APOD: A Mercury Transit Music Video from SDO (2016 May 11)

Comments and questions about the APOD on the main view screen.
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APOD: A Mercury Transit Music Video from SDO (2016 May 11)

Post by APOD Robot » Wed May 11, 2016 4:13 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 earlier this week 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 are being proudly displayed.

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Re: APOD: A Mercury Transit Music Video from SDO (2016 May 11)

Post by sallyseaver » Wed May 11, 2016 4:33 am

This video really is VERY cool. I especially liked the close-up images. The movement of Mercury is so smooth and "pure." We know that the movement of a planet works the way we see it here, but I think this is the first time we've actually seen it (with this kind of video quality). The video also points out the different aspects of the Sun itself. I have been very appreciative of the SDO imagery over the last 1.5 years... this is another priceless gift. Thank you SDO!!

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Re: APOD: A Mercury Transit Music Video from SDO (2016 May 11)

Post by RedFishBlueFish » Wed May 11, 2016 9:08 am

This is a very good project to have taken the time to do.

Thanks!

KAB

Re: APOD: A Mercury Transit Music Video from SDO (2016 May 11)

Post by KAB » Wed May 11, 2016 11:07 am

Exquisite, a work of art. And fascinating.

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Re: APOD: A Mercury Transit Music Video from SDO (2016 May 11)

Post by Coil_Smoke » Wed May 11, 2016 12:05 pm

SPF 2000 ! ... Wow, How big is the Sun in the sky on Mercury ?

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Re: APOD: A Mercury Transit Music Video from SDO (2016 May 11)

Post by njhollenkamp » Wed May 11, 2016 1:23 pm

Awesome video. How long is this footage covering?

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Re: APOD: A Mercury Transit Music Video from SDO (2016 May 11)

Post by Grizzly » Wed May 11, 2016 2:02 pm

Coil_Smoke wrote:SPF 2000 ! ... Wow, How big is the Sun in the sky on Mercury ?

Not sure, but by my calculations it would be about 2 and a half times the size of the sun in the Earth's sky. I think. Maybe. It seems so large here because of the telescopic effect.

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Re: APOD: A Mercury Transit Music Video from SDO (2016 May 11)

Post by Jim Leff » Wed May 11, 2016 3:34 pm

My favorite part was the last few seconds, as Mercury completed its transit and kept going laterally against the background of the corona. I was sorry it wasn't illuminated from this direction, so we could see it recede and disappear behind the sun. I'd have liked a visceral sense of its orbital distance from how wide to the "right" it would appear to swing before receding.
Last edited by Jim Leff on Wed May 11, 2016 3:41 pm, edited 1 time in total.

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Re: APOD: A Mercury Transit Music Video from SDO (2016 May 11)

Post by Jim Leff » Wed May 11, 2016 3:37 pm

Coil_Smoke wrote:SPF 2000 ! ... Wow, How big is the Sun in the sky on Mercury ?
Here is solar size as seen from every planet: http://www.astronoo.com/en/children/sun ... -size.html

I wonder if we'd feel not just surprise and marvel but also a deep revulsion at its unnaturally small size viewed from an outer planet....if the sight would offend some deep unconscious faculty, ala the "uncanny valley" revulsion.

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Re: APOD: A Mercury Transit Music Video from SDO (2016 May 11)

Post by Chris Peterson » Wed May 11, 2016 4:20 pm

Jim Leff wrote: Here is solar size as seen from every planet: http://www.astronoo.com/en/children/sun ... -size.html

I wonder if we'd feel not just surprise and marvel but also a deep revulsion at its unnaturally small size viewed from an outer planet....if the sight would offend some deep unconscious faculty, ala the "uncanny valley" revulsion.
While the image correctly represents the relative size of the Sun seen from different places, it doesn't capture the visual appearance accurately, since very few people are likely to have a visual impression of the Sun from Earth like that represented in the image. The Sun is very small, and combined with its brightness even at sunset, we don't really note its size much at all. Consider a more realistic image of a sunset, and ask yourself how much difference the size changes would really make.

Image
And at any time other than sunset, the Sun might as well be a point source. We'd notice the quality of shadows changing more than we'd notice the Sun was a different size.
Chris

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Re: APOD: A Mercury Transit Music Video from SDO (2016 May 11)

Post by pferkul » Wed May 11, 2016 4:32 pm

I was wondering why Mercury appears to be elliptical, especially away from the center of the sun? Attached is a simple measurement from ImageJ.
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Re: APOD: A Mercury Transit Music Video from SDO (2016 May 11)

Post by Chris Peterson » Wed May 11, 2016 5:44 pm

Jim Leff wrote:My favorite part was the last few seconds, as Mercury completed its transit and kept going laterally against the background of the corona. I was sorry it wasn't illuminated from this direction, so we could see it recede and disappear behind the sun. I'd have liked a visceral sense of its orbital distance from how wide to the "right" it would appear to swing before receding.
It would be 48 solar widths to the right when it swings back towards the Sun on June 9, and then it would go "behind" the Sun around July 6, except it would no longer be on the ecliptic, so it wouldn't go behind the Sun at all, but would be about three solar widths north of the Sun from our vantage.
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Re: APOD: A Mercury Transit Music Video from SDO (2016 May 11)

Post by BillBixby » Thu May 12, 2016 2:11 am

From 1:31 to 1:38 it looked like the sun was watching Mercury through a set of eyes. Gotta cut down on my coffee intake...

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Re: APOD: A Mercury Transit Music Video from SDO (2016 May 11)

Post by Jim Leff » Fri May 13, 2016 2:05 am

Hmm, I don't know about that one, Chris.

It's intrinsically hard to argue about a subjective perception, especially with the sun/moon illusion involved....plus, as you say, the brightness issue interfering with any precise perception of size. But we do have a pretty sharp sense of the moon's apparent size, which of course is the same. And the photo you used to illustrate your point doesn't ring true for me as a representation of that size....while the drawing on the site I linked to does.

Anyway, in terms of my original point - revulsion of seeing an unfamiliarly small Sun from other planets - I don't think you can get around the fact that it will seem disconcertingly smaller/fainter/different, at least from the outer planets. Hard point to argue. And I do imagine even a small difference would create a visceral sense of discomfort, even if one isn't staring at it, gauging it, etc. You'd simply experience a "something's wrong" sensation, above/beyond the unfamiliarity of the immediate environment. I suppose the sun is "baked in" more to our psychology to an extent that would make itself known from other viewpoints.

Chris Peterson wrote:
Jim Leff wrote: Here is solar size as seen from every planet: http://www.astronoo.com/en/children/sun ... -size.html

I wonder if we'd feel not just surprise and marvel but also a deep revulsion at its unnaturally small size viewed from an outer planet....if the sight would offend some deep unconscious faculty, ala the "uncanny valley" revulsion.
While the image correctly represents the relative size of the Sun seen from different places, it doesn't capture the visual appearance accurately, since very few people are likely to have a visual impression of the Sun from Earth like that represented in the image. The Sun is very small, and combined with its brightness even at sunset, we don't really note its size much at all. Consider a more realistic image of a sunset, and ask yourself how much difference the size changes would really make.

Image
And at any time other than sunset, the Sun might as well be a point source. We'd notice the quality of shadows changing more than we'd notice the Sun was a different size.

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Re: APOD: A Mercury Transit Music Video from SDO (2016 May 11)

Post by Jim Leff » Fri May 13, 2016 2:07 am

Thanks, interesting! From the video, it seems way closer than that. Telescope effect, angular effect, etc.
Chris Peterson wrote:
Jim Leff wrote:My favorite part was the last few seconds, as Mercury completed its transit and kept going laterally against the background of the corona. I was sorry it wasn't illuminated from this direction, so we could see it recede and disappear behind the sun. I'd have liked a visceral sense of its orbital distance from how wide to the "right" it would appear to swing before receding.
It would be 48 solar widths to the right when it swings back towards the Sun on June 9, and then it would go "behind" the Sun around July 6, except it would no longer be on the ecliptic, so it wouldn't go behind the Sun at all, but would be about three solar widths north of the Sun from our vantage.

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Re: APOD: A Mercury Transit Music Video from SDO (2016 May 11)

Post by Nitpicker » Fri May 13, 2016 2:54 am

Jim Leff wrote:Thanks, interesting! From the video, it seems way closer than that. Telescope effect, angular effect, etc.
I don't think you can get any visual sense of how close Mercury is to the Sun from watching the video (other than that it is closer than Earth). The only clues come from measuring the timing of the transit, and plugging the results into a simple orbital model.

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Re: APOD: A Mercury Transit Music Video from SDO (2016 May 11)

Post by Jim Leff » Fri May 13, 2016 5:53 am

Nitpicker wrote:
I don't think you can get any visual sense of how close Mercury is to the Sun from watching the video (other than that it is closer than Earth).

Oh, absolutely! But that doesn't mean the eye doesn't try....