Physical Science 9.2b - Rotation and Revolution

[prchecker]

very interesting video thanks

[theworldofwonder]

Dear Mr. Owens, i would like to know what kind of electronics you are using in this video? the model and the conmpany? thank you

[804YankeeFan]

Dear Mr. Owens. Could you please explain something to me. Why does the earth's rotation not impede the cars or vehicles movement on the ground?

[docdhaliwal]

@804YankeeFan

dude, when u walk on the fast moving train, does ur speed actually impedes ??????

think about it and u will get ur answer

[hwz77]

derekowens, can u explain something to me? im new at learning geography and i really dont understand something.

it is said that countries near the equator (e.g. Singapore) do not have four seasons, but dry and wet seasons. however, i do not understand that as based on the earth's rotation, a dot on the equation should also experience concentrated light+heat and dispersed light+heat since it is not something at the poles.

[kevinsantoso1]

hei man, i need your help what software do you use, i need it for work

[HammadTunio]

great dude you ARe Awesome..

[sm88hunk]

brilliant work done .. thanks :)

[guyKLumpur]

Mr Lecturer, I would like to know: is the earth tilted from it's north/south imaginary line towards the right or towards the left? From your drawing it looks like the Earth is tilted towards the left, but on some diagrams they are shown as if the earth is tilted towards the right. Thank you.

[derekowens]

@guyKLumpur Whether the earth is tilted left, right, forward, or back, would depend on what season it is, and from what point of view your diagram is drawn. When it is summer in the northern hemisphere, the north pole of the earth is tilted toward the sun. Hope that helps! DO



[guyKLumpur]

@derekowens thanks for the answer, yeah that i know, when summer the earth is tilted towards the sun, but that does not answer my question. maybe i should ask : what is the actual tilt of the earth from it's imaginary north/south exist, towards the left or right, when you see it far from outer space?

[derekowens]

@guyKLumpur Well, the earth orbits the sun in an ellipse. This ellipse defines a plane, what we call the plane of the earth's orbit. The axis of the earth is not perpendicular to this plane, but is tilted 23 degrees. Whether it is tilted left or right depends on where you imagine looking at it from. If you were looking at it from a position so that it appeared tilted 23 degrees to the right, then if you looked at it from the opposite side it would appear tilted to the left.

[guyKLumpur]

@derekowens Great..now i get what u mean..one more thing that was not explained is that the earth obits around the sun in an ellipse manner, meaning at one moment it's position is a bit higher than the sun and the next moment it's position is lower than the sun. So is it right to say that at the time of both equinoxes, the position of the sun and the earth are at the same level or at a perpendicular position to each other, if u know what I am trying to say? Thank you..

[derekowens]

@guyKLumpur The shape of the orbit is not a perfect circle. It is close to being circular, but it is really an ellipse, so yes, the earth is closer (slightly) to the sun at some times. This has nothing to do with the equinoxes or the seasons, though. The seasons and the equinoxes are a result of the tilt of the axis, not the tiny variation in the distance from the sun.

[amm891]

Awsome! You are the master of explaining things! and master of drawing also =)

Big thankyou from St Petesburg, Russia!

[HeyRuka]

I love you.

[erez1979]

hi man, it's good, BUT - i believe that your eplanation for summer/winter by the angel of the rays reaching the surface is WRONG.

not because it is not true, it is true, and you are right in your explanation,

the problem is that you took the less considerable cause and made it the major and only cause for the seasons.

it is ot the angel which effects the most - this explanation is true for a small size source of energy light and heat.

[derekowens]

@erez1979 What, then, would you say is the major cause of the seasons, and why?

[BoltOfThundor]

@derekowens "youtube(dot)com/watch?v=IhqzW­97_47w&feature=related"

delivered

the earth doesn't spit at a equal distance, mind you.

[sullivanseven]

man this video is amazing, bows!

[NosoCOMINSOON]

That sounded stupid I think I understand lol I live in the U.S. it goes spring summer winter in the south it goes summer spring winter right? .. I think I had the seasons mixed..

[derekowens]

@NosoCOMINSOON I believe the change of seasons follows the same pattern in the southern hemisphere as it does in the north. Spring, summer, winter, fall. It's a matter of definition, really. Spring is defined as the season after winter.

[NosoCOMINSOON]

I don't get it. How come on the right of the screen its summer in the north but on the left its not. Does the earth move away from the Sun during winter in the north? I mean if its always at the same distance I don't get how that makes sense...its not like theres left and right in space the distance is the same 360 degrees.

[ELSA1243]

THANK YOU IM IN ARGENTINA AND YOU HELP ME TO DO MY ENGLISH HOMEWORK

[raajasify]

really helpfull. thanks!

[MiraMiri990]

Watched this in class it was very awesome with the pictures

[SuperJuniorFaith]

Thank you for the video ^.^

i undestand what's going on at the begning but still don't get it when you were like its summer on the north pole while its winter in the south :s

does it mean that that other half has the oppisite seasons? :s

sorry if my Q is stupid... i just don't get it ^.^ thank you in advance! :)

[derekowens]

@SuperJuniorFaith That's correct. When it is summer in the northern hemisphere it is winter in the southern hemisphere! Right now I'm enjoying a warm spring morning in Atlanta, but it's probably getting pretty cold down there in New Zealand and South Africa!

[SuperJuniorFaith]

@derekowens Thanks...but... Im from korea...and how come when its summer here it summer too in america, europ, arbian gulf and asia and africa? :s

its like almost the whole countries are the same? :s

sorry for my to many Q...

[derekowens]

@SuperJuniorFaith  Yes, that's right. Korea is also in the Northern hemisphere, so the seasons there are the same as in the US and in Europe. The different here applies to the northern and southern hemispheres, not to eastern and western. Much of the world's population is in the northern hemisphere, including all the countries you mention except Africa. Part of Africa is in the north and part in the south.

[SuperJuniorFaith]

@derekowens O yah thanks ^.^ ... isnt this true too? that the nearest country to the equator is the hottest and as long as it goes far from it its gets to the coldest ? which is of course the northern and southern hemisphere right? ^.^

[derekowens]

@SuperJuniorFaith I see what you are thinking. It gets hotter as you get closer to a radiating heat source. In this case, though, the difference in distance is negligible. If the equator is 93,000,000 miles from the sun, then the poles are about 93,004,000 miles from the sun, and the 4000 miles is an insignificant amount compared to the 93,000,000. It is the angle of the light striking the surface that causes it to be hot at the equator and cold at the poles.

[ToasteDash]

Thank you. Very easy to understand.

[RJJacobson]

Thanks Derek. it's amazing to me how many incredibly well educated folks have never considered the full moon rise / sun set scenario and why as well they see a half moon during the day. If you do get time in your busy life to do such an animation, it would be widely circulated I am sure.

Best, Jane

[RJJacobson]

I am having a rough time explaining to folks that the full moon sets with the rising sun, while the crescent moon rises (sort of) - with- the rising sun.

Is there an animation or videos that demonstreates this. After all...we are standing On earth, so it's kinda hard to get it! Thanks, Jane J

[derekowens]

@RJJacobson RJ, That's a great topic. I don't have a video on that specifically, but yes, video would definitely be the way to explain that. If I get time to make such a video I will try to let you know. Thanks, DO.

[TeenageIronman]

Are the rotations or the sun and moon exact?

[derekowens]

@TeenageIronman The sun is not solid, and the whole sun does not rotate in a rigid manner. Different parts of the sun rotate at different speeds.  The moon is basically a rigid body, though, and the rotation and revolution of the moon are known with a high degree of accuracy.

[oonaboona]

But WHY is the earth tilted on it's axis? Did it get knocked that way by some cataclysm? I can't seem to find an adequate explanation on the web.

[derekowens]

@oonaboona That's a good question. I don't know the answer, and I don't know if anyone does. My guess would be what you mentioned - some sort of cataclysm. Any guess is just conjecture, though, since we can't really test it.

[dcarrera01]

@derekowens: Consider how planets are formed. They are formed by numerous planetesimals banging together. It is not surprising that the resulting object's rotation would not be perfectly aligned with its orbit. Earth's tilt is not abnormal. It is greater than that of Mercury, Venus and Jupiter, but smaller than that of Mars, Saturn, Uranus and Neptune.

[derekowens]

@dcarrera01 Yes, that is a very good point. In fact, it relates to the gravitational "multi-body" problem. These are complex, chaotic systems, and it should not be surprising to find that everything doesn't line up perfectly.

[adekants]

@oonaboona That's God's idea! Pretty smart, huh?

[Cmtz]

@oonaboona our own moon knocked us to a tilt a couple of million of years ago.

[browneyesKL]

Very nicely explained. Thank you!

[adaliaz28]

this is a great way to demonstrate rotation n revolution.

i have a question:

isnt the earth rotating at an incredibly high speed at all times?

how are we able to get night and day while spinning? is it because the size of the earth makes 1000 mph seem very slow?

[derekowens]

@adaliaz28 Your question was, "how are we able to get night and day while spinning?". The answer is that we get night and day *because* we are spinning. The earth spins once per day, so that part of earth that you are on goes onto the shadow side and back to the sunny side once each day. And it seems slow because it is a low rotational speed. One revolution per day is not a very fast angular speed. Imagine standing at the north pole. You would rotate once per day, very slowly..........

[fethdor]

I never realized that summer for the Northern hemisphere was winter for the southern hemisphere. I was checking another diagram, and for us in the northern hemisphere, i find it funny that we are in winter when we are closest to the sun, although I guess distance does not matter much to solar radiation when in space, only the angle of the rays, as you said. Thanks for this video.

[Danofromtheblock]

This is very well explained! I have a big test tomorrow.. this info is very clear! Thanks!

[virrgodoll]

thx

[steffenie]

good lecture!!! thanks a lot......

[021829954]

this gave me the mental picture i needed to understand the seasons and rotation ,thanks

[woosahxz50]

How we are looking at the earth is confusing.

[kiddomanz]

You really helped Me alot To understand about the earth i truelly appreciate it, Your a really Good teaccher thanks.

[gunnardurs]

hy.... I past all day  asking my sef about the muvement of the earth.... thanks.....i have a question? what program or equipment do you use and whats your profetion or what do you study?...I am from ARGENTINA sorry if I dont write correctly.

[sportsnut712001]

But the main PROBLEM is that the Earths ORBIT arownd the Sun is not any ordinary CIRCLE! And the distance to the Sun is different every time! This is a fact, nobody is thinking that much about. Why not?

[derekowens]

@sportsnut712001 That's a good question. Yes, the orbits are basically elliptical, but the eccentricity of the ellipse is pretty low, which means that they are pretty close to being circular rather than being highly elliptical. The math for the circular orbits is much easier, and is generally more appropriate for 8th grade Physical Science or for high school Physics, so we often approximate the orbits as circular, while understanding that they are really slightly elliptical.

[sportsnut712001]

@derekowens How good You KNOW that?

[matsulli32]

These videos are fantastic, clear and effective resources. Thank you!

[jamalrajin]

terrific

i have question

that

is there any posibility that the have to change his polar possition excedently.

because being a muslim we belived that at the day of judgment the sun will rise from west???????

scintifically can you prove it????

i`ll be thanx full to you if satisfy me.............

[gothicappearance]

this really helped me, I'm taking a test tomorrow about this & I didn't know anything about this..but know I do :D

[marsCubed]

The world rotates at approx 1,000 miles per hour

Earth goes around the sun at 67,000 miles per hour.

The solar system goes around the galactic centre at 492,120 miles per hour.

Our (milkyway) galaxy rotates around the local group of galaxies at 89,500 mph.

Relative to the Cosmological Microwave Background, our Galaxy is moving at approximately 900,000 mph towards the constellations Hydra and Centaurus.

Correct my figures if wrong (shouldn't be too out), just had to approx work a couple out.

TY

[PisoMornar]

... <-- and the second question:

2. Are summers hotter on the southern hemisphere because Earth is closer to the Sun in January (closest in Perihelion around the January 4th, while furthest from the Sun around July 4th, which is Aphelion) or is the difference in those two distances insignificant?

P.S. is this a drawing pad you're using or? Your drawings are so awesome, wish I could draw like this.. :D

Thanks

[derekowens]

@PisoMornar  From what I understand, the difference in the distance from the sun does not affect the temperature. The different temperatures in the different seasons are due only to the angle of the sun striking the earth. Hope that helps!

[PisoMornar]

This is so great!! :D

I have a couple of questions I hope you will answer as perfectly clearly as you explained everything in the video:

1. Does it become dark more slowly in the summer than in the winter, or is it just me? It seems to me that in the winter day turns into night in several minutes, while in the summer, it lasts for at least a half an hour. I have a few theories why that might be (if I'm not simply crazy :D ), but am not really sure...

... -->

[derekowens]

@PisoMornar Hmmm... that's a good question. I *think* it probably just seems like it gets dark more slowly in the summer because the days last longer. It seems to get dark more quickly in the winter just because it is dark earlier. I'm just guessing, though - haven't worked out the orbital mechanics on that one.

[LGAGAFAN21]

thanx loads!! realy didnt understand when my teacher explained u made me understand better!!

[freethisone]

you never said how.....

[almomiyz]

Thank you very much. can you pleas Make it possible to view PowerPoint.

[freethisone]

@almomiyz see my movies, i have solved coral casle. and precession.. have you?

[movieman0222]

Thanks for the clear explanation.

[freethisone]

@movieman0222 no unclear.

i will make clesr how precession is made.

see my movie for answers

[GOPIEGOPIEEATPIE]

Thank you so much for this video cuz it helpd me with science grade 7 !

[derekowens]

Yes, I'll do that. Still busy grading exams at the moment. More playlists are coming, though.

[KurdishSaladin]

can you please make a playlist for your videos, its much esaier to follow up, thx