It looks like you're using an Ad Blocker.
Please white-list or disable AboveTopSecret.com in your ad-blocking tool.
Some features of ATS will be disabled while you continue to use an ad-blocker.
SCIENCE CHECK: SuperEarths
One of the most interesting things NASA's Kepler mission has discovered is that there is a whole class of planets larger than the Earth but not as big as Neptune. These are called Superterrans or SuperEarths(10). These planets are often defined as planets which are anywhere from 1.5 to 10 times as massive as our Earth and often between 1.2-2.4 Earth radii wide.
Though our Solar System does not contain such a planet, we are finding they are remarkably common circling other stars in our Milky Way galaxy, especially small, dim, M-type (Red Dwarf) stars (more on this later). In fact so far they are the most common type of extrasolar planet (exoplanet) we've found:
Super-Earths Have Long Lasting Oceans
Another team of astronomers took a closer look at that dash of water. There’s no doubt that life, as we know it, needs liquid water. The Earth’s oceans cover about 70 percent of the surface and have for nearly the entire history of our world. So the next logical step suggests that for life to develop on other planets, those planets would also need oceans.
Water, however, isn’t just on Earth’s surface. Studies have shown that Earth’s mantle holds several oceans’ worth of water that was dragged underground. If water weren’t able to return to the surface via volcanism, it would disappear entirely.
Laura Schaefer, also from the CfA, used computer simulations to see if this so-called deep water cycle could take place on Earth-like planets and super-Earths.
She found that small Earth-like planets outgas their water quickly, while larger super-Earths form their oceans later on. The sweet spot seems to be for planets between two and four times the mass of Earth, which are even better at establishing and maintaining oceans than our Earth. Once started, these oceans could persist for at least 10 billion years.
“If you want to look for life, you should look at older super-Earths,” said Schaefer. It’s a statement that applies to both realms of research presented today.
SCIENCE CHECK: Encephalization
Encephalization(13) is defined as the amount of brain mass related to an animal's total body mass. Quantifying an animal's encephalization has been argued to be directly related to that animal's level of intelligence. It may also refer to the tendency for a species toward larger brains through evolutionary time. Anthropological studies indicate that bipedalism preceded encephalization in the human evolutionary lineage after divergence from the chimpanzee lineage. Compared to the chimpanzee brain, the human brain is larger and certain brain regions have been particularly altered during human evolution. Most brain growth of chimpanzees happens before birth while most human brain growth happens after birth.
Brain size usually increases with body size in animals (positive correlation), large animals usually have larger brains than smaller animals.The relationship is not linear, however. Generally, small mammals have relatively larger brains than big ones. Mice have a direct brain/body size ratio similar to humans (1/40), while elephants have a comparatively small brain/body size (1/560), despite being quite intelligent animals.
Several reasons for this trend are possible, one of which is that neural cells have a relative constant size. Some brain functions, like the brain pathway responsible for a basic task like drawing breath, are basically similar in a mouse and an elephant. Thus, the same amount of brain matter can govern breathing in a large or a small body. While not all control functions are independent of body size, some are, and hence large animals need comparatively less brain than small animals. This phenomenon has been called the cephalization factor:
(E and S are body and brain weights and C is the cephalization factor.)
To compensate for this factor, a formula has been devised by plotting the brain/body weight of various mammals against each other and a curve fitted so as to give best fit to the data.
There is an equation called the "Encephalization Quotient" (EQ) which quantifies encephalization, The cephalization factor and the subsequent encephalization quotient was developed by H.J. Jerison in the late 1960s.
I did a rough "back of napkin" calculation of the "Greys" based on an average of multiple descriptions and found the ES and EQ for this alleged alien species. What I found was that if the "Greys" brain is given a similar composition to that of Earthly vertebrate species then they could be quite superior to humans intellectually in just about every way.
With a substantially higher brain to body ratio (ES) and an encephalization quotient (EQ) of a range between 8.5-9.4 (dependent on descriptions) our grey aliens could appear to have a substantially larger capacity for intelligence than human beings whose EQ is in the range of 7.4-7.8.
Furthermore this higher intellectual capacity may have been due to a much higher population than humanity currently occupies as well as socialization factors on their home world (more on this later). Here's an excerpt from an interesting article from Discover magazine entitled "The Inevitable Social Brain"(14)
It would seem that the trajectory humanity has been on over its history has been in the direction of a higher ES. How high might our ES be in a 500 million to 1 billion years? Or better to put it another way, how much smarter might we be if we were at our present level, 500 million or 1 billion years ago? You'll see a little later why I post that question.
The article continues:
One interesting fact though is that the median cranial capacity of our species seems to have peaked around one hundred thousand years ago. The average human today has a smaller brain than the average human alive during the Last Glacial Maximum! (see this old post from Panda’s Thumb, it’s evident in the charts) This may be simply due to smaller body sizes in general after the Ice Age. Or, it may be due to the possibility that social changes with the rise of agriculture required less brain power.
Ultimately if Dunbar and his colleagues are correct, if social structure is the most powerful variate in explaining differences in brain size when controlling for phylogenetics and body size, then in some ways it is surprising to me. After all, it does not seem that ants have particularly large brains, despite being extremely social and highly successful. Clearly the hymenoptera and other social insects operate on different principles from mammals. Instead of developing “hive minds,” it seems as if in mammals greater social structure entails greater cognitive structure.
The HZ (habitable zone) for an M dwarf is so close in that nearly all habitable planets are at risk of being
tidally locked, even at the far freeze-out edge of the HZ. A tidally locked planet faces clear
challenges to habitability. The constant exposure to the nearby star is fixed to a single side
of the planet. This could create a “night” side which is far too cold, or a “day” side far
to hot for life. A small day–night boundary could be the only region capable of sustaining
As the freeze-out limit for the HZ can be mitigated by a dense heat-trapping atmosphere,
so too can the day–night concerns for tidally locked planets. A very dense atmosphere could
thermally distribute the solar radiation to the night side (e.g. Tarter et al., 2007). This could
bring enough heat to the eternally dark face of the planet to support life (Joshi et al., 1997).
SCIENCE CHECK: Habitable Planets in Resonant Orbits Around M-type (Red Dwarf) stars.
Here is an excerpt from an Space.com article on habitable planets in resonant orbits around M-type stars.
Another problem these long spans of darkness pose for life is the cold, which could freeze the atmospheres of these planets. Still, the investigators note that heat can flow from the dayside of such a planet to its nightside and prevent this freezing if that planet's atmosphere is sufficiently dense and can trap infrared light from the planet's star. This heat flow could lead to very strong winds, but this does not necessarily make the world uninhabitable, they added.
However, the researchers noted that the strength of a world's magnetic field depends in large part on how quickly it spins, which suggests that planets with orbits like Mercury's might have relatively weak magnetic fields. This could mean these worlds are not as good at deflecting harmful electrically charged particles streaming from their red dwarfs and other stars that can damage organisms and strip off the atmospheres of these planets.
The investigators suggested that dense atmospheres could help keep such planets habitable in the face of radiation from space. They added that life might be confined to certain spots on the surfaces of those planets that experience relatively safe levels of radiation. Are astronomers capable of detecting habitable planets with a 3:2 spin orbit resonance?
SCIENCE CHECK: Colors of Vegetation on Alien Worlds
What color would plants and other photosynthetic life be on a world circling a star different from our sun, such as the hypothetical SuperEarth circling a nearby small, dim M-dwarf star?
This is a subject currently under investigation by the Virtual Planetary Laboratory at my university (University of Washington) who have examine what forms photosynthesis would take around stars spectrally different from our own. You can read abut their preliminary findings in this excerpt of a story here: For plants on alien worlds, it isn't easy being green - New Scientist (18)
Here's an excerpt:
A star slightly dimmer than the Sun would deliver a solar-like spectrum to the surface of a terrestrial planet, so its foliage would look much like the Earth's.
But plants would be different on planets orbiting small M-type stars, or red dwarfs, which are between 10% and 50% the mass of the Sun. Red dwarfs, which comprise 85% of the galaxy's stars, emit strongly at invisible infrared wavelengths but produce little blue light.
"They'll definitely be absorbing in the infrared," unlike terrestrial plants, Kiang told New Scientist. Because they would benefit by absorbing visible light, she says they might look black, although she admits that any colour might be possible. Whatever their colour, the plants would likely look dark to humans because little visible light would reach the ground.
The oldest potentially habitable alien planet
Also this year, astronomers announced the discovery of Kapteyn b, a super Earth that orbits in the habitable zone of a red dwarf located just 13 light-years away from our solar system.
Kapteyn b is 11.5 billion years old, making it the most ancient known planet that may be capable of supporting life. To put that age into perspective: Earth is less than 4.6 billion years old, while the universe itself was born 13.8 billion years ago. So if life took root early in Kapteyn
b's history, it has had a very long time to evolve.
A newfound alien world might be able to support life — and it's just a stone's throw from Earth in the cosmic scheme of things.
An international team of astronomers has discovered an exoplanet in the star Gliese 832's "habitable zone" — the just-right range of distances that could allow liquid water to exist on a world's surface. The planet, known as Gliese 832c, lies just 16 light-years from Earth. (For perspective, the Milky Way galaxy is about 100,000 light-years wide; the closest star to Earth, Proxima Centauri, is 4.2 light-years away.)
It is a "super-Earth", meaning, as you might expect, bigger than Earth: estimated at 4.8 times the mass of Earth. Depending on its diameter, that could mean surface gravity notably greater than what we're used to: things weigh more, rain falls faster, landscapes are sculpted with a heavier hand.
It orbits within its star's habitable zone—the proper distance so that water can be in liquid form—but since that star is a red dwarf, and much fainter than the Sun, that proper distance is much closer, about a tenth the Earth-Sun distance. Being so close to its star, Gliese 667 Cc only takes about 28 days to complete an orbit and mark its own year. Imagine a birthday party every month!
"One sidelight of super Earths is that beyond 1.5 times our (Earth's) radius, it’s hard to get into orbit with chemical rockets. Using the best chemical rocket payload percentages we’ve managed, it’s impossible to get out of such a deep gravity well. With nuclear thermal, there’s little trouble, as they have specific impulses (Isp) ~ 4 times our best H2-O2 rockets. So smart life on such big worlds will have to get to nuclear to get to space. Not a big limitation–after all, we did both at about the same time.
originally posted by: Scdfa
Jade, I'm sure you're an adorable little student, and probably well-intentioned too, but I need to address a few errors in your post.
1. You seem to be confusing what you know about aliens with what I know about aliens. This mistake does not serve you well in this discussion. Do you really think everyone, everybody in the world is just like you, having to guess whether or not aliens are here? That no one else is in a position to know more than you do? You realize that is an absurd notion, correct?
I will continue this a little later, but I can tell you that a person such as yourself who has nearly three thousand postings in a year and a half has little time left over to be seriously investigating UFO sightings, or having a sighting of your own. It won't happen through your telescope, either. You don't know much about aliens, but you sure have a lot to say about what you don't know. You might want to address that imbalance.
originally posted by: Indigent
Awesome thread I will read it all when I'm not on an iPad and can do more but, you say at some point grays are smaller than humans Possibly due to they originating from higher gravity planets. How does this works?
Did earth had lower gravity before in the times of the dinosaurs that allowed creatures to grow bigger, or was it just a different atmospheric composition that made this possible?
I would think higher gravity demands more bone density to support the structure, not the other way around, so yeah they would be smaller perhaps, but not fragil.
Therefore the earliest printed reference I can find to this species is in the Raymond Fowler's 1978 book The Andreasson Affair about the alleged abduction of Betty Andreasson in January of 1967.