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30 Billion Earth Sized Planets?
Tha_Chaotic_1 writes "The BBC is running a story about a prediction that there are around 30 billion earthlike planets in the universe. This comes following the discovery of the 100th gas giant outside our solar system. Optimistic?"
I think this number is a bit high. I'm not sure they've taken into account that solar systems too close to the center of the galaxy due to the "galactic doughnut" effect. Anything to close to the center of the galaxy, in the doughnut hole, would not be habitable due to excess bombardment of gamma-rays.
Looks like they *think* that they've poked around in a 100 light year radius of earth. Given the extremely poor precision in which distances are measured this may be a bit optimistic.
Also from the article:
And if stellar statistics gathered in our local region of space are applied to our galaxy of 300 billion stars, then there may be 30 billion Jupiter-like worlds and perhaps as many Earth-like worlds as well.
Since our universe is not uniform this may be an abuse of statistics. They've only looked at one very small corner. This is a heck of a Monte-Carlo simulation, though!
Especially when you consider that no-one claims to have seen an Earth-sized planet orbiting another star. But then, no-one would claim that meant there were no such planets.
The figure of 30 billion Earths appears to be extrapolated from two things. One, that the galaxy contains an estimated 300 billion stars. Two, that of about 1,000 stars surveyed, astronomers have detected planets orbiting about 100 of them, or 10%.
If this holds for the galaxy as a whole, then 30 billion stars have planetary systems. To say that this implies an average of one Earth-sized planet per planetary system sounds like stretching the data. Sure, we have some theories on how planets form, and every new discovery presents much-needed data to test them, but until someone actually detects a planet the size of ours, we have no idea how common they really are.
Just another wannabe fantasy novelist...
Not to nitpick, but is should be noted that the article states that there are probably around 30 billion earth-like planets in our galaxy, not in the whole universe. A significant point, considering that there are around 10 billion large galaxies and 100 billion dwarf galaxies.
.1% of those have had intelligent life, that's 300,000,000,000,000 planets that have had intelligent life forms in the known universe. Of course, you have to factor in the time spans involved...
Wow, if there are 30 billion in our galaxy, that would make around 300,000,000,000,000,000,000 earth like planets in the known universe. If 1/10th of those are capable of supporting life (a pessimistic view when you consider that at least one out of four in our solar system is capable, not to mention mars and europa), then that's still 30,000,000,000,000,000,000 planets that can support life. If even 1% of those actually have life, and
On a side note, MS word spell checker recognizes europium, but not europa.
Don't Bogart the fish sticks
This article contains so much flawed logic, it boggles the mind. First, [t]he latest find is a gas giant and orbits a Sun-like star 293 light-years away. Though how this relates to a 100 light year sphere around earth confuses me. Second, with about 300 billion stars in our galaxy, there could be about 30 billion planetary systems in the Milky Way alone. While the 300 billion stars is correct, a vast majority of them are on the galatic disk or in the galatic core, where the gravity of the densely packed stars would prevent planet formation according to any currently held theory, except maybe Electric Universe. Lastly, most of the exo-solar planets that have been found so far are multiple Jupiter-sized and orbiting so close to the star that it doesn't resemble our solar system, the only one we really know about, making any inferences about the existence of other planets useless and pointless. While 100 exo-solar plants found is a cheer for modern astronomy and a good sign for the likelyhood of ETs, this article uses poor logic to make a bang from a whimper
Jeez. That's not too optimistic.
Considering that there are >100 billion galaxies, each with around 100 billion stars, that just means one earth-like planet for every 300 billion stars or three galaxies.
This seems like an underestimation to me. I would say more like 1,000,000,000 earth-like planets in every galaxy.
If half of all stars had planets (a resonable guess), at least a few of these would have stable orbits around orange dwarf stars and have a similar composition to earth.
Planets with similar size and orbit to earth would most likely develop life. (Planets smaller than earth would have their atmospheres drift off and oceans boil away, like Mars) Bacterial life is most likely quite common in the universe. It developed here on earth and most likely developed on Mars. Any planet with a resonable climate, liquid water, and volcanism (it provides necessary chemicals) will likely develop bacterial life. Volcanism is very common on all larger planets, the habitable zone is large, encompassing three planets (Venus, Earth, and Mars), so planets in habitable zones are undoubtedly very common, and oceans are common. Earth has oceans, Europa does, and Mars used to.
BTW, Venus really is in the habitable zone. It's very high pressure CO2 atmosphere just creates an extreme greenhouse effect, heating it up hot enough to melt lead. Mars used to have liquid water and more of an atmosphere, which made it warmer. Mars most likely had life.
Now, more advanced multicellular life is much more rare. First of all, it was three billion years on earth before multicellular life just happened to evolve. So on many planets, bacteria probably just never evolved much farther. Secondly, multicellular animal life is aerobic and needs oxygen. So unless the atmosphere is already oxygen-rich, photosythesizing bacteria would have to develop first.
Bacterial life is common, multicellular life is much less common. (Maybe occuring 10% of the time that bacterial life does.) Now intelligent life. There might only be 30 billion planets with technical civilizations in the universe. First of all, intelligence has to evolve. When you think about it, life has been around for 3.7 billion years. In that time, modern humans have only been around for about 150,000 years. Of that time, we have only been capable of sending and recieving radio signals in intersteller distances for 40 years. Most likely we will annihilate ourselves with antimatter weapons in the next 10,000 years.
For a planet with multicellular life, lets say 1 in 10 will develop intelligent life at some point. And probably many of these intelligent creatures won't develop radio. And those that do will probably only have a radio civilization lastling less than 10,000 years.
So lets see: In our galaxy, 1 in every 100 stars has an earthlike planet. Half of these have life. So 1 in every 200 systems has life. 10% of these have multicellular life, so 1 in 2,000. 10% of these have had intelligent life at some point, 1 in 2,000,000. Say 1 in five of these develop a radio civilization, so 1 in ten million. If radio civilzations last an average of 10,000 years, there is one radio civilization currently for every 5 billion stars. So there may be several in our galaxy. But communicating with them is probably pointless because they would most likely be thousands of lightyears away.
If you don't understand any of my sayings, come to me in private and I shall take you in my German mouth.
Firstly, to respond to an earlier post, the article did say "billions of Earths in our galaxy," not in the entire universe. It was the very first sentence, for heaven's sake.
The biggest question in my mind, with regards to this article, however, is the following statement:
there could be about 30 billion planetary systems in the Milky Way alone; and a great many of these systems are very likely to include Earth-like worlds, say researchers.
"Say researchers" is a pretty glib way to support such a big statement. Since current planet-finding techniques can only pinpoint gas giants, I suspect we can really have no idea what percentage of planetary systems contain earth-like planets. So it's this logical jump that is really the issue. And the article is a little thin on the explanation of this reasoning.
Finally, I would say that a figure that's calculated using sound statistical methods is never optimistic nor pessimistic, it's just that, in this case, the margin of error might very well be something on the order of plus or minus 30 billion.
Accountability on the heads of the powerful.
Power in the hands of the accountable.
I'm starting to disagree on the Venus bullshit. Greenhouse effects simply can't raise temperatures that high, not even with the most extreme conditions.
Did you know that Venus is actually hotter on the dark side, even though that can't possibly be if it is a greenhouse effect?
Or that it actually sustaining a net energy loss? That's right, it's bleeding off more heat than it is taking in from our friend, the sun. Explain that.
Or the fact that its atmosphere is revolving around the planet many times faster than the planet itself is doing.
Something funky is going on.
"The BBC is running a story about a prediction that there are around 30 billion earthlike planets in the universe."
Make that 30 billion earthlike planets in our _galaxy_. If there are only 30 billion in the universe it's probably pretty lonely around here.
Warning: this article may contain humor, sarcasm, parody, and perhaps even irony. Read at your own risk.
There's also a theory that says that you may well need to have at least one gas giant further out from your star to help deflect space schmutz from wiping your species out too early. Since we have 4 very large planets further out from our planet, we've got a lot of gravity wells helping to keep the inner system cleaner than it would normally be. Then again, this may be a rather common configuration - if a star forms and a gas giant forms, then the eddys between the forming star and forming gas giant may just be what turns into a smaller planet. Where's a Wayback Machine when you need one? *sigh*
I believe this is an overestimate.
I thought Lucas was crazy to assume that there could be a galaxy with so many habitable worlds.
The majority of these are most likely not habitable.
If you don't understand any of my sayings, come to me in private and I shall take you in my German mouth.
That calculation doesn't work. Our local environment is likely to be reasonably good for planet formation. Closer to the core and closer to the fringes of our galaxy, planets probably become less frequent.
When life absorbs gamma radiation, that life is generally destroyed. The harmful mutations that exposure to gamma sometimes produces are basically a mild case of destruction.
Before anyone comments on consequent high mutation rates and speculates on rapid adaptation, it's worth pointing out that increasing the mutation rate increases the organism's genetic burden, or in other words reduces the organism's survivability. High replacement rates entail a high `genetic death' rate for the species.
Life consists of highly specific, nested, complex structures. Think of a lunar rover built from Lego bricks [looks like a fabulous place of employment!]. Units like the wheels represent a unique and specific structure by themselves; the whole rover represents a structure of structures. Doing something like bashing a chord or segment out of a wheel not only impairs the wheel's function, it also impairs the entire rover's function. What you're proposing is akin to suggesting that `improving' the rover's structure can be done by subjecting it to higher than normal levels of machinegun fire.
Got time? Spend some of it coding or testing
Um, it seems likely that of the 100 systems surveyed, zero of them have habitable planets due to `excess bomardment of' jupiter-sized and larger planets.
Every single `sol-like' system so far described has a serious spoiler to it like a jupiter-sized planet orbiting about where Mercury is in our system. This doesn't fit any of our theories of planetary formation; if anything it implies that any solid bodies present would be orbiting within that star's corona... like living in a microwave full of flares.
Even if a solid planet did circle at earth-like distances, there's nothing like a brown dwarf crossing your orbital path to - sooner or later - ruin your whole day.
Got time? Spend some of it coding or testing
Our really big gas giants all (both) have planet-sized moons. This may imply likely habitable-sized moons orbiting a Jupiter or larger sized planet. In the case of the really big planets (say, six Jupiters on up) even a `planet' orbiting `too far' out may radiate enough heat to make a moon habitable.
Since we know next to nothing about other planetary systems, let's speculate freely. What about a planet of, say, ten or twenty Jupiters' mass, with a Saturn-sized `moon' around which a nominally habitable sub-moon orbits. Set the whole array within a multiple star-system (say, an ordinary star with a close-orbiting dense companion).
The sunsets would be fabulous (`and this clip shows the changing magneto-optical effects from Whitestar in Primary's rings and atmosphere, backlit by the rich hues of Redstar and offset by the brilliant blue orb of Secondary as we orbit past it, all framed by the spectacular Western Ringwall Mountains...'), and the almanacs would be collectors' items, all fourteen volumes of them. (-:
I like my idea for a planet better than theirs, and as you said, have just as much evidence for it... (-:
Got time? Spend some of it coding or testing