# My this is Big.

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I came across the Image this morning, in a News Bulletin, so I thought I might place it on SGL,
to let the unaware, become aware, of the vastness out there, and in particular the following.

The Star is VY Canis Majoris, and it is shown in a comparison to our sun.
the small rectangle at the bottom also indicates our suns comparative size.
VY Canis Maj. is one of the largest and luminous d=stars known, and was at one time the largest.
It has a diameter of 13.2 Astronomical Units, our sun earth distance being One AU.
It is 3,900 light of years from Earth.   If the star was placed at the centre of the Solar System, It's physical size
would extend beyond the Orbit of Jupiter. It is also a Semi Regular Variable, with a period of 2,000 days.
There are some variations in the estimates of it's radius.
Isn't that vast Cosmos just full of interesting stuff?

CREDITS.   (Data extracted from Wiki)

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That's a big star! ?

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That is a really big star - its helps to put things into perspective.

Jim

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It is enormous.

Wiki says the radius is 1420 times that of the Sun, and its mass is 17 solar masses.
That makes its density 17 / 14203 = 0.0000000059  times that of the Sun, which works out to 0.0000083 kg/m3.

At sea level, our atmosphere has a density of 1.2 kg/m3, so VY Canis Majoris is a whole lot of almost nothing!

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That is big!

I thought 1 AU was the distance from the sun to earth, not the diameter of the sun. 1.46*10^8km, if I remember correctly.

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52 minutes ago, Joe12345 said:

That is big!

I thought 1 AU was the distance from the sun to earth, not the diameter of the sun. 1.46*10^8km, if I remember correctly.

4 hours ago, barkis said:

The Star is VY Canis Majoris has a diameter of 13.2 Astronomical Units, our sun being One AU.

I had to look this up:

from Wiki: "The solar radius is approximately 695,700 kilometres (432,288 miles), which is about 1/215th of an astronomical unit"

Wiki: A more recent and accurate VLTI measurement gives the star VY Canis Majoris a radius of 1420 ± 120 solar radii

So, 1420 solar radii * (1/215th of an AU) = 6.6 AU radius = 13 AU diameter

That is big!

Edited by Vox45
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3 hours ago, Vox45 said:

I had to look this up:

from Wiki: "The solar radius is approximately 695,700 kilometres (432,288 miles), which is about 1/215th of an astronomical unit"

Wiki: A more recent and accurate VLTI measurement gives the star VY Canis Majoris a radius of 1420 ± 120 solar radii

So, 1420 solar radii * (1/215th of an AU) = 6.6 AU radius = 13 AU diameter

That is big!

An Astronomical Unit is the Earth Sun distance, so 13.2 AU x (Earth Sun distance), is YV Can. Maj. diameter.
Perhaps I ought to have cut and pasted Wiki's exact text, but It's something I don't practice much. Smacks of Idleness,
but it might have prevented confusion in this case .

Our figures differ by .2 AU, hardly worth worrying about.
I'm sure in due course, the data of this giant will change again.

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14 hours ago, barkis said:

An Astronomical Unit is the Earth Sun distance, so 13.2 AU x (Earth Sun distance), is YV Can. Maj. diameter.
Perhaps I ought to have cut and pasted Wiki's exact text, but It's something I don't practice much. Smacks of Idleness,
but it might have prevented confusion in this case .

Our figures differ by .2 AU, hardly worth worrying about.
I'm sure in due course, the data of this giant will change again.

I was not trying to correct you on this I was just trying to dispel confusion about the radius of the sun as being 1/215th of an AU and not a diameter of 1 AU as originaly posted.

22 hours ago, barkis said:

It has a diameter of 13.2 Astronomical Units, our sun being One AU.

I assure you, I was not trying to be pedant about it. It was more for my own understanding and love of discussion about things astro

Great post by the way ! it keeps things in perspective

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1 hour ago, Vox45 said:

I was not trying to correct you on this I was just trying to dispel confusion about the radius of the sun as being 1/215th of an AU and not a diameter of 1 AU as originaly posted.

I assure you, I was not trying to be pedant about it. It was more for my own understanding and love of discussion about things astro

Great post by the way ! it keeps things in perspective

Not to worry,   I didn't intend to  seem I was fussy,   I was more concerned I  had  possibly misled you,  or anyone else who joined the thread.   I never get upset,  life's too short anyway.   It is important that  details are in the main correct,   and  members have every right  to ensure  they are.

We can all learn something new,  and we have vast pool of knowledge  on SGL.

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That is one BIG star!

Thanks for boggling my mind!

Dave

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I wonder what the escape velocity is ? .
Not that anyone will ever be parked there, and wishing to get off it .

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The scale is mind boggling. It's this sort of stuff that makes astronomy amazing, the sizes, distances and time scales are at the edge of what is imaginable (sometimes beyond).

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Great. Just when we think we've sorted it out, someone comes along with an even bigger sun. Can't we just stick to the plan?

Nice one, thanks.

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Mind boggling. And in the same vein i was reading about IC1101 which is the largest currently known galaxy at nearly 2 million light years across.

" Just how large is it?  At its largest point, this galaxy extends about 2 million light-years from its core, and it has a mass of about 100-trillion stars. To give you some idea of what this means, the Milky Way is just 100,000 light-years in diameter. If our galaxy were to be replaced with this super-giant, it would swallow up both Magellanic clouds, the Andromeda galaxy, the Triangulum galaxy, and almost all the space in between. That is simply staggering. "

Just crazy crazy stuff.

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Ok guys who ate all the nebula?    ....awww ...who do you think, it was that  VY Canis Majoris  over there  ...look at him    ....even ate all the tasty dark nebula!

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• 2 weeks later...

I've been fascinated by VY Canis Majoris ever since I read about it several months ago. On some lists it is the largest known star in the Universe. Other lists, name other stars, but it is among the largest.

For comparison sake, it is said that the sun could hold approximately 1 million earths, VY Canis Majoris can hold approximately one billion Suns.

I haven't done so yet, but the star is visible in a modest scope or binos and I plan to have a look-see. It is about 8th magnitude currently. Of course, it will appear quite ordinary. But knowing what it actually is will add a thrill to the view, I'm sure. Looking at Canis Major, it is south near the tail area and to the east.

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There are some lovely videos on YouTube that show size comparison starting with planets in the solar system then the sun and through various stars ending with VY Canis Majoris. I've used this one in the classroom and it really does get you thinking about scale.  I haven't checked the maths but I like the comparison at the end which shows the time it would take a passenger jet to fly around the star - lovely perspective that let's you get your head around the massive size of the thing.

Jim

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On 07 March 2016 at 17:06, Vox45 said:

I had to look this up:

from Wiki: "The solar radius is approximately 695,700 kilometres (432,288 miles), which is about 1/215th of an astronomical unit"

Wiki: A more recent and accurate VLTI measurement gives the star VY Canis Majoris a radius of 1420 ± 120 solar radii

So, 1420 solar radii * (1/215th of an AU) = 6.6 AU radius = 13 AU diameter

That is big!

And I thought it was it was a long way to the shops!

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Simply amazing ! Blows my mind to consider the size of these massive giants !

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21 hours ago, saac said:

There are some lovely videos on YouTube that show size comparison starting with planets in the solar system then the sun and through various stars ending with VY Canis Majoris. I've used this one in the classroom and it really does get you thinking about scale.  I haven't checked the maths but I like the comparison at the end which shows the time it would take a passenger jet to fly around the star - lovely perspective that let's you get your head around the massive size of the thing.

Jim

Good video but yes i think their maths is flawed. I make it 355 years to orbit it once, but i t could be my maths.

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Only looks about 2" across on my monitor...

When my daughter was small one of her favourite books was 'Is a Blue Whale the Biggest Thing There Is?" which went on scaling up bigger and bigger with things such as crates of 'Sun-sized oranges' and comparing them to the red giant Betelgeuse.

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Very good video. Liked the music as well

Steve.

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On 20/03/2016 at 00:29, joe1950 said:

I've been fascinated by VY Canis Majoris ever since I read about it several months ago. On some lists it is the largest known star in the Universe. Other lists, name other stars, but it is among the largest.

For comparison sake, it is said that the sun could hold approximately 1 million earths, VY Canis Majoris can hold approximately one billion Suns.

I haven't done so yet, but the star is visible in a modest scope or binos and I plan to have a look-see. It is about 8th magnitude currently. Of course, it will appear quite ordinary. But knowing what it actually is will add a thrill to the view, I'm sure. Looking at Canis Major, it is south near the tail area and to the east.

If you like looking at "odd" stars you might want to have a peek  at HD 140283 - in Libra (https://en.wikipedia.org/wiki/HD_140283) - it is known as the "Methuselah" star because it is believed to be almost as old as the universe (it is about mag 7.2). It got a pensioner's bus-pass before Yoda was even born, and is probably the closest Population II star to earth. Given that it is very poor in "metals" (other than a bit of lithium), it possibly doesn't have much in the way of potentially habitable planets, let alone planets with very, very old ruins on them that could feature in some "Star Trek" episode (complete with "Greek" architecture so you know the ruins are old).

P

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23 minutes ago, nameunknown said:

Given that it is very poor in "metals" (other than a bit of lithium), it possibly doesn't have much in the way of potentially habitable planets, let alone planets with very, very old ruins on them that could feature in some "Star Trek" episode (complete with "Greek" architecture so you know the ruins are old).

P

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