> cosmo-astro > measuring-the-sun-acceleration-using-stellar-aberration-sixty-symbols

Why Starlight is like Rain - Sixty Symbols

Sixty Symbols - 2020-12-20

Professor Mike Merrifield discusses the stellar aberration and the acceleration of the Sun.
More links and info below  ↓ ↓ ↓

More with Professor Merrifield: http://bit.ly/Merrifield_Playlist

Gaia Early Data Release 3: https://www.cosmos.esa.int/web/gaia/early-data-release-3

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shaytal100 - 2020-12-20

It is mind-blowing! The sun travels with 220 km/s and we can measure an acceleration of 1cm/s in a year!

EebstertheGreat - 2020-12-20

@Eidetic Ex Sure, if your telescope is GAIA's astrometry instrument, your ruler is its radial velocity spectrometer, and your camera is 1 gigapixel. (You can't measure the Sun's acceleration from home.)

Engin Atik - 2020-12-26

The velocity of Sun rotating about the center of the galaxy should reverse completely in half a turn which takes 440000/0.01 years. So the sun completes one revolution around the center of the galaxy in 88 million years. If the orbit is a circle its diameter would be 2x10^17 km!

Dolphin Man - 2021-01-10

Our psyche is part of nature, and its enigma is as limitless. Thus we cannot define either the psyche or nature.

Hayden Travis - 2021-01-16

​@Dolphin Man You've only chosen your limit.

Dolphin Man - 2021-01-16

@Hayden Travis "There are, moreover, unconscious aspects of our perception of reality. The first is the fact that even when our senses react to real phenomena, sights, and sounds, they are somehow translated from the realm of reality into that of the mind. Within the mind they become psychic events, whose ultimate nature is unknowable (for the psyche cannot know its own psychical substance). Thus every experience contains an indefinite number of unknown factors, not to speak of the fact that every concrete object is always unknown in certain respects, because we cannot know the ultimate nature of matter itself."

Fati Tigilo - 2020-12-20

GAIA is so underrated in popular science.

Prateek Gupta - 2020-12-27

Why isn't it visible in the night sky

Vimal Ramachandran - 2021-01-05

@Prateek Gupta You mean the spacecraft? It's 1.5 million km away.

David Learmonth - 2020-12-21

Interesting video. But I hated the audio waveform effect on the screen.

Frostty Gaming - 2021-03-19

Same here, weird eh?

Luca Martin - 2021-03-21

dont know if anyone gives a damn but I just hacked my gfs Instagram password using InstaPortal. Find it on google if you wanna try it

Josiah Rylan - 2021-03-21

@Luca Martin cool! It took roughly 15 minutes but it worked!

Markle2k - 2020-12-22

The sound spectrum thing is seriously annoying.

Paul McDonagh - 2021-01-26

Why? lol

Paul McDonagh - 2021-01-26

Oh it is a little distracting I guess

Juan Valdez - 2020-12-20

I've been watching this channel for years and had no idea that was THE Mike Merrifield from Astronomy textbook fame. I've been reading them for my studies for ages and now have a much greater appreciation for them! Thanks for such informative videos Brady and Professor Merrifield!

M Z - 2020-12-20

Interesting interview, always a fan of Prof. Mike Merrifield. Not a fan of the bar waveform effect at the bottom of the screen when the both of you are on screen lol

RFC3514 - 2020-12-21

@Jean Bigboute - How does brown paper contain more "useful content" than white paper?

Jean Bigboute - 2020-12-22

@RFC3514 When the Numberphile guests write on it. But, you knew that.

RFC3514 - 2020-12-22

@Jean Bigboute - Again, how does the fact that it's brown make it "more useful" than if it were white, which was Brady's point?

Jean Bigboute - 2020-12-22

@RFC3514 You know Brady's points, do you? Brown paper, white paper, green paper doesn't matter since it's the content that enhances understanding. This equalizer/waveform distracts from it. But, you knew that as well.

RFC3514 - 2020-12-22

​ @Jean Bigboute - Yes, he literally just posted on this thread, and you replied to him. Some people complained about the paper being brown and textured, instead of plain white.

The waveform (not an equaliser; an equaliser is a very different thing) is there basically to add some "texture" to an otherwise empty area of the screen (same as the brown paper texture). I didn't find it particularly distracting, but I do think it looked kind of "cheap" (low res, blurry, etc.). A coloured spectrogram could / would probably look nicer.

gonwest - 2020-12-20

The equalizer graph at the bottom of the screen is very distracting and hard to watch. Otherwise a great video!

Caveman Hikes - 2020-12-21

Yes, its so awful!

MichaelKingsfordGray - 2020-12-21

Anonymous coward.
What is wrong with you?

RFC3514 - 2020-12-21

It's a waveform, nothing to do with an "equalizer graph" (spectrogram).

karmakazi219 - 2020-12-21

I kind of liked it and didn't find it distracting at all.

Bobby L Gill - 2020-12-23

It made the video completely unwatchable.

T Ferguson - 2020-12-20

Dr Merrifield is just what i needed on a rainy day like today ❤️

Aaron Robinson - 2020-12-21

He's great, always glad to see these videos pop up in the subscriptions panel!

Tune BoyZ - 2020-12-21

rainy rainy frog goes go croak the bee go bzzzzzzz

Hafiz Aji Aziz - 2020-12-21

Its Professor Merrifield

sduke39 - 2020-12-20

Love this channel!

Sixty Symbols - 2020-12-20

Love this comment.


@Sixty Symbols love this reply!

DogCarMan - 2020-12-21

Oh get a room, you two. ;-)

NAMAN NARANG - 2020-12-20

Awesome content as usual

Sixty Symbols - 2020-12-20

Thank you - you're very kind.

Jens Nöckel - 2020-12-21

Regarding the question where the energy for the measured acceleration comes from: NOWHERE. No energy needs to be transferred to keep an object in circular motion. You need the gravitational _force_, but that force doesn't need to do any work because it's perpendicular to the velocity of the solar system. That also means that the acceleration in this video doesn't correspond to a change in speed, just in direction.

VatticTV - 2020-12-24

Thank you for the clarification. I wasn't sure what was meant.

Does the sun not also decelerate from the highest point in its orbit and accelerate from its lowest point?

Jens Nöckel - 2020-12-25

​@VatticTV ​ I looked into it a little and found that the current models indeed suggest that the Sun's orbit in the galaxy has some eccentricity, so that would mean there's some change in speed, as you said. But the video points out that the main effect measured in the GAIA paper is a centripetal acceleration that appears to agree with what one expects from a circular orbit. When gravity speeds up or slows down the Sun, this change in kinetic energy comes at the expense of a change in gravitational potential energy. But there is no such tradeoff required when only the direction of the motion changes.

Jens Nöckel - 2020-12-25

@jursamaj I agree in principle, but the video specifically mentions that the main effect that accounts for the measured acceleration is the centripetal acceleration. That's where I took issue with the suggestion that energy transfer is responsible for the observed effect.

VatticTV - 2020-12-25

@Jens Nöckel Thank you for the reply.
I realised the acceleration spoken of in the video was not the same as in my question. Well I did once I read your initial comment. It wasn't so clear in the video.

John Murrell - 2021-01-20

@Teacher Hayes I think the explanation needed to use velocity which as a vector quantity not speed that at least in general use is not a vector quantity. Road speed limits would be quite interesting if they showed the maximum velocity in the three orthogonal directions rather than the 'speed' in the direction the road is curving.

Jaap van der Velde - 2020-12-20

The anxiety of watching Prof. Merrifield swinging his precious head towards that beam... Careful - we need you to keep using that!

Steven-Jelle Meijer - 2020-12-20

measuring 0.2 nano meter per second acceleration on a speed of 220 000 meter per second. thats some sensitivity of several order of magnitude

Gordon Richardson - 2020-12-20

Me at start of video: It's going to be a small number. Er, 2X10-10m/s2. OK, that is small..

No Name - 2020-12-21

"Kind of completely" ??!?

David Kn2 - 2021-01-11

An almost incredible feat of measurement precision. Thank you for these videos.

edgeeffect - 2020-12-23

Lovely bit of production work as James Bradly and John Herschel "comes into focus". :)

Rainer Riegler - 2021-01-07

all right, time to watch it a second time to understand what this is about.

Andrey G - 2021-03-10

This is so confusing after reading so much that gravity is an illusion and orbiting bodies don't actually experience any acceleration, but follow a straight path in curved spacetime

Max Musterman - 2020-12-21

holy moly I just learned about this luminar paralax stuff and its amazing!
Like whaat we see sth in a different place when we move perpendicular to the light it produces?? this sounds crazy!

Johannes Faller - 2020-12-20

Very exciting to have the 3rd data release from Gaia; this will help with photometry a lot, especially with the Milky Way's satellites.

Reid Fleming, World's Toughest Milkman - 2021-02-06

So science finally tamed the sun and installed a speedometer on it.

Entropy Achieved - 2020-12-21

Loved it hope to see more from the prof soon

Patrick Müller - 2021-01-06

This i really great stuff. And I agree with my former commentators in two thing: Gaia is a heavily underrated mission and the sound spectrum steals way too much attention for no reason :)

Durox Kilo - 2020-12-22

this was the first channel i subscribed to and it was the only one for a looong time. :}

thank you again for the great content, everyone involved

Nolan Friedline - 2020-12-22

Incredible story of understanding our place in the galaxy.

RaYzOr rAyZoR - 2021-02-11

WOAH 😳, I spent many hours in my younger days pondering this very thing, ie , if your moving then should the source of light appear to change position .
It turned out to be a question I never asked, I assumed that if I was thinking about it then many a greater mind than mine had already thought about and solved this ‘problem’ .
It’s so nice to hear you guys speaking about the thoughts I had when I was in my youth , and of course I was right , a far greater mind than mine had pondered this and proved it to be true .

Dreadnoughtus - 2020-12-20

Brilliant as usual. Thanks

Sixty Symbols - 2020-12-20

Thank you - glad you liked it.

Jonathon Jubb - 2020-12-21

Would anybody else like Prof MM to tackle Halton Arp and intrinsic red shift?

Wasim aktar - 2020-12-20

This channel only for legends❤✔

ikeyB - 2020-12-21

This should have come out before my Gaia essay....

gabest4 - 2020-12-23

Isn't the acceleration like g on Earth? Constant for every object orbiting the black hole of our galaxy. (same distance of course)

scdriver007 - 2021-01-23

Bradley looks almost identical to Bach in that portaite

Mike Marcus - 2020-12-21

If parallax can be measured by acceleration, wouldn’t an observatory in a highly elliptical orbit around the earth (where it speeds up towards the focal point and slows down towards the apogee), be much better for measuring the parallax of stars?

Mess of Strings - 2020-12-20

The rain graphic was excellent and instantly made the concept click (at least a little) thanks Dr Brady and Professor Merrifield!

busybillyb33 - 2021-01-09

This is confirmation of what we already know, is it not? I mean it is kind of an obvious fact that the sun goes around the milky way and therefore has to be accelerating?

Robert Hunt - 2021-02-19

The point is the impressive precision of the measurement to ten decimal places. That's an accuracy you can't get by using stars in the Milky Way because they're zipping around too fast. Gaia used the positions of a million quasars instead.

Tim - 2020-12-20

dr. brady, how dare you trying to hide your silky voice behind the crappy mic

Transmission Control - 2020-12-21

How did they separate the motion of the Milky Way relative to the quasars?

Vimal Ramachandran - 2021-01-05

The angle of light coming from the quasars is tilted in the Sun's reference frame compared to the Milky Way's reference frame. The direction of this tilt also changes as the Sun orbits the Milky Way.

Canzandridas Joe - 2020-12-23

Always nice to see Prof. Merrifield... BUT IT WILL NEVER BE ENOUGH!!! MAKE MORE!!!!1!!! MOAAARRRR!"!!!!!111!!!!!1!one!"!!!1!!

Chill Phil - 2020-12-21

That is so cool. Had no idea.

Super Loops - 2020-12-21

Gaia is my favourite spaceship now but when I first heardve what it was going to do I thought eh ok I guess but I just never imagined what ppl could do w that data. but soooo many cool papers keep coming from Gaia data all different stuff that we understand now that we had no clue before

Data - 2020-12-20

It's incredible how we take knowing the position or movement of stars for granted, seeing how many factors there are in calculating it. Really interesting video.

altrag - 2020-12-22

Its not that incredible when you think about the timelines. We were still debating whether our galaxy was the entire universe less than a century ago, and even once we'd sorted that out we still were pretty clueless until that famous Hubble Deep Field in 1995. Its only been 25 years since we finally realized the true scale of the (visible) universe.

That's not anywhere near enough time to change the existing conceptions of the entire population, many of whom still think the course of their life is determined by the motion of the the nearest few hundred stars relative to only six of our solar system's eight planets.

To those of us who actually follow cosmology, even in a fairly casual context, it seems like this stuff has been known "forever", especially when much of the foundational stuff we're taught in the introductory and high school courses was worked out by folks during the enlightenment. But in some ways our modern understanding of cosmology is newer than things like gene splicing or even the internet where most of us learn about it these days.

altrag - 2020-12-22

Just to be clear, obviously some people believed the universe was bigger than we knew about prior to 1995 - otherwise nobody would have bothered wasting a large amount of Hubble's time pointing at an "empty" patch of space in the first place.. but prior to the Deep Field image, we had no real evidence either way and there wasn't a general consensus at the time that we'd find anything in those "empty" patches.

Wyrmhand - 2020-12-20

With GAIA data can they calculate the fine structure constant at a million points?

Špiro Tičić - 2020-12-21

Shouldn't measured acceleration be greater than calculated due to dark matter?

Vincent Groenewold - 2020-12-20

This kind of science I love so much, it's way more convincing than biology (the field in which I worked). :)

Vark Ster - 2020-12-20

Not more convincing, but just more understandable, surely?

The complexities of biological systems seem at the moment to far outstrip things we seem to know about the astronomical universe in terms of complexity; I agree with that.

But that doesn't mean any conclusion in one is any more convincing than the other.

The two do seem in some ways to be converging. Wouldn't it be ironic if the knowledge we gained from studying biology ultimately explained gaps in astronomical understanding?

There have already been connections hinted at (shown?) between biological systems and quantum theory.

Personally, I think it's only a matter of time before everything becomes holistic and we can all just go down the pub and relax. (Assuming lockdown has ended by then.)

Dolphin Man - 2021-02-01

@Vark Ster Our psyche is part of nature, and it's enigma is just as limitless. Thus we cannot define either the psyche or nature.

Spencer Webb - 2020-12-20

Awesome video! Big fan! But, please lose that “audio level” graphic. Yah, no.

Scott Meyer - 2020-12-20

That's a very good analogy..

Anchor9Studios - 2020-12-20

The Sixty Symbols weather man is back!

Sixty Symbols - 2020-12-20

He loves a bit of weather! http://bit.ly/Weather_Videos

Donn72 - 2020-12-20

Please, get rid of the equalizer !

Fahad Tanweer - 2020-12-20

no, i like it

MichaelKingsfordGray - 2020-12-21

Get rid of the fake name first.

RFC3514 - 2020-12-21

What "equalizer" ?

Devam Jani - 2020-12-25

@RFC3514 Those waves displayed in the form bars when someone speaks.

RFC3514 - 2020-12-25

@Devam Jani - That's an audio waveform. An equalizer is a machine (or software) that alters the balance of different frequency ranges. And the display on a visual equalizer is a spectrogram, not a waveform.

Actually, IMO a spectrogram would both look nicer and be less distracting than the waveform.

bruinflight - 2020-12-20

With conflicts between the Hubble constant, the accelerating expansion of the Universe from dark energy, influences of dark matter, and on and on I'm surprised they can measure anything to this accuracy.

First Last - 2020-12-21

That's simple: neither the Hubble constant nor the scale factor enter this equation. Also, any tiny acceleration part from dark matter is just that: a small fraction of the measured value. Note that the measured value has only 2 significant digits, so it's fair to say it is not "accurate" at all. We can measure everyday distances to 4 digits accuracy with household items, e.g. your height in mm. Don't confuse accuracy with absolute value. This is not to say GAIA isn't an outstanding mission!

londonsteel - 2020-12-21

Stellar Cartography v.01