Starship Asterisk*

Waterton Lake Eclipse

Explanation: Recorded on April 15th, this total lunar eclipse sequence looks south down icy Waterton Lake from the Waterton Lakes National Park in Alberta, Canada, planet Earth. The most distant horizon includes peaks in Glacier National Park, USA. An exposure every 10 minutes captured the Moon's position and eclipse phase, as it arced, left to right, above the rugged skyline and Waterton town lights. In fact, the sequence effectively measures the roughly 80 minute duration of the total phase of the eclipse. Around 270 BC, the Greek astronomer Aristarchus also measured the duration of lunar eclipses - though probably without the benefit of digital clocks and cameras. Still, using geometry, he devised a simple and impressively accurate way to calculate the Moon's distance, in terms of the radius of planet Earth, from the eclipse duration. This modern eclipse sequence also tracks the successive positions of Mars, above and right of the Moon, bright star Spica next to the reddened lunar disk, and Saturn to the left and below.

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Hi,

There's a typo in the title: eclispe.

As I recall the rule of thumb, the moon moves through its own diameter every hour. If that's true, how can exposures ten minutes apart show discreet images of the moon separated by spaces? You don't state that the camera is fixed, true, but neither do you state that it was moved a bit between exposures to separate the images of the moon. Am I way off on this?

norman wrote:As I recall the rule of thumb, the moon moves through its own diameter every hour. If that's true, how can exposures ten minutes apart show discreet images of the moon separated by spaces? You don't state that the camera is fixed, true, but neither do you state that it was moved a bit between exposures to separate the images of the moon. Am I way off on this?

Yes, you are way off. The moon moves through its own diameter every two minutes, as does the sun.

(Both the moon an the sun have angular diameters of about half a degree. The motion is dominated by the earth's rotation, 360 degrees in 24*60=1440 minutes, which is 1 degree per 4 minutes. QED.)

It would be interesting to learn from the photographer how he created this image. I think there's quite a lot going on beyond the "obvious" 28 exposures of the moon.

To my eye, the mountains on the left are probably illuminated by the moon on the right; and the mountains on the right are probably illuminated by the moon on the left. The sky appears to be taken from two separate frames too; there's a clear join line down the middle. But each separate exposure of the moon appears to be reflected in the frozen lake. So all in all we have something like 59 layers in the photo: the mountains and sky on the right, from an early frame; the mountains and sky on the left from a late frame; 28 exposures of the moon, all overlaid; and 28 exposures of the lake, all blended together somehow.

Or at least, that's how I'd do it. It would be interesting to now how it was actually done.

StewartR wrote:

norman wrote:As I recall the rule of thumb, the moon moves through its own diameter every hour. If that's true, how can exposures ten minutes apart show discreet images of the moon separated by spaces? You don't state that the camera is fixed, true, but neither do you state that it was moved a bit between exposures to separate the images of the moon. Am I way off on this?

Yes, you are way off. The moon moves through its own diameter every two minutes, as does the sun.

(Both the moon an the sun have angular diameters of about half a degree. The motion is dominated by the earth's rotation, 360 degrees in 24*60=1440 minutes, which is 1 degree per 4 minutes. QED.)

Well, the rule of thumb that the moon moves through its own diameter every hour is true, it is just that this movement is relative to the fixed stars, which appear to rotate with the celestial sphere.

Nitpicker wrote:

StewartR wrote:

norman wrote:As I recall the rule of thumb, the moon moves through its own diameter every hour. If that's true, how can exposures ten minutes apart show discreet images of the moon separated by spaces? You don't state that the camera is fixed, true, but neither do you state that it was moved a bit between exposures to separate the images of the moon. Am I way off on this?

Yes, you are way off. The moon moves through its own diameter every two minutes, as does the sun.

(Both the moon an the sun have angular diameters of about half a degree. The motion is dominated by the earth's rotation, 360 degrees in 24*60=1440 minutes, which is 1 degree per 4 minutes. QED.)

Well, the rule of thumb that the moon moves through its own diameter every hour is true, it is just that this movement is relative to the fixed stars, which appear to rotate with the celestial sphere.

Nice conflict resolution Nitpicker. As is so often the case in arguments, there’s at least some truth on both sides.

APOD Robot wrote: Around 270 BC, the Greek astronomer Aristarchus also measured the duration of lunar eclipses - though probably without the benefit of digital clocks and cameras.

information like that never ceases to amaze me.

CURRAHEE CHRIS wrote:

APOD Robot wrote: Around 270 BC, the Greek astronomer Aristarchus also measured the duration of lunar eclipses - though probably without the benefit of digital clocks and cameras.

information like that never ceases to amaze me.

Recently I've been imagining a 24-hour analog clock that displays: sidereal time by rotation of the clock face around the celestial pole; solar time by rotation of the Sun on a hand centered at the ecliptic pole and moving along the ecliptic; and the phase of the Moon by the movement of another hand that moves along the ecliptic, offset by the motion of a cam to show the Moon's path north and south of the ecliptic -- thus you could easily see when the Moon's nodes coincide with new and full Moon, resulting in eclipses. Might as well throw in Jupiter moving along the ecliptic, too.

I've browsed online to look for something comparable, but I haven't found anything either real or virtual exactly like I'm envisioning. Unfortunately I'm neither a clockmaker nor a computer programmer, so I won't actually create this clock. If anybody wants to collaborate on this, please drop me a line.

And by the way, this is a breathtakingly beautiful image! Thank you Mr. Takasaka!

Indeed, it is a beautiful, fascinating image.

Ann

That is one of the most beautiful and inspiring pictures APOD has ever done. We could not see eclipse in east due to cloud but this one almost makes up for missing it.
Going right into my screen saver made up of APOD pictures.

In the off season there may be 30 people in Waterton village (the lights in the picture). There are hundreds more deer and bighorn sheep. It's worth a visit if only for the haunting sound of the wind and the extremely clear skies.

CURRAHEE CHRIS wrote:

APOD Robot wrote: Around 270 BC, the Greek astronomer Aristarchus also measured the duration of lunar eclipses - though probably without the benefit of digital clocks and cameras.

information like that never ceases to amaze me.

Probably. Probably? Really? Is there a possibility that Aristarchus had a digital clock?
----

Beautiful sequence picture. One of the best ever. Thank you,

.Diana.

Diana wrote:

CURRAHEE CHRIS wrote:

APOD Robot wrote: Around 270 BC, the Greek astronomer Aristarchus also measured the duration of lunar eclipses - though probably without the benefit of digital clocks and cameras.

information like that never ceases to amaze me.

Probably. Probably? Really? Is there a possibility that Aristarchus had a digital clock?
----

Beautiful sequence picture. One of the best ever. Thank you,

.Diana.

Given that the Greeks were able to invent the Antikythera, who knows what else they might have devised that hasn't survived as an archeological relic? I understand they were fond of watching Sophocles reruns on their DVR's.

Diana wrote:Probably. Probably? Really? Is there a possibility that Aristarchus had a digital clock?

Sure. Every time he counted down from ten on his fingers.

Chris Peterson wrote:

Diana wrote:Probably. Probably? Really? Is there a possibility that Aristarchus had a digital clock?

Sure. Every time he counted down from ten on his fingers.

On his fingers?? That, would be thumbthing

Aristarchus was a guy ahead of his time....having it basically correct, that the Earth is not the center of the Universe, and the Earth goes around the Sun, (For which Galileo was made to recant). Thus, we could have had a MORE correct model of the Solar System nearly 1700 YEARS EARLIER than Copernicus,.....but Ptolemy was more accepted, and so the Geocentric System stayed in vogue....as well as being clung to in religious circles...more is the pity...

Very interesting shot today....I "watched" the Eclipse with Stellarium...as it was cloudy....(me sad)....

:---[===] *

The positions of Saturn are stated to be left and below those of Spica. There are however two trails below Spica (both visible but better seen on my monitor on enlarging the image) so I wonder which is Saturn? I would also be grateful if someone could please tell me what is the set of positions in the top left corner that are steeply inclined (possibly a satellite passed through?).

Anthony Barreiro wrote:

CURRAHEE CHRIS wrote:

APOD Robot wrote: Around 270 BC, the Greek astronomer Aristarchus also measured the duration of lunar eclipses - though probably without the benefit of digital clocks and cameras.

information like that never ceases to amaze me.

Recently I've been imagining a 24-hour analog clock that displays: sidereal time by rotation of the clock face around the celestial pole; solar time by rotation of the Sun on a hand centered at the ecliptic pole and moving along the ecliptic; and the phase of the Moon by the movement of another hand that moves along the ecliptic, offset by the motion of a cam to show the Moon's path north and south of the ecliptic -- thus you could easily see when the Moon's nodes coincide with new and full Moon, resulting in eclipses. Might as well throw in Jupiter moving along the ecliptic, too.

I've browsed online to look for something comparable, but I haven't found anything either real or virtual exactly like I'm envisioning. Unfortunately I'm neither a clockmaker nor a computer programmer, so I won't actually create this clock. If anybody wants to collaborate on this, please drop me a line.

The time piece you are describing sounds very much like the time piece used by former Headmaster Albus Dumbledor of Hogwarts School. Perhaps his estate would be willing to part with it, for a reasonable sum. I don't recall in which book he referred to this timepiece.

BillBixby wrote:

Anthony Barreiro wrote:Recently I've been imagining a 24-hour analog clock that displays: sidereal time by rotation of the clock face around the celestial pole; solar time by rotation of the Sun on a hand centered at the ecliptic pole and moving along the ecliptic; and the phase of the Moon by the movement of another hand that moves along the ecliptic, offset by the motion of a cam to show the Moon's path north and south of the ecliptic -- thus you could easily see when the Moon's nodes coincide with new and full Moon, resulting in eclipses. Might as well throw in Jupiter moving along the ecliptic, too.

I've browsed online to look for something comparable, but I haven't found anything either real or virtual exactly like I'm envisioning. Unfortunately I'm neither a clockmaker nor a computer programmer, so I won't actually create this clock. If anybody wants to collaborate on this, please drop me a line.

The time piece you are describing sounds very much like the time piece used by former Headmaster Albus Dumbledor of Hogwarts School. Perhaps his estate would be willing to part with it, for a reasonable sum. I don't recall in which book he referred to this timepiece.

I had only considered physical and virtual realities, not fictional.

It's missing the moon, but perhaps the other planets will make up for it: http://www.vancleefarpels.com/us/en/art ... -timepiece

https://www.youtube.com/watch?v=LUtUDSltl-M

owlice wrote:It's missing the moon, but perhaps the other planets will make up for it: http://www.vancleefarpels.com/us/en/art ... -timepiece

https://www.youtube.com/watch?v=LUtUDSltl-M

Thanks, Owlice. The watch is a heliocentric orrery, a different animal than a sidereal clock. Still, if anybody is feeling generous and wants to gift me with this little bauble, I wouldn't say no.