How the Earth Moves - Professor Carolin Crawford

Our spaceship Earth is in constant motion -- rotating and revolving as it traverses through space: www.gresham.ac.uk/lectures-and...
This is a story of our evolving understanding of the geography of Earth's position in space -- a story of parallax, aberration and astrometry that stretches from the ancient Greeks to the most modern satellite, Gaia.
The transcript and downloadable versions of the lecture are available from the Gresham College Website: www.gresham.ac.uk/lectures-and...
Gresham College has offered free public lectures for over 400 years, thanks to the generosity of our supporters. There are currently over 2,500 lectures free to access. We believe that everyone should have the opportunity to learn from some of the greatest minds. To support Gresham's mission, please consider making a donation: gresham.ac.uk/support/

[@berniekraska741]

Excellent presentation! Once again, thank you Caroline.

[@DaytakTV]

I spend my time working on subjects such as physics and chemistry for college and my free time is spent watching phenomenal lectures such as this. To learn about the world around us, and the rest of the universe, is to truly be alive and conscious. I am a happy man :)

[@katyjasso8742]

nllkkk

[@maryseacross9652]

Exactly

[@SV67943]

I wish they would record the MP3 audio on an entirely separate mic setup, so the sound guy can get all of that hiss out of the recording, and maybe better deal with the dropoffs as she turns her head. It's probably dialed in perfectly for the room itself. Nitpicking aside, I love this series and the fact that Gresham College even puts material up for the public. Thank you.

[@Vlaid65]

Great presentation. Enjoyed it immensely.

[@SupernovaA-dj8dh]

Carolin Crawford, thanks, another informative lecture! So glad to be alive after the accumulation of knowledge of all the scientists. Theres another lecture today,10-22, wish I could fly over to London.Lets see 6 a.m. here, the lecture might be going on right now.

[@GreshamCollege]

Supernova1987A Not quite - we're packing our bags, ready to for Professor Crawford in two hours' time. Hopefully one day you can make it across to watch one in person...

[@SupernovaA-dj8dh]

GreshamCollege I will be there in spirit , awaiting my inbox as a boy near Christmas.

[@venom6622]

Carolin Crawford ROCKS!!!

[@adrianaghitoaie2996]

venom6622 yeah she is a very good liar !!!!!!!! but she didn,t convinced me!!!!!!!!!!!!

[@qcislander]

@@adrianaghitoaie2996 Can you please explain what it is that she didn't convince you of. I'm genuinely curious to know what she's got wrong.

[@arneilliloan7805]

Professor, thank you so much for this important lecture that you've share i learn lot's and I,will be able to discuss it in a class as my report.

[@TrishCanyon8]

Love to listen to her lectures

[@praaht18]

Elegant!

[@roundearth2619]

I can't wait for that galactic reference point to be set. so interesting

[@vickyiitope7664]

Thank you for uploading this I don't know what I have done.

[@Stone2home]

Fantastic.

[@vincentb9827]

thanks a lot merci beaucoup

[@thedeester100]

If your frame of reference is inside the event horizon of a black hole does the speed of light change?

[@jkellner3]

Good as it gets

[@Biggus63]

She's very good.

[@JimiChurri]

I think at 51:15 she meant to say that the speed of the earth around the sun is 107000 km/h, not 107 million. Great lecture!! thx

[@adrianaghitoaie2996]

martiberro yeah great LIES lecture!!!!!!!!

[@Sixstringman]

I miss this women's lectures.

[@DaytakTV]

Oh wow! So, the Michelson-Morley Experiment looks a lot like the Laser Interferometer Gravitational Wave Observatory, which is capable of mind-boggling precision. Interesting!

[@taunteratwill1787]

+KZbinExplorer My god !! Woooow! Bloody hell!! Awsome!! Save us dear lord!! Spectacular!! I can die now!! Where is the Guiness Book!!

[@dockovacs4089]

Surprising to not hear any mention of barycenters.

[@alimotaich]

How come we throughout time always have seen the same star constallations? I dont understand have that works when the planet is moving through space?

[@agimasoschandir]

+Ali Motaich What constellations there are have changed. Constellations, technically asterisms, are due more to culture. Different cultures put together different (sometimes the same but with different names) stars to form imagined images. The star patterns themselves, due to the position of the stars, takes ten thousands of years, but humans have a written record of them going back to about 1300 bce, but it is possible such star patterns may go back 30,000 years for humans.

[@brendonhansford]

What is your inspiration?

[@The_18th_Fret]

I'm a complete physics noob but am enjoying learning more, so can someone tell me how this "speed of light is constant for everyone" applies to Einstein's theory of general relativity and space-time not being the same everywhere? Thanks. Great talk btw, thoroughly enjoyed it and learned a lot!

[@Vlaid65]

+Weird Fishes Motion.

[@The_18th_Fret]

Vlaid65 Care to elaborate? lol

[@roundearth2619]

+Weird Fishes and gravity plays into it

[@taunteratwill1787]

+Weird Fishes constantes are relative too.

[@jamesallison7455]

Is that a college or a museum or something like that

[@taunteratwill1787]

+james allison It's more something else like that.

[@JSprayaEntertainment]

52:55 yin yang !

[@SeanMauer]

Does anyone know how the planets are oriented to the motion of the sun around the galaxy? I think it's assumed perpendicular but it's not known.

[@helloadj]

You can see that for your self. if you look at the movement of the Milky way galaxy during any clear night it looks like a big rainbow moving over your head. Since we are inside the milky way galaxy all you can see from earth is a big band of white stars stretching from North pole to South pole. for the sake of simplicity we can assume all planets rotate the sun on the same plane, and that plane is almost the same to the path of the sun during day time it is always east to west. to summarize if the plane of the Galaxy runs from north to south and the plane of the planets is from east to west we can easily deduce it is perpendicular. Of course this is my simple eye observation this summer so expect a lot of errors in it

[@SeanMauer]

Ade Speed Or it could be that earth's orbit is in the plane of the milky way but because of it's tilt the galaxy has the North South stretch. However your explanation could work as well. What I don't get is why this is information is not to be found anywhere to my internet or book knowledge. I've seen some video graphics depicting the perpendicular mode, but nothing that indicates this is known.

[@MahraiZiller]

SeanMauer The ecliptic of the solar system (generally the orbital paths of the planets around the Sun) is inclined to the ecliptic of the galaxy (the orbital path of the solar system around the galaxy), by about 60+ degrees. Not really perpendicular. Hope this answers your question ;)

[@helloadj]

I found a wonderful program to follow the planets and stars every night. It will give you an amazing visualization of the Solar system and our galaxy as a whole. It is free and can be downloaded here. www.stellarium.org After tweaking some settings I found Mahra is wright. The angle is not exactly perpendicular it is 60 degrees.

[@RAITHWILSON123]

very interesting but if all this is true then i have one question to you and would like a response please as no one seems to be giving me an answer to this .the earth orbits the sun aprrox 365 days a year and does one rotation 24 hours .please explain why if at 12 noon in summer it is daylight yet at 12 noon 6 months later we are still in daylight ,shouldnt we be in the dark at 12 noon winter if what your saying is correct?

[@blakesnipe5347]

If our calendar year were based on sidereal days that would be the case, but it is not. The calendar year is based on solar days. Sidereal days are the length of time it takes the Earth to rotate once relative to the background stars. The length of this sidereal period is about 23 hours and 56 minutes. At this point, the Earth has made one rotation, but since it has orbited the Earth ~ 1/365th of the way around, the sun is not in the same place. It takes an extra 4 minutes for the Earth to rotate around to a position so that it has made a full rotation relative to the sun (which is actually slightly more than a full rotation relative to the stars). Over the course of 6 months, those 4 minutes per day add up to about 12 hours, so indeed - if the calendar were based on a sidereal day, then high noon would have the sun high up in the sky on one day, and at that same "time" six months later, it would be midnight. BUT - our calendar is NOT based on sidereal days, but solar days - 24 hours long, so noon is daytime every day. Because the calendar is based on solar days and not sidereal days, the stars are not in the same position at the same time each night. No matter what, SOMETHING is going to give. If you based your days on sidereal periods of the Earth, then the sun will move a little each day - and as you say, in six months, it would be on the opposite side of Earth at the same time, but the stars would be in the same position at the same time each night - and we would never see constellations on the other side of Earth (because it would always be daytime when we see them). Since we use the solar day as the length of our day, the sun remains in the same position at the same time each day (ignoring the changes due to the relative position of the sun in relation to the tilt of the Earth), but the stars move a little bit at the same time each night. Because this is the calendar we actually use, constellations you see during the summer are entirely different than the ones you see during the summer - not including the northern constellations you see year round in the northern hemisphere (and vice versa for the southern hemisphere), so the phenomenon you expect to happen DOES happen - it just happens with the stars instead of the sun. You have a choice - base your days on rotation relative to the stars and have the stars appear in the sky in the same positions at the same time each night while the sun moves a little each day - OR - base your days on rotation relative to the sun and have the sun appear in the sky at the same time each day while the stars move a little each night. We chose the latter obviously!

[@Fransamsterdam]

To be honest I expected more about eccentricity, precession, things like that. The title of the lecture could be better: How earth did not move, though people thought it did. Nevertheless, thumb up!

[@count69]

You are right, this has nothing about how the Earth moves, it is literally as you say "How Earth remains still and we have modeled it to move"

[@MuchLowerThanThat]

54:24 and further. So, only in 5 years from now we will be able to see how the sun and the galaxy move relatively to the other galaxies... ok then, what were all previous words and even numbers printed in school astronomy books about? were they just guesses? it's really annoying that books just boldly tell us "it's like that" or "like this" while every new fancy tool changes our prospective. Anyway, great lecture, thank you!

[@elk205]

How fast is the Sun traveling around the Milky Way???

[@Max_Ohm]

12 miles per second

[@qcislander]

Just for the record...Chichen Itza is in *North* America. Even geographic dissenters would place it in Central America. kzbin.info/www/bejne/eajUhJive5d1fJY

[@pillettadoinswartsh4974]

0:48 - the Milky Way moves too.

[@ronaldderooij1774]

In QED motion is meaningless. Time is of the essence, but not in order of history to future (as far as light is concerned).

[@mrearly2]

Excellent science fiction!

[@ivx8345]

Thank you "professor" mrearly.

[@larue085]

so if these new satellites come to show earth in the center of the universe then what?

[@taunteratwill1787]

+LaRue They don't, i won't allow it.

[@McPrfctday]

So all the planets are the sun's rings. Like Saturn's rings. All this time I didn't know that all the sun's planets were on the same plane (marbles on a table). I thought the planets were on various planes.

[@RonJohn63]

"I thought the planets were on various planes." Really? In grammar school (I presume you're American) science class they never showed you a model of the Solar System?

[@McPrfctday]

RonJohn63 Not a 3D model, no. All I've ever seen are 2D representations which show relative size but not relative distance from the sun or each other nor relative angle of orbit to the sun nor to each other. I assumed the posters etc were drawn that way because... How could someone draw a 3D poster? (is what I thought). I thought grammar schools were only an English thing where you had to pass your 11+ exam to get in. I'm English and I went to a school that was an ex grammar school. I missed the grammar school thing because I was born in 1970 and too young.

[@jomen112]

The reason the planets is in the same plane is due to basic principles in physics: when gravity collapse a cloud onto itself it will start to spin. Because of centrifugal forces (a radially outward force) the spinning will cause the collapsing cloud to turn into a disk shape. It is within this disk shape (where the stuff is present) the planets will form around a star.

[@RonJohn63]

McPrfctday _How could someone draw a 3D poster?_ No need for a 3D poster in order to show relative orbital planes. Here's a perfect example (though it still isn't to scale): www2.open.ac.uk/openlearn/futurelearn/moons/images/large/ou_moon_art_2240_plutos_eccentric_orbit_expanded.jpg

[@McPrfctday]

RonJohn63 Yes, so it's only Pluto that's on a different plane. I honestly thought that the planets were all orbiting at different angles.

[@paulmccarten6007]

If the earth's a ball zooming around "space"....... Why is it FLAT & NOT MOVING?

[@ThomasDanielsen1000]

That's easy: it's not flat!

[@louisbarbisan8471]

Benjamin Stone. NO, one below is the one you're looking for. Edge Bob said......Bla Bla Bla. Have you been to space to see the earth spin? Beware of the red cross. They're everywhere.

[@sheardsheep8978]

The Earth is a Time Toroid Stop Watch.

[@alextvmantvman3894]

doesn't move at all, get gyroscope and test it.

[@zholud]

False. Moon does not change it’s shape. Stopped watching at 2:20

[@apburner1]

Bullshit. Everyone knows we are riding on the backs of turtles.

[@alextvmantvman3894]

and Polaris stays at the same spot for millennia.

[@ThomasDanielsen1000]

How do you know? Where you around a millenium ago to check?

[@Stone2home]

Hang on... does this mean the Flat Earth Society may be wrong?

[@vincentb9827]

of course , yes

[@charles-mr4oz]

No. All science could be wrong

[@robertheilmeier2671]

+charles You DO know that the very technology that enabled you to write your comment here is BASED on and WORKS only because of the validity of that science, all of which "could be wrong" in your opinion, do you? Now isn´t this ironic?

[@theradgegadgie6352]

The FES exist to make even the stupidest of us (me, probably) feel superior to SOMEONE.

[@ErikOosterwal]

It's all relative. I'm sure you could come up with some very elaborate and complicated models, as well as some new ways to do mathematics, so that the flat-Earth model can predict the movement of heavenly bodies.

[@taunteratwill1787]

This must be very disappointing for the flat Earthers. I mean all those lies about a globe shaped Earth and planets. :-))

[@theclubvids]

Flat Earth, Plane Earth, Terra Firma, Yahweh's Terrarium... cats outta the bag. I can see for miles and miles and miles.

[@boterlettersukkel]

To bad that conspiracy nuts never have *EVIDENCE* for their claims.

[@edge_bob]

Bla Bla Bla. Have you been to space to see the earth spin. Beware of the red cross.

[@ivx8345]

Edge Bob knows all.

[@jordainecallum9177]

You don't have to be in space to know sattelites take pictures its very impossible for gov all over the world to keep such secret from you causw its even hard to keep a secret between two person much less millions

[@adrianaghitoaie2996]

YEAH LIES LIES LIES GREAT IMAGINATION CAROLINE!!!!!!!!! you should go to work for Hollywood!!!!!!!!

[@ThomasDanielsen1000]

Prove her wrong or shut up!