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

[APOD Robot]

Venus and Jupiter are Far

Explanation: On June 30 Venus and Jupiter were actually far apart, but both appeared close in western skies at dusk. Near the culmination of this year's gorgeous conjunction, the two bright evening planets are captured in the same telescopic field of view in this sharp digital stack of images taken after sunset from Poznań in west-central Poland. In fact, banded gas giant Jupiter was about 910 million kilometers from Poland. That's over 11 times farther than crescent Venus, only 78 million kilometers distant at the time. But since the diameter of giant planet Jupiter is over 11 times larger than Venus both planets show about the same angular size. Of course, 16th century Polish astronomer Nicolaus Copernicus would also have enjoyed the simultaneous telescopic view including Jupiter's four Galilean moons and a crescent Venus. Observations of Jupiter's moons and Venus' crescent phase were evidence for the Copernican or heliocentric model of the solar system.

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[David J. Wilson]

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.

[Ron-Astro Pharmacist]

Wow. Seeing is believing and knowing the planets are on the same visual plane is one thing but taking an image that demonstrates what our vision is unable to view to is surely the height of an astrophotographer’s craft. I think Copernicus would be proud of his fellow countryman but could only have dreamed of seeing two planets as clearly as in today's APOD. A far cry from what Galileo could later illustrate from his view of a much closer moon but only the beginning for many who chose to follow in his footsteps.

galileo-moon-sketches.jpg (6.14 KiB) Viewed 5999 times

A big thanks to all who continue that evolution.

[DavidCortner]

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

[Guest]

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.

[Boomer12k]

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....

:---[===] *

[mikeA]

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

[Ann]

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

Click to view full size image

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

[chrissionair]

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?

[Guest2]

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....

[Cousin Ricky]

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).

[mikeA]

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!

[Cousin Ricky]

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.)

[Cousin Ricky]

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

Click to view full size image

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.)

[Joe Stieber]

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.

[Charles Bull]

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

[Charles Bull]

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

...if it *had been* oriented correctly.

[caliu]

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.

[Cousin Ricky]

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

I can't believe I'm reading this in an astronomy forum.

[geckzilla]

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.

[DavidCortner]

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.

[Boomer12k]

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....

:---[===] *

[Ann]

Thanks, Cousin Ricky and DavidCortner!

Ann

[felopaul]

no comment .....

Click to view full size image

[Cousin Ricky]

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.