Misc. science facts

[twilyth]

I feel a little stupid for not having known this but it seems that the moon's rate of rotation is almost perfectly synchronized with its orbit - which is why we only see the same "face." Although technically this isn't completely true. When the moon is closest to earth its rotation is slightly slower and we see about 8 degrees more of the surface on one side. At the farthest point, the rotation is faster and we 8 degrees more on the other side. The phenomenon is called tidal locking.

The rotational period of the moon wasn't always equal to its orbit around the planet. Just like the gravity of the moon affects ocean tides on the Earth, gravity from Earth affects the moon. But because the moon lacks an ocean, Earth pulls on its crust, creating a tidal bulge at the line that points toward Earth. [Infographic: Inside Earth's Moon]

Gravity from Earth pulls on the closest tidal bulge, trying to keep it aligned. This creates tidal friction that slows the moon's rotation. Over time, the rotation was slowed enough that the moon's orbit and rotation matched, and the same face became tidally locked, forever pointed toward Earth.

The moon is not the only satellite to suffer friction with its parent planet. Many other large moons in the solar system are tidally locked with their partner. Of the larger moons, only Saturn's moon Hyperion, which tumbles chaotically and interacts with other moons, is not tidally synchronized.

The situation is not limited to large planets. The dwarf planet Pluto is tidally locked to its moon Charon, which is almost as large as the former planet.

Earth (and other planets) do not escape completely unscathed. Just as the Earth exerts friction on the spin of the moon, the moon also exerts friction on the rotation of the Earth. As such, the length of day increases a few milliseconds every century.

In fact over the eons, earth's day has gone from about 6 hours to the current 24 as the moon has moved further and further from the earth

Sedimentary rocks such as sandstone also testify to the quicker days of yore. As moon-spawned tides wash over rocks they deposit mineral specks, layer upon layer. In southern Australia, for example, these vertically accumulating tidal "rhythmites" have pegged an Earth day at 21.9 hours some 620 million years ago. This equates to a 400-day year, although other estimates suggest even brisker daily rotations then.

Here's what would happen if the moon didn't rotate

 

[twilyth]

 

[twilyth]

Methane lakes extend more than 200 meters below surface of Saturnian moon

DEEP DOWN One of the largest seas on Titan, Ligeia Mare, seen in this false-color radar image taken by the Cassini spacecraft, extends more than 200 meters below the moon’s surface.

 

[INSTG8R]

Easy with the Triple Posting in your own thread...

 

[Steevo]

Methane lakes extend more than 200 meters below surface of Saturnian moon

I think the US is found some WMD, so we may be invading to capture ummm, them.

 

[twilyth]

Easy with the Triple Posting in your own thread...

Yeah. I guess this thread is a little like public masturbation. But at least I'm doing it quietly over in a corner.

 

[INSTG8R]

Yeah. I guess this thread is a little like public masturbation. But at least I'm doing it quietly over in a corner.

Ya think?

 

[twilyth]

I'm not sure what you're upset about. I'm just trying to share things I think people will find interesting and avoid polluting the subforum with a lot of extraneous threads. You can always put me on ignore if you find this especially annoying.

 

[Steevo]

Keep going baby.

 

[INSTG8R]

I'm not sure what you're upset about. I'm just trying to share things I think people will find interesting and avoid polluting the subforum with a lot of extraneous threads. You can always put me on ignore if you find this especially annoying.

I do and you just like to see yourself in text...

 

[twilyth]

I don't know why you would think that but I'd be happy for you to PM me so I could find out.

 

[twilyth]

LHC discovers 2 new hadrons

Following the recent confirmation of tetraquark particles, this may not be quite as exciting but it's still interesting, even if the discovery fits nicely within the standard model.

In addition to the masses of these particles, the research team studied their relative production rates, their widths—which is a measurement of how unstable they are—and other details of their decays. The results match up with predictions based on the theory of Quantum Chromodynamics (QCD).

“QCD is a powerful framework that describes the interactions of quarks, but it is not that precise,” Blusk says. “If we do see something new, we need to be able to say that is not the result of uncertainties in QCD, but that it is in fact something new and unexpected. That is why we need precision data and precision measurements like these—to refine our models.”

 

[the54thvoid]

Ya think?

I wouldn't classify this as double posting when it is releasing newer and separate items of info, highly relevant to the thread title. Stop being a pedantic robot and let our resident factual science book post as they please.

Twilyth-please keep up the good work, I enjoy your science posts.

 

[the54thvoid]

For the record, this is an example of double posting. Very different from the context that Twilyth has you so upset over.

 

[Drone]

10 things you may not know about the Solar System

10 things you might not know about space

 

[twilyth]

10 things you may not know about the Solar System

10 things you might not know about space

From the first article

2. Pluto is smaller than the USA. The greatest distance across the contiguous United States is nearly 2,900 miles (from Northern California to Maine). By the best current estimates, Pluto is just over 1400 miles across, less than half the width of the U.S. Certainly in size it is much smaller than any major planet, perhaps making it a bit easier to understand why a few years ago it was “demoted” from full planet status. It is now known as a “dwarf planet.”

From the second

Some stars have more fuel than our sun, which is to say that they are more massive. Some stars have twice more, some 10 times more, and a relative few have 100 times more fuel as our sun. In fact, one “hypergiant” star designated as R136a1, is thought to be 265 times the mass of our sun. You might think that such stars, with such great mass, and such enormous reservoirs of fuel, would shine a very long time. But you would be wrong. In fact, very massive stars guzzle their nuclear fuel at prodigious rates, causing them to run out quickly. Our sun and similar stars have lifetimes of about 10 billion years, but a star 10 times more massive than the sun will “burn” for only about 30 million years, about one third of one percent as long!. A truly massive star 100 times more mass (and hence vastly more fuel) than our sun, may live only 100,000 years or so. If the sun’s lifetime were the same as the average human, a star 100 times as massive would live about six hours! And R136a1 would be gone in roughly the time it takes to watch a single episode of “The Big Bang Theory!”

 

[Drone]

^ Thanks for pointing that out, here's some cool info about that monster star R136a1:

R136a1 is 165000 ly from Earth, located in the Large Magellanic Cloud (a nearby dwarf galaxy which orbits the Milky Way)

R136a1 is a hypergiant with a radius of ~24 million km, which is ~35 times larger than the sun.

R136a1 is estimated to have a mass of ~265 times that of the sun, making it the most massive known star. It also has the highest luminosity, close to 10 million times greater than the Sun.

 

[Drone]

Gravitational lensing
​

Einstein's Theory of Relativity predicted that massive objects would bend and warp the fabric of spacetime. The more massive the object, the more severe the bending.

Einstein predicted that starlight passing near the massive object would follow invisible curved spacescape and be deflected from an otherwise straight path. In effect, the object acts as a lens, bending and refocusing the light from the distant source into either a brighter image or multiple and distorted images.

This stuff is extremely complicated involving tensor calculus, differential equations, Riemannian metric, Minkowski spacetime and lots of equations by Einstein, Ricci, Levi-Civita and many other great minds. Unfortunately I can't cover everything here because it's pretty much (tons of formulae) and I have only begun to understand, which is really hard let alone explain it to others. I have a really long journey ahead lol. Anyway, here are some famous examples of gravitation lensing:

The four dots are multiple images of supernova SN Refsdal taken with the Hubble Space Telescope. That's pretty crazy, isn't it? Four images of one thing.

Another crazy example called Einstein cross.

What looks like a galaxy with five nuclei really has just one (at center) surrounded by a mirage of four images of a distant quasar. The galaxy lies 400 million ly away; the quasar about 8 billion. The quasar images flicker or change in brightness over time as they're microlensed by the passage of individual stars within the galaxy. Each star acts as a smaller lens within the main lens.

Some links:

http://imagine.gsfc.nasa.gov/docs/features/news/grav_lens.html

http://www.spacetelescope.org/science/gravitational_lensing/

http://astro.berkeley.edu/~jcohn/lens.html

 

[twilyth]

Gravitational lensing might not be the only explanation for why light bends around massive objects - http://physicsworld.com/cws/article...-of-light-could-explain-sn1987-neutrino-burst

Photons are technically massless but they can spontaneously transform into pairs of matter/anti-matter particles that do have mass. Those particles would be influenced by gravitational effects. In fact, because they are so much more massive than neutrinos, light should be slowed down more than neutrinos originating from the same source - and that's what we seem to see in the above example.

Also, Einstein's explanation depends on time being an integral dimension of reality, something that is very hotly debated at present, especially since no one can really give a very good explanation for what is generally referred to as the "arrow of time" problem. Beyond that, Julian Barbour has shown that the space-time construct is not essential for general relativity to work. It can just as easily work within a timeless Machian dynamic framework.

 

[Drone]

Kinda sorta oversimplified but nice video by Fraser Cain

 

[twilyth]

On a related note, most of the mass of ordinary matter actually consists not of the quarks that make up protons and neutrons but of the massless gluons that hold them together. In fact, the mass of the up and down quarks only makes up about 1% of the mass of a proton. That's based on the resting mass of quarks but quarks in a proton make up a dynamic system. Even so, most of the mass still comes from the gluons and what are known as 'sea quarks'.

 

[rtwjunkie]

On a related note, most of the mass of ordinary matter actually consists not of the quarks that make up protons and neutrons but of the massless gluons that hold them together. In fact, the mass of the up and down quarks only makes up about 1% of the mass of a proton. That's based on the resting mass of quarks but quarks in a proton make up a dynamic system. Even so, most of the mass still comes from the gluons and what are known as 'sea quarks'.

I feel my head exploding from information overload....

Seriously, good stuff! I like this thread!

 

[twilyth]

Don't feel bad. Even the people that spend their lives studying the quantum real don't really understand it. That's why you have at least 3 different interpretations of quantum mechanics.

 

[Drone]

The human eye can see 'invisible' infrared light

... under certain conditions



Normally a photon, is absorbed by the retina, which then creates a molecule called a photopigment, which begins the process of converting light into vision. In standard vision, each of a large number of photopigments absorbs a single photon. But packing a lot of photons in a short pulse of the rapidly pulsing laser light makes it possible for two photons to be absorbed at one time by a single photopigment, and the combined energy of the two light particles is enough to activate the pigment and allow the eye to see what normally is invisible.

The visible spectrum includes waves of light that are 400-720 nm long. But if a pigment molecule in the retina is hit in rapid succession by a pair of photons that are 1 µm long, those light particles will deliver the same amount of energy as a single hit from a 500-nm photon, which is well within the visible spectrum. That's how we are able to see it.

 

[twilyth]

I'm not sure if archeology technically fits under science and tech so I'll just leave a blurb in this thread for the article - http://www.sciencealert.com/new-evi...nd-the-golden-fleece-was-based-on-true-events

It seems that the Greek myth of the search for the golden fleece was based on historical fact. It turns out that the area Jason traveled to, Colchis, was and still is know for its gold deposits. Then as now, these are washed away by streams from rock outcroppings and can be captured. The method that was used at the time involved sheep skins that helped to trap the gold particles. And it's believed that this is the basis for the story. It's an interesting read.