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Ocean
07-26-2010, 10:27 PM
I invented a new term (I think): stars-awesome. What can be more awesome than the stars?

Here I am in the Southern hemisphere, in a mountainous area, with dark clear skies. Despite the full moon, the milky way is clearly visible. It goes across the zenith, dense with stars, some faint, some bright, some far apart, almost falling out, while others cling together tight as if they were, well yes, space-cold. Oh my! Stars-awesome alright!

AemJeff
07-26-2010, 10:31 PM
I invented a new term (I think): stars-awesome. What can be more awesome than the stars?

Here I am in the Southern hemisphere, in a mountainous area, with dark clear skies. Despite the full moon, the milky way is clearly visible. It goes across the zenith, dense with stars, some faint, some bright, some far apart, almost falling out, while others cling together tight as if they were, well yes, space-cold. Oh my! Stars-awesome alright!

Can you see the Magellanic Clouds? Galaxies-Awesome!

bjkeefe
07-26-2010, 10:31 PM
I invented a new term (I think): stars-awesome. What can be more awesome than the stars?

Here I am in the Southern hemisphere, in a mountainous area, with dark clear skies. Despite the full moon, the milky way is clearly visible. It goes across the zenith, dense with stars, some faint, some bright, some far apart, almost falling out, while others cling together tight as if they were, well yes, space-cold. Oh my! Stars-awesome alright!

Never mind that. Get to the important scientific observations. Which way is the water spinning when it goes down the drain???

;)

Ocean
07-26-2010, 10:35 PM
Never mind that. Get to the important scientific observations. Which way is the water spinning when it goes down the drain???

;)

Empirical observation in the bathroom sink about 60 seconds ago: water drains counterclockwise.

bjkeefe
07-26-2010, 10:55 PM
Empirical observation in the bathroom sink about 60 seconds ago: water drains counterclockwise.

All right, thanks. Now on your way home, please stop off in Australia and confirm this.

#americansruleatgeography

Ocean
07-26-2010, 11:03 PM
All right, thanks. Now on your way home, please stop off in Australia and confirm this.

#americansruleatgeography

Okay, next time I'll do it.

SkepticDoc
07-27-2010, 12:11 AM
Draining in bathtubs and toilets

It is a common belief that the direction of rotation of a bathtub or toilet vortex is determined by the hemisphere it happens on. Whereas theoretically Coriolis forces affect the draining flow, in practice, various stronger factors—such as turbulence, temperature distribution, and wall shape—dominate.

In 1908, the Austrian physicist Otto Tumlirz described careful and effective experiments which demonstrated the effect of the rotation of the Earth on the outflow of water through a central aperture.[26] The subject was later popularized in a famous article in the journal Nature, which described an experiment in which all other forces to the system were removed by filling a 6 feet (1.8 m) tank with 300 US gallons (1,100 l) of water and allowing it to settle for 24 hours (to remove any internal velocity), in a room where the temperature has stabilized. The drain plug was then very slowly removed, and tiny pieces of floating wood were used to observe rotation. During the first 12 to 15 minutes, no rotation was observed. Then, a vortex appeared and consistently began to rotate in a counter-clockwise direction (the experiment was performed in the Northern hemisphere, in Boston, MA). This was repeated and the results averaged to make sure the effect is real. The report noted that the vortex rotated, "about 30,000 times faster than the effective rotation of the earth in 42° North (the experiment's location)". Thus, the Coriolis effect does indeed play a role in vortex rotation for draining liquids that have come to rest for a long time and may be observed under carefully controlled laboratory conditions.[27][28]

In reality, this experiment shows that the Coriolis effect is a few orders of magnitude smaller than various other influences on drain direction, the direction in which water was initially added to the container and its geometry. In the above experiment, if the water settles for 2 hours or less (instead of 24), then the vortex can be seen to rotate in either direction. Most toilets flush in only one direction, because the toilet water flows into the bowl at an angle.[29] If water shot into the basin from the opposite direction, the water would spin in the opposite direction.[30]

The idea that toilets and bathtubs drain differently in the Northern and Southern Hemispheres has been popularized by several television programs, including The Simpsons episode "Bart vs. Australia" and the The X-Files episode "Die Hand Die Verletzt".[31] Several science broadcasts and publications, including at least one college-level physics textbook, have also stated this.[32] Some sources that incorrectly attribute draining direction to the Coriolis force also get the direction wrong, claiming that water would turn clockwise into drains in the Northern Hemisphere.[32]

The Rossby number can also tell us about the bathtub. If the length scale of the tub is about L = 1 m, and the water moves towards the drain at about U = 60 cm/s, then the Rossby number is about 6 000. Thus, the bathtub is, in terms of scales, much like a game of catch, and rotation is unlikely to be important. The dominant physical process that creates the rapid vortex close to the plug hole is the conservation of angular momentum. The radius of rotation decreases as water approaches the plug hole so the rate of rotation increases, equivalent to bringing your arms and legs in while spinning on a chair.

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

Cool Video (http://www.youtube.com/watch?v=49JwbrXcPjc)

AemJeff
07-27-2010, 12:16 AM
http://antwrp.gsfc.nasa.gov/apod/ap060809.html

uncle ebeneezer
07-27-2010, 12:33 AM
Wow what a cool site. Thanks Jeff.

This one made me think of you, Ocean, down there beneath the Southern sky (http://antwrp.gsfc.nasa.gov/apod/ap100514.html).

And this one reminded me that if there is something out there watching us, it is surely a cat (http://antwrp.gsfc.nasa.gov/apod/ap100509.html).

JonIrenicus
07-27-2010, 12:44 AM
Now I am sad, I have yet to be any place with less civilization blanketing the skies with layers of soot and ash and haze and smoky lights.

Ocean
07-27-2010, 10:39 AM
Wow what a cool site. Thanks Jeff.

This one made me think of you, Ocean, down there beneath the Southern sky (http://antwrp.gsfc.nasa.gov/apod/ap100514.html).

I wish I could take a picture like that!

And this one reminded me that if there is something out there watching us, it is surely a cat (http://antwrp.gsfc.nasa.gov/apod/ap100509.html).

Hey, we just need to add the pyramid underneath, and we're done!

Ocean
07-27-2010, 10:46 AM
Now I am sad, I have yet to be any place with less civilization blanketing the skies with layers of soot and ash and haze and smoky lights.

Don't be sad. There's plenty of time and plenty of places, at least at our humble human scale.

SkepticDoc
07-28-2010, 08:45 AM
The Coriolis effect is amusing trivia but it is not significant in the real world:

http://www.dvandom.com/coriolis/sink.html

http://www.ems.psu.edu/~fraser/Bad/BadCoriolis.html

Maybe I need some help, it stuck to my mind since College Physics...:)

Lyle
07-28-2010, 10:05 AM
Go up in to the mountains in a place like New Mexico and you'll get an awesome night sky. Really anyplace high up and out West, and you'll get an impressive sky.

uncle ebeneezer
07-28-2010, 12:16 PM
+1 to that! When I was in Yosemite recently one of the highlights was waking up in the middle of the night and stepping out of the tent and just being blown away when I looked up at the sky. Awesome is the only word for it.

SkepticDoc
08-13-2010, 05:15 PM
Our friend Osmium is also interested in the Coriolis effect:

http://clearscience.tumblr.com/post/932281177/the-coriolis-effect-has-to-do-with-things-in

http://clearscience.tumblr.com/post/937345898/yesterday-we-talked-about-the-coriolis-effect

http://clearscience.tumblr.com/post/942454228/we-talked-about-the-coriolis-effect-and-said-it

bjkeefe
08-14-2010, 12:04 AM
Our friend Osmium is also interested in the Coriolis effect:

Thanks for the reminder.

Would that he would deign to put his site in his sig, so that the more scatterbrained of his friends could remember to drop in every now and again.

SkepticDoc
08-14-2010, 07:14 AM
Thanks for the reminder.

Would that he would deign to put his site in his sig, so that the more scatterbrained of his friends could remember to drop in every now and again.

I have his RSS headlines in my iGoogle page, along with Wonkette and several others, it is like like my personal HuPo!

bjkeefe
08-16-2010, 11:21 PM
I have his RSS headlines in my iGoogle page, along with Wonkette and several others, it is like like my personal HuPo!

Thanks for the suggestion, but that's not really an option for me. I already subscribe to so many feeds I can't keep up with them all, unfortunately. I find it useful, therefore, to have some other reminder to check in from time to time.