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Eris, Sun, Dysnomia (APOD 19 Jun 2007)

Posted: Tue Jun 19, 2007 8:58 am
by JohnD
Dysnomia = 'bad name' in dog Latin?

APOD 19 JUNE 2007 THE SUN AS SEEN FROM ERIS

Posted: Tue Jun 19, 2007 11:11 am
by Carl Horn
G'day,
The artist's view shows the sun in the background. Pictures I've seen of the sun as seen from Pluto show a small dot not much bigger than a star as seen from Earth. The sun in this picture as seen from Eris is much bigger. Which is correct?
Carl Horn
Nelson, New Zealand
:?:

APOD 2007 June 19 - Eris

Posted: Tue Jun 19, 2007 11:11 am
by l3p3r
I understand that this is just an artist's impression... but the picture is flawed in just about every way it is possible for such a picture to be flawed. The sun seems very big at two pluto orbits distance, Dysnomia is practically grazing the surface of Eris it is so close, the shadow on Dysnomia is pitch black whereas the dark side of Eris is partly illuminated.

I would say this picture, for example, is much more representative of the actual Eris system. http://en.wikipedia.org/wiki/Image:2006-16-a-full.jpg

Posted: Tue Jun 19, 2007 11:24 am
by jimmysnyder
In Greek mythology, Dysnomia was Eris' daughter. The word means lawlessness.

Re: APOD 2007 June 19 - Eris

Posted: Tue Jun 19, 2007 11:27 am
by Angus McPresley
l3p3r wrote:I understand that this is just an artist's impression... but the picture is flawed in just about every way it is possible for such a picture to be flawed. The sun seems very big at two pluto orbits distance, Dysnomia is practically grazing the surface of Eris it is so close, the shadow on Dysnomia is pitch black whereas the dark side of Eris is partly illuminated.

I would say this picture, for example, is much more representative of the actual Eris system. http://en.wikipedia.org/wiki/Image:2006-16-a-full.jpg

I came to this forum to say almost the exact same thing. The sun is WAY too big. It would look more like a bright pinprick from that distance.

The closeness of Dysnomia to Eris could just be perspective thing, though, I guess -- it could be a lot closer to the viewpoint. Which could explain how Eris' shadow could be partially illuminated -- it could be reflected off Dysnomia (given that the sun was that bright at that distance, which we know it would not be).

Posted: Tue Jun 19, 2007 12:00 pm
by l3p3r
Hi Carl!
Seems we both posted the same thing - at exactly the same time! (to the minute)

http://asterisk.apod.com/vie ... hp?t=12366

Perspective

Posted: Tue Jun 19, 2007 12:05 pm
by Kingslasher
The only way the sun could appear that large in relation to Eris is in a telescopic view from much farther out. However, that would make the observer see almost entirely the dark side and since that is not the case, I agree the artist's perspective is deeply flawed.

Re: APOD 2007 June 19 - Eris

Posted: Tue Jun 19, 2007 12:10 pm
by gargoyle
100% on the mark.
l3p3r wrote:I understand that this is just an artist's impression... but the picture is flawed in just about every way it is possible for such a picture to be flawed. The sun seems very big at two pluto orbits distance, Dysnomia is practically grazing the surface of Eris it is so close, the shadow on Dysnomia is pitch black whereas the dark side of Eris is partly illuminated.

I would say this picture, for example, is much more representative of the actual Eris system. http://en.wikipedia.org/wiki/Image:2006-16-a-full.jpg

Re: APOD 2007 June 19 - Eris

Posted: Tue Jun 19, 2007 3:20 pm
by RichardSRussell
Angus McPresley wrote:
l3p3r wrote:I understand that this is just an artist's impression... but the picture is flawed in just about every way it is possible for such a picture to be flawed. The sun seems very big at two pluto orbits distance, Dysnomia is practically grazing the surface of Eris it is so close, the shadow on Dysnomia is pitch black whereas the dark side of Eris is partly illuminated.

I would say this picture, for example, is much more representative of the actual Eris system. http://en.wikipedia.org/wiki/Image:2006-16-a-full.jpg

I came to this forum to say almost the exact same thing. The sun is WAY too big. It would look more like a bright pinprick from that distance.

The closeness of Dysnomia to Eris could just be perspective thing, though, I guess -- it could be a lot closer to the viewpoint. Which could explain how Eris' shadow could be partially illuminated -- it could be reflected off Dysnomia (given that the sun was that bright at that distance, which we know it would not be).
I too came to this forum to say almost exactly the same thing.

However, since I always at least TRY to figure out a logical explanation for why something appears the way it does, I suggest that perhaps, in the artist's mind, this is what Eris and Dysnomia will look like after the Sun goes nova.

Re: APOD 2007 June 19 - Eris

Posted: Tue Jun 19, 2007 3:40 pm
by Andy Wade
I was going to say that Dysnomia looks more like one of those holes in the surface of Mars... :lol:
OK, I'll get my coat... :)

Re: APOD 2007 June 19 - Eris

Posted: Tue Jun 19, 2007 9:35 pm
by salientNZ
[quote="Angus McPresley"]
I came to this forum to say almost the exact same thing. The sun is WAY too big. It would look more like a bright pinprick from that distance.
[/quote]

I also came here to say the same thing. And also to rant a bit :-).
[rant]
Why is it that virtually every artist's impression on APotD is seriously flawed ! Show this picture to almost any Astronomer, and they'll tell you that it is seriously wrong.

In this case, the error is seriously compounded by describing the artist as a "scientific artist". Codswallop! There's sod all science in this picture.
[/rant]

Cheers,
Brent.

Posted: Tue Jun 19, 2007 10:23 pm
by JohnD
Oh, come on!
They are "artists".
They "interpret reality".
A true image would show a tiny speck of light and a dim sphere. Where's the fun in that?

You'll be saying next that the Mona Lisa didn't really have a smile, that Monet was just a half blind old man and that Guernica would have been better served by a photograph.

John

Posted: Tue Jun 19, 2007 11:11 pm
by rigelan
Codswallop? I like it.

Posted: Tue Jun 19, 2007 11:17 pm
by BMAONE23
http://antwrp.gsfc.nasa.gov/apod/ap070619.html
Yes it is art for art's sake but if I were doing it, I would try to approximate the relative size of the sun as would be viewed from this distance. (It should be markedly smaller than it is) I would be certain that the lighting conditions would be proper enough to be believeable. (the lit surface shouldn't be any lighter than the dark side was depicted). Probably the biggest problem, the Lighting angle of ERIS is different than that of Dysnomia. (Granted that though Sun depicted is far too close, the lighting angles do receede back to the star)

It would be more likely a depiction of Gliese 581d

Posted: Wed Jun 20, 2007 2:08 am
by rigelan
Actually, i meant I liked the word 'codswallop'. The picture is nice too.

Posted: Wed Jun 20, 2007 7:02 am
by Andy Wade
rigelan wrote:Actually, i meant I liked the word 'codswallop'. The picture is nice too.
Cod's 'Wallop' is the eggs from the Cod fish. It's used as a general term (here in England at least) to describe anything that is useless, rubbish or undersirable. As opposed to Caviar, presumably.
Sounds good too, especially in an argument when you're describing someone else's point of view.
"You're talking a right load of old codswallop!" :wink:

Posted: Wed Jun 20, 2007 8:52 am
by craterchains
Andy Wade wrote:Cod's 'Wallop' is the eggs from the Cod fish. It's used as a general term (here in England at least) to describe anything that is useless, rubbish or undersirable. As opposed to Caviar, presumably.
Sounds good too, especially in an argument when you're describing someone else's point of view.
"You're talking a right load of old codswallop!" :wink:
Much of the so called "artist depictions" are just that, codswallop.
Please, and now scientific artist? Codswallop indeed, , ,

Norval

Posted: Wed Jun 20, 2007 11:23 am
by l3p3r
In this case, the error is seriously compounded by describing the artist as a "scientific artist". Codswallop! There's sod all science in this picture.
It's almost as bad as the "science" they claimed to have in that abysmal movie Sunshine!

Eris

Posted: Sat Apr 26, 2008 10:27 pm
by Chuck Bennett
Last summer (June or July of 2007) you ran a picture of the planet Eris which you said was larger than Pluto. Is the the same as the rumored "Planet X" which is supposed to come close to the earth in 2012?

Posted: Sun Apr 27, 2008 2:34 am
by Qev
http://en.wikipedia.org/wiki/Eris_%28dwarf_planet%29

No, Eris is just a trans-Neptunian object, and the ninth-largest known satellite directly orbiting the Sun. Its orbit never brings it closer to the Sun than about 39 AU.

Re: Eris

Posted: Sun Apr 27, 2008 5:13 am
by Case

Re: Eris

Posted: Sun Apr 27, 2008 9:11 am
by SittingDownMan
Thank you for that one.
The picture on the day after that one
http://apod.nasa.gov/apod/ap070620.html
is also a lovely image. A view of three worlds, and a star off to the right.

Human beings have actually walked on two of the worlds in that image.


:) SDM