APOD: Venus and Jupiter are Far (2015 Jul 03)

Post a reply


This question is a means of preventing automated form submissions by spambots.
Smilies
:D :) :ssmile: :( :o :shock: :? 8-) :lol2: :x :P :oops: :cry: :evil: :roll: :wink: :!: :?: :idea: :arrow: :| :mrgreen:
View more smilies

BBCode is ON
[img] is ON
[url] is ON
Smilies are ON

Topic review
   

Expand view Topic review: APOD: Venus and Jupiter are Far (2015 Jul 03)

Re: APOD: Venus and Jupiter are Far (2015 Jul 03)

by FullMoon » Tue Jul 07, 2015 2:12 am

I've admired APOD for a long time. There are so many superb images of the universe, be it faraway galaxies or our own solar system. And then our own sun and moon, which constitute much of my work.

Jupiter looks particularly nice with its marble-like stripes. No big spot to spoil it in this shot.

Re: APOD: Venus and Jupiter are Far (2015 Jul 03)

by Bubbles Not » Mon Jul 06, 2015 4:18 pm

mccolingrath wrote:Why does Venus look like it was cut and pasted into the final image? There is an obvious square around Venus which has a slightly different background color than the rest of the image.
APOD Robot wrote:...stack of images[/url]...

Re: APOD: Venus and Jupiter are Far (2015 Jul 03)

by mccolingrath » Mon Jul 06, 2015 6:44 am

Why does Venus look like it was cut and pasted into the final image? There is an obvious square around Venus which has a slightly different background color than the rest of the image.

Re: APOD: Venus and Jupiter are Far (2015 Jul 03)

by geckzilla » Sun Jul 05, 2015 7:03 am

Cousin Ricky wrote:I understand well that there is often a fine line between pedantry and correcting someone who is just plain wrong, but asking for a correctly oriented astrophoto is not even wrong.
It happens rather frequently, but usually with deep space imagery. This doesn't bother me so much as when someone comes to tell us that the moon is wrong because it was shot in the southern hemisphere or along the equator or something. If there's some standard north up, fine, but northern-hemisphere-centrism is tiresome.

Re: APOD: Venus and Jupiter are Far (2015 Jul 03)

by Cousin Ricky » Sun Jul 05, 2015 5:18 am

geckzilla wrote:
Cousin Ricky wrote:
Charles Bull wrote:It would have been a better picture if it were oriented correctly.
I can't believe I'm reading this in an astronomy forum.
This is an astronomy and pedant forum, though.
I understand well that there is often a fine line between pedantry and correcting someone who is just plain wrong, but asking for a correctly oriented astrophoto is not even wrong.

Re: APOD: Venus and Jupiter are Far (2015 Jul 03)

by felopaul » Sat Jul 04, 2015 8:10 am

Re: APOD: Venus and Jupiter are Far (2015 Jul 03)

by Ann » Sat Jul 04, 2015 2:39 am

Thanks, Cousin Ricky and DavidCortner!

Ann

Re: APOD: Venus and Jupiter are Far (2015 Jul 03)

by Boomer12k » Sat Jul 04, 2015 1:07 am

As for me....Ptolemy SHOULD have gone to Aristarchus of Samos...and OBSERVED the correctness...and just nodded....but NOOOOOOoooooo...he had to be the one who was RIGHT...the "Fred Hoyle" of the day....

Took around 1500+ more years to get it corrected...and the Church did not help any with Galileo...

Some people on Yahoo Comments have stated this as a reason why Religion is false...but I point out it was a "SCIENTIST" and his studies, and theories, etc....that was incorrect...he just had everybody convinced...

It takes an open mind to look passed the "apparencies" and "illusions" of the night sky....It is totally AMAZING that Aristarchus could put it together, BC......even the correct order and distance of the planets around the Sun...at least those that were known....

:---[===] *

Re: APOD: Venus and Jupiter are Far (2015 Jul 03)

by DavidCortner » Fri Jul 03, 2015 10:03 pm

Ann, as Cousin Ricky pointed out, epicycles (and epi- epicycles within epicycles) were the key. They are requrired to make the Ptolemaic system reflect what we see in the unmagnified sky. In the simpified version you posted, Venus could appear at any distance from the Sun, even opposite the Sun in the sky. That, of course, never happened, and so Ptolemy et al needed to add complexity: they needed something to insure that Venus was always within 50-ish degrees of the Sun. An epicycle worked just fine until Galileo saw that Venus was not always only partially illuminated: sometimes it was fully illuminated. Maybe a sufficiently motivated Ptolemaniac could find a way to save the appearances with ever more complex epicycles, but too much is just too much and Copernicanism offered a vastly simpler (if somewhat humbling) alternative.

Re: APOD: Venus and Jupiter are Far (2015 Jul 03)

by geckzilla » Fri Jul 03, 2015 7:59 pm

Cousin Ricky wrote:
Charles Bull wrote:It would have been a better picture if it were oriented correctly.
I can't believe I'm reading this in an astronomy forum.
This is an astronomy and pedant forum, though.

Re: APOD: Venus and Jupiter are Far (2015 Jul 03)

by Cousin Ricky » Fri Jul 03, 2015 6:45 pm

Charles Bull wrote:It would have been a better picture if it were oriented correctly.
I can't believe I'm reading this in an astronomy forum.

Re: APOD: Venus and Jupiter are Far (2015 Jul 03)

by caliu » Fri Jul 03, 2015 3:29 pm

Boomer12k wrote:Finally got out and got my shots...not very good...my camera is a Samsung F40 video camcorder, but takes stills, and the focus kept going in and out. So, I ended up with some "Light Fans", "Light Bleed"....instead of points...My other shots, though foreground was focused, did not fair better. So....it is a camera issue. Need DSLR camera, I guess.

Really cool to see the details of Jupiter Cloud Bands.

It was too hot, and I was too tired to get out the Scope....

:---[===] *

They are two different photos, made telescope and dedicated video camera, then are assembled on a black background.

Re: APOD: Venus and Jupiter are Far (2015 Jul 03)

by Charles Bull » Fri Jul 03, 2015 1:11 pm

Charles Bull wrote:It would have been a better picture if it were oriented correctly.
...if it *had been* oriented correctly.

Re: APOD: Venus and Jupiter are Far (2015 Jul 03)

by Charles Bull » Fri Jul 03, 2015 1:09 pm

It would have been a better picture if it were oriented correctly.

Re: APOD: Venus and Jupiter are Far (2015 Jul 03)

by Joe Stieber » Fri Jul 03, 2015 12:50 pm

chrissionair wrote:It has to be mentioned that the picture shown is not possible, or is it? Because Venus is blended from the sun above, but if so, there would be day not night!
So i think the photographer mirrored the image. Am i right?
The image has been rotated 90 degrees counter-clockwise, probably to make a horizontal composition, which better fits most computer screens. To see it in a "normal" view, it would need to be rotated 90 degrees clockwise. That would put the sun below-right of Venus as one might expect.

The Jovian moons in the picture are, from top to bottom as presented, Callisto, Europa, Io and then Ganymede below Jupiter.

Re: APOD: Venus and Jupiter are Far (2015 Jul 03)

by Cousin Ricky » Fri Jul 03, 2015 11:31 am

Ann wrote:
DavidCortner wrote:Not to be TOO picky (is that possible?), but it wasn't the _crescent_ phases of Venus that did the trick. The full and gibbous phases were the problems for Ptolemy's followers. See, for example:
http://astro.unl.edu/classaction/animat ... emaic.html
Source: Archives of Pearson Scott Foresman,
donated to the Wikimedia Foundation
My interest in the Ptolemaic model has been minimal indeed, so I have no real right to say that I'm surprised by the animation that you showed us. I thought, however, that the Ptolemaic model postulated that all the planets and the Sun orbited the Earth. The animation you posted shows Venus orbiting a point halfway between the Earth and the Sun. But this picture on the left, which is supposedly an illustration of the Ptolemaic model, seems to show Venus orbiting the Earth, not orbiting a point source between the Earth and the Sun.

Ann
Your illustration shows a simplified version of the Ptolemaic model. The animation is closer to Ptolemy's actual model, showing an epicycle of Venus. (Even that is a simplification, as compound epicycles had to be added over time to the model to compensate for the inaccuracies in Ptolemaic predictions. I believe the proliferation of epicycles is what prompted Copernicus to seek another model. I don't know if Copernicus was aware of Occam's razor, but he certainly had that intuitive sense.)

Re: APOD: Venus and Jupiter are Far (2015 Jul 03)

by Cousin Ricky » Fri Jul 03, 2015 11:15 am

David J. Wilson wrote:I don't think that the moons of Jupiter, on their own, would have caused insuperable difficulty for the Ptolemaic system. The phases of Venus were the clincher.
Perhaps not, but they did resolve a philosophical question. The Copernican system had two centers of motion, the Earth (for the Moon) and the Sun (for everything else). This was perceived as an inconsistency. The discovery of Jupiter's moons proved that a single center of motion was not a property of the universe, and therefore, there was no inconsistency in the Copernican model. (And more broadly, this realization may have helped dispel the notion that nature conforms to human philosophical ideals: a second blow for what would later be known as the Copernican principle.)

Re: APOD: Venus and Jupiter are Far (2015 Jul 03)

by mikeA » Fri Jul 03, 2015 10:57 am

Cousin Ricky wrote:
mikeA wrote:Am I missing something? Wikipedi-ing around I find that the first telescopes were made in 1608 while Copernicus died in 1543?
The description does not say that Copernicus saw this view; it only says that this view supported the Copernican system. Indeed, a link in the description points to an article about Galileo, who was the first to make these observations (not necessarily in the same telescopic field).
The description says "Copernicus would also have enjoyed the simultaneous telescopic view including Jupiter's four Galilean moons and a crescent Venus". However, I have just realised that this could also mean that he would have enjoyed seeing this photograph if he was around today!

Re: APOD: Venus and Jupiter are Far (2015 Jul 03)

by Cousin Ricky » Fri Jul 03, 2015 10:49 am

mikeA wrote:Am I missing something? Wikipedi-ing around I find that the first telescopes were made in 1608 while Copernicus died in 1543?
The description does not say that Copernicus saw this view; it only says that this view supported the Copernican system. Indeed, a link in the description points to an article about Galileo, who was the first to make these observations (not necessarily in the same telescopic field).

Re: APOD: Venus and Jupiter are Far (2015 Jul 03)

by Guest2 » Fri Jul 03, 2015 9:57 am

Canon Koppernigk did not have access to any telescopes or any telescopic view of any planet.... telescopes were invented after hjs death. Galileo, Brahe, Kepler etc did, and some went on to support the Copernican system. The Copernican system actually in essence was not a strict heliocentric one, as Koppernigk had the centre of the 'universe' as the point in space which was the centre of the earths orbit, the sun in the vicinity. It was Kepler really who sorted everything out, a true heliocentric system working off (the unread) theory in Koppernigks book..... Read 'The Sleepwalkers' by Arthur Koestler for a true myth breaking analysis of some of the history in science....

Re: APOD: Venus and Jupiter are Far (2015 Jul 03)

by chrissionair » Fri Jul 03, 2015 8:41 am

It has to be mentioned that the picture shown is not possible, or is it? Because Venus is blended from the sun above, but if so, there would be day not night!
So i think the photographer mirrored the image. Am i right?

Re: APOD: Venus and Jupiter are Far (2015 Jul 03)

by Ann » Fri Jul 03, 2015 7:02 am

DavidCortner wrote:Not to be TOO picky (is that possible?), but it wasn't the _crescent_ phases of Venus that did the trick. The full and gibbous phases were the problems for Ptolemy's followers. See, for example:
http://astro.unl.edu/classaction/animat ... emaic.html
Source: Archives of Pearson Scott Foresman,
donated to the Wikimedia Foundation
My interest in the Ptolemaic model has been minimal indeed, so I have no real right to say that I'm surprised by the animation that you showed us. I thought, however, that the Ptolemaic model postulated that all the planets and the Sun orbited the Earth. The animation you posted shows Venus orbiting a point halfway between the Earth and the Sun. But this picture on the left, which is supposedly an illustration of the Ptolemaic model, seems to show Venus orbiting the Earth, not orbiting a point source between the Earth and the Sun.

Ann

Re: APOD: Venus and Jupiter are Far (2015 Jul 03)

by mikeA » Fri Jul 03, 2015 6:53 am

Am I missing something? Wikipedi-ing around I find that the first telescopes were made in 1608 while Copernicus died in 1543?

Re: APOD: Venus and Jupiter are Far (2015 Jul 03)

by Boomer12k » Fri Jul 03, 2015 6:03 am

Finally got out and got my shots...not very good...my camera is a Samsung F40 video camcorder, but takes stills, and the focus kept going in and out. So, I ended up with some "Light Fans", "Light Bleed"....instead of points...My other shots, though foreground was focused, did not fair better. So....it is a camera issue. Need DSLR camera, I guess.

Really cool to see the details of Jupiter Cloud Bands.

It was too hot, and I was too tired to get out the Scope....

:---[===] *
Attachments
SAM_0668.JPG
SAM_0668.JPG (7.65 KiB) Viewed 5906 times

Re: APOD: Venus and Jupiter are Far (2015 Jul 03)

by Guest » Fri Jul 03, 2015 5:51 am

Interestingly enough, although Venus appears to show less of itself than Jupiter because of the crescent, it does have the brightest magnitude because of its much closer distance to the sun and to us. That is counterintuitive for the least.

Top