Starship Asterisk*

http://en.wikipedia.org/wiki/Noctilucent_cloud wrote:
<<Noctilucent clouds were first observed in 1885, two years after the 1883 eruption of Krakatoa. It remains unclear whether their appearance had anything to do with the volcano, or whether their discovery was due to more people observing the spectacular sunsets caused by the volcanic debris in the atmosphere. Studies have shown that noctilucent clouds are not caused solely by volcanic activity, although dust and water vapour could be injected into the upper atmosphere by eruptions and contribute to their formation. Scientists at the time assumed the clouds were another manifestation of volcanic ash but, after the ash had settled out of the atmosphere, the noctilucent clouds persisted.

Noctilucent clouds are composed of tiny crystals of water ice 40 to 100 nanometers in diameter and exist at a height of about 76 to 85 kilometers (47 to 53 mi),higher than any other clouds in Earth's atmosphere. Much like the more familiar lower altitude clouds, the noctilucent clouds are formed from water collecting on the surface of dust particles. The sources of both the dust and the water vapour in the upper atmosphere are not known with certainty. The dust is believed to come from micrometeors, although volcanoes and dust from the troposphere are also possibilities. The moisture could be lifted through gaps in the tropopause, as well as forming from the reaction of methane with hydroxyl radicals in the stratosphere.

The exhaust from Space Shuttles, which is almost entirely water vapour, has been found to generate individual clouds. About half of the vapor is released into the thermosphere, usually at altitudes of 103 to 114 kilometers (64 to 71 mi). This exhaust can be transported to the Arctic region in little over a day, although the exact mechanism of this very high-speed transport is unknown. As the water migrates northward, it falls from the thermosphere down into the colder mesosphere, which occupies the region of the atmosphere just below. Although this mechanism is the cause of individual noctilucent clouds, it is not thought to be a major contributor to the phenomenon as a whole.

As the mesosphere contains very little moisture, approximately one hundred millionth that of air from the Sahara desert, and is extremely thin, the ice crystals can only form at temperatures below about −120 °C (−184.0 °F). This means that noctilucent clouds form predominantly during summer when, counterintuitively, the mesosphere is coldest. noctilucent clouds form mostly near the polar regions, because the mesosphere is coldest there. Clouds in the southern hemisphere are about 1 km higher up than those in the northern hemisphere.

Ultraviolet radiation from the Sun breaks water molecules apart, reducing the amount of water available to form noctilucent clouds. The radiation is known to vary cyclically with the solar cycle and satellites have been tracking the decrease in brightness of the clouds with the increase of ultraviolet radiation for the last two solar cycles. It has been found that changes in the clouds follow changes in the intensity of ultraviolet rays by about a year, but the reason for this long lag is not yet known.

Noctilucent clouds are known to exhibit high radar reflectivity, in a frequency range of 50 MHz to 1.3 GHz. This behavior is not well understood but Caltech's Prof. Paul Bellan has proposed a possible explanation: that the ice grains become coated with a thin metal film composed of sodium and iron, which makes the cloud far more reflective to radar. Sodium and iron atoms are stripped from incoming micrometeors and settle into a layer just above the altitude of noctilucent clouds, and measurements have shown that these elements are severely depleted when the clouds are present. Other experiments have demonstrated that, at the extremely cold temperatures of a noctilucent cloud, sodium vapor can rapidly be deposited onto an ice surface.>>

orin stepanek wrote:Did you ever wonder if the water vapor in these clouds eventually find its way back to Earth or does it eventually drift off into space! Are we gradually loosing our oceans to the cosmos? Presumably taking billions of years.

emc wrote:So the Earth is somewhat leaking into outer space… interesting.

http://en.wikipedia.org/wiki/Cosmic_dust wrote:
At the Earth, generally, an average of 40 tons per day of extraterrestrial material falls to the Earth. The Earth-falling dust particles are collected in the Earth's atmosphere using plate collectors under the wings of stratospheric-flying NASA airplanes and collected from surface deposits on the large Earth ice-masses (Antarctica and Greenland / the Arctic) and in deep-sea sediments.

http://en.wikipedia.org/wiki/Earth wrote:
<<Due to thermal energy, some of the molecules at the outer edge of the Earth's atmosphere have their velocity increased to the point where they can escape from the planet's gravity. This results in a slow but steady leakage of the atmosphere into space. Because unfixed hydrogen has a low molecular weight, it can achieve escape velocity more readily and it leaks into outer space at a greater rate than other gasses. The leakage of hydrogen into space is a contributing factor in pushing the Earth from an initially reducing state to its current oxidizing one. Photosynthesis provided a source of free oxygen, but the loss of reducing agents such as hydrogen is believed to have been a necessary precondition for the widespread accumulation of oxygen in the atmosphere. Hence the ability of hydrogen to escape from the Earth's atmosphere may have influenced the nature of life that developed on the planet. Most of the hydrogen loss comes from the destruction of methane in the upper atmosphere.>>

The Retention or Loss of Planetary Atmospheres wrote:How fast the atmosphere of the planet would be lost depends upon how the average speed of exospheric particles compares to the escape velocity of the planet. Although the high-velocity tail of particle speeds can extend to many times the average speed, the number of particles in the tail becomes smaller and smaller as you go to higher and higher speeds. If the escape velocity is many times larger than the average speed, so few particles escape at any given time that it takes immense time periods for any gas to escape; whereas, if the escape velocity were a little lower, so that there were more particles which had enough speed to escape, the time required to lose a given part of the atmosphere would be considerably less.

...

The question of whether an atmosphere can escape is usually expressed in terms of the Jeans theory (by James Jeans, 1916?). There seems to be some disagreement in the exact results, which are complicated ... The rate of loss of an atmosphere depends upon the ratio of escape velocity to average particle speed in the upper atmosphere. IF THE RATIO IS 5, THE ATMOSPHERE ESCAPES IN TIMES OF THE ORDER OF 100 MILLION YEARS. (General agreement about this result).

As the ratio goes down (4, 3, etc) the atmosphere escapes much more rapidly (100 to 1000 times more rapidly for each unit change, depending upon the reference consulted), and as it goes up (6, 7, etc) the atmosphere escapes much more slowly (100 to 1000 times more slowly, as per previous statement).

Hence, times to escape are:

About 100 million years, if ratio is 5.
Well under 1 million years, if ratio is 4 (more particles in high-velocity tail).
Well under 10 thousand years, if ratio is 3 (still more high-velocity particles).
Well over 10 billion years, if ratio is 6 (fewer high-velocity particles).
Well over 1 trillion years, if ratio is 7 (still fewer high-velocity particles).

SO, NORMAL GASES, with ratio of 16 to 20, are held onto forever (as we might expect, since we're breathing them, after 4.5 billion years of Earth history).
HOWEVER, lighter gases move faster (at atomic level) than heavy ones, because Temperature is proportional to particle mass, as well as square of speed. Oxygen atoms move 40% faster than oxygen molecules, helium atoms move 4 times faster, and hydrogen atoms move almost 6 times faster, than the "average" of normal particles. Therefore, the ratio of 16 to 20 times for normal air molecules is cut to 11 to 14 for oxygen atoms (still high enough to hold on, forever and ever), 4 to 5 for helium (lost in times of the order of millions to tens of millions of years), and 3 (plus or minus) for hydrogen (lost in times of the order of thousands or tens of thousands of years).

IN OTHER WORDS, the Earth can hold onto either molecular or atomic nitrogen and oxygen, but slowly loses helium, and more rapidly loses hydrogen, so that over long periods of time, all the hydrogen and helium in the atmosphere should slowly leak into space.

Actually, losses can be even greater, as this ignores the possibility (substantial possibility, according to some calculations) that ionized particles can be accelerated along the magnetic field lines, and into space, at an even greater rate. For helium, in particular, the loss rate must be of the order of a million years or less, given the low helium abundance in our atmosphere, and the rate of helium production by radioactive decay inside the Earth, which is considerably faster than predicted by these numbers, and loss of ionized helium particles along magnetic field lines in the arctic and antarctic is thought to be the primary loss mechanism.

neufer wrote:

orin stepanek wrote:Did you ever wonder if the water vapor in these clouds eventually find its way back to Earth or does it eventually drift off into space! Are we gradually loosing our oceans to the cosmos? Presumably taking billions of years.

After it evaporates and then dissociates the light hydrogen atoms will eventually drift off into space which explains why a small planet like Mars (with an escape velocity of just 5 km/s) is so dessicated.

emc wrote:So the Earth is somewhat leaking into outer space… interesting.

Chris Peterson wrote:

emc wrote:So the Earth is somewhat leaking into outer space… interesting.

Yes, but we're also picking up water all the time (or perhaps, from time to time) from cometary material.

neufer wrote:I thought about that scenario as well but it is not at all clear to me that a cometary collision into the ocean would add more water than it subtracts. (I just don't know.)

Chris Peterson wrote:

neufer wrote:I thought about that scenario as well but it is not at all clear to me that a cometary collision into the ocean would add more water than it subtracts. (I just don't know.)

I'm not talking about big collisions, but about small ones, where nothing solid ever reaches the ground. Just ordinary meteors with some water content.

http://antwrp.gsfc.nasa.gov/apod/ap090511.html wrote:
Visible meteors are typically sand-sized grains of ice and rock that once fragmented from comets.

emc wrote:So the Earth leaks, the Sun leaks (isn’t our sun leaving a trail as it travels around the Milky Way, traveling with the Milky Way?), the Milky Way leaks,,, everything leaks. ...

bystander wrote:I suspect even the universe leaks, but I can't prove it.

emc wrote:

bystander wrote:I suspect even the universe leaks, but I can't prove it.

Now THAT is interesting… what would the universe leak into?

bystander wrote:

emc wrote:

bystander wrote:I suspect even the universe leaks, but I can't prove it.

Now THAT is interesting… what would the universe leak into?

Why, the multiverse, or an alternative universe!

wiki wrote:http://en.wikipedia.org/wiki/Multiverse“A multiverse of a somewhat different kind has been envisaged within the multi-dimensional extension of string theory known as M-theory.[11] In M-theory our universe and others are created by collisions between p-branes in a space with 11 and 26 dimensions (the number of dimensions depends on the chirality of the observer)[12][13]; each universe takes the form of a D-brane[14][15]. Objects in each universe are essentially confined to the D-brane of their universe, but may be able to interact with other universes via gravity, a force which is not restricted to D-branes[16]. This is unlike the universes in the "quantum multiverse", but both concepts can operate at the same time.”

emc wrote:

wiki wrote:... our universe and others are created by collisions between p-branes in a space ...

Perhaps the universe leaks into “p-branes”, kind of like my gray hair on the barber floor.

bystander wrote:

emc wrote:

wiki wrote:... our universe and others are created by collisions between p-branes in a space ...

Perhaps the universe leaks into “p-branes”, kind of like my gray hair on the barber floor.

No, I think the leakage is caused by collisions between pea-brains, in space. So, to stop the leakage, we just need to keep the pea-brains out of space. But, first, we've got to know how they're getting there.

bystander wrote:to stop the leakage, we just need to keep the pea-brains out of space. But, first, we've got to know how they're getting there.

apodman wrote:

bystander wrote:to stop the leakage, we just need to keep the pea-brains out of space. But, first, we've got to know how they're getting there.

They are beamed there directly from internet forums. To prevent this, the moderator should set the transporter for maximum dispersion. Sorry to sound cruel, but a scientific fact is a scientific fact.

emc wrote:

apodman wrote:

bystander wrote:to stop the leakage, we just need to keep the pea-brains out of space. But, first, we've got to know how they're getting there.

They are beamed there directly from internet forums. To prevent this, the moderator should set the transporter for maximum dispersion. Sorry to sound cruel, but a scientific fact is a scientific fact.

Wait a minute... That will be adding to the leakage and I think our moderator wants to stop leakage. (I think he is having grandiose ideas) Besides, as much as I would like to, I’ve never been beamed anywhere… so what’s up with that?

bystander wrote:

emc wrote:

wiki wrote:... our universe and others are created by collisions between p-branes in a space ...

Perhaps the universe leaks into “p-branes”, kind of like my gray hair on the barber floor.

No, I think the leakage is caused by collisions between pea-brains, in space. So, to stop the leakage, we just need to keep the pea-brains out of space. But, first, we've got to know how they're getting there.

http://www.gardening-for-wildlife.com/hummingbird-brain.html wrote:
They're Not Albert Einstein,
but the Hummingbird Brain is Unique.

<<A hummingbird's brain is smaller than a pea, what kind of a brain could this diminutive bird possibly have? This bird's brain is studied for episodic memory—memory that encodes particulars of what, where, and when—used to be considered exclusively human.

Biologists working with corvids—birds in the family that includes jays, crows, nutcrackers, and magpies—began to wonder about that. Some corvid species are food-cachers: they hide stashes of acorns or pine nuts in summer or fall to sustain themselves during winter and early spring, when other food is scarce. When they returned to their cache, had they made a random search or had they remembered where the items had been hidden?

Better-than-chance retrieval performance suggested that birds like western scrub-jays, pinyon jays, and Clark’s nutcrackers had a well-developed spatial memory.

The brains of these species have a larger-than-average hippocampus, an area thought to be responsible for processing memory. Corvids have relatively big brains for birds (and scrub-jays have large hippocampi even for corvids). If you’d expect any kind of bird to be capable of memnonic prodigies, it would probably be a scrub-jay.

However, episodic-like memory may not be unique to jays.

Very similar processes have now been documented in, of all things, hummingbirds.

The hummingbird's brain?

In a study that appeared in Current Biology, Susan Healy and Jonathan Henderson of the University of Edinburgh describe their fieldwork with rufous hummingbirds in the Canadian Rockies. (The rufous hummer is an early spring migrant through the Bay Area; its close relative, the Allen’s hummer, stays to nest). Healy and Henderson placed eight artificial flowers in an alpine meadow patronized by hummingbirds. Some of the “flowers” were refilled with hummer food at 10-minute intervals, others at 20-minute intervals.

Can a hummingbird's brain actually think?

Tallying visits by three male rufous hummers, the researchers found the birds could distinguish between the 10-minute and 20-minute “flowers” and remember their locations and when they had last drained them. Over several days, they reliably returned to the “flowers” just after they had been refilled; once again, a matter of what, when, and where.

It makes sense for hyperactive birds like hummers to maximize their foraging efficiency. Return to a flower too soon, and the nectar won’t have been replenished; too late, and a rival may have beaten you there. With a long migration route and a short breeding season, rufous hummers can’t afford to waste time and energy in the search for food.

Healy and Henderson point out that their male hummers were able to track the timing of nectar supplies while defending their territories and courting females. So you have not only episodic memory but serious multitasking.

Several studies show hummers know when a flower is ready.
All this when a hummingbird's brain is smaller than a pea.

No one knows how large a hummer's hippocampus is, absolutely or relatively. But the bird doesn’t have a whole lot of neurons to work with. It may not the size of the hummingbird brains that enables these kinds of mental processes, but the complexity of the wiring.

Smaller does not necessarily equate to dumber: the minuscule brain of the hummer appears to have the bandwidth to do what it needs to do.
............................................
Hummers have song?

Back to the brain we go.

Vocal learning has been repeatedly demonstrated in two bird orders, Passeriformes (specifically the oscine songbirds) and Psittaciformes (parrots), and is believed to occur in a third, the Trochiliformes (hummingbirds). By comparing brain structures in these three bird orders, which are widely separated from one another on the avian family tree. Rockefeller University biologist Claudio Mello and his colleague Erich Jarvis, of Duke University, have shown that the same areas that control song learning and production in songbirds and parrots are also present in hummers. A finding that strengthens the case for vocal learning in our hummers.

Most people are surprised to learn that these tiny birds have songs. The songs aren't particularly loud and you sort of have to know what to listen for. They are higher pitched than those of songbirds, but the songs are amazingly rich, and in some species they can be quite complex.

In the 1950s biologists began to investigate the processes by which birds imitate the sounds they hear and incorporate them into songs. Appropriately enough, that work began with songbirds, a suborder that includes almost half the nearly 8,500 living species of birds.

W. H. Thorpe, of the University of Cambridge, was the first to demonstrate learning in birds by performing what is now considered to be a classic experiment, involving the isolation of male chaffinches (European songbirds) in soundproof chambers equipped with speakers. Young chaffinches that heard recorded chaffinch songs were able to imitate these songs. Birds deprived of the recordings developed abnormally simple songs.

Next was the hummer's brain.

Isolation experiments are exceedingly difficult to do with hummingbirds, however. Because of their extraordinarily fast metabolism. Baby hummers must be fed every ten minutes around the clock. In 1990, this type of experiment was conducted on one species of trochilid, the Anna's hummingbird (Calypte anna).

The late Luis Felipe Baptista, of the California Academy of Sciences, and Karl Schumann, at the Zoologisches Forschungs-institut in Bonn, Germany, found that a male Anna's raised in isolation produced a much simpler song than did wild males.

The song was also very different from that of three males hand-raised together. The outcomes suggested that the males were imitating each other's vocalizations--evidence that the brain can learn songs. In the 1970's and 1980's, Fernando Nottebohm, of Rockefeller University, and several colleagues set about mapping the parts of the hummingbird's brain involved in the singing process.

The researchers identified six anatomically distinct areas--clusters of cells called nuclei--in the forebrain of songbirds.

The hummer's brain nuclei are organized into two distinct paths: The posterior pathway, which controls song production, and the anterior pathway, which controls song learning. Together these pathways form a song control system that must be intact if birds are to sing the songs they've learned.

Forebrain nuclei similar in structure and location have also been found in the budgerigar (an Australian parakeet). No such nuclei have been found in the birds most closely related to songbirds, the suboscines (woodcreepers, ovenbirds, antbirds), or in other nonlearners of songs such as pigeons and doves (order Columbiformes) and chickens, turkeys, and quails (order Galliformes).

Before Mello and Jarvis, no one had bothered to look for these nuclei in a brain.

Working with songbirds in the 1990s, bird researchers added a novel tool to their toolbox. A gene called ZENK, that would make the search for nuclei in a hummingbird's brain much easier. Nottebohm, Mello, and Jarvis noticed that the number of activated ZENK genes in certain areas of the brain was very low when the songbirds were quiet.

When the birds sang or heard songs, however, ZENK activity increased. By measuring the levels of activated ZENK in specific locations.

The researchers were able to see the previously identified nuclei "in action." ZENK gave the researchers a window into the brain, enabling them to see how certain behaviors set into motion the molecular activity of cells in specific brain areas.

Hovering

In 2006, a couple of Canadian scientists dug into some hummingbird brains this is what they found.

"This was a very exciting moment for us," said Dr. Doug Wong-Wylie, Canada Research Chair in Behavioural and Systems Neuroscience and psychology professor at the University of Alberta. "As soon as we looked at these specimens it was obvious that something was different in this bird's brain than other species."

Wong-Wylie and Dr. Andrew Iwaniuk, also from the Department of Psychology in the Faculty of Science, compared the hummer brain to 28 other bird species.

Hummers are well known for their wing speed and ability to hover and fly forward and backward with more precision than a helicopter. It is critical that the hummer remain perfectly still as it feeds itself while darting in and out of flower blossoms with pinpoint accuracy. The bird must be able to maintain a stable position space, despite the fact that their wings are beating 75 times per second and that disruptive effects such as wind gusts could throw them off.

Much work has been done on the its physiological make up--such as its enlarged heart, high metabolic rate and specialized wing kinematics--but nothing has been done on the neural specializations of the bird.

"Part of the reason this type of work hasn't been done before is because of access to the birds," said Iwaniuk. "In Canada especially they tend to be uncommon, they come from exotic locales and they are not easy to catch, so we were very fortunate to be able to study the specimens we did."

The scientists found that a specific nuclei--one that detects any movement of the entire visual world--was two to five times bigger in the hummingbird than in any other species, relative to brain size.

The brain is smaller than a fingertip. The doctors reasoned that it is this nucleus helps the hummingbird stay stationary in space, even while they're flying. These birds must have a good optomotor response considering they are stationary 90 per cent of the time. This specific nuclei is likely responsible for that.>>

BMAONE23 wrote:

emc wrote:Wait a minute... That will be adding to the leakage and I think our moderator wants to stop leakage. (I think he is having grandiose ideas) Besides, as much as I would like to, I’ve never been beamed anywhere… so what’s up with that?

Actually, with beaning them directly into space with maximum dispersal, you will force their cells to carmalize. This will eventually form a hard candy shell around the entire globe thereby eliminating leakage.