1. Comment #418025 by BicycleRepairMan on September 22, 2009 at 4:31 pm

One thing I always wonder when hearing things like this is that those microbes in the sandstone have, like all life, evolved for billions of years. presumably, its ancestors lived in much more life-friendly habitats, where it probably is much more likely that life will form, and after eons spread to the wierdest places. In other words, had the entire planet been nothing but antartic sandstone, there probably wouldnt have been any microbes either. just a thought

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2. Comment #418027 by squinky on September 22, 2009 at 4:40 pm

I love learning about life's origins (who doesn't£) but there are two important considerations that render this whole Drake equation business mere speculation.
1) No one knows the conditions under which the first replicators formed (hot, cold, high salt, within wet rock, on ice, etc) and thus how "common" the most critical niche is. Said another way, Europa or Mars or other planets and moons may be able to sustain life but they may have never been equipped to allow spontaneous evolution of life in the first place which is why they would be sterile. Panspermia simply kicks the can down the road and appears highly implausible at interstellar distances.
2) The transition from replicators to cells is a massive one requiring access to lots of organic molecules (starting materials) which are thought to arrive on comets. Any theories about life's origins must include organic chemistry. There is a lot more to it than the amino acids found on the interstellar bodies.

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3. Comment #418029 by George Lennan on September 22, 2009 at 4:49 pm

No no no - they've got it all wrong! Never mind cells! Never mind water! "Evolving the Alien" ("What Does a Martian Look Like" in the US) by Stewart & Cohen makes a fantastic case for adaptive diversity through natural selection using the most exotic substrates the universe may have to offer, in environments we can only begin to imagine.

Anyone interested in this field should read that book before taking a single step into the 'how likely?' arena.

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4. Comment #418131 by SomeDanGuy on September 22, 2009 at 9:58 pm

I'm with George, above.
All these articles on the "probability of life" should really be called the "probability of life LIKE OURS".
Who says water is the only solvent? Who says there is such a narrow temperature range where self-replicators can form?
Life on other planets would form based on whatever conditions it evolved in; there's no reason to think our rocky, aqueous planet is the only way to do things.

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5. Comment #418143 by astroprof on September 22, 2009 at 10:31 pm

The reason that people are focused on 'life like us' is that H2O is extremely abundant, and environments where liquid ANYTHING is possible are relatively rare. So life elsewhere likely uses water. that's what we mean by 'life like us.' we know of no example of life that does not use water. On the other hand, researchers are starting to think about 'weird life' (that's really what its called) that uses things other than DNA and water, so don't fret, we will not miss Carl Sagan's famous silicon-based giraffe when it walks by.

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6. Comment #418145 by Steve Zara on September 22, 2009 at 10:36 pm

Comment #418143 by astroprof

The reason that people are focused on 'life like us' is that H2O is extremely abundant, and environments where liquid ANYTHING is possible are relatively rare.

Liquid hydrogen in the centres of gas giants? Just think of the fish that swim in those seas? (No, I'm not serious)

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7. Comment #418146 by Crazycharlie on September 22, 2009 at 10:38 pm

OK everyone, since we're talking about planets thousands of light years away from our solar system that may harbor life, let's all speculate. As of today, there are 369 known and cataloged extra-solar planets or "exoplanets". Since astronomers have only just started looking, I mean really looking in the last few years, it's obvious that's just the tip of the iceberg. Though astronomers are careful not to speculate too much, I will. Our unremarkable, average little star has eight planets and those planets have no less than 170 moons orbiting them--yes, that's right, 170 moons, don't forget the potential for life to evolve on moons too. Given there's billions of stars just in our galaxy, there must be BILLIONS OF PLANETS also. Just the sheer number of possible planets and moons alone means billions of places life, intelligent or not, could evolve. There's life out there (just speculation on my part) but, there it is.

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8. Comment #418149 by Steve Zara on September 22, 2009 at 10:49 pm

As of today, there are 369 known and cataloged extra-solar planets or "exoplanets".

I just can't get over the excitement of that. When I was young, there were endless articles about how incredibly difficult, if not impossible, it would to be detect extrasolar planets. I really never expected such a discovery in my lifetime.

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9. Comment #418153 by Crazycharlie on September 22, 2009 at 11:10 pm

Steve Z.-- If you're interested, the Planetary Society's web site has the catalog. Search- browse space topics & click Extra-solar planets. The catalog not only lists the planets but, the planet mass, planet radius, orbital periods etc. Absolutely amazing.

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10. Comment #418155 by Sally Luxmoore on September 22, 2009 at 11:19 pm

I heard something today on what is my favourite mind bogglingly exciting astronomy discovery.

http://www.bbc.co.uk/iplayer/episode/b00mr37s/Home_Planet_22_09_2009/

(Apologies to those not in the UK - BBC i-player is unavailable to you, I think)

Approx two thirds of the way through, this science programme dealt with a request from a listener to re-check a 'fact' that he had always loved - that there were more stars in the universe than there are grains of sand on all the beaches and deserts on Earth.

They brought on an astronomer who talked about the kind of maths sampling techniques that had to be used and how this was normal in astronomy - all very interesting - and then she described how a university (Hawaii, I think) had gone through all the calculations.
Not only was the listener's 'fact' not wrong, there are probably 1,000 times MORE stars in the universe than there are grains of sand on earth. I was so thrilled I was bouncing up and down in my seat (in my car, waiting at a red light - yes - the mad woman that everyone should beware of).
It was a great moment and is still making me happy.

Funny that insignificance frightens some people, and thrills others.

Edit - as and for the planets circling all those stars ....

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11. Comment #418159 by Steve Zara on September 22, 2009 at 11:28 pm

Comment #418153 by Crazycharlie

I am very interested. Thank you.

Comment #418155 by Sally Luxmoore

Funny that insignificance frightens some people, and thrills others.

Yes, I agree. A universe of a few stars, or even just one galaxy, would seem a small place to me.

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12. Comment #418160 by Crazycharlie on September 22, 2009 at 11:40 pm

Sally L.-- Exactly! I got goose bumps just reading your post. I'll speculate further- I'd bet that probably MOST of those stars you mentioned, since stars are formed from incredibly huge clouds of gas & dust that gravitationally collapse, always have enough material left over for planets.

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13. Comment #418162 by Sally Luxmoore on September 22, 2009 at 11:49 pm

We are so lucky to be living now.
I have always been fascinated at the medieval idea of the firmament (I even like the word) and the images of it as an upturned bowl over the flat earth

http://www.infidelguy.com/heaven_sky_files/image001.jpg" alt=/>

- but what we have is SO much better!

Edit - sorry - tried and failed to include an image...

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14. Comment #418171 by Scot Rafkin on September 23, 2009 at 12:24 am

Comment #418143 by astroprof

...and environments where liquid ANYTHING is possible are relatively rare

That's just not true, at least in our solar system. Venus is shrouded in highly concentrated liquid sulfuric acid clouds; some have speculated that its clouds could host airborne extraterrestrials. Mars may very well have liquid water in the subsurface and almost certainly did in the past. Saturn, Jupiter, Neptune, Uranus, all have clouds made of liquids. Europa probably has a liquid subsurface ocean. Titan has organic lakes with spectral signatures of liquid methane and ethane and the same liquid in clouds. Titan may also have an ammonia-water liquid in the subsurface much like Europa. Enceladus has water vapor spewing out of the south pole. Io spews liquid and gas sulfur. Indeed, most of the planets and a not insignificant number of their satellites have liquids. Assuming we have a rather ordinary stellar system, the same probably holds true for extra-solar systems.

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15. Comment #418227 by sillygirl on September 23, 2009 at 5:29 am

I am having memories of my sixth grade science book, many years ago. When we studied the planets there was this segment about the probability of life outside of earth. It had a bunch of math about how many stars and how likely any star was to have any surrounding planets and how likely any planet was to support life. It concluded that it was statistically so unlikely that it could be called impossible. At twelve I was so suspicious of the numbers that I couldn't even bother being disappointed. I asked the teacheer about it and she kind of blushed. She said the books were really old and it was all speculation anyway so we can never really know. I still get so excited every time I hear something that proves every single one of those "obvious facts" was ludicrous.

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16. Comment #418249 by Quetzalcoatl on September 23, 2009 at 8:11 am

Steve Zara-

I just can't get over the excitement of that. When I was young, there were endless articles about how incredibly difficult, if not impossible, it would to be detect extrasolar planets. I really never expected such a discovery in my lifetime.

Stick around- within twenty years we'll be studying earth-sized extrasolar planets. That will be really exciting.

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17. Comment #418252 by mmurray on September 23, 2009 at 8:41 am

Our unremarkable, average little star has eight planets and those planets have no less than 170 moons orbiting them--yes, that's right, 170 moons, don't forget the potential for life to evolve on moons too. Given there's billions of stars just in our galaxy, there must be BILLIONS OF PLANETS also. Just the sheer number of possible planets and moons alone means billions of places life, intelligent or not, could evolve. There's life out there (just speculation on my part) but, there it is.

@Crazycharlie: While I share your excitement and I think you are more likely right than wrong I still don't think we can rule out the possibility that our unremarkable, average little star has one really remarkable feature namely it is the only place in the universe where life has evolved. I just don't buy the probability of argument because we don't know the numbers. Sure there are 10^22 stars but if the chance of abiogenesis is 10^23:1 then we are lucky to be here and one planet with life in the whole universe is better than expected.

I would love to be wrong on this and it does seem planets are common but realistically we far we have found life on only one planet. Personally I think we need

1. A good model for abiogenesis. If we knew this we would have some feel for how rare it is going to be.

2. Definite proof that life evolved separately on Mars. That would probably settle the question of the rarity of abiogenesis as well.

3. Some data from Kepler. The preliminary data is really amazing.

4. One of these guys

http://en.wikipedia.org/wiki/New_Worlds_Mission

Feel free to say this is bullshit it is certainly not my area expertise and it is certainly exciting to be alive now and watching this unfold.

Michael

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18. Comment #418257 by Goldy on September 23, 2009 at 9:26 am

17. Comment #418252 by mmurray
So far we've been to the Moon,sent a probe or two to planets (and moons) in our solar system and only peeked from a rather large distance at other planets....some of which I believe we can only see by the effect they have on their stars.
I think we can be a little more confident of life ;-)

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19. Comment #418262 by mmurray on September 23, 2009 at 9:47 am

17. Comment #418252 by mmurray
So far we've been to the Moon,sent a probe or two to planets (and moons) in our solar system and only peeked from a rather large distance at other planets....some of which I believe we can only see by the effect they have on their stars.
I think we can be a little more confident of life ;-)

Hi Goldy. We haven't seen anything that is inconsistent with earth being the only place in the universe in which life has evolved. I agree some of the data is good as planets seem common and presumably earth like planets are also common. But maybe planets are common but life is extremely rare. I don't think we know enough about the numbers yet.

Michael

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20. Comment #418267 by Quetzalcoatl on September 23, 2009 at 10:01 am

The question is whether it's more reasonable to assume that Earth is the only planet with life than it is to assume that other life-bearing worlds are out there. Personally, given the immense number of stars out there , and the possibly even more immense number of planets that are likely to be in orbit of them, assuming that Earth is the only one with life is a bit of a stretch, in my opinion. How common life is: that's another question.

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21. Comment #418273 by Goldy on September 23, 2009 at 10:15 am

Did I not read that all the components needed for life as we know it are found in bodies such as comets?

Interesting subject, better than what constitutes a national dish :-) But it's time for me to hit the hay.

Night all

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22. Comment #418292 by SteveN on September 23, 2009 at 11:42 am

Comment #418162 by Sally Luxmoore:

We are so lucky to be living now.

I couldn't agree more, when one compares our state of understanding of the universe now with that of previous centuries, we are indeed fortunate to be living now. On the other hand, I am sometimes dismayed by the fact that there are going to so many mind-bogglingly wonderful things discovered in the future (e.g. extraterrestrial life?) that I will never know about. Curse these mortal bodies!

SteveN
P.S. I fall firmly on the 'life does not have to resemble our sort of life' side of the fence. Statements such as "For instance, while visible and infrared wavelengths are important for life and processes such as photosynthesis, ultraviolet and X-rays are harmful.", especially from someone working in the field, strikes me as very narrow-minded. There may be beings sitting in their pools of liquid methane saying "For instance, while visible and ultragamma wavelengths are important for life and processes such as radiosynthesis, infraviolet and radio-rays are harmful."

As Richard has often said, all it takes for life to get going is the accidental emergence of a molecule (or even non-molecular pattern?) that has the property of self-replication. It would be ridiculous at this stage of our knowledge to claim that such an entity can only appear in a liquid water environment.

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23. Comment #418294 by mmurray on September 23, 2009 at 11:52 am

The question is whether it's more reasonable to assume that Earth is the only planet with life than it is to assume that other life-bearing worlds are out there. Personally, given the immense number of stars out there , and the possibly even more immense number of planets that are likely to be in orbit of them, assuming that Earth is the only one with life is a bit of a stretch, in my opinion.

The immense number of stars isn't an argument by itself. If N is the number of stars and p the probability of there being life on a planet orbiting that star then the expected number of stars with life is Np. Sure N is like 10^22 but I don't think we know much about p. It seems clear that once life gets going it's pretty tenacious and can survive in a range of environments but I don't think we know how hard it is for it go to get going. I'm no expert in abiogenesis and would be happy to hear arguments for p > 10^{-22}. At the moment I just don't think we can decide what is reasonable because we don't have decent estimates of p. Better theories of abiogenesis would help, life on Mars that didn't come from earth would be great, earth like planets around nearby stars that seem to exhibit seasonal changes caused by life would be great ... I just hope we discover some of these in my lifetime.

Michael

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24. Comment #418299 by God fearing Atheist on September 23, 2009 at 12:12 pm

22. Comment #418292 by SteveN
There may be beings sitting in their pools of liquid methane saying "For instance, while visible and ultragamma wavelengths are important for life and processes such as radiosynthesis, infraviolet and radio-rays are harmful.

The issue is the energy of a photon at those wavelengths. They have the energy to break even the strongest molecular bonds, and are therefore "dangerous" to any chemical** life.

I suggest an important part of the reported study will be quantifying the impact of photon energy against possible forms of chemical life.

**I say "chemical" because I read a SciFi novel 30 years ago about life on a neutron star)

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25. Comment #418330 by SteveN on September 23, 2009 at 2:31 pm

Comment #418299 by God fearing Atheist

The issue is the energy of a photon at those wavelengths. They have the energy to break even the strongest molecular bonds, and are therefore "dangerous" to any chemical** life.

What you say is undoubtedly true for life as we know it. However, I feel that you may still be falling into the 'provincial' trap. It would, for example, be feasible for life to get started on a planet bathed in gamma radiation in shielded locations, possibly in 'black smokers' at the bottom of their methane oceans. Organisms could then gradually evolve to be resistant to (or to even utilise) the gamma radiation in order to expand into new habitats. I am reminded of the fact that oxygen was initially a deadly poison for most forms of early life on Earth (and still is, for some) and that the early Earth (lacking oxygen) had no ozone layer and was therefore presumably bathed in 'deadly' ultraviolet light.

I also liked your qualifier about chemical life. I suspect that the novel you are referring to is 'Dragon's Egg' by (I think) Robert Forward. It was this book, with its description of life forms formed from degenerate matter living their lives at speeds orders of magnitude greater than our plodding chemical bodies allow, that first opened my eyes (many decades ago) to the possibilities of exotic forms of life elsewhere in the universe. In a similar vein, a story I read more recently (probably by Stephen Baxter, but I'm not sure) described the rise and fall of 'space-faring' civilisations during the initial milliseconds of the Big Bang in a universe that was rapidly expanding and cooling but was no bigger than maybe a basketball. Perhaps such novels should be required reading for all budding exobiologists ;-)

Cheers,


SteveN

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26. Comment #418333 by Steve Zara on September 23, 2009 at 2:40 pm

Comment #418330 by SteveN

There are certain fungi that use melanin to trap energy from ionising radiation. They grow in the ruins of Chernobyl.

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27. Comment #418336 by squinky on September 23, 2009 at 2:52 pm

mmurray has a point about the probability of abiogenesis though the more we learn about how common Earthlike planets are and how common organic chemicals are in space, I suspect the probabilites may not be that bad. I disagree with point 2: if life did originate on Earth and get transferred to Earth, the probability of abiogenesis has not changed, it just moved starting points.

There are two hard problems of abiogenesis: the origin of sustainable replicators (chemistry) and the transition from replicators to prokaryotic cells (life). We don't yet understand the chemistry but I think one day we will. Life from chemical soup is even more difficult.

Goldy, you wrote "Did I not read that all the components needed for life as we know it are found in bodies such as comets£"
You read wrong. There are many amino acids found on interstellar bodies (eg. comets) and we have a good idea of how nucleic acids are built but I've seen no theories on how to make the sugar part of DNA or RNA. It's a huge open question.

*Edit* For those of you interested in this subject, below is the state of the art. It's heavy on chemistry but naturally, that's where it all began:
http://www.rsc.org/chemistryworld/News/2008/April/08040801.asp
http://www.nature.com/nature/journal/v459/n7244/full/459171a.html

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28. Comment #418367 by God fearing Atheist on September 23, 2009 at 5:02 pm

5. Comment #418330 by SteveN

I was going to argue with you about sufficient intensity of energetic gamma rays smashing any complex molecule to bits, but then I saw:-

26. Comment #418333 by Steve Zara
There are certain fungi that use melanin to trap energy from ionising radiation. They grow in the ruins of Chernobyl.

... so I'll just shurrup!

Yes, it probably was "Dragon's Egg".

27. Comment #418336 by squinky
but I've seen no theories on how to make the sugar part of DNA or RNA. It's a huge open question.

See the current issue of Scientific American (September 2009, pp.38-45), where John Sutherland's*" work on synthesis of RNA via 2-aminooxazole is discussed. This route bypasses the synthesis of sugar.

(** John Sutherland et al., University of Manchester, UK, if anyone wants to try to find the paper(s) direct.)

EDIT: Spelling of "2-aminooxazole"

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29. Comment #418382 by squinky on September 23, 2009 at 6:06 pm

God-fearing
I should say no theory until Sutherland's work which is amazing. I referenced his Nature paper in my original post as state of the art.

Sutherland is my new hero. You Brits should be proud--his discovery is hugely important.

*Edit* My earlier point is that let's assume Sutherland has it completely right. Saying life can and should arise from 2-aminooxazole and other chemicals to form RNA and ultimately life (as they clearly did on Earth) is just as risky a claim as saying prokaryotes must advance into terrestrial vertebrates. There are many many steps that must occur.

Knowing what we do about evolution, it is easy to work backward in time to estbalish an organism's path but going forward is unpredictable and hindered by extinction at every turn. One can easily imagine this chemistry occuring on other planets but if one thing is out of place (like copper or more carbon reserves or ammonia or amino acids, etc) it means extinction.

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30. Comment #418391 by God fearing Atheist on September 23, 2009 at 6:35 pm

squinky, I think you mean this one for Sutherland:-

Sutherland (Nature)

The one you referenced is Szostak (Nature), who also co-authored the SciAm article I referenced.

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31. Comment #418392 by squinky on September 23, 2009 at 6:41 pm

God fearing,

Yes, of course. I forgot I linked Szostak's review of Sutherland to make it easier for non-chemists at this site to follow.

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32. Comment #418418 by mmurray on September 23, 2009 at 9:37 pm

I disagree with point 2: if life did originate on Earth and get transferred to Earth, the probability of abiogenesis has not changed, it just moved starting points.

What I meant was if you could show that life began independently on both Earth and Mars that would make it seem that life beginning was not so hard.

Thanks for the links.

Michael

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33. Comment #418431 by Tagred on September 23, 2009 at 11:02 pm

8. Comment #418149 by Steve Zara on September 22, 2009 at 10:49 pm

I just can't get over the excitement of that. When I was young, there were endless articles about how incredibly difficult, if not impossible, it would to be detect extrasolar planets. I really never expected such a discovery in my lifetime.

Here here, it is truly one of the most fantastic and awe inspiring discoveries in science. Not because of the new information realised or anything ike that, but just bringing the wonder of the universe into our homes.

I'm very surprised much more hasn't been said about the discoveries on mainstream news or tv or anywhere else for that matter.

It is one of those things i always hoped to see in my lifetime but never thought it would happen. Even those fuzzy pics of an exo-solar system thrills my imagination.

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34. Comment #418432 by Tagred on September 23, 2009 at 11:07 pm

32. Comment #418418 by mmurray on September 23, 2009 at 9:37 pm

What I meant was if you could show that life began independently on both Earth and Mars that would make it seem that life beginning was not so hard.

Thanks for the links.

Michael

I think by the shear fact that planets aren't as uncommon as once thought makes the chances of any form of life anywhere that bit more likely. The drake equation probably does need seeing to.

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35. Comment #418434 by Frankus1122 on September 23, 2009 at 11:19 pm

Comment #418155 by Sally Luxmoore

Thanks for that little tidbit about the grains of sand on the Earth and the stars in the Universe. I will use that with my class tomorrow. I was trying to explain how big the Universe was a few days ago. This may help. But it is still really hard to fathom. It is just toooo big.

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36. Comment #418439 by Sally Luxmoore on September 23, 2009 at 11:36 pm

Frankus1122

That's great - it's definitely an example of how we can spread ideas with this website.

I don't know what age you teach, but I hope that what you say raises the hairs on the backs of their necks - and I hope that experience is something that stays with them. Good luck!

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37. Comment #418440 by mmurray on September 24, 2009 at 12:00 am

Thanks for that little tidbit about the grains of sand on the Earth and the stars in the Universe. I will use that with my class tomorrow. I was trying to explain how big the Universe was a few days ago. This may help. But it is still really hard to fathom. It is just toooo big.

There are some great pictures out there particularly from Hubble. I also like this:

http://www.sdss.org/includes/sideimages/sdss_pie2.html

It is a slice of the the sphere around us out to 2 billion light years. Every dot is a galaxy. Galaxies typically contain 100 billion (100,000,000,000) stars and conveniently for those of us with dodgy memories the visible universe has around 100 billion galaxies.

Michael

EDIT: This is the one I was thinking of. It's a galaxy cluster. When you first look you think they are stars and then you realise they are galaxies

http://hubblesite.org/newscenter/archive/releases/2009/17/image/a/format/xlarge_web/

If you want to encourage a bit of mind expanding get the students to look at this at this

http://www.co-intelligence.org/newsletter/comparisons.html

which has the relative size of earth, sun, etc, etc up to Antares. Most pictures in books get the size of the sun dramatically wrong. It is really, really big.

Other Comments by mmurray

38. Comment #418441 by Sally Luxmoore on September 24, 2009 at 12:10 am

Here are some more good sites, on the mind boggling theme:

http://www.rense.com/general72/size.htm - On the relative sizes of the planets in our solar system, compared with stars of increasing mass.

http://www.atlasoftheuniverse.com/universe.html - The 'zoom out' facility makes this a real hit.

http://aether.lbl.gov/Images/resizenowmap.jpg- The big bang expansion - in an amazing image.

http://micro.magnet.fsu.edu/primer/java/scienceopticsu/powersof10/ - orders of magnitude in 'action'

Enjoy!

Other Comments by Sally Luxmoore

39. Comment #418442 by Sally Luxmoore on September 24, 2009 at 12:20 am

mmurray

Galaxy cluster site now added to my 'favourites' - that's fantastic.

We each seem to have hit on the same images on different sites for the planet and stars comparison, up to Antares - but never mind!

Other Comments by Sally Luxmoore

40. Comment #418444 by mmurray on September 24, 2009 at 12:23 am

Thanks for those Sally.

There is an interesting thing about large stars pointed out to me by Steve Zara. There is a limit too how massive they can get because the radiant energy from the core tends to blow off the outer layers. This is called the Eddington limit. So the big ones are a lot less dense than the sun.

http://en.wikipedia.org/wiki/List_of_largest_known_stars

http://en.wikipedia.org/wiki/List_of_most_massive_stars

Michael

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41. Comment #418446 by Sally Luxmoore on September 24, 2009 at 12:29 am

For school-aged children, there's this:
http://www.noao.edu/education/peppercorn/pcmain.html

Richard did a version of this - shown in the DVD 'Breaking the science barrier' with a class of Oxfordshire schoolchildren who probably had no idea how lucky they were...

Other Comments by Sally Luxmoore

42. Comment #418447 by Sally Luxmoore on September 24, 2009 at 12:34 am

mmurray

That's brilliant (sorry about the pun). The info from Steve is another hair-raiser.

I have been wondering... Since Jupiter is so huge (by the standards of our solar system, at any rate) and 'collects' so many comets and asteroids etc due to its strong gravitational pull, does that mean that it is infinitesimally slowly becoming more solid? Do the solid objects sink to the core, or somehow get vaporised?

Other Comments by Sally Luxmoore

43. Comment #418449 by mmurray on September 24, 2009 at 12:35 am

We each seem to have hit on the same images on different sites for the planet and stars comparison, up to Antares - but never mind!

Yes that seems to be the internet standard pic. I wonder who did it first ?

Michael

Other Comments by mmurray

44. Comment #418455 by thomas guihen on September 24, 2009 at 12:57 am

Quetz - Regarding your comments on the possibility of extraterrestial life. We must not make the assumption that it will be remotely anything like here on Earth. Also we must not assume that it has to exist in the same time frame. Maybe life has already existed, maybe it has yet to. Arthur C. Clarke once observed that just because some of the outer planets have ammonia based atmospheres doesn't automatically imply life couldn't exist. Just because it is poisonous to humans doesn't necessarily mean it would be to others. Take a fish out of water and it will die. Yet without that very same atmosphere we would be dead. For all we know there could be entities which are so advanced as to defy physical form and immune to human detection no matter how long we live for. I used to believe we were the only sentient beings in the Universe. I still do, but am slighty less certain of it. I don't think however there will be any definitive answers to this for a very, very long time, if ever at all.

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45. Comment #418489 by flistr8 on September 24, 2009 at 2:54 am

I thought BicycleRepairMan made quite the insightful comment to start this thread.

My guess is life is common in the universe but self-conscious life as has developed on earth is a lot more rare. Just thinking about all the variables that had to play out in just the right fashion to allow humans to evolve is staggering.

Sally said "Funny that insignificance frightens some people, and thrills others." I would add that those it frightened created religion and those it thrilled discovered science.

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46. Comment #418495 by squinky on September 24, 2009 at 3:54 am

Sally,

Great links--you've collected some of my favorites.

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47. Comment #418507 by mmurray on September 24, 2009 at 5:33 am

Sally

I had seen a couple of those but not this one

http://www.atlasoftheuniverse.com/universe.html

I really like the way they give you a feel for where we are in the galaxy.

Thanks - Michael

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48. Comment #418519 by SteveN on September 24, 2009 at 6:57 am

Comment #418367 by God fearing Atheist

I was going to argue with you about sufficient intensity of energetic gamma rays smashing any complex molecule to bits ...

I fully agree that energetic gamma rays will smash up complex molecules, but the point I was trying to make is that it would be possible for life to get started in environments shielded from the radiation and then to gradually evolve means of protection from this in order to colonise new regions. I can imagine lead impregnated shells, for example, or the equivalent of DNA being associated with heavy metals as a shield, or simply super-efficient DNA repair mechanisms and a rapid turnover of proteins to remove those damaged by radiation. As the character played by Jeff Goldblum said in Jurassic Park, "Life finds a way", or even better " If there is one thing the history of evolution has taught us it's that life will not be contained. Life breaks free, expands to new territory, and crashes through barriers, painfully, maybe even dangerously." I realise that Jurassic Park is hardly an authorative source for scientific opinion, but these two quotes always struck me as being appropriate.

Cheers,

SteveN

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49. Comment #418524 by Quetzalcoatl on September 24, 2009 at 8:02 am

Thomas Guihen-

Indeed, and nothing I said in my comment disagrees with that. I've said the exact same things before. Apart from the only sentient beings in the universe bit.

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50. Comment #418533 by thomas guihen on September 24, 2009 at 8:35 am

Quetz - I wasn't implying any disagreeament. I was merely expressing my opinion on the subject. I would have been very surprised if you had major reservations about what I claimed anyway. I may read a lot of science-fiction but I knew that what I stated was perfectly feasible!

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