Planet Six, long believed to be the outermost of the solar system, will be at opposition on July 20.
The moment of the opposition is July 22, 20 hours Universal Time – no, July 20, 22 UT! This is the sort of trap that catches arithmophobes like me, who are liable to show up at 8 on the 9th instead of 9 on the 8th.
Here is Saturn rising, just after Jupiter, which passed the “anti-Sun” point on July 14.
See the end note about enlarging illustrations.
And here is a space view: a survey of Saturn’s oppositions all around its orbit, like the picture we showed for Jupiter.
You can look at the Jupiter and Saturn pictures in alternation, because I’ve made them “open in separate windows”. If you do, remember that the Saturn picture it at a smaller scale, because it reaches out farther.
The constellation boundaries are painted on an imaginary sphere of radius 11 astronomical units (Sun-Earth distances). Saturn’s mean distance from the Sun is 9.5 AU.
The sightlines from Earth to Saturn are at the dates of opposition.
We think of Jupiter as going around the Sun in 12 years and Saturn in 30, so that Jupiter spends one year in each zodiacal constellation, and Saturn spends two and a half years in each. But, more exactly, each of those planets’ orbital periods is a bit shorter than those simple ideals. Jupiter’s is 11.85, and Saturn’s is 29.5.
Thus Jupiter’s course of 2020 is slightly overlapped by its course of 12 years later (2031). And Saturn’s course of 2020 is half overlapped by its course of 30 years later (2049).
Believe me, an arithmophobe has to think carefully to get even those additions right! It would be easier if we were now in the year 2001.
Each successive year, Earth has to go around an extra part of a month to overtake Saturn; so the oppositions move later in the year, until they skip a year. One falls near the end of 2032, so there is none in 2033 and the next is in early 2034.
And, the astronomical constellations being irregular, Saturn has (in this cycle) no opposition in Scorpius and two in Ophiuchus.
In the picture, the globes representing Saturn are exaggerated 100 times in size. Stalks from them are perpendicular to the ecliptic plane. Saturn was at its descending node through the plane only this year, in February, so at opposition it really is almost exactly opposite to the Sun – barely south of the “anti-Sun.” It will ascend through the plane half an orbit later, in June 2034, so that the opposition in January of that year will also be only just south of the ecliptic.
At the present opposite, Saturn’s magnitude is 0.1; it can be as bright as -0.5, as in 2031 and 2032, or as dim as 0.6, as in 2024, 2025, and 2039.
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A further trap for arithmophobes is the clash between the American and British ways of expressing dates.
A Yank and a Brit agree to fight a duel on 10/11/2020. The Yank is at the appointed spot on October 11, and the Briton is there on 10 November.
And a machine interprets the expression and gets 0.0000642921.
Which is about as much sense as there is in either system, or so thinks the astronomer. It should be 2020 Oct 11!
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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.
Sometimes I make improvements or corrections to a post after positing it. If you click on the title, rather than on ‘Read more’, I think you are sure to see the latest version.
This weblog maintains its right to be about astronomy or anything under the sun.
I’ve fallen into the gravity well of how to express dates, and I can’t get out!
When I was a young soldier in the US Army, I learned to write dates in this format: 05 AUG 2020. Using a three letter abbreviation for the month makes the date unambiguous, and it only uses one more column than using a two-digit number for the month. But the month abbreviations only make sense in one language. I’ve seen some EU documents that use Roman numerals for the month, e.g. 05 XIII 2020, or 2020 XIII 05. Roman numerals are the same in every language. I imagine it would be fairly straightforward to program a computer to translate the Roman numerals I – XII into the Arabic numerals 01 – 12, and vice versa.
But, other than Roman numerals, what have the Romans ever done for us?
Hmm, interesting coincidence. After writing the above comment, I went to the dictionary.com crossword puzzle page. Today’s puzzle has the theme “When In Rome.” The clue for one of the themed answers is a ten-letter word, “1,100 fancy homes?”
I wrote a short and crude Fortran Roman-number conversion program. The obstacle is that Roman numerals vary in length from 1 to 15 characters (MMDCCCCLXXXVIII); over 2m000 it could be more. This have been easier for Basic to handle.
If you were only translating I through XII into 01 through 12, you would only have twelve if-then statements.
By the way, I was looking for a link to an old Loonies radio comedy routine, couldn’t find it, settled on the Monty Python movie bit. The Loonies were a platoon in the Roman Legion.
Platoon Sergeant — “Count Off!”
First Soldier — “Aye!”
Second Soldier — “Aye aye!”
Third Soldier — “Aye aye aye!”
Fourth Soldier — “Aye Ex!”
That would be the ninth soldier. The fourth soldier should have said “Intra Venus!”
Whoops! Math was never my best subject.
Roman numerals for the month are the way upmarket people write the date and I sometimes do although I’m not upmarket!I got into the habit at Oxford when a person,now high up in the English government,wrote out my membership card to a college society using that format.i don’t know why the USA use the month first then only other country I can think of that does that is Hungary although there must be others too?the USA also loves Farhenheit strangely England has adopted Celsius with reasonable enthusiasm and hardly anyone uses Farhenheit.i had an American girlfriend from Long Island and always wanted temperature in Farhenheit so I got into the habit of translating them into Kelvin and telling her how many Kelvin it was where I was!
MM/DD/YY does not follow any logical sequence but in defense of the American system, imagine looking at a 12 page calendar hanging on a wall in order to find the date of an event. The first thing you do is flip the pages of the calendar to locate the event. You do notice the date first, but of more importance is which page (or month) of the calendar you are looking at. Then you narrow down the event to the exact date in that month. As an afterthought, you may or may not specify the year. That’s why Americans use MM/DD/YY.
Also, there are fewer syllables needed in the American system. Europeans say the 12th of March, whereas Americans say March the 12th, or simply March 12th. March 12th has the fewest syllables, which saves a few microseconds when conversing.
I know it’s confusing, but I don’t see it changing anytime soon unfortunately. It’s similar to the metric system. As a child I was taught that Americans will eventually use the metric system because it’s more practical. I’ve been waiting 60 years for that to happen. It would also be nice if everyone in the world used one language.
At least nobody got hurt in the duel.
Calendar on the wall: First, you’ve got to make sure it’s for the right year.
Europeans can also say March 12.
The real nuisance is that the US and UK systems differ and are ambiguous. With comouter systems, one is often unsure which system is being used. Much more than microseconds is wasted by hesitating and trying to ascertain whether the second number is meant to represent month or day.
It might be convenient if everyone used the same language, but it would be a terrible loss. Each language is a universe.
I agree that it’s a nuisance. I wasn’t so much defending the American way as I was explaining how I think it came about. It’s like finding a passage in a book. First you find the page number, then the paragraph.
a personal aside
It so happens that a foot-thick stack of Astronomical Calendars are just beyond arm’s reach from where I sit now. And I will soon re-read what I probably haven’t read for decades – since I did sort of skip over the things that I’d read in the past as the years went by. It is entirely possible/probable that I have absorbed a description of yours and lost conscious assignment of its source mea culpa if so. I guess its safest and most noble to “plagiarize” directly to the originator! In which case you might want to change the word “never” in my penultimate sentence to “rarely”. You were certainly meant an exception to “never”! What I had in mind in “never” was the ubiquitous educational materials and articles that are widely disseminated. Even in specialist texts, the proper imaginative picture is lacking (at least in those I’ve seen). In vulgar circles I still hear/read about how toilets swirl the other way in the Southern hemisphere and such – but I know you know better.
I’ll take that as a smile anyway.
now you may discard this aside
The English use the standard European system of writing dates day/month/year and the only country in Europe to use the system of the USA month/day/year is Hungary,well the only one I’ve seen.
Souls vs should
The Province of Quebec, which is not ordinarily noted for extremes of logical behavior, in this case behaved impeccably and settled the matter in a way that every computer agrees with: today is 20200719. As a dual American-Canadian citizen, I formerly had to think twice about whether I was dealing with a DDMMYYYY or MMDDYYYY jurisdiction: now I just use computerese unless explicitly instructed to do otherwise.
Gravitational stresses on the Earth are approaching maximum during the next few months. Normally they follow outer planetary oppositions by about two months – similar to the seasonal temperature lag.
But this year things are different. All outer planets lie in the same quadrant. As the Jupiter Saturn induced stress maximizes in September, Mars rushes in to join them, during its closest approach within the next 10 years. Neptune has already transited and Uranus follows Mars two weeks later. Meanwhile, Venus and the Sun pull at their strongest opposite the aforementioned outer planets, particularly at maximum lag time for Jupiter and Saturn.
Realize that we imagine the Earth as a solid while walking on the surface. But the real comparison is that the surface is akin to the skin of an apple, whilst the interior is a molten fluid – very far from being solid.
Expect this fluid to bubble up through the surface in volcanic eruptions, and the skin (AKA bedrock) to fracture along already well known fault lines. Danger spots? The Pacific “Ring of Fire,” dormant faults such as the Willamette where it enters the Columbia River, Western American, Mexican, and Andean volcanos, and those in Italy & Sicily.
Pray for those poor should directly affected!
I think what you might mean is “change in angular momentum stress” rather than gravitational.
I often hear people speaking of lunacy and such as being the stress of the moon’s gravity on the brain floating in the skull and such. Not. Of course an orbit is a kind of freefall – the following of equilibrium. I do think there might be something to lunacy though – as based on sleep disturbance from prolonged lighting; which means TV-in-bed in the ’50s -’80s, and your iPad in the present – is causing lunacy in the modern times.
I also get into trouble when saying that the planets do not orbit the Sun. Rather the planets orbit the barycentre of the system – as does the Sun. You can easily find a plot of the orbit of the Sun about the barycentre – although it, oddly, is usually shown as the barycentre moving about the Sun! (pretty weird that). Anyway, the Sun DOES undergo change-in-angular-momentum stress variation as the tightness of the curve changes (n.b.1990). I wonder at the moment what impact that aspect has on the other planets – Guy, have you thought about that?
The tidal force of an object as felt on Earth is proportional to the mass of the object times the inverse cube of the distance of that object from Earth. Bigger objects have more effect than smaller objects. Close objects have a huge effect. Distant objects have a trivial effect.
The most familiar demonstration of this relationship is that the Sun is 27 million times more massive than the Moon, while the Moon is 400 times closer than the Sun. Tides raised by the Moon on Earth are twice as high as tides raised by the Sun.
Plugging the masses and closest distances of the other planets to Earth into this equation reveals that Venus, coming closest to Earth, can have the greatest effect on Earth’s tides, a whooping 1/10,000 the effect of the Sun. Jupiter is bigger than Venus, but farther away; Jupiter’s greatest tides are 1/100,000 as high as the Sun’s tides. In other words, if the Sun raises tides of about a meter in the ocean (which is less dense and more fluid than magma), Venus’ greatest tides are 1/10 of a millimeter and Jupiter’s greatest tides are 1/100 of a millimeter. All the other planets have tidal influences on Earth that are orders of magnitude smaller than Jupiter’s.
I have a long list of things to worry about. Volcanic eruptions caused by planetary alignments are way way way down the list.
Indeed, I recall public worry about a “planetary convergence” in the mid 1980s, a period during which I was lecturing in a planetarium devoted to celestial navigation. At the time I calculated the cumulative ocean tidal effect as 2/10s of one hundredth of an inch (give or take a micron). I think that was publicised as The Jupiter Effect or some such.
A more novel, though not as tight convergence occurred around Orthodox Easter in 2002. On one of two evenings of opportunity I took a photograph (35mm film and 50 mm lens, that included all 7 classical planets in the frame. The horizon obscured the Sun – which was nevertheless in the frame, also Moon, Mercury, Venus, Mars, Jupiter, Saturn. I was able to develop the film to actually be able to discern all those in the photo. It is possible that my jumping up and down with excitement may have caused a magnitude -11 earthquake.
Are you sure that planetary alignment was in 2002 and not 2000? The alignment of all the naked eye planets in the May 2000 evening sky ignited my interest in skywatching. That was a once-in-a-lifetime opportunity.
Yes, I’m quite sure. The 2000 grouping was tighter, but the Sun was between the planets V J Sa (Su) Me Ma so that one saw some planets in the evening and others in the morning.
In 2002, mid-May, the Sun was to one side so that they all could be seen at once in the evening: (Su) Me Sa Ma V Mo J and the Moon was in the mix – therefore all 7 Classical Planets – the ones the days of the week are named after -were in view at one go in one photo. I have not discovered another occasion when this was so propitious – though I’m no Jean Meeus.
I’m sorry to go on about this – but it dredges up another bugaboo of mine (so many!) Tides are not raised by the attraction of fluid toward a Mass at all!
The obvious evidence of this is the fact that a tide appears to be raised on the opposite side of the planet too!
A beginning picture is to imagine a sphere of fluid. Placed under the influence of a proximate mass (a state of free-fall) the sphere will elongate to a football-like shape to express equilibrium within the lines of force. Raindrops would be this shape except for the friction of air blunting the front end. The Earth as a fluid body is elongated in line with massive objects (Sun & Moon predominantly). The solid, crustal earth rotates through this elongated shape. Simply seen, it is the land that passes through high and low tide (football ends) twice a day. Given boundaries and complex shorelines, the land bounces and deflects the elongated fluid as it crashes into it and makes observed tidal behavior more complex. But gravity does NOT act like a magnet – attracting fluids and such. The imaginative picture is that the solid land floats in the midst of an elongated fluid drop. The fluid interior is also elongated and the floating crust is also stressed as it heaves over the elongation – which dynamic is changed far more by weekly spring/neap than by planetary alignments!
The Moon does not rotate relative to its orbit about the Earth (always shows the same side). Were there an ocean on the Moon, there would be NO EARTH TIDE on the Moon (but there would be a ~monthly Sun tide). Hope that was worth the extra verbosity. This is true – yet I never hear or see it expressed.
More work for the moderator – I hope he’s smiling :-)
If you still have any of my Astronomical Calendars, you can find this description of tides in the latter part of the “Moon” section.
Here’s how Bowditch’s American Practical Navigator, the official US government encyclopedia of all things nautical, explains the high tide on the opposite side of the Earth from the Moon: the Moon pulls the water on the near side more than it pulls on the center of the Earth, and it pulls on the center of the Earth more than it pulls on the water on the opposite side of the Earth. That’s enough of an explanation for most sailors, who tend to be incorrigibly geocentric.
A friend once asked me to explain why, at Stinson Beach north of the San Francisco Bay Golden Gate, extreme minus tides tend to occur in the late afternoon or early evening in the winter, and in the morning in the summer. I researched. Her observation conforms to the past few years of the NOAA tide tables for several locations along the continental US Pacific coast. I drew diagrams of the Earth, Moon, and Sun. I pondered. My ultimate conclusion was “I don’t know. Tides are complicated.” In defense of my ignorance, I pointed out that even in this age of supercomputers and artificial intelligence, tide tables still rely on hydrographic surveys compiling reams of observations by analog detectors. If you have an answer I will gratefully pass it on to my friend.
By the way, we have dim prospects for observing the Seeliger effect from San Francisco tonight. Darned clouds and fog, but at least it’s not hot.
YYYY MM DD HH MM SS.ss is how I’ve done it since the 2nd grade (50-ish years ago) when, being faced with having to write a date and being ignorant of the convention, I made one up that made sense. It reads easily, sorts beautifully by ASCII and is universally unambiguous. I petitioned in 2000 to PLEASE adopt this system before came the post-y2k date ambiguity problem in spades. I argued that with the third millennium (2001) there would begin a stealth problem whereby dates are written in various formats in all innocence – only to become hazardous to interpret at some later time – by any 6 digit stamp in all fields – until 2013. So, feks. what’s 03 04 02 supposed to mean now? Well, my petition went unheeded. In my experience people just wrinkle their nose for similar reasons to resisting (in the U.S.) 24-hour time format – they think it seems “military”. Nope, just unambiguous.
btw, to stray a little, I also prefer the English units for all-things-human. I never confuse miles/yards/feet/inches/fractions because the units are implied in the way a number feels. I know countless examples of confusion in the metric system – where unit digits look the same except for the position of a radix. Metrics is fine for science/physics etc. But I think even buildings built in metrics have ugly proportions – especially the oblongs of doors and windows. [Another life observation is that the ear prefers simple ratios as beautiful – and I use “ratio” in the correct sense here as being a “relationship of integers” – and the eye prefers, to coin a term, irratios, or irrational proportions] The traditional units are connected to human experience and is good for human-related matters – like how a temperature feels. In the U.S. they spoiled the introduction of metrics by introducing it as a conversion problem. Yuk. If it had been presented as just another standalone unit system, that had its place alongside, I’m certain we would use it now. But metric nuts and bolts I can’t stand.
I’m so glad that we’ve (so far) resisted to dividing the calendar and day by 10 too! (Yes, I do know about the Mayans)
11 .86 and 29.46 years respectively, to be more accurate.