APOD: A Mercury Transit Music Video from SDO (2019 Oct 21)

Comments and questions about the APOD on the main view screen.
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APOD: A Mercury Transit Music Video from SDO (2019 Oct 21)

Post by APOD Robot » Mon Oct 21, 2019 4:11 am

Image A Mercury Transit Music Video from SDO

Explanation: What's that small black dot moving across the Sun? Mercury. Possibly the clearest view of Mercury crossing in front of the Sun in 2016 May was from Earth orbit. The Solar Dynamics Observatory obtained an uninterrupted vista recording it not only in optical light but also in bands of ultraviolet light. Featured here is a composite movie of the crossing set to music. Although the event might prove successful scientifically for better determining components of Mercury' ultra-thin atmosphere, the event surely proved successful culturally by involving people throughout the world in observing a rare astronomical phenomenon. Many spectacular images of this Mercury transit from around (and above) the globe were proudly displayed. The next transit of Mercury will take place in three weeks: on 2019 November 11.

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Re: APOD: A Mercury Transit Music Video from SDO (2019 Oct 21)

Post by Ann » Mon Oct 21, 2019 4:34 am

Click to play embedded YouTube video.
Interesting. Mercury moves so fast. The sunspots, by contrast, seem stationary.

Anyway, today's APOD reminded me of this unforgettable scene from 2001: A Space Odyssey. Johann Strauss' An der schönen blauen Donau will surely never be the same!

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Re: APOD: A Mercury Transit Music Video from SDO (2019 Oct 21)

Post by heehaw » Mon Oct 21, 2019 9:16 am

Is this in real time? Surely not! How long did the transit take?

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Re: APOD: A Mercury Transit Music Video from SDO (2019 Oct 21)

Post by orin stepanek » Mon Oct 21, 2019 10:42 am

450px-Mercury_transit_2.jpg
Sol is a small star; yet the transit kind of gives one the impression of how massive the sun is in relation to the planet Mercury! :mrgreen:

Oops; I see another black spot! Am I pointing to a sun spot instead of Mercury? Anyway one of them is Mercury! :oops:
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Re: APOD: A Mercury Transit Music Video from SDO (2019 Oct 21)

Post by sillyworm 2 » Mon Oct 21, 2019 11:51 am

Now I'm in the mood for some soccer!

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Re: APOD: A Mercury Transit Music Video from SDO (2019 Oct 21)

Post by FrankTKO » Mon Oct 21, 2019 12:27 pm

Why is it "rare"? I would think every orbit that Mercury did would place it between us and the sun? More than once a year?

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Re: APOD: A Mercury Transit Music Video from SDO (2019 Oct 21)

Post by E Fish » Mon Oct 21, 2019 1:08 pm

Ann wrote:
Mon Oct 21, 2019 4:34 am
Click to play embedded YouTube video.
Interesting. Mercury moves so fast. The sunspots, by contrast, seem stationary.

Anyway, today's APOD reminded me of this unforgettable scene from 2001: A Space Odyssey. Johann Strauss' An der schönen blauen Donau will surely never be the same!

Ann
I show that exact same video to one of my science classes when we talk about gravity!

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Re: APOD: A Mercury Transit Music Video from SDO (2019 Oct 21)

Post by neufer » Mon Oct 21, 2019 1:32 pm

FrankTKO wrote:
Mon Oct 21, 2019 12:27 pm

Why is it "rare"? I would think every orbit that Mercury did would place it between us and the sun? More than once a year?
It is "rare" for the same reason that solar eclipses by the Moon are "rare" (i.e., less than once a month).

The orbital planes of Mercury and of the Moon lie at an angle to the orbital plane of the Earth.

The orbital plane of Mercury only intersects the orbital plane of the Earth along a single line corresponding to Earth's position in the second week of May or of November. Every 116 days Mercury passes above or below the sun except when it [i.e., inferior conjunction] happens in the second week of May or of November when the planes cross and a transit is possible.
Last edited by neufer on Mon Oct 21, 2019 1:52 pm, edited 1 time in total.
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Re: APOD: A Mercury Transit Music Video from SDO (2019 Oct 21)

Post by neufer » Mon Oct 21, 2019 1:47 pm

Ann wrote:
Mon Oct 21, 2019 4:34 am

Interesting. Mercury moves so fast. The sunspots, by contrast, seem stationary.
This should be the first check of a Kepler spacecraft transit
as to whether it involves a planet or a star spot:
  • 1) planets transit in a matter of hours
    2) starspots transit in a matter of days
Kepler observing our own solar system from a distant star would see sunspots transit in about 13 days
while the Earth would be observed to transit in 13 hours (or less).

The only solar system planet that could possibly transit in as long as 13 days
would be one orbiting way out at 242 AU ... or Planet Nine.
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Re: APOD: A Mercury Transit Music Video from SDO (2019 Oct 21)

Post by TheZuke! » Mon Oct 21, 2019 2:01 pm

I put on my headphone to listen to the music,
I was a little disappointed that the music wasn't "King of Pain" by The Police. B^)

"There's a little black spot on the sun today
It's the same old thing as yesterday
There's a black hat caught in the high tree top
There's a flag pole rag and the wind won't stop
I have stood here before inside the pouring rain
With the world turning circles running 'round my brain
I guess I'm always hoping that you'll end this reign
But it's my destiny to be the king of pain [...]"

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Re: APOD: A Mercury Transit Music Video from SDO (2019 Oct 21)

Post by neufer » Mon Oct 21, 2019 2:25 pm

TheZuke! wrote:
Mon Oct 21, 2019 2:01 pm

I was a little disappointed that the music wasn't "King of Pain" by The Police. B^)
  • "KoP" by The Police... oh please!
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Re: APOD: A Mercury Transit Music Video from SDO (2019 Oct 21)

Post by orin stepanek » Mon Oct 21, 2019 3:33 pm

neufer wrote:
Mon Oct 21, 2019 2:25 pm
TheZuke! wrote:
Mon Oct 21, 2019 2:01 pm

I was a little disappointed that the music wasn't "King of Pain" by The Police. B^)
  • "KoP" by The Police... oh please!

+1; :wink:
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Re: APOD: A Mercury Transit Music Video from SDO (2019 Oct 21)

Post by MarkBour » Mon Oct 21, 2019 4:16 pm

orin stepanek wrote:
Mon Oct 21, 2019 3:33 pm
neufer wrote:
Mon Oct 21, 2019 2:25 pm
TheZuke! wrote:
Mon Oct 21, 2019 2:01 pm

I was a little disappointed that the music wasn't "King of Pain" by The Police. B^)
  • "KoP" by The Police... oh please!
+1; :wink:
Okay, then how about "I'll be watching you ..." ? (Actual song title is "Every Breath you Take".)
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Re: APOD: A Mercury Transit Music Video from SDO (2019 Oct 21)

Post by JohnD » Mon Oct 21, 2019 5:14 pm

"Every breath you take" Remarkable that such a song should be a big hit - its from the PoV of a stalker. See lyrics: https://www.google.co.uk/search?source= ... zAKu4X_l3Y

But I digress. I believe that in the 17th century, led by Edmund Halley, the transits by Mecruy and Venus were crucial in determining the distance of the Earth from the Sun. Observers had to note the precise time when the disc of either planet crossed the rim of the Sun, and this proved difficult, due to the limitations of observing equipment of the time. Captain Cook's epic voyage was undertaken, in part, to observe Venus in transit, and yielded controversy.


Now, seeing a transit as it were close up and in enormous detail, it is still as difficult, as the rim of the Sun is diffused by prominences. The heroic nature of the work of early astronomers can only be appreciated better in the light of their modern successors!

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Re: APOD: A Mercury Transit Music Video from SDO (2019 Oct 21)

Post by stowaway » Mon Oct 21, 2019 7:07 pm

This transit could not have happened without the efforts of all the women at NASA.

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Re: APOD: A Mercury Transit Music Video from SDO (2019 Oct 21)

Post by pferkul » Mon Oct 21, 2019 7:22 pm

Why does the apparent shape of Mercury change as it transits? If we were looking at its shadow on the curved surface of the Sun then it would make sense. However as a back-lit object, it is unclear to me why Mercury should appear to have a changing elliptic outline. See attached image analysis from three frames.
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Re: APOD: A Mercury Transit Music Video from SDO (2019 Oct 21)

Post by MarkBour » Mon Oct 21, 2019 8:46 pm

orin stepanek wrote:
Mon Oct 21, 2019 10:42 am
450px-Mercury_transit_2.jpgSol is a small star; yet the transit kind of gives one the impression of how massive the sun is in relation to the planet Mercury! :mrgreen:

Oops; I see another black spot! Am I pointing to a sun spot instead of Mercury? Anyway one of them is Mercury! :oops:
Yep, your second thought is correct. So it's even more impressive. Mercury is the tiny speck.
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Re: APOD: A Mercury Transit Music Video from SDO (2019 Oct 21)

Post by neufer » Mon Oct 21, 2019 8:54 pm

MarkBour wrote:
Mon Oct 21, 2019 8:46 pm
orin stepanek wrote:
Mon Oct 21, 2019 10:42 am

Sol is a small star; yet the transit kind of gives one the impression of how massive the sun is in relation to the planet Mercury! :mrgreen:

Oops; I see another black spot! Am I pointing to a sun spot instead of Mercury? Anyway one of them is Mercury! :oops:
Yep, your second thought is correct. So it's even more impressive. Mercury is the tiny speck.
  • Better Call Sol.
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Re: APOD: A Mercury Transit Music Video from SDO (2019 Oct 21)

Post by MarkBour » Mon Oct 21, 2019 9:00 pm

pferkul wrote:
Mon Oct 21, 2019 7:22 pm
Why does the apparent shape of Mercury change as it transits? If we were looking at its shadow on the curved surface of the Sun then it would make sense. However as a back-lit object, it is unclear to me why Mercury should appear to have a changing elliptic outline. See attached image analysis from three frames.
Great question. I wonder if it is aberration in the lensing. Perhaps the first capture of the transit was near the edge of the viewport of the camera in your examples. When watching the featured video, at 1:45 one sees Mercury exiting the disc of Sol, and it looks quite round, not eccentric at all. And I don't see any appearance of eccentricity near the edge of Sol in this one: https://www.nasa.gov/sites/default/file ... te_sdo.jpg

In any case, I liked your question, because when you wrote "its shadow on the curved surface of the Sun" I had a moment of cognitive dissonance, like an optical illusion, but one that happened only in the mind, not while staring at the image ... which was funny ... I didn't know I could experience an optical illusion from a memory.
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Re: APOD: A Mercury Transit Music Video from SDO (2019 Oct 21)

Post by BDanielMayfield » Mon Oct 21, 2019 9:09 pm

stowaway wrote:
Mon Oct 21, 2019 7:07 pm
This transit could not have happened without the efforts of all the women at NASA.
I readily agree that this transit could not have been recorded without the efforts of women at NASA and at other organizations, but transits happen whether people are looking or not.
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Re: APOD: A Mercury Transit Music Video from SDO (2019 Oct 21)

Post by JohnD » Tue Oct 22, 2019 10:22 am

It was abberations in the appearance of the Venusian disk, called the "Black Drop Effect", that led to significant differences in transit times recorded by Cook, the professional navigator and by Green, the professional astronomer, at Tahiti in 1769. Green died on the return voyage, which allowed British astronomers, not least the Astronomer Royal, to blame him, causing Cook dismay and to defned his dead colleague.

We no longer need to measure the transits to know planetary orbits, but how would the moment when the discs become tangent be defined today, when as the video clealry shows, prominences and other disturbances blur the Sun's edge?
John

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Re: APOD: A Mercury Transit Music Video from SDO (2019 Oct 21)

Post by neufer » Tue Oct 22, 2019 1:08 pm

JohnD wrote:
Tue Oct 22, 2019 10:22 am

We no longer need to measure the transits to know planetary orbits, but how would the moment when the discs become tangent be defined today, when as the video clealry shows, prominences and other disturbances blur the Sun's edge?
  • Clealry it would not be possible without the efforts of all the women at NASA.
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Re: APOD: A Mercury Transit Music Video from SDO (2019 Oct 21)

Post by BDanielMayfield » Tue Oct 22, 2019 1:57 pm

neufer wrote:
Tue Oct 22, 2019 1:08 pm
JohnD wrote:
Tue Oct 22, 2019 10:22 am

We no longer need to measure the transits to know planetary orbits, but how would the moment when the discs become tangent be defined today, when as the video clealry shows, prominences and other disturbances blur the Sun's edge?
  • Clealry it would not be possible without the efforts of all the women at NASA.
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Re: APOD: A Mercury Transit Music Video from SDO (2019 Oct 21)

Post by JohnD » Tue Oct 22, 2019 2:13 pm


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Re: APOD: A Mercury Transit Music Video from SDO (2019 Oct 21)

Post by Chris Peterson » Tue Oct 22, 2019 2:20 pm

JohnD wrote:
Tue Oct 22, 2019 10:22 am
It was abberations in the appearance of the Venusian disk, called the "Black Drop Effect", that led to significant differences in transit times recorded by Cook, the professional navigator and by Green, the professional astronomer, at Tahiti in 1769. Green died on the return voyage, which allowed British astronomers, not least the Astronomer Royal, to blame him, causing Cook dismay and to defned his dead colleague.

We no longer need to measure the transits to know planetary orbits, but how would the moment when the discs become tangent be defined today, when as the video clealry shows, prominences and other disturbances blur the Sun's edge?
Well, you would want to do this experiment the same way it was originally done: using white light (they had no choice, of course). In white light the limb of the Sun is very well defined and lacks prominences and other distorting structures.

And what I'd do is not worry about trying to determine visually when contacts occur. Since I can image with extremely high temporal accuracy, I can calculate the moments of contact by looking at the position of Mercury and the Sun at different times. This also would allow for creating a mean image size for both bodies, averaging out the distortions caused by atmospheric seeing. I'll bet such an approach would yield much more accurate results than trying to visually determine the moments of contact, either visually or photographically.
Chris

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