APOD: One Night, One Telescope, One Camera (2018 Jul 28)

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APOD: One Night, One Telescope, One Camera (2018 Jul 28)

Post by APOD Robot » Sat Jul 28, 2018 4:07 am

Image One Night, One Telescope, One Camera

Explanation: Taken on the same night, from the same place, with the same telescope and camera, these postcards from our Solar System are shown at the same scale to provide an interesting comparison of apparent sizes. Spanning about half a degree in planet Earth's sky, the Moon is a stitched mosaic of six images. The others are the result of digitally stacked frames or simple single exposures, with the real distances to the objects indicated along the bottom of each insert. Most of the Solar System's planets with their brighter moons, and Pluto were captured during the telescopic expedition, but elusive Mercury was missed because of clouds near the horizon. The International Space Station was successfully hunted, though. The night was July 21st. Telescope and camera were located at the Centro Astronomico de Tiedra Observatory in Spain.

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Re: APOD: One Night, One Telescope, One Camera (2018 Jul 28)

Post by MarkBour » Sat Jul 28, 2018 6:00 am

Fantastic! Too bad Mercury was uncooperative. Not long ago, I asked what the record was for number of planets in one image. This is close to that notion -- I think it's another good challenge as to how many could at least be stitched together into one image, taken at nearly the same time from one location. I would say that "one night" would count as good. I would have allowed imagery from any location (e.g. Hubble, Cassini), but I think that viewing from the surface of Earth might be the best place anyway.

It seems unlikely that this is the first time anyone has ever accomplished this, but it's the most comprehensive set I've ever seen. For all I know, from this mosaic, you've set a world record.

In any case, it is very nice work, Fernando.
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Re: APOD: One Night, One Telescope, One Camera (2018 Jul 28)

Post by heehaw » Sat Jul 28, 2018 8:56 am

What a nice idea!

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Re: APOD: One Night, One Telescope, One Camera (2018 Jul 28)

Post by Cousin Ricky » Sat Jul 28, 2018 5:51 pm

This is some kind of awesome!

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Re: APOD: One Night, One Telescope, One Camera (2018 Jul 28)

Post by Chris Peterson » Sat Jul 28, 2018 6:26 pm

MarkBour wrote:
Sat Jul 28, 2018 6:00 am
Fantastic! Too bad Mercury was uncooperative. Not long ago, I asked what the record was for number of planets in one image.
A couple of weeks ago I simultaneously observed Mercury, Venus, Jupiter, and Saturn. About an hour later I saw Venus, Jupiter, Saturn, and Mars. That was pretty cool. With a fisheye I could have easily imaged either group of four. That frame would also have contained Pluto, although it wouldn't have been bright enough to show up.

With current practical technology (and the right date) I think the best we could hope to capture in a single image would be all the planets from Venus to Neptune. So, six. Mercury would probably be out because the sky would still be too bright for the dimmer planets to show. And Pluto would be out because no very wide angle lens system is likely to be able to record such a dim object given a reasonable exposure time.
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Re: APOD: One Night, One Telescope, One Camera (2018 Jul 28)

Post by Joe Stieber » Sat Jul 28, 2018 8:31 pm

Just for fun, I like to visually spot all seven of the major planets in a single night when circumstances permit, with unaided eyes and small optics like binoculars. The current (and soon to end) evening elongation of Mercury provided many opportunities, and I ended up doing it five times. I would start with Mercury, and failure there would end the night’s effort. I also like to spot other solar system objects along the way; for example, the Moon, the minor planet/asteroid (4) Vesta, and in one case, a comet, C/2017 S3 (PANSTARRS). Although I often pick up one or more artificial satellites while I’m out looking (possibly the ISS), I don’t include these man-made objects.

Perhaps arbitrarily, I’m little concerned about trying to see dim (134340) Pluto. I’ve seen it many times in the past, but I would need my 12.5-inch Newtonian to do it, and even with that scope, it’s borderline because of its inherent dimness coupled with atmospheric extinction at its current low altitude in Sagittarius. It would also require going from my suburban location to the relatively dark New Jersey Pinelands.

The last time I saw all the planets in one night was July 19-20, 2018, and to make it a slightly more challenging, I decided that I had to see each object in my 85 mm spotting scope (which has no finder scope). Of course, bright objects like Venus, Jupiter, Saturn, Mars and the Moon aren’t challenging (but they had shown surprising detail in the spotter), and when you follow them on a regular basis with binoculars, Vesta, Neptune and Uranus are fairly easy to locate, as was C/2017 S3 this time. Mercury is probably the trickiest one, mainly because of the fickle nature of clouds. It can be wonderfully clear in most of the sky, but there are often streaky clouds along the respective area of the horizon anyway, so it’s pot luck finding it between clouds. Even when it’s clear along the horizon, Mercury’s varying brightness, residual twilight and/or an unfavorable angle of the ecliptic may require binoculars to find it or even see it.

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Re: APOD: One Night, One Telescope, One Camera (2018 Jul 28)

Post by johnmg4b2GMAIL.COM » Sat Jul 28, 2018 8:55 pm

What is that number under Venus?

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Re: APOD: One Night, One Telescope, One Camera (2018 Jul 28)

Post by neufer » Sat Jul 28, 2018 8:55 pm

Joe Stieber wrote:
Sat Jul 28, 2018 8:31 pm

Perhaps arbitrarily, I’m little concerned about trying to see dim (134340) Pluto. I’ve seen it many times in the past, but I would need my 12.5-inch Newtonian to do it, and even with that scope, it’s borderline because of its inherent dimness coupled with atmospheric extinction at its current low altitude in Sagittarius.
Lack of contrast at its current low altitude in Sagittarius :?:
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Re: APOD: One Night, One Telescope, One Camera (2018 Jul 28)

Post by Chris Peterson » Sat Jul 28, 2018 9:23 pm

neufer wrote:
Sat Jul 28, 2018 8:55 pm
Joe Stieber wrote:
Sat Jul 28, 2018 8:31 pm

Perhaps arbitrarily, I’m little concerned about trying to see dim (134340) Pluto. I’ve seen it many times in the past, but I would need my 12.5-inch Newtonian to do it, and even with that scope, it’s borderline because of its inherent dimness coupled with atmospheric extinction at its current low altitude in Sagittarius.
Lack of contrast at its current low altitude in Sagittarius :?:
And extinction. He's looking through a bit over two atmospheric masses. With the typical East Coast pollution and summer humidity, that could reduce the brightness by 0.7 to 1 magnitude, from an already dim 14.2.
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Re: APOD: One Night, One Telescope, One Camera (2018 Jul 28)

Post by Joe Stieber » Sat Jul 28, 2018 10:06 pm

neufer wrote:
Sat Jul 28, 2018 8:55 pm
Joe Stieber wrote:
Sat Jul 28, 2018 8:31 pm

Perhaps arbitrarily, I’m little concerned about trying to see dim (134340) Pluto. I’ve seen it many times in the past, but I would need my 12.5-inch Newtonian to do it, and even with that scope, it’s borderline because of its inherent dimness coupled with atmospheric extinction at its current low altitude in Sagittarius.
Lack of contrast at its current low altitude in Sagittarius :?:
Indeed, that's what it all boils down to. A dim object, dimmed even more by light absorption and scattering by a long path through the atmosphere at low altitude, needs a dark enough background to raise contrast enough to be seen. Of course, I should have noted that "current low altitude" refers to my own observing location, which is nominally at 40°N latitude. Pluto would be well positioned for most folks in the Southern Hemisphere.

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Re: APOD: One Night, One Telescope, One Camera (2018 Jul 28)

Post by ta152h0 » Sun Jul 29, 2018 3:06 am

I took a photo of the Moon on July 26,2018 at 12:57 AM and I think I caught a collision at about 2=11 o;clock position on the face.
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Re: APOD: One Night, One Telescope, One Camera (2018 Jul 28)

Post by alter-ego » Sun Jul 29, 2018 4:03 am

Chris Peterson wrote:
Sat Jul 28, 2018 6:26 pm
MarkBour wrote:
Sat Jul 28, 2018 6:00 am
Fantastic! Too bad Mercury was uncooperative. Not long ago, I asked what the record was for number of planets in one image.
A couple of weeks ago I simultaneously observed Mercury, Venus, Jupiter, and Saturn. About an hour later I saw Venus, Jupiter, Saturn, and Mars. That was pretty cool. With a fisheye I could have easily imaged either group of four. That frame would also have contained Pluto, although it wouldn't have been bright enough to show up.

With current practical technology (and the right date) I think the best we could hope to capture in a single image would be all the planets from Venus to Neptune. So, six. Mercury would probably be out because the sky would still be too bright for the dimmer planets to show. And Pluto would be out because no very wide angle lens system is likely to be able to record such a dim object given a reasonable exposure time.
I did some searching for simultaneous, 8-"planet" visibility within a fisheye view. I located an example where the fainter planet was Mars, and Mercury has a good chance for being imaged. These 8-planet examples are expectedly very rare. The example below is May 5, -1972 TDT. The sun is 10° below the horizon for an observer on the equator. Mercury has an extincted magnitude of about +0.7, while Mars +2.2 with extinction. Jupiter (lower altitude than Mercury) has about -0.9 with extinction. Interestingly, Neptune might not be imaged as comes in at 9.1 mag w/extinction and Uranus is 5.6. I'd say for this example, Pluto definitely won't be imaged, Neptune is questionable, but Mercury is has a good chance.
 
All Planet Visibility, 7 + Pluto.JPG
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Re: APOD: One Night, One Telescope, One Camera (2018 Jul 28)

Post by Chris Peterson » Sun Jul 29, 2018 4:15 am

alter-ego wrote:
Sun Jul 29, 2018 4:03 am
Chris Peterson wrote:
Sat Jul 28, 2018 6:26 pm
MarkBour wrote:
Sat Jul 28, 2018 6:00 am
Fantastic! Too bad Mercury was uncooperative. Not long ago, I asked what the record was for number of planets in one image.
A couple of weeks ago I simultaneously observed Mercury, Venus, Jupiter, and Saturn. About an hour later I saw Venus, Jupiter, Saturn, and Mars. That was pretty cool. With a fisheye I could have easily imaged either group of four. That frame would also have contained Pluto, although it wouldn't have been bright enough to show up.

With current practical technology (and the right date) I think the best we could hope to capture in a single image would be all the planets from Venus to Neptune. So, six. Mercury would probably be out because the sky would still be too bright for the dimmer planets to show. And Pluto would be out because no very wide angle lens system is likely to be able to record such a dim object given a reasonable exposure time.
I did some searching for simultaneous, 8-"planet" visibility within a fisheye view. I located an example where the fainter planet was Mars, and Mercury has a good chance for being imaged. These 8-planet examples are expectedly very rare. The example below is May 5, -1972 TDT. The sun is 10° below the horizon for an observer on the equator. Mercury has an extincted magnitude of about +0.7, while Mars +2.2 with extinction. Jupiter (lower altitude than Mercury) has about -0.9 with extinction. Interestingly, Neptune might not be imaged as comes in at 9.1 mag w/extinction and Uranus is 5.6. I'd say for this example, Pluto definitely won't be imaged, Neptune is questionable, but Mercury is has a good chance.
 
Mercury is easy. Uranus/Neptune are easy. The tradeoff would seem to be between those.
Chris

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Re: APOD: One Night, One Telescope, One Camera (2018 Jul 28)

Post by alter-ego » Sun Jul 29, 2018 4:23 am

Chris Peterson wrote:
Sun Jul 29, 2018 4:15 am
alter-ego wrote:
Sun Jul 29, 2018 4:03 am
Chris Peterson wrote:
Sat Jul 28, 2018 6:26 pm


A couple of weeks ago I simultaneously observed Mercury, Venus, Jupiter, and Saturn. About an hour later I saw Venus, Jupiter, Saturn, and Mars. That was pretty cool. With a fisheye I could have easily imaged either group of four. That frame would also have contained Pluto, although it wouldn't have been bright enough to show up.

With current practical technology (and the right date) I think the best we could hope to capture in a single image would be all the planets from Venus to Neptune. So, six. Mercury would probably be out because the sky would still be too bright for the dimmer planets to show. And Pluto would be out because no very wide angle lens system is likely to be able to record such a dim object given a reasonable exposure time.
I did some searching for simultaneous, 8-"planet" visibility within a fisheye view. I located an example where the fainter planet was Mars, and Mercury has a good chance for being imaged. These 8-planet examples are expectedly very rare. The example below is May 5, -1972 TDT. The sun is 10° below the horizon for an observer on the equator. Mercury has an extincted magnitude of about +0.7, while Mars +2.2 with extinction. Jupiter (lower altitude than Mercury) has about -0.9 with extinction. Interestingly, Neptune might not be imaged as comes in at 9.1 mag w/extinction and Uranus is 5.6. I'd say for this example, Pluto definitely won't be imaged, Neptune is questionable, but Mercury is has a good chance.
 
Mercury is easy. Uranus/Neptune are easy. The tradeoff would seem to be between those.
I think that's the case.
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Re: APOD: One Night, One Telescope, One Camera (2018 Jul 28)

Post by neufer » Tue Jul 31, 2018 3:41 pm

ta152h0 wrote:
Sun Jul 29, 2018 3:06 am

I took a photo of the Moon on July 26, 2018 at 12:57 AM and I think I caught a collision at about 2=11 o;clock position on the face.
https://en.wikipedia.org/wiki/Alpha_Capricornids wrote:
<<Alpha Capricornids is a meteor shower that takes place as early as 15 July and continues until around 10 August. The meteor shower was discovered by Hungarian astronomer Miklos von Konkoly-Thege in 1871. This shower has infrequent but relatively bright meteors, with some fireballs. Peter Jenniskens and Jeremie Vaubaillon identified the parent body as asteroid 2002 EX12, which in the return of 2005 was found weakly active near perihelion. This object is now called comet 169P/NEAT.

According to Jenniskens and Vaubaillon, the meteor shower was created about 3,500 to 5,000 years ago, when about half of the parent body disintegrated and fell into dust. The dust cloud evolved into Earth's orbit recently, causing a shower with peak rates of 2-5/h, sometimes having outbursts of bright flaring meteors with rates up to 5-9/h. The bulk of the dust will not be in Earth's path until the 24th century. The Alpha Capricornids are expected to become a major annual storm in 2220–2420 A.D., one that will be "stronger than any current annual shower.">>
  • Did it look something like this:
http://www.esa.int/spaceinimages/Images/2018/07/Two_lunar_flashes_GIF wrote:
Click to play embedded YouTube video.

Two lunar flashes GIF
Released 27/07/2018 2:06 pm
Copyright Moon Impacts Detection and Analysis System (MIDAS)/Jose Maria Madiedo

<<On 17 July 2018, an ancient lump from space thwacked into the Moon with enough energy to produce a brilliant flash of light. With another space rock seemingly in pursuit, a second flash lit up a different region of the Moon almost exactly 24 hours later.

This GIF shows both lunar flashes, edited to within just moments of each other.>>
Last edited by neufer on Tue Jul 31, 2018 7:05 pm, edited 1 time in total.
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Re: APOD: One Night, One Telescope, One Camera (2018 Jul 28)

Post by BDanielMayfield » Tue Jul 31, 2018 4:33 pm

Great APOD! Some details though about the scope and camera would be helpful.

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Re: APOD: One Night, One Telescope, One Camera (2018 Jul 28)

Post by MarkBour » Tue Jul 31, 2018 5:26 pm

Chris Peterson wrote:
Sat Jul 28, 2018 6:26 pm
A couple of weeks ago I simultaneously observed Mercury, Venus, Jupiter, and Saturn. About an hour later I saw Venus, Jupiter, Saturn, and Mars. That was pretty cool. With a fisheye I could have easily imaged either group of four. That frame would also have contained Pluto, although it wouldn't have been bright enough to show up.

With current practical technology (and the right date) I think the best we could hope to capture in a single image would be all the planets from Venus to Neptune. So, six. Mercury would probably be out because the sky would still be too bright for the dimmer planets to show. And Pluto would be out because no very wide angle lens system is likely to be able to record such a dim object given a reasonable exposure time.
Interesting thoughts on the practical limits. I, too, recently saw those 5 in one evening. I thank APOD for alerting me to their presence and my phone app for helping me find them. I'm counting it as the first time I've ever seen Mercury. I'm wondering if this month has been an especially good time for planet viewing, or if I'm just becoming more aware.
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Re: APOD: One Night, One Telescope, One Camera (2018 Jul 28)

Post by Chris Peterson » Tue Jul 31, 2018 5:52 pm

MarkBour wrote:
Tue Jul 31, 2018 5:26 pm
I'm wondering if this month has been an especially good time for planet viewing, or if I'm just becoming more aware.
Certainly there are cycles of better and worse planetary viewing, both in terms of position in the sky and nearness to opposition. And yes, we're in a pretty good spot right now. But such periods are far from rare. So your increased awareness is probably an important component.

(Saturn and Jupiter are currently getting closer together in the sky, and will remain close for a number of years. They'll be very close at the end of 2020, just six arcminutes apart. A truly spectacular sight and imaging opportunity that will be- Saturn separated from Jupiter by the same amount as the Galilean moons! Mars and the inner planets go through much quicker cycles. So there will be many opportunites in the next years to see all the bright planets either together or over a single evening.)
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Re: APOD: One Night, One Telescope, One Camera (2018 Jul 28)

Post by MarkBour » Wed Aug 01, 2018 5:29 pm

Chris Peterson wrote:
Tue Jul 31, 2018 5:52 pm
(Saturn and Jupiter are currently getting closer together in the sky, and will remain close for a number of years. They'll be very close at the end of 2020, just six arcminutes apart. A truly spectacular sight and imaging opportunity that will be- Saturn separated from Jupiter by the same amount as the Galilean moons! Mars and the inner planets go through much quicker cycles. So there will be many opportunites in the next years to see all the bright planets either together or over a single evening.)
Thanks for pointing that out ... it's something to look forward to !
Capture2.jpg


I'm wondering how often something like this happens:

Once every billion years or so?

Never?
(Maybe orbital resonances make it impossible.)
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Re: APOD: One Night, One Telescope, One Camera (2018 Jul 28)

Post by neufer » Wed Aug 01, 2018 6:29 pm

MarkBour wrote:
Wed Aug 01, 2018 5:29 pm

I'm wondering how often [planetary alignment] happens:

Once every billion years or so?

Never? (Maybe orbital resonances make it impossible.)
If one limits oneself to just the five visible planets:

:arrow: Just after sunset on Sat 2040 Sep 8 23:25 UTC:

New York View toward western horizon : Sat 2040 Sep 8 23:25 UTC

Such a close alignment happen only about once ever 1,000 years :!:

For both Uranus & Neptune to be in these 7.7º wide groupings
happens only once every (360/7.7)2 ~ 2,000 millennia :!:


----------------------------------------------------------------------------

The next time all 8 planets line up such that they can all be viewed at once
(rather than just sometime over the entire night) will be May 6, 2492:
http://wtamu.edu/~cbaird/sq/2013/08/28/when-do-the-planets-in-our-solar-system-all-line-up/ wrote:
When do the planets in our solar system all line up?
By Dr. Christopher S. Baird: August 28, 2013
<<The closest the eight planets will come to being aligned will be on May 6, 2492. This image shows what you would see if you were off the coast of New York City and you looked due south at 5:10 am on May 6, 2492, as calculated by the software program Stellarium 0.13.3. As you can see, the planets are not visually sitting on top of each other, which would be the case if they were all located on a line emanating from the earth (as would be needed to maximize their net gravitational force on the earth). Furthermore, they are not even visually sitting on a line in the sky. They are simply in the same general region of the sky. Public Domain Image, source: Christopher S. Baird.>>
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Re: APOD: One Night, One Telescope, One Camera (2018 Jul 28)

Post by alter-ego » Thu Aug 02, 2018 4:32 am

neufer wrote:
Wed Aug 01, 2018 6:29 pm

If one limits oneself to just the five visible planets:

:arrow: Just after sunset on Sat 2040 Sep 8 23:25 UTC:

New York View toward western horizon : Sat 2040 Sep 8 23:25 UTC

Such a close alignment happen only about once ever 1,000 years :!:

The millennia estimate is a bit long. The 2040, 5-planet grouping separation actually is ~9.4°. Referencing the 1994 paper by De Meis and Meeus, between the years -3101 TDT and +2735 TDT, there are ten 5-planet groupings within ≤ 10°. The average then (over 5700 years) for such a grouping ≈ 570 years.
The next time all 8 planets line up such that they can all be viewed at once
(rather than just sometime over the entire night) will be May 6, 2492:
http://wtamu.edu/~cbaird/sq/2013/08/28/when-do-the-planets-in-our-solar-system-all-line-up/ wrote:
When do the planets in our solar system all line up?
By Dr. Christopher S. Baird: August 28, 2013
<<The closest the eight planets will come to being aligned will be on May 6, 2492. This image shows what you would see if you were off the coast of New York City and you looked due south at 5:10 am on May 6, 2492, as calculated by the software program Stellarium 0.13.3. As you can see, the planets are not visually sitting on top of each other, which would be the case if they were all located on a line emanating from the earth (as would be needed to maximize their net gravitational force on the earth). Furthermore, they are not even visually sitting on a line in the sky. They are simply in the same general region of the sky. Public Domain Image, source: Christopher S. Baird.>>
The separation for this 7-planet grouping ~165°, and happens to contain Pluto too, though not labeled.
Interestingly, there's another (7+Pluto) grouping that is visible on (and about) July 30, 2478 which is tighter. The separation for this group ~133°. Regarding the 8-"planet" groupings, my limited search over the De Meis / Meeus 5700 years indicates there are at least 20 such groupings, and likely more. I don't know Dr. Baird's tool for calculating his example or why he missed the case I listed. It's clear there is a better grouping occurring 14 years earlier.
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Re: APOD: One Night, One Telescope, One Camera (2018 Jul 28)

Post by neufer » Thu Aug 02, 2018 12:36 pm

https://science.nasa.gov/science-news/science-at-nasa/2000/ast30mar_1m wrote:
<<The five naked-eye planets cluster together in the sky within a circle 25 degrees or less in diameter once every 57 years, on average. The next time it will happen is September 8, 2040. The 2040 grouping will include Mercury, Venus, Mars, Jupiter, Saturn and the crescent Moon. Clustered well to the east of the Sun, the planets will stage a spectacular show at 7:30 p.m. in the evening. (Mark your calendar now!)>>
alter-ego wrote:
Thu Aug 02, 2018 4:32 am
neufer wrote:
Wed Aug 01, 2018 6:29 pm

If one limits oneself to just the five visible planets:

Just after sunset on Sat 2040 Sep 8 23:25 UTC:

New York View toward western horizon : Sat 2040 Sep 8 23:25 UTC

Such a close alignment happen only about once ever 1,000 years :!:
The millennia estimate is a bit long.

The 2040, 5-planet grouping separation actually is ~9.4°. Referencing the 1994 paper by De Meis and Meeus, between the years -3101 TDT and +2735 TDT, there are ten 5-planet groupings within ≤ 10°. The average then (over 5700 years) for such a grouping ≈ 570 years.
Close enough for government work.
  • I was ball-parking the somewhat longer (more accurate :?: ) study below :
8 September 2040 is the 6th closest alignment in the 8213-year period
  • 8213 years / ~6 close alignments ≈ a millenium.
(Note that 8 September 2040 also includes the Moon for good measure :!: )
https://web.archive.org/web/20051214013307/http://www.sunspot.noao.edu/PR/alignment.html wrote:
National Solar Observatory
Sacramento Peak
Planetary Alignments

<<I've studied the alignment (as seen from the Earth) of the planets Mercury through Saturn for a period of 3,000,000 days between 4713 BC and AD 3501. The alignment width shows periodic behavior with main periods of about 10.9, 20.1, and 200 years.

For example, the alignment of September 2040 is closest on 8 September 2040. It is the 6th closest alignment in the 8213-year period at an alignment width of 7.7 degrees, and the central point is about 24 degrees to the east of the Sun, i.e., the planets are all to the east of the Sun (that is, visible during the early evening).>>
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Re: APOD: One Night, One Telescope, One Camera (2018 Jul 28)

Post by MarkBour » Thu Aug 02, 2018 10:49 pm

5:10 am May 6, 2492. No heavy drinking on Cinco de Mayo, or I'll sleep through it.
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Re: APOD: One Night, One Telescope, One Camera (2018 Jul 28)

Post by neufer » Fri Aug 03, 2018 12:19 am

MarkBour wrote:
Thu Aug 02, 2018 10:49 pm

5:10 am May 6, 2492. No heavy drinking on Cinco de Mayo, or I'll sleep through it.
May 6, 2492 will be BORING :!:

Sunset, Sat 2040 Sep 8 will be the thing to see.
(I predict a dozen APODs minimum.)
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Re: APOD: One Night, One Telescope, One Camera (2018 Jul 28)

Post by alter-ego » Fri Aug 03, 2018 4:57 am

neufer wrote:
Thu Aug 02, 2018 12:36 pm
https://web.archive.org/web/20051214013307/http://www.sunspot.noao.edu/PR/alignment.html wrote: ...
For example, the alignment of September 2040 is closest on 8 September 2040. It is the 6th closest alignment in the 8213-year period at an alignment width of 7.7 degrees, and the central point is about 24 degrees to the east of the Sun, i.e., the planets are all to the east of the Sun (that is, visible during the early evening).>>
Well, your definitions do clarify things.
There're many average periods depending on grouping size. However, although the statistically based "alignment width" may be a more mathematically better definition for a single, position-distribution parameter, it's certainly not visually intuitive.
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