/ The pale blue dot picture

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Pursued by a bear 13 Feb 2020

Terrific to see that the classic pale blue dot picture has been re-mastered.  Terrific too to see the picture taken by the Cassini mission some years later, of which I was unaware.

You, me, everyone who is or ever was, every hope and ambition, every dream that was ever dreamt, all on that small dot of luminous blue.

Humbling, isn't it?

https://www.bbc.co.uk/news/science-environment-51491471

T.

1
The Lemming 13 Feb 2020
In reply to Pursued by a bear:

Does this image prove the earth is flat?

2
FactorXXX 13 Feb 2020
In reply to The Lemming:

> Does this image prove the earth is flat?

No, it proves that it is far away...

The Lemming 13 Feb 2020
In reply to FactorXXX:

You been watching Father Ted?

FactorXXX 13 Feb 2020
In reply to The Lemming:

> You been watching Father Ted?

Possibly...

Blue Straggler 14 Feb 2020
In reply to The Lemming:

> Does this image prove the earth is flat?

Are you funny ? 

1
Andy Hardy 14 Feb 2020
In reply to The Lemming:

It's not got enough resolution to pick out the 4 elephants and the turtle

Wyn 14 Feb 2020
In reply to Andy Hardy:

If you look carefully, you can just about make out Donald Trump's ego.

This is probably my favourite image.  Although thinking about it too much makes my head hurt.

https://hubblesite.org/image/3886/category/58-hubble-ultra-deep-field

jkarran 14 Feb 2020
In reply to Pursued by a bear:

That Cassini shot! Thanks for sharing

jk 

Coel Hellier 14 Feb 2020
In reply to Pursued by a bear:

> Terrific too to see the picture taken by the Cassini mission some years later, of which I was unaware.

Whenever I give talks to school kids about planets and discovering planets, I include that picture.  (Usually, with the question "what do you think that is?"  The suggestions are usually "a moon of Saturn?" or similar, which is actually a good guess.)

Tom V 14 Feb 2020
In reply to jkarran:

Any idea what causes the light edges on the planet's rim?

stevieb 14 Feb 2020
In reply to Wyn:

> If you look carefully, you can just about make out Donald Trump's ego.

> This is probably my favourite image.  Although thinking about it too much makes my head hurt.


that's just a close up of their granite worktop

Coel Hellier 14 Feb 2020
In reply to Tom V:

> Any idea what causes the light edges on the planet's rim?

Refraction of light in the planet's atmosphere. 

Edit to add: There's a neat illustration of this effect (regarding Earth) at:  https://twitter.com/david_kipping/status/1227691888737693696

Post edited at 10:37
DaveHK 14 Feb 2020
In reply to Andy Hardy:

> It's not got enough resolution to pick out the 4 elephants and the turtle

Just the one turtle? I thought they went all the way down?

henwardian 14 Feb 2020
In reply to Coel Hellier:

> Refraction of light in the planet's atmosphere. 

> Edit to add: There's a neat illustration of this effect (regarding Earth) at:  https://twitter.com/david_kipping/status/1227691888737693696

There are gaps in the lit-up atmosphere of Saturn... is this caused by the shadows of the rings? I'm not sure quite how that would work out... if it isn't ring shadows, I'm a bit suspicious/confused by the lighter and darker bits of rim.

In the second one, I can't get my head around how anything other than post-processing could generate the progressing outline of earth and the sun coming out of the eclipse at the bottom right.

Toerag 14 Feb 2020
In reply to DaveHK:

> Just the one turtle? I thought they went all the way down?

Have you heard about the baby one they've found?

https://www.bbc.co.uk/news/world-latin-america-51485011

Wyn 14 Feb 2020
In reply to stevieb:

Now there's an idea - "Kosmic Kitchens"

Coel Hellier 14 Feb 2020
In reply to henwardian:

> There are gaps in the lit-up atmosphere of Saturn... is this caused by the shadows of the rings?

I think so, yes.  In this image the Sun is close to directly away from the camera, behind Saturn.

> I can't get my head around how anything other than post-processing could generate the progressing outline of earth and the sun coming out of the eclipse at the bottom right.

It's because the  Earth, Sun and the spacecraft are moving relative to each other. The bright-ring effect caused by refraction will depend sensitively on the precise alignment of the Sun and Earth. 

henwardian 14 Feb 2020
In reply to Coel Hellier:

> It's because the  Earth, Sun and the spacecraft are moving relative to each other. The bright-ring effect caused by refraction will depend sensitively on the precise alignment of the Sun and Earth. 

Hmm, yes and no... While all 3 are moving, it's only really the movement of the satellite that is changing things because the the earth is orbiting the sun and so is the satellite (with a path that is, to within a tiny degree, exactly the same as the earth. The sun is moving but that movement is really relative to the other things in the galaxy, not the solar system, which is, in it's entirety moving in the same direction and speed as a unit.

When the sun is obscured behind the earth, there should be a complete bright ring around the edge as there is plenty of atmosphere to refract light (unlike in a normal solar eclipse with the moon where the ring you can see is the suns atmosphere). Even if the satellite is close enough to the earth that the earth is relatively a fair bit bigger than the sun, the bright spot of the sun poking out should occur when there is relatively symmetrical bright ring effect on either side of that bright spot and there isn't - the left and lower side is still dark.

I can't see this as anything other than a sequence of photos taken in succession where some sort of obscuring black plane is being pulled down the photo gradually rather than a genuine sequence of shots showing the progression of the eclipse. I could be wrong but I'd need someone to explain to me exactly you could get this sequence in another way.

Coel Hellier 14 Feb 2020
In reply to henwardian:

> While all 3 are moving, it's only really the movement of the satellite that is changing things because the the earth is orbiting the sun and so is the satellite (with a path that is, to within a tiny degree, exactly the same as the earth.

Except that the satellite is in Lunar orbit. But yes, what matters is the motion of the satellite relative to the Earth-Sun axis.

> When the sun is obscured behind the earth, there should be a complete bright ring around the edge as there is plenty of atmosphere to refract light

But realise that "refraction" does not scatter it light in all directions.  It diverts the path of the light into one particular direction. 

See e.g. https://en.wikipedia.org/wiki/Refraction#/media/File:Refraction_photo.png

So, no, in general you would not see a bright ring just because the sun is behind the earth.  You would only see the bright refracted light from a limited range of places.   And thus, since the spacecraft is moving, it would only see parts of the ring at any one time.

One could, in principle, see a complete ring, but then the spacecraft would have to be precisely along the Sun-Earth line, AND it would have to be at exactly the right distance from the Earth to see the ring.  Presumably neither of those hold exactly in the case of this movie.

It's also possible that local weather is affecting which parts of the ring one can see.  Clouds would presumably greatly dim that part of the rim, compared to a clear sky. 

Tom Last 14 Feb 2020
In reply to Pursued by a bear:

“It’s only a model...”

Robert Durran 14 Feb 2020
In reply to jkarran:

> That Cassini shot! Thanks for sharing

Yes, I must have seen it before, but it is boggling. As are many of Cassini's.

The Lemming 15 Feb 2020

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