We have high expectations ...

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ChrisGreaves
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We have high expectations ...

Post by ChrisGreaves »

... of our very own Graeme, of course, this week.
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Graeme
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Re: We have high expectations ...

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That's always nice when that happens!

At the moment it's just Mars, Jupiter and Saturn in the evening. Mercury and Venus are morning objects. Uranus and Neptune are not naked eye objects.

I remember a few years ago when all five were visible across the evening sky. That's quite rare.

If you keep a lookout at Jupiter and Saturn, they're in the South West just after sunset, they're moving closer to each other as each night goes by. The closest conjunction is 21st December but by then they are only at 10° altitude at night fall and not about for long before they set.

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Re: We have high expectations ...

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Graeme wrote:
15 Nov 2020, 18:05
That's always nice when that happens!
Agreed.
Even close-to-happening is not bad. These web pages/photos were taken some ten years ago with a cheap little digital camera.
http://www.chrisgreaves.com/Tripping/Wa ... 202008.htm
http://www.chrisgreaves.com//Tripping/W ... 202008.htm
http://www.chrisgreaves.com//Greaves/Ad ... th2009.htm

That's why the world needs people like you!

Back in 1998 from the balcony of an apartment in the south-west corner of Toronto I was able to locate Venus AND Mercury with my naked eye, two evenings in a row.
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Re: We have high expectations ...

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Nice images there Chris. I like the Lunar Venusian conjunctions.

Not many people can say they have seen Mercury. It's only visible for a short while after sunset or before sunrise. Always a bit of a treat!

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Re: We have high expectations ...

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Graeme wrote:
15 Nov 2020, 19:42
Nice images there Chris. I like the Lunar Venusian conjunctions. Not many people can say they have seen Mercury. It's only visible for a short while after sunset or before sunrise. Always a bit of a treat!
Thanks Graeme. The experience of the event/sightings was far greater than the images. I had read that Mercury was difficult to sight. I cheated a bit: the first night Venus was easy but I used binoculars to locate Mercury ("half an inch above the second pylon to the west of the red building"), then put down the binoculars and relaxed my eyes until Mercury appeared nakedly, in a manner of speaking. The second night I did not need to use the binoculars.

We were blessed, of course, with an exceptionally high level of car fumes above the Highway 401 which (fumes) mingled with the fumes of the jets taking off on 33R from Pearson!

The other conjunctions came from a different apartment, a later time, when my balcony faced West rather then North.
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Re: We have high expectations ...

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ChrisGreaves wrote:
14 Nov 2020, 16:01
... of our very own Graeme, of course, this week.
Also next month:-
This event, known as a grand conjunction, happens about once every 20 years.

But the closeness of the two planets makes this a very rare conjunction.

With only about a 10th of a degree separating the two planets — that's a fifth of the width of the Moon — this is the closest they will have appeared in the sky to each other in nearly 400 years. The last time it occurred was in 1623.


With eager anticipation
Chris (who is praying for -10c and clear skies)
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Re: We have high expectations ...

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It should be quite an event! 21st is closest conjunction.

The interweb will be flooded with images!

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Re: We have high expectations ...

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Graeme wrote:
15 Nov 2020, 18:05
At the moment it's just Mars, Jupiter and Saturn in the evening. ...
Monday night, I think it was, around 2am (OK, Tuesday? morning) I caught a glimpse of what might have been two bright objects over to the SW. I did not have on my long-distance glasses, and was near-freezing, so I scuttled back inside and told myself that I had, at least, seen The Conjunction". :please:

I am fascinated by the differing accounts in the news.

The first of its kind in 400 years caught my eye. 400? A different web page (link below) said 800. How can astronomers be out by a factor of two in Our Sun's planetary calculations? In fairness, further down the article did mention 800 years "nearly 800 years since the alignment of Saturn and Jupiter occurred at night." My emphasis.

I remain puzzled, but I suppose it is an editor's prerogative to choose how to manufacture click-bait.

This article (800 years) had a pretty good explanation (for my level) and an excellent simulation at the 0m53s mark of the video clip from Saskatchewan.

I always note with interest when the planets in question are on the opposite side of the sun from us. That means that they are reflecting 100% full-face of the illuminating sunlight, but the inverse-square law (an extremely handy phrase to drop into any conversation) means that the reflected light is greatly reduced by distance.

A real mathematician (hint, hint) could calculate the optimal orbital position (relative to Earth) for any planet to achieve maximal brightness to the human eye. I bet that my high school mathematics teacher, Brian Feld, would have done it in his head in less time than it took to tell me to extract the proverbial digit :grin:

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Last edited by ChrisGreaves on 18 Dec 2020, 18:12, edited 1 time in total.
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Re: We have high expectations ...

Post by HansV »

For the 'outer' planets (Mars and beyond) are brightest when they are in opposition. Their maximum brightness varies - for Mars because of its rather eccentric orbit, and for Saturn depending on the angle at which we see its rings.
The inner planets are behind the sun when they are in opposition; they appear brightest when they are at the points where the tangent from Earth touches their orbits,
See How Bright Are the Planets?
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Re: We have high expectations ...

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It doesn't look like I'll see the closest conjunction of Jupiter and Saturn on 21 Dec, the forecast is for solid grey skies. I did get a glimpse of them on Wednesday evening, together with a crescent moon. I suppose I should have got my camera out. There's a chance the clouds will part on Sunday but I'm not holding my breath.

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Re: We have high expectations ...

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ChrisGreaves wrote:
18 Dec 2020, 13:37
A real mathematician (hint, hint) could calculate the optimal orbital position (relative to Earth) for any planet to achieve maximal brightness to the human eye.

What Hans said for the superior planets! The two inferior planets go through phases like the Moon does as viewed from the Earth. One might expect them to be brightest when they are at right angles to the Sun because they would be half lit. But they are brighter when they are nearer to the Earth in their orbit (inverse square law (probably (I managed to get that in the sentence!))) When they are nearer to Earth the lit phase reduces so the optimum % lit is 22% as in Hans' link (I thought it was 24%! (but around that figure))

400 years, 800 years visible to us? Jupiter takes 12 years to orbit the Sun, Saturn takes 30 odd. So every 12 years plus the bit to catch up with the distance Saturn moved in those 12 years, the two planets are in conjunction. (Mathematician required again!) But because both their orbital planes are tilted with respect to the mean solar system plane (and the tilts precess) the closeness of the conjunction varies. So although 3' of arc is definitely close, the phrase "haven't been this close for n years" requires quantifying.

I hate to rain on your fireworks Chris but at 02:00 Jupiter and Saturn were well set. You must have seen Sirius, Rigel or maybe two of the Orion belt stars. Time for a play with Stellarium?

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Re: We have high expectations ...

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Graeme wrote:
18 Dec 2020, 20:23
I hate to rain on your fireworks Chris but at 02:00 Jupiter and Saturn were well set.
Graeme, cut me a bit of slack here, OK? :grin: :grin: If I have trouble remembering which day it was, you must anticipate my problems remembering the time of night! It might have been midnight, or even eleven o'clock; I go to bed around 8:30pm.
And before you ask: yes, I have numerous clocks around the place, all with the batteries removed, and all with the hands set at 10:50.
At The Landfall Garden House, it is always time for elevenses!
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Re: We have high expectations ...

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ChrisGreaves wrote:
19 Dec 2020, 09:55
you must anticipate my problems remembering the time of night!

Understood Chris.

Forget clocks then. Once the Sun is below the horizon, you have about 2 hours then Jupiter and Saturn will be below the horizon too!

HTH!

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Re: We have high expectations ...

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Graeme wrote:
19 Dec 2020, 10:22
Forget clocks then. Once the Sun is below the horizon, you have about 2 hours then Jupiter and Saturn will be below the horizon too!
Thank you, Graeme.
I had completely mis-understood the positions.
I thought that Jupiter-Saturn were rising in the East as the sun was setting in the west.
For the past couple of months I have been seeing what I thought was Jupiter in the east just after sunset.

Now as i was typing that, i think i see my error.
Just as Venus flips from a morning star to an evening star as it passes behind/afore the sun (the flip takes place in about a week), so too must Jupiter-Saturn have flipped from a sunset-event in the eastern sky to a sunset event in the western sky.
Is that right?
Untitled.png
I now see the error of my ways. :stupidme: The location is set to St John's Newfoundland, about 120Km south of here as a crow would fly.

Thanks
Chris
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Re: We have high expectations ...

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I don't think a crow would fly from Bonavista to St John's in a straigh line...
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Re: We have high expectations ...

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ChrisGreaves wrote:
19 Dec 2020, 11:26
Just as Venus flips from a morning star to an evening star ...
Close, Venus and Mercury do the flippy thing because they're the two inferior (not in a judgemental way!) planets, comets (when they're within Earth's orbit) do the same thing. Everything else becomes visible as they appear from behind the Sun, in the East and then as the months pass they move across the night sky from East to West. For instance, Jupiter was visible in the East after sunset a few months ago, then in October (I think!) it was at opposition (due South at midnight), now it sets 2 hours after the Sun goes down. All the Zodiac constellations do this. The boundary of Taurus and Gemini is there now with Orion the mighty warrior below. If you get up at 4 in the morning (As I do these days more often!) and have a quick look outside, you will see the southern aspect in a preview of how it will be in a couple of months in the evening! Useful for planning astronomy viewing sessions!

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Re: We have high expectations ...

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Graeme I erred in my post
I forgot to put in a GRIN. I have edited the post to put in TWO grins (you deserve them). I want you to know that I was being flippant when i asked that you cut me a bit of slack. If anything, you are cutting me too much slack already.
OK
:grin: :grin: :grin:
Graeme wrote:
19 Dec 2020, 11:59
Close, Venus and Mercury do the flippy thing because they're the two inferior ... ... Everything else becomes visible as they ... move across the night sky from East to West.
Yes! YES!! That makes me remember the stories of the early observations, when some of the planets made strange retrograde movements. To make matters worse I have explained the apparent "flipping" of the two inferiors to people by graphically showing my left forefinger orbiting quite closely to the balled fist of my right hand.

Trouble is if I start doing that here I might be committed to an institution!

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Re: We have high expectations ...

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HansV wrote:
19 Dec 2020, 11:36
I don't think a crow would fly from Bonavista to St John's in a straight line...
It could if it took off from Bonavista on a heading of 270º, that is, due west.
Do not watch this video; it will be of no help at all.
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Re: We have high expectations ...

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ChrisGreaves wrote:
19 Dec 2020, 13:48
I forgot to put in a GRIN.

No worries Chris, I saw your tongue firmly in your cheek. It was my response where the Grin was missing! :grin:

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