Posted on 03/13/2012 11:17:18 PM PDT by nickcarraway
When the moon hits your eye using a Canon Rebel XTi DSLR, this is what you get. Did you see the moon rise this past weekend? It was full, and gorgeous, and at the right angle - huge.
Case in point: this photo of Mount Hamilton taken by photographer Rick Baldridge. He says he snapped the photo Saturday night at 6:08 p.m. near the San Jose airport.
Baldridge says he used a DOS-based program called SKYMAP to pinpoint the exact location he needed to get the moon over the Lick Observatory.
After he performed what seems to us to be graduate-level math equations, he said he figured out the Taylor Street Rock Garden off of Highway 87was the right spot. He said finding the location was the most difficult part of the project.
As you can see, he nailed the location. The moon provided the perfect frame for the Lick Observatory.
The photograph was chosen as today's "Astronomy Picture of the Day" by NASA:
APOD writers described it like this:
The lunar disk frames historic Lick Observatory perched on the mountain's 4,200 foot summit. Both observatory and Moon echo the warm color of sunlight (moonlight is reflected sunlight) filtered by a long path through the atmosphere. Substantial atmospheric refraction contributes the Moon's ragged, green rim. Of course, the March Full Moon is also known as the Full Worm Moon. In the telescopic photo, Lick's 40 inch Nickel Telescope dome is on the left. The large dome on the right houses Lick's Great 36 inch Refractor.
We had to crop the image at the top. The full photo is below.
The Moon Illusion Explained
http://facstaff.uww.edu/mccreadd/intro9.htm
Moon illusion:
“The Moon illusion is an optical illusion in which the Moon appears larger near the horizon than it does while higher up in the sky. This optical illusion also occurs with the sun and star constellations. It has been known since ancient times, and recorded by numerous different cultures.”:
http://en.wikipedia.org/wiki/Moon_illusion
Great site-thanks for the link and map.
Mercury had been visible several days ago.. Unfortunately, since Mar 5, it has begun moving back in the direction of the Sun and is now impossible to see.
Bummer. Think I’ve seen it once or twice.
Ever try Iridium Flares? That kept me busy for a while.
The Moon illusion: The Ebbinghaus illusion:
http://en.wikipedia.org/wiki/Moon_illusion#Relative_size_hypothesis
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"The Ebbinghaus illusion or Titchener circles is an optical illusion of relative size perception. In the best-known version of the illusion, two circles of identical size are placed near to each other and one is surrounded by large circles while the other is surrounded by small circles; the first central circle then appears smaller than the second central circle."
You’re both wrong. The moon illusion is still a mystery. Refractive models don’t work as refraction artificially elevates an objects apparent position in the sky in relation to it’s true position. That’s why you can’t use a sextant to navigate with stars that are close to the horizon.
It’s not simply a cognitive illusion such as perspective, as monocular lenses and mechanical recording devices also “see” it. When I was last in college in the 1990’s it was a mystery we studied in astronomy, and a quick search before posting here confirms that it still hasn’t been solved.
Nope, that’s been debunked when purely mechanical measurements have been taken with a cmos sensor. The truth is we don’t know.
Purely mechanical measurements confirm the Moon is the same size at the horizon as when its high in the sky. Perhaps, there is some very slight difference (assuming what you're saying is correct), but that isn't a primary factor in the creation of the illusion.
wow!
"A simple way of demonstrating that the effect is an illusion is to hold a small object (say, 1/4 inch wide) at arm's length (25 inches) with one eye closed, positioning it next to the seemingly large Moon. When the Moon is higher in the sky, positioning the same object near the Moon reveals that there is no change in size."
Proof of Illusion:
http://en.wikipedia.org/wiki/Moon_illusion#Proof_of_illusion
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When I was last in college in the 1990’s it was a mystery we studied in astronomy, and a quick search before posting here confirms that it still hasn’t been solved.
True, it hasn't been fully solved, but illusion it is.
Probably caught a hundred or so over the past decade or two, the brightest being an incredible minus 8. What about the International Space Station (ISS)? Those can be similarly spectacular at times, depending on local circumstances.
bttt
Nice find!
That’s why you can’t use a sextant to navigate with stars that are close to the horizon.
We used a sexton. With our conversion tables it worked just fine. You don’t take the sighting on the middle of the moon but on the lower limb.
And when the effect is seen at sea with nothing in the foreground?
When the Moon is near the horizon, hold out your arm and cover the Moon with your thumb. Then wait 6 hours and try it again.
Comes out the same.
The Moon will change sizes over the course of a month. It’s orbit is an ellipse and thus it is closer or further away from us at different times.
If you can watch the Moon rise up out of the ocean, it is something special to see.
What is more to the point is why you would still be using SkyMap when the Cartes Du Ciel software is out there.
Take a look here. It is free and incredibly useful for the amateur astronomer, or, casual sky watcher.
http://www.ap-i.net/skychart/start
THANK YOU!!
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