Explanation: As viewed from a well chosen location at sunset, the gorgeous Full Moon rose behind Mount Hamilton, east of San Jose, California on March 7. The lunar disk frames historic Lick Observatoryperched 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.
Very nice picture. We happened to drive by Lick one afternoon; probably a Sunday. When we saw it was there we drove on up. Not much going on but a neat experience.
Re: APOD: Lick Observatory Moonrise (2012 Mar 10)
Posted: Sat Mar 10, 2012 10:37 am
by sagansmyhero
WOA!!!
Compare this shot with the one Baldridge shot in 2008..
Look how much the moon has rotated! The sea that's at 12 o'clock today was past 1 o'clock 4 years ago.
What's up with that???
An axial tilt of 6.68º plus an inclination of 5.14º
Re: APOD: Lick Observatory Moonrise (2012 Mar 10)
Posted: Sat Mar 10, 2012 1:46 pm
by orin stepanek
March 8, 4:39 a.m. EST — Full Worm Moon. In this month, the ground softens and the earthworm casts reappear, inviting the return of the robins. The more northern tribes called this the Full Crow Moon, when the cawing of crows signals the end of winter, or the Full Crust Moon because the snow cover becomes crusted from thawing by day and freezing at night. TheFull Sap Moon, marking the time to tap maple trees, is another variation.
Might be a good month to go fishing!
Re: APOD: Lick Observatory Moonrise (2012 Mar 10)
Posted: Sat Mar 10, 2012 2:37 pm
by Larry Heinrich
The irregularities in the perimeter of the picture are interesting. Are they real or just a phenomenon of the picture?
Larry Heinrich
Look how much the moon has rotated! The sea that's at 12 o'clock today was past 1 o'clock 4 years ago.
What's up with that???
An axial tilt of 6.68º plus an inclination of 5.14º
Click to play embedded YouTube video.
It is interesting, in addition to the lunar axial tilt and orbial inclination, the Earth's axial tilt should be explicitly mentioned. The largest wobble component is driven by the angle difference between the Earth equator and the moons orbit which varies between approximately 18° and 28°over 18 years (≈ 23.4°+/- 5.1°). Art, your posted diagram shows the important parameters, but the timescale for the large wobble, and the importance of the Earth's axial tilt was not clear. If one visualizes two lines: one line that is parallel to the Earths axis (a north-south line) that is drawn through the center of the moon, and a second line drawn through the Moon's rotation axis (connecting the lunar poles), the Position Angle is defined as the angle between between these lines. Currently, the change in PA is seen to oscillate ±24°(48°total) over each lunar orbit. I think it's correct to say the PA change is what sagansmyhero was asking about.
The video shows the moon at 1 hour intervals over the entire year of 2011. There is also a fairly lengthy discussion at the youtube site
Re: APOD: Lick Observatory Moonrise (2012 Mar 10)
Posted: Sun Mar 11, 2012 2:34 pm
by neufer
alter-ego wrote:
It is interesting, in addition to the lunar axial tilt and orbial inclination, the Earth's axial tilt should be explicitly mentioned. The largest wobble component is driven by the angle difference between the Earth equator and the moons orbit which varies between approximately 18° and 28°over 18 years (≈ 23.4°+/- 5.1°). Art, your posted diagram shows the important parameters, but the timescale for the large wobble, and the importance of the Earth's axial tilt was not clear. If one visualizes two lines: one line that is parallel to the Earths axis (a north-south line) that is drawn through the center of the moon, and a second line drawn through the Moon's rotation axis (connecting the lunar poles), the Position Angle is defined as the angle between between these lines. Currently, the change in PA is seen to oscillate ±24°(48°total) over each lunar orbit. I think it's correct to say the PA change is what sagansmyhero was asking about.
Thanks, alter-ego. You are quite right about the 23.4°axial tilt of the earth being the main factor here.
As regards the orientation of the Lick Observatory Moonrise vis-a-vis the horizon there are basically two primary effects:
1) The full moon has a counter clockwise twist each March Equinox as observed all night by everyone on the planet.
(Likewise, the full moon has a clockwise twist each September Equinox as observed by everyone on the planet.)
2) The rising full moon in the Northeast has a clockwise twist vis-a-vis the horizon each December Solstice as it tries to point forwards towards Polaris.
(Likewise, the setting full moon in the Northwest has a counter clockwise twist vis-a-vis the horizon each December Solstice as it tries to point backwards towards Polaris.)
The lunar axial tilt of 6.68º and lunar inclination of 5.14º affect both the magnitude & timing of these regular predictable "twists" but these are, as you say, secondary factors (and they do not change much over just 4 years).
Re: APOD: Lick Observatory Moonrise (2012 Mar 10)
Posted: Mon Mar 12, 2012 3:50 pm
by Thunderbumper
I was taught that a lerge moon at moonrise is an optical illusion created by the human brain. How then can this picture be possible unless it was altered?
Re: APOD: Lick Observatory Moonrise (2012 Mar 10)
Posted: Mon Mar 12, 2012 4:57 pm
by Chris Peterson
Thunderbumper wrote:I was taught that a lerge moon at moonrise is an optical illusion created by the human brain. How then can this picture be possible unless it was altered?
It is an illusion. The Moon is about 1/2° across regardless of where it is in the sky. The distance from the camera to the observatory is such that the observatory subtends about 1/6°, and the hill it is sitting on is about 1/2°. No digital trickery required.
If the photographer doubled his distance from the observatory, the Moon would still be 1/2°, but the observatory would subtend half the angle it currently does, making the Moon seem even larger (or the observatory smaller).
Re: APOD: Lick Observatory Moonrise (2012 Mar 10)
Posted: Mon Mar 12, 2012 5:05 pm
by neufer
Thunderbumper wrote:
I was taught that a lerge moon at moonrise is an optical illusion created by the human brain.
mtbdudex wrote:I'd really like more details on this shot.
Camera, lens, settings, and if cropped or not.
Almost exactly same shot as 4 years ago........................
Rick's flickr page http://www.flickr.com/photos/xb70man/se ... 317773324/
shows how he planned & set up the 2008 moonrise shot. It also has a neat slideshow showing the complete moonrise.
He "Used Canon XTi DSLR through a Stellarvue 80mm ED Refractor, 560mm F.L., f7.0 ISO 100, 1/100sec exposure."
He also did a sunrise 3 days later, from a different southbay location.
And another moonrise shot in 2009, from a 3rd location, all about 20 miles west of the observatory.
The 2012 shot appears to use twice the magnification, or cropping.
Re: APOD: Lick Observatory Moonrise (2012 Mar 10)
Posted: Tue Mar 13, 2012 4:40 am
by Beyond
neufer wrote:
Thunderbumper wrote:
I was taught that a lerge moon at moonrise is an optical illusion created by the human brain.
Lick Observatory Moonrise
