The Venus-Saturn conjunction is still to come – day after tomorrow – and it’s worth revisiting the description I gave a few days ago, if only to see Eric David’s comment. He not only shows his beautiful photograph of Venus drawing near to Saturn, over a river (the Shenandoah?), but points out a kind of paradox.
“I wondered if one more graphic could help illustrate an interesting aspect of your map of the sky showing Venus passing Saturn. … in February 2019, our sightline showed Venus above the ecliptic by about 2 degrees, while in December 2019, against the exact same stars, our sightline shows Venus 2 degrees below the ecliptic. So, somewhere in Venus’ orbit between those two points, it must have gone through descending node? We are in a different position in our orbit, by more than 2/12 of the way around, so I assume Venus is in a significantly different place in its orbit as well, is that right?”
It is, and the whole thing is not easy to visualize without, as Eric suggests, further diagramming. In making that map, I had thought of including the whole path of Venus from February to December; it would have formed an S-shape, like the path for Saturn, but on a far larger scale, making the map crowded, and still not clarifying what happens. To do that, we need a spatial picture.
See the end note about enlarging illustrations.
The view is from 15° north of the ecliptic plane, and shows the paths of Earth, Venus, and Saturn in the months of February and December, with sightlines from Earth to those planets at the Feb. 18 and Dec. 11 conjunctions.
Also the line of nodes of Venus’s orbit, which in 2019 Venus crosses on March 14 (descending), July 5 (ascending), and Oct. 25 (again descending).
From February to December, Saturn has chugged a relatively short way along its orbit; Earth has almost completed an orbit (just two months short); but Venus has overlapped itself. To help clarify this, I’ve also shown Earth and Venus (in gray) half way between those times, in July.
You still need to wind Venus around with your finger from February to July and December. That helps, perhaps not completely, in getting your head around it. A Mercury situation would be even more complex. All would be simpler if planets were only outward from us – no bustling Mercury and Venus! Simpler but not as beautiful.
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Home-planet department:
Australia is being punished for electing a prime minister who denies climate science and is only interested in exporting coal.
https://www.theguardian.com/australia-news/2019/dec/07/australia-fires-blazes-too-big-to-put-out-as-140-bushfires-rage-in-nsw-and-queensland?CMP=Share_iOSApp_Other
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In the last days before Britain’s December 12 general election, there are desperate calls for “tactical voting.” That means, “holding your nose” and voting for C when you like B better. Or, more drastically, calls for candidates C and D to withdraw. Why? Because in countless constituencies, such as the one I live in, there are two sides: Conservative, which wants brutal Brexit; and Labour, Liberal Democrat, Green, and Scottish National Party, which want no Brexit or at least for the people to get a chance to vote on whatever Brexit deal is at last negotiated, if any. So the latter side, though probably more numerous and, in my opinion, more wise, is divided, and may lose its chance to stop the reckless prime minister.
Yesterday evening here, there was a hustings, held in a youth center. All the parties’ candidates promised to be there and face questions – except the Conservative. I hope somebody did suggest to them that C, D, E, and F should step down in favor of B and urge their supporters to vote for B. I doubt it; the tendency should have been started earlier.
In any case, tactical voting and tactical withdrawal are messy, questionable solutions.
There is a simple solution that would forever prevent this recurrent agony: Approval Voting. Wikipedia can tell you what that is, or you can acquire my (now enlarged) booklet about it.
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ILLUSTRATIONS in these posts are made with precision but have to be inserted in another format. You may be able to enlarge them on your monitor. One way: right-click, and choose “View image”, then enlarge. Or choose “Copy image”, then put it on your desktop, then open it. On an iPad or phone, use the finger gesture that enlarges (spreading with two fingers, or tapping and dragging with three fingers). Other methods have been suggested, such as dragging the image to the desktop and opening it in other ways.
This weblog maintains its right to be about astronomy or anything under the sun.
Been having some fine views of the low Venus but Saturn is still not quite in conjunction territory.regarding the election looming over England I think that you only have 2 parties standing labour and conservative as you can split the conservative party into 3(core conservative, right wing conservative Britexit and left wing conservative liberal and we must not forget the liberals backing up the Cameron conservative government nor Vince cable giving away the Royal mail to a Canadian hedge fund for a fraction of the true value….the sins of the Fathers?).
Guy, thank you so much for the extremely clear explanation of the planet positions! Your diagrams make total understanding a cinch. I am reminded of a comment you made in an Astronomical Calendar of many years ago when you memorialized the passing of one of your contributors, Jim Loudon I believe, who wrote about spaceflight. He apparently insisted on explaining things “exhaustively”, which I think your diagrams do in the most efficient manner possible. Thanks again!
I should have added that the image of Venus and Saturn to which Guy was referring was taken in front of a series of ponds at a local sand and aggregate quarry, not a scenic river like the Shenandoah! The ponds serve as a stopping point for migrating flocks of geese and other waterfowl in the fall and spring. The Rappahannock River is a half mile away from where the picture was taken but access to it is very limited in our area.
Eric David’s observation was astute, and the illustration is masterful, thank you! I caught a glimpse of Venus and Saturn yesterday evening during a rare break in the clouds. I enjoyed imagining where we all are in our various orbits around the Sun. If I’d seen this illustration beforehand my imagination would have been more precise.
Living here in California, I know what it feels like to have out of control wildfires burning outside my city. I don’t think it makes sense to say that Australia is being punished. Who’s doing the punishing? All the causes of these fires have come into being over a longer time frame than the term of any one politician, and they would continue to exist even after a change of government. Of course we all need to stop extracting and burning fossil fuels, and we need to develop viable alternatives. But I think a sober recognition of cause and effect would be more helpful than moralizing.
Good luck with the election and sorting out Brexit. From my outside perspective it would make sense to hold another referendum.
Sure. Sometimes one chooses between slogan and exhaustive – between pithy over-simplified expression, and carefully phrased and less trenchant expression.
Nevertheless, the dreadful fires in California and Australia and Brazil are as bad as they are because global temperature is continuing to rise, and that is in large part because men to wwhom huge power has been given – Tramp, Morrison, Bolzonaro – are doing the opposite of what should be done.
I think the issue is more than rhetorical. Atmospheric carbon dioxide concentrations have been increasing for 200 years and are now higher than anytime in the past 15 million years. Even if we stopped emitting carbon dioxide today it would take at least 40 years for the climate to stabilize. I wish we could just tar and feather Trump, Morrison, Bolsonaro, et al., drive them out into the wilderness, and have a party. But getting climate criminals out of public office, while necessary, is really just a tiny part of what we need to do. Making climate catastrophe a simple story of good guys and bad guys is a counterproductive oversimplification.
You and I agree about the problem and what needs to be done. I just don’t like the trope of describing wildfires as just punishment for the victims who are losing their homes and sometimes their lives.
I suppose that you could tar and feather them,if you survived the encounter with their bodyguards!,but remember that they are just a front for far more sinister oligarchs behind them.the sort of grinning people with beards who say airlines can be carbon neutral….how do you get 4 tons of metal,cargo and people into the air without generating a lot of carbon simple you can’t.or other oligarchs who’ll plug electric cars and insult cave rescuers but won’t tell you how much energy is used to make these cars or where the powers is coming from to power them electric cars only 1 person will be sat in most of the time.