have that to have that to have that and so on.    Perhaps it will all come together some day.  We need to take a long view.

Our earth is unique??? What prompts you to believe this? Humanity once thought that the Earth was the center of the universe...now we find that we ain't even the center of our galaxy. Our earth unique? Not really likely considering the scale and numerical content of the universe that we know.

Quote

 

"Break us out of Orbit Mr. Sulu.  Get a move on, 1000 gees impulse to the outer marker, then full impulse to the System Warp Limit ... then Warp 5 when she can take it"

But even at Warp 5, 100 p.c. still will take about 40 days. 

 

Yep, fantastical magical like technology, and most certainly at this time far in advance of anything we could even hope to dream on. But if we are able to survive any potential cosmological catastrophe, or our own Earthly follies, then perhaps in 500 years, a 1000 years, or 10,000 years we may have a better idea of how to achieve such fantastic technology.

Edited January 6, 2018 by beecee

[Raider5678]

1 hour ago, beecee said:

Our earth is unique??? What prompts you to believe this? Humanity once thought that the Earth was the center of the universe...now we find that we ain't even the center of our galaxy. Our earth unique? Not really likely considering the scale and numerical content of the universe that we know.

 

I, like others, believe in the rare earth Hypothesis. 

So yes, unique, however probably not the only one.

[Moontanman]

1 hour ago, Raider5678 said:

I, like others, believe in the rare earth Hypothesis. 

So yes, unique, however probably not the only one.

 

4 hours ago, HB of CJ said:

Lots of exo planets found but they are ALL dead'uns.  Let them go.  We can not live there.  Look for Earth like planets.  Perhaps in the near future we can focus, (pun intended) on "G" type stars closer to earth?  Maybe include the early "K" type also but that should be it.  Perhaps also focus on "G" and hotter "K" type stars less than 100 p.c. from Earth?  Restricting the playing field of observation might give us some results that might be meaningful for even closer future looks?

Perhaps the next generation of space telescopes can do this?  That would be nice.  But ... will we ever find an Earth like exo planet?  No.  Our Earth is unique.  We MIGHT find a few exo planets were it might be POSSIBLE for mankind to live upon.  I find it interesting that so many different fields of scientific study and advance coincide with each other.   You gotta have that to have that to have that and so on.    Perhaps it will all come together some day.  We need to take a long view.

"Break us out of Orbit Mr. Sulu.  Get a move on, 1000 gees impulse to the outer marker, then full impulse to the System Warp Limit ... then Warp 5 when she can take it"

But even at Warp 5, 100 p.c. still will take about 40 days. 

 

3 hours ago, beecee said:

Earth like planets, within habitable/Goldilocks zones, are always the hardest to detect for obvious reasons.

Any star will have a potential habitable zone.

 

Our earth is unique??? What prompts you to believe this? Humanity once thought that the Earth was the center of the universe...now we find that we ain't even the center of our galaxy. Our earth unique? Not really likely considering the scale and numerical content of the universe that we know.

Yep, fantastical magical like technology, and most certainly at this time far in advance of anything we could even hope to dream on. But if we are able to survive any potential cosmological catastrophe, or our own Earthly follies, then perhaps in 500 years, a 1000 years, or 10,000 years we may have a better idea of how to achieve such fantastic technology.

Rare Earth? You mean the Hypothesis of the book "Rare Earth"? While many if not most of the assertions in that book have been discounted we really don't know enough really make a call on that one way or another.

The idea that a planet would be just like the Earth is more of a science fiction dream than reality. The Earth could be habitable somewhat closer to the sun and quite a bit further away from the sun but the planet would not necessarily be habitable by humans. Life on Earth is part of a positive feedback loop that determines much of what we think of as the reasons earth is perfect for life. If the Earth were as far away as Mars it could still be habitable by life but not the life as currently known on Earth. The feedback loop of life and planet would have to result in an atmosphere thicker and higher in CO2 than what we currently experience. "We" are currently not adapted to those conditions and little of Earth's complex life is either. Looking at from that perspective I would be surprised if we find any planet suitable for Earth life. 

If you mean suitable for complex life then then there may very well be bodies in our own solar system that qualify. A recent discovery on Mars might be evidence of complex life.

https://www.space.com/39294-mars-rover-curiosity-weird-tube-structures.html

Quote

Have trace fossils been found on Mars?

In browsing the first new batch of 2018 photos taken by the Curiosity rover's Mars Hand Lens Imager (MAHLI), researcher Barry DiGregorio speculated on whether the Red Planet robot found trace fossils on Mars. DiGregorio is a research fellow for the Buckingham Centre for Astrobiology in the United Kingdom and author of the nonfiction books "Mars: The Living Planet" and "The Microbes of Mars."

"They look remarkably similar to Ordovician trace fossils I have studied and photographed here on Earth," DiGregorio told Inside Outer Space. "If not trace fossils, what other geological explanations will NASA come up with?"

 

Ice moons of Jupiter like Europa are now thought to be possible abodes of complex life, mostly due to oxygen being created  transferred to the oceans via radiation and subduction of the Ice.

What it boils down to is that Earth sized doesn't mean earth life any more than being in the goldilocks zone means Earth like. So many variables for Earth life are quite arbitrary and even slight variations could mean that humans couldn't live there without breathing masks at the very least. 

I would be willing to assert that an actual planet we could land on and step out on the surface unprotected is quite unlikely but that doesn't mean the planet could be as covered in complex life as our own planet. In fact there are some slight hints that the Earth, far from being the perfect planet may very well be very much less ideal for life than other planets.  

[Raider5678]

44 minutes ago, Moontanman said:

If you mean suitable for complex life then then there may very well be bodies in our own solar system that qualify. A recent discovery on Mars might be evidence of complex life.

https://www.space.com/39294-mars-rover-curiosity-weird-tube-structures.html

 

1

I meant this, yes.

Additionally, while that link is interesting it's still a far cry from conclusive evidence, obviously.

My theory vs your theory on how many planets may contain complex live are both speculations. We've only ever observed one planet extensively, and two if you count Mars, which in my opinion we've barely been able to study as much as Earth for obvious reasons.

That, in my opinion, is too small of a sample to make a conclusive proof. Just two planets. Now really neither of our theories necessarily mean anything until we can prove it. My theory can't be proven until we've covered several thousand Earth-like planets, if not tens of thousands. Your's can be proven by just finding life once in less than 10,000 prospective planets(10,000 earth like rocky planets/moons is just where I personally draw the line for "rare", and this is up to debate). 

 

 

 

Also, what slight hints do you have that there are planets more suitable for humans than Earth? I didn't see that and that'd be interesting. 

 

 

[Moontanman]

42 minutes ago, Raider5678 said:

I meant this, yes.

Additionally, while that link is interesting it's still a far cry from conclusive evidence, obviously.

My theory vs your theory on how many planets may contain complex live are both speculations. We've only ever observed one planet extensively, and two if you count Mars, which in my opinion we've barely been able to study as much as Earth for obvious reasons.

That, in my opinion, is too small of a sample to make a conclusive proof. Just two planets. Now really neither of our theories necessarily mean anything until we can prove it. My theory can't be proven until we've covered several thousand Earth-like planets, if not tens of thousands. Your's can be proven by just finding life once in less than 10,000 prospective planets(10,000 earth like rocky planets/moons is just where I personally draw the line for "rare", and this is up to debate). 

 

 

 

Also, what slight hints do you have that there are planets more suitable for humans than Earth? I didn't see that and that'd be interesting. 

 

 

Actually I started a thread about Planets that are friendlier to life than Earth. It has to do with estimates of things like life of plate tectonics, magnetic fields, thicker atmospheres, longer lived stars, that sort of thing... 

You are correct that we have one data point, drawing a curve from that one data point is premature at the very least... 

If we find life inside our solar system beyond the Earth then we have reason to think life is common. If we find life on Saturn's moon Titan using methane instead of water then we will be on pretty solid ground that life is common. 

It is frustrating to try and speculate at this point but still fun...