I’ve been asked to provide some information on the upcoming eclipse Sunday, so here it is.
I’ll actually miss the first part of the Heartland conference (Sunday night and Monday) due to the promise to my children we’d see this together. Timing for the eclipse, getting back from the spot I’ve picked out in the high desert and airplane schedules didn’t pencil out.
Click to enlarge. Image by Anthony using Google Earth as basis.
Images, data, and other facts:
Click to enlarge
Diagrams of the moon’s shadow from Magdalena Ridge Observatory New Mexico Tech
What you may see (with a proper filter) is this:
University of Manitoba western USA path:
From NASA
Description of the 2012 Annular Solar Eclipse
The 2012 May 20 eclipse occurs at the Moon’s descending node in central Taurus. An annular eclipse will be visible from a 240 to 300 kilometre-wide track that traverses eastern Asia, the northern Pacific Ocean and the western United States. A partial eclipse is seen within the much broader path of the Moon’s penumbral shadow, that includes much of Asia, the Pacific and the western 2/3 of North America (Figure 1).
The annular path begins in southern China at 22:06 UT. Because the Moon passed through apogee one day earlier (May 19 at 16:14 UT), its large distance from Earth produces a wide path of annularity. Traveling eastward, the shadow quickly sweeps along the southern coast of Japan as the central line duration of annularity grows from 4.4 to 5.0 minutes.
Tokyo lies 10 kilometres north of the central line. For the over 10 million residents within the metropolitan area, the annular phase will last 5 minutes beginning at 22:32 UT (on May 21 local time). The annular ring is quite thick because the Moon’s apparent diameter is only 94% that of the Sun. Traveling with a velocity of 1.1 kilometres/second, the antumbral shadow leaves Japan and heads northeast across the Northern Pacific. The instant of greatest eclipse [1] occurs at 23:52:47 UT when the eclipse magnitude [2] reaches 0.9439. At that instant, the duration of annularity is 5 minutes 46 seconds, the path width is 237 kilometres and the Sun is 61° above the flat horizon formed by the open ocean.
The shadow passes just south of Alaska’s Aleutian Islands as the central track slowly curves to the southeast. After a 7000 kilometre-long ocean voyage lasting nearly 2 hours, the antumbra finally reaches land again along the rugged coastlines of southern Oregon and northern California (Figure 2) at 01:23 UT (May 20 local time).
Redding, CA lies 30 kilometres south of the central line. Nevertheless, it still experiences an annular phase lasting 4 1/2 minutes beginning at 01:26 UT. It is already late afternoon along this section of the eclipse path. The Sun’s altitude is 20° during the annular phase and decreasing as the track heads southeast. Central Nevada, southern Utah, and northern Arizona are all within the annular path.
By the time the antumbra reaches Albuquerque, NM (01:34 UT), the central duration is still 4 1/2 minutes, but the Sun’s altitude has dropped to 5°. As its leading edge reaches the Texas Panhandle, the shadow is now an elongated ellipse extending all the way to Nevada. Seconds later, the antumbra begins its rise back into space above western Texas as the track and the annular eclipse end.
During the course of its 3.5-hour trajectory, the antumbra’s track is approximately 13,600 kilometres long and covers 0.74% of Earth’s surface area. Path coordinates and central line circumstances are presented in Table 1.
Partial phases of the eclipse are visible primarily from the USA, Canada, the Pacific and East Asia. Local circumstances for a number of cities are found in Table 2 (Canada, Mexico and Asia) and Table 3 (USA). All times are given in Universal Time. The Sun’s altitude and azimuth, the eclipse magnitude and obscuration are all given at the instant of maximum eclipse.
The NASA JavaScript Solar Eclipse Explorer is an interactive web page that can quickly calculate the local circumstances of the eclipse from any geographic location not included in Table 1:
eclipse.gsfc.nasa.gov/JSEX/JSEX-index.html
This is the 33rd eclipse of Saros 128 (Espenak and Meeus, 2006). The family began with a series of 24 partial eclipses starting on 0984 Aug 29. The first central eclipse was total and took place on 1417 May 16. After three more totals and four hybrid eclipses, the series changed to annular on 1561 Aug 11. Subsequent members of Saros 128 were all annular eclipses with increasing durations, the maximum of which was reached on 1832 Feb 01 and lasted 08 minutes 35 seconds. The duration of annularity of each succeeding eclipse is now dropping and will reach 4 minutes with the last annular eclipse of the series on 2120 Jul 25. Saros 128 terminates on 2282 Nov 01 after a string of 9 partial eclipses. Complete details for the 73 eclipses in the series (in the sequence of 24 partial, 4 total, 4 hybrid, 32 annular, and 9 partial) may be found at:
eclipse.gsfc.nasa.gov/SEsaros/SEsaros128.html
The above information is based on the article published in the RASC Observer’s Handbook for 2012.
Footnotes
[1] The instant of greatest eclipse for solar eclipses occurs when the distance between the Moon’s shadow axis and Earth’s geocentre reaches a minimum.
[2] Eclipse magnitude for solar eclipses is defined as the fraction of the Sun’s diameter occulted by the Moon.
[3] Eclipse obscuration is defined as the fraction of the Sun’s area occulted by the Moon.
[4] The Saros is a period of 6,585.3 days (18 years 11 days 8 hours) in which eclipses (both solar and lunar) repeat. The geometry isn’t exact but close enough for a Saros series to last 12 or more centuries.
Orthographic Map of the Annular Solar Eclipse
The following map shows the overall regions of visibility of the partial eclipse as well as the path of the Annular eclipse through Asia, the Pacific and North America. It uses high resolution coastline data from the World Data Base II (WDB).
Interactive Map of the Path of Annularity
An implementation of Google Map has been created which includes the central path of the 2012 total solar eclipse. This allows the user to select any portion of the path and to zoom in using either map data or Earth satellite data.
Detailed Maps of the Path of Annularity
Although a NASA eclipse bulletin was not published for this eclipse, Jay Anderson still generated a series of detailed eclipse maps.
Michael Zeiler and Bill Kramer have also produced an excellent set of maps for the annular eclipse using the NASA Besselian elements.
Eclipse Elements, Shadow Contacts and Path of Annularity
The following tables give detailed predictions including the Besselian Elements, shadow contacts with Earth, path of the antumbral shadow and topocentric data (with path corrections) along the path.
- Table 1 – Elements of the Eclipse
- Table 2 – Shadow Contacts and Circumstances
- Table 3A – Path of the Antumbral Shadow
- Table 3B – Path of the Antumbral Shadow (Extended Version)
- Table 4A – Physical Ephemeris of the Antumbral Shadow
- Table 4B – Physical Ephemeris of the Antumbral Shadow (Extended Version)
- Table 5 – Local Circumstances on the Central Line
- Table 6 – Topocentric Data and Path Corrections Due to Lunar Limb Profile
Coordinate Tables for the Path of Annularity
The following tables provide detailed coordinates for the path of the antumbral shadow as well as the zones of grazing eclipse. They are listed in a format convenient for plotting on maps.
- Table 7A – Mapping Coordinates for the Antumbral Path
- Table 7B – Mapping Coordinates for the Antumbral Path (North America; Extended – 15´ step size)
- Table 8A – Mapping Coordinates for the Zones of Grazing Eclipse
- Table 8B – Mapping Coordinates for the Zones of Grazing Eclipse (North America; Extended – 15´ step size)
Local Circumstances
The following table gives the local circumstances of the eclipse from various cities throughout the Western Hemisphere. All contact times are given in the tables are in Universal Time.
Explanation of Eclipse Maps and Tables
The following links give detailed descriptions and explanations of the eclipse maps and tables.
- Map 1 – Orthographic Map of the Eclipse Path
- Table 1 – Elements of the Eclipse
- Table 2 – Shadow Contacts and Circumstances
- Table 3 – Path of the Umbral (or Antumbral) Shadow
- Table 4 – Physical Ephemeris of the Umbral (or Antumbral) Shadow
- Table 5 – Local Circumstances on the Central Line
- Table 6 – Topocentric Data and Path Corrections Due to Lunar Limb Profile
- Table 7A & 7B – Mapping Coordinates for the Central Path
- Table 8A & 8B – Coordinates for the Zones of Grazing Eclipse
- Mean Lunar Radius
- Lunar Limb Profile
- Limb Corrections to the Path Limits: Graze Zones
Weather
Eclipse Photography
Reproduction of Eclipse Data
All eclipse calculations are by Fred Espenak, and he assumes full responsibility for their accuracy. Permission is freely granted to reproduce this data when accompanied by an acknowledgment:
“Eclipse Predictions by Fred Espenak, NASA’s GSFC”
==============================================
WARNING & Admonition:
Do not look at the sun during the eclipse with the naked eye or even with sunglasses, use an approved solar filter, solar glasses, or solar projection system.
Attempts to use a binoculars, telescope, or other optical viewing device without a proper filter will likely result in instant and permanent eye damage!
We built a huge image device when there was an eclipse in the UK. From memory it was a tube about 8foot long with a 3-4mm hole in a bit of card one end and a sheet of paper at the other. I think we had a black sheet taped around it.
The advantage is that adults can take young children under the sheet — they think that is fun — but the important bit is that you can point out the bit that is missing and describe it … I think a coin can show how the moon is moving.
Anthony,
Enjoy ecilpse time with family.
Hope to see you at ICCC-7 on Tues. Perhaps a libation?
John
I’m really annoyed about this. The first chance I get to see an eclipse in my lifetime, with the path of maximum visibility within 15 miles of my house, and I am stuck working in a 3rd world hell hole.
Good for you Anthony, spending a big deal like this with your kids. Consider this an attaboy!
I live ~10 miles from the center line (Lower Texas Panhandle), won’t even have to drive. Just set up the tripod, and Mr Whitman has a wonderful idea, libations while awaiting the big event! The last full eclipse we had in these parts was in 1994. I’m delivering mail, outside all day, perfect setup! Total cloud cover, looked like dusk. Durnit. Sunny forecast for this one though!
Oh, and many thanks for Mr Espenak for doing the grunt work to allow people to partake of this event!
Good for you Anthony! Enjoy this with your kids. As an old N. Californian, I’m guessing you’ll be somewhere southeast of Susanville (maybe near Honey Lake?). As I recall, that’s pretty open country. Wherever, this should be a real treat. Living in S. Arizona now so we won’t get to see much, but I’ll be looking.
While I’m here, I’d just like to add my sincere thanks for all you do!
Should be pretty cool, with the sun almost setting.
I hope none of the dread “pollution filled thunderstorm anvils” block your view.
You are bringing welders goggles, or their equivalent ?
Anthony,
That’s a good promise to keep :). It’s a thing of wonder, so enjoy!
BTW, thank you for the prominently displayed warning regarding how to view the sun. That message can never be repeated enough.
Have fun!
Many Thanks!
A friend and I are heading to the Nevada desert just a little south of the centerline and will be photographing the eclipse. Hopefully high clouds from the incoming trough on Sunday night will hold off. Looks like the closer to the coast you get the more clouds there are going to be.
Anyone know if the chips in digital cameras can handle the sun if they are stopped way down? I shot an eclipse on film on a Pentax about 15 years ago by stopping the aperture all the way down, and using a few second exposure 3X by having the shutter open and just removing the lens cap at three positions of the moon as it crossed the sun. Worked perfectly.
You’re a good man, Anthony Watts! I’ve never seen an annular & am told they are quite spectacular, so hat’s off to you and yours!
BTW, Chicago is undergoing the NATO meetings, with various greens/anarchists/hippies etc. marching around, so don’t worry about your delay in getting here. Our police are itching to use their brand-new riot gear, so let’s hope the opposition is smart enough to not tempt them! Safe travels.
“The annular path begins in southern China at 22:06 UT.”
I’m a bit slow. Could someone explain what this means? 22 hundred hours is… 10:20 p.m. local time? What is the “annular path”?
Bill Parsons says:
May 18, 2012 at 7:19 pm
22 hundered hours UT is 22:00hrs (or 10PM) UT. And UT is Universal Time – also known as Greenwhich Mean Time.
The’annular path’ is the area on the earth’s surface over which the annular eclipse is visible. When plotted on a 2 dimensional map it looks like along narrow path – see the maps above.
An even rarer astronomical event occurs onJune 5th/6th – a transit of Venus. The next onewon’t be until December 2117..
Really glad you have your priorities sorted
Do enjoy and savour the Family Time
Andi
I had the opportunity to see one (annular not total) when I was in the Navy in the South China sea. Pretty cool. The light level was similar to 97% total eclipse (seen that too), as dim as a very cloudy day but the sun still seems as bright as ever. Very weird looking.
Andy, looks like you’re missing the start of the ICCC-7 for the same reason I am. I’m in Santa Fe awaiting the sunset ring. No kids this time, but the last annular down here in 1994 we brought them all along – one of our crazy adventures they’ll always remember.
BTW, Andy and I are speaking back-to-back at the ICCC, after seeing the eclipse.
Reblogged this on gottadobetterthanthis and commented:
Impressive amount of information. Note that we cannot see it here in central Oklahoma. (Local weather is expecting cloud cover and likely rain.)
I wish you all a good weather.
Tomorrow I perdicks a monster will try to eat the sun! But I will shoo it away, if you each send me $1000.
magician@scamhome.con
To put lunar dynamics in context of the fuss over human control over global climate,there was an issue in the mid 19th century where men were genuinely embarrassed over the assertion that the moon spins as it makes a lunar circuit of the Earth.Even though we can now send an astronaut to the moon who can look out at a rotating Earth from a non rotating moon,the idea that the moon spins is so ingrained that people find it impossible to believe otherwise.
That is what will happen to this issue of global warming,no matter how good and clever the arguments are,the assertion that humans can control global temperature will stick and plague the flow of information between planetary dynamics and terrestrial sciences or astronomy in general.
The notable feature of the following article is that when faced with the absurdity of a spinning moon,the person assuming lunar rotation did not adapt to a better view but merely seen it as an attack on the mainstream doctrine –
http://books.google.ie/books?id=MfU3AAAAMAAJ&pg=PA27&dq=moon+does+not+rotate&hl=en&ei=Ywt5TPu7DJDGswbJ58SyDQ&sa=X&oi=book_result&ct=result&resnum=10&ved=0CFgQ6AEwCQ#v=onepage&q&f=false
GKELL1 says:
May 19, 2012 at 12:38 am
the idea that the moon spins is so ingrained that people find it impossible to believe otherwise.
They shouldn’t believe otherwise as the Moon does indeed rotate.
Eclipse Photography
My son, Mikael, took this photo of an annular eclipse:
http://earthsky.org/space/the-most-amazing-ring-eclipse-photo-ever
That’s a good promise to keep :). It’s a thing of wonder, so enjoy!
BTW, thank you for the prominently displayed warning regarding how to view the sun. That message can never be repeated enough. Can I view the sun with this glasses? I don’t like to damаge my eyes ( http://amzn.to/JVibhG )
Have fun!
In the 1960s I watched a total eclipse from a beach on Cape Cod, though not actually “total,” since I was a very few miles from totality, maybe 2 miles, maybe 6 miles. I forget. I looked at the eclipsed sun without any filter by glancing at it for only a fraction of a second each time. Nothing happened to my vision. So I wonder if the warnings are just playing it safe, i.e., better to tell people not to look than to tell them they can look for a fraction of a second.
There was a man standing near me with a German shepherd. When it got very near to totality, the dog put his face in the sand and whimpered.
Seeing a total eclipse made me understand why primitive people are frightened by them. The sun was high in the sky on a cloudless day, and it got dark. That’s frightening. What’s more, it was like being in outer space; you could see that the moon and the sun are just spheres in a big 3-d space. Maybe you need to know that they’re spheres to see exactly that, but in any case it’s frightening.
Anthony,
We in Australia will recall the 1771 Captain Cook’s first voyage on the Endeavour, accompanied by Joseph Banks and Daniel Solander in observing the transit of Venus across the face of the Sun, and the means to calculate distance from Earth to the Sun.
Fortunately your kids will not be suffering from scurvy or other deprivations at sea. Such has life moved on.
Enjoy with your family, and I am sure Heartland will get you up to speed on the sessions you may have missed.
And now, thank you, to read the links and information you have posted………………
Thanks for this article and I hope that tomorrow evening is cloud-free and everyone (West of 110°) enjoys the spectacle.
I saw the Aug 11, 1999 total eclipse from the centreline just north of Rouen, France. It was simply stunning: while it seemed a little anti-climactic in the opening partial phase, about 30 seconds from totality the lights just went out (as if in a theatre) to deep dusk, but with lighter horizons all around! The temperature dropped, the birds all went quiet and there was this dark ball overhead which (in totality only – NOT DURING ANY ANNULAR ECLIPSE, OR WHEN ANY PART OF THE SUN IS DIRECTLY VISIBLE) you could look at directly.
My overwhelming thought was that, even just two or three centuries ago, people must have thought the end of the world was on them. It certainly sent shivers up my spine – perhaps the same folk memory is the cause of all the “harbinger of doom” (or “the sky is falling”) theories.
Hang on a moment: it’s my birthday on Monday which starts here in the UK about 6 minutes after the instant of greatest eclipse, at 23:54 UT! Gulp …!!
Smoking Frog says: May 19, 2012 at 4:09 am
In the 1960s I watched a total eclipse from a beach on Cape Cod…
I’ll bet that’s the one Steven King has included in some of his books, including a big plot point in The Dark Half. I’ll bet that was really neat, being on the water’s edge, and watching it.
Well, I clearly need practice converting from military time.
Anyway, what I still don’t understand is what will be visible outside the annular path — outside the “Limits of Visibility” will there be any eclipse of the sun? any dimming effects?
Weather permitting, I’ll be watching the moon take a bite size chunk of the sun here in northern Norway. The midnight sun is up and the spectacle starts around 1:30 am Monday. Saw the same show last year. It was amazing seeing the moon just hanging there in space.
Reply to Leif Svalgaard
I assure you that if the moon rotated once as it makes a circuit of the Earth we would see all sides once,if it rotated twice as it makes it monthly circuit of the Earth we would see all sides twice and so on.The moon doesn’t rotate and knowing that it always keeps the same face to the Earth would require you to make an inhuman effort to convince yourself that it does.Sound familiar in another case ?.
The website I referenced is disturbing in a specific way as it points to the same type of future for the climate issue where no decisive group exists to look at the core problem and as the modeling community is dominant in the education sector,the history of misdeeds and distortions will be slowly lost to history or downplayed.
The point is that if any individual here can look out at the moon and conclude that it spins (there was only even one person in history who asserted that it did) then what are the chances that they can interpret climate properly or indeed any topic in astronomy and terrestrial sciences ?.
.
Anthony,
We’re headed for the Chico area from SF. Any viewing suggestions there?
Highway 36 East of Red Bluff, CA, wide open space with good NW horizon view.
GKELL1 says (May 19, 2012 at 1:56 pm): “I assure you that if the moon rotated once as it makes a circuit of the Earth we would see all sides once,if it rotated twice as it makes it monthly circuit of the Earth we would see all sides twice and so on.”
Heh heh. Good one.
My turn. Er, ahem…we’re all doomed, DOOMED I tell you, by CO2. Hee hee.
How many miles should we drive on Highway 36?
Jessie says:
May 19, 2012 at 4:18 am
===============
Yep, it ain’t gonna stop.
I’m in Mexico, I hope I’ll be able to see it well enough. Are you planning on watching the solar eclipse? Take my quick poll http://knockoutsurveys.com/will-you-watch-the-solar-eclipse.html
Leif S. take a look at the “Astronomy picture of the Day”: http://apod.nasa.gov/apod/
Some useful information, including what viewers from different latitudes will see tomorrow evening.
http://eclipse-maps.com/Eclipse-Maps/Gallery/Pages/Annular_solar_eclipse_of_2012_May_20.html
Reply to Gary Hladik
This issue of a non rotating moon is important for a specific technical reason.As planets move along their orbital circumference they turn to the central Sun,this motion is completely separate to daily rotation to the Sun and is captured in the sequence of photos –
http://www.daviddarling.info/images/Uranus_rings_changes.jpg
So,the behavior of the moon around the Earth is completely different than the behavior of any planet around the Sun but so accustomed are people to imagining the moon spins as it orbits the Earth that this important information is lost to silence or incomprehension.
The old ‘no tilt/no seasons’ idea must go for Uranus has a polar climate due to its inclination while the Earth has a largely equatorial climate due to its inclination hence ’tilt’ does not cause the seasons,it only determines what type of climate a planet experiences for a complete circuit of the Sun.In short,climate studies haven’t really begun in earnest.
Anthony,
Thanks mucho for the Red Bluff viewing suggestion. Hopefully we can make it that far north!
Keith Pearson, formerly bikermailman, Anonymous no longer says:
May 19, 2012 at 9:41 am
Smoking Frog says: May 19, 2012 at 4:09 am
In the 1960s I watched a total eclipse from a beach on Cape Cod…
I’ll bet that’s the one Steven King has included in some of his books, including a big plot point in The Dark Half. I’ll bet that was really neat, being on the water’s edge, and watching it.
Yes, pretty neat. One reason I like King is that he does a good job of depicting mid-century New England. (I don’t like his politics or personality, though.)
I can’t say that I’m aware of the eclipse in his works, but I haven’t read everything.
BTW, his first name is Stephen.
GKELL1 says:
May 19, 2012 at 1:56 pm
Reply to Leif Svalgaard
I assure you that if the moon rotated once as it makes a circuit of the Earth we would see all sides once,if it rotated twice as it makes it monthly circuit of the Earth we would see all sides twice and so on.The moon doesn’t rotate and knowing that it always keeps the same face to the Earth would require you to make an inhuman effort to convince yourself that it does.Sound familiar in another case ?.
Are you serious? If it didn’t rotate, we would see all sides. Any given observer wouldn’t see all sides, though. He’d see more than 180 degrees of the moon, but he wouldn’t be able to see more than that without changing his location on the earth’s surface.
Keith Pearson, formerly bikermailman, Anonymous no longer says:
May 19, 2012 at 9:41 am
Smoking Frog says: May 19, 2012 at 4:09 am
In the 1960s I watched a total eclipse from a beach on Cape Cod…
I’ll bet that’s the one Steven King has included in some of his books, including a big plot point in The Dark Half. I’ll bet that was really neat, being on the water’s edge, and watching it.
I posted a message to you just before I posted to GKELL1, but the 2nd one has appeared and not the 1st. Anyway, yes, pretty neat. I won’t bother repeating everything I said in the 1st message.
Reply to Smoking Frog in response to the lunar orbital cycle of the Earth
Smoking Frog says “Are you serious? If it didn’t rotate, we would see all sides”
The issue of carbon dioxide and human control over the planet’s climate is just one in a series of ill-conceived conclusions while the idea of a spinning moon is also in the same category as it defies common sense.It would not normally dignify a response as a person walking/orbiting a central object with an outstretched arm pointing at that object is imitating the orbital behavior of the moon as it makes a circuit of the Earth and why we see the same face constantly.
I see this as a test case for the climate issue ,a clear and decisive resolution opens up a more productive picture for the Earth’s orbital behavior as it makes a circuit of the Sun and there are a lot of major modifications and adjustments involved in streamlining inputs into climate and obliterating older and meaningless ones.On the other hand,if the idea of a spinning moon persists,it only affirms the general tendency of this era to not only persist in error but to do so aggressively.If readers are wondering why the proponents of global warming theory are behaving in a certain way,they can gain some insight via Galileo’s comments,likewise those who adhere to a spinning moon or any other wayward conclusion –
“The same thing has struck me even more forcibly than you. I
have heard such things put forth as I should blush to repeat–not so
much to avoid discrediting their authors (whose names could always be
withheld) as to refrain from detracting so greatly from the honor of
the human race. In the long run my observations have convinced me that
some men, reasoning preposterously, first establish some conclusion In
their minds which, either because of its being their own or because of
their having received it from some person who has their entire
confidence, impresses them so deeply that one finds it impossible ever
to get it out of their heads. Such arguments in support of their fixed
idea as they hit upon themselves or hear set forth by others, no
matter how simple and stupid these may be, gain their instant
acceptance and applause. On the other hand whatever is brought forward
against it, however ingenious and conclusive, they receive with
disdain or with hot rage–if indeed it does not make them ill. Beside
themselves with passion, some of them would not be backward even about
scheming to suppress and silence their adversaries. I have had some
experience of this myself.” Galileo
very cool
uniquebloggertips.com
OK – I’ll take the bait as this is starting to irritate. GKELL1 says: “… a person walking/orbiting a central object with an outstretched arm pointing at that object is imitating the orbital behavior of the moon as it makes a circuit of the Earth”.
Here’s a URL with a silly diagram, in plan view, which I think depicts what you mean –
http://i46.tinypic.com/2wf01uc.jpg
Can’t you see that, to the same extent as you orbit the central object with your outstretched arm (each of the straight lines) pointing towards the object (the blue blodges representing the same face always shown toward the object), you have also rotated on your vertical axis by reference to any fixed point such as that of the diagram view? (And if the orbit happens to be elliptical, with the axial rotation constant, you also get libration – exactly as for the moon.)
If you don’t see this, I just give up. And I’m not taking the bait on any link to climate!
TimC says OK – ” I’ll take the bait as this is starting to irritate.”
There is no bait and neither does the moon rotate as a separate motion to its monthly circuit around the Earth.That irritation you are experiencing is exactly what the global warming proposers are experiencing when they encounter opposition to their fixed idea and it is not a good sign.
A reasonable person will accept that if the moon rotated once in its orbital circuit of the Earth,we would see all locations of the moon once during a circuit,if it rotated twice for each circuit of the Earth we would see all locations twice .We see the same side of the moon at all times because this arises solely from its orbital behavior and rotation is an unnecessary complication and besides,a spinning moon defies common sense.
Should anyone imagine that modeling is a recent development and the introduction of unwanted assertions can produce wayward conclusions,they need only take heed of the comments of Copernicus,this goes for astronomy as well as climate –
“. although they have extracted from them the apparent motions, with numerical agreement, nevertheless . . . . They are just like someone including in a picture hands, feet, head, and other limbs from different places, well painted indeed, but not modeled from the same body, and not in the least matching each other, so that a monster would be produced from them rather than a man. Thus in the process of their demonstrations, which they call their system, they are found either to have missed out something essential, or to have brought in something inappropriate and wholly irrelevant, which would not have happened to them if they had followed proper principles. For if the hypotheses which they assumed had not been fallacies, everything which follows from them could be independently verified.” De revolutionibus, 1543
If there is no decisive resolution to this topic then it will give readers an indication of where the climate issue is going to go.
Just one more try: GKELL1 says “A reasonable person will accept that if the moon rotated once in its orbital circuit of the Earth, we [I assume viewed as from Earth] would see all locations of the moon once during a circuit” (parentheses added).
I disagree with both your premise and your conclusion. As the moon rotates once around its own axis in approximately the same period as its keplerian orbit around the Earth, and the axial and orbital rotations are both in the same direction, *viewed as from Earth* one rotation (orbital) effectively cancels out the other (axial), leaving the moon presenting exactly the same face to Earth. However the sun and all the other planets do indeed “see” all locations of the moon, in exactly the same way as they do the Earth, as the earth and moon are effectively binary planets.
As from Earth you would only “see all locations of the moon once during a circuit” (a lunar month) if either the lunar day was approximately *half* the lunar month (with axial and orbital rotations in the same directions) or in the improbable case that the moon did not rotate on its axis at all – that every star observed from the moon’s surface always had a fixed, constant, altitude and azimuth from given points on the lunar surface (it wouldn’t of course have poles or any gyroscopic stability – it would probably just wobble all over the place).
Afraid I must now leave you to your musings and go back to trying to see how to spot that eclipse on CA coastal webcams …
This conversation took a strange turn… However:
http://en.wikipedia.org/wiki/Tidal_locking
We’ve passed maximum extent here in Calgary, and I have to say I managed to jury rig a brilliant way of viewing. Reading glasses and a sheet of paper. The reading glasses are so weak that the sun’s disc is almost an inch across. The huge bite taken out of it was crisply visible. Unfortunately it was so bright that my attempts to take pictures failed, even with my Nex5 at min aperture and 1/4000th… still too bright.
I’m proud to point out that I got to use this as a teachable moment for a few people.
Eclipses aren’t at all rare; about 7 happen every year, and they alternate solar and lunar. For most people solar ecl;ipses happen in daylight, with both the sun and the moon on the same side of the earth as the observe, at new moon timer, but for some people that is the darkest night.
Lunar eclipses happen for most people, at night, with the sun and the moon on opposite sides of the earth at full moon times. Eclipse conditions (either way) will tend to have higher than average tides; other things being equal, but not necessarily as high as the last full moon tide two weeks ago, at lunar perigee.
It is super easy to view solar eclipses without any special optical equipment. A sheet of cardboard, with a hole punched in it will project an image of the sun and moon shadow on another surface in the card shadow. And you don’t even need the sheet of cardboard, if you have a tree with dense leaves you can just let the sun shine through the leaves, onto a paper, and you will get multiple eclipse images all at once. A nail or a pencil will make a nice hole. The bigger the hole, the further you place the imaging screen from the hole, but the image will be brighter.
Works for sunspots as well; use small hole and long distance.
TimC says:” I disagree with both your premise and your conclusion. As the moon rotates once around its own axis…”
In this matter,as in climate,I have taken the view of Pascal in that counter assertions tend to aggravate rather the resolve an issue so rather than try to disprove lunar rotation it is better to widen observations to look at how planets behave as the circle the Sun .
“When we wish to correct with advantage and to show another that he errs, we must notice from what side he views the matter, for on that side it is usually true, and admit that truth to him, but reveal to him the side on which it is false. He is satisfied with that, for he sees that he was not mistaken and that he only failed to see all sides.” Pascal
The North/South poles of the Earth act like a beacon for the planet’s orbital behavior in that apart from daily rotation,all locations on the planet will turn to the central Sun as the planet makes a circuit of the Sun.It is absolutely crucial for a new approach to climate hence it is not a matter of disproving a spinning moon but talking up the Earth’s orbital behavior.It just happens that the planet Uranus provides ideal observations which set off its daily rotation to the central Sun (running South to North) against its annual orbital component which turns East to West –
http://www.newscientist.com/data/images/ns/cms/dn12529/dn12529-1_800.jpg
http://hubblesite.org/newscenter/archive/releases/1999/11/video/b/
The problem with the climate issue is that the assertions are so narrow that the proponents have left themselves nowhere to go and they register any opposition as an assault on their intelligence and their models .Rightly understood,the moon doesn’t turn as it orbits the Earth but the Earth does turn in two different way to the central Sun and that is a point of departure for modifying the explanation for the seasons,why natural noon cycles vary and a multitude of new avenues.
Excuse the pun,but it is better to put a positive spin on the issue rather than end in stalemate as it did in the mid 19th century insofar as a conceptual stalemate provides no clear resolution and that is what can be expected with climate if this continues to run on the way it does,In short,genuine climate studies will be dragged down to the narrowest possible view and the flow of information from astronomical inputs into terrestrial effects will cease and I say that with the utmost dismay.
It was an awsome view, just got home from Redding, we made up to Whiskeytown Lake. Talk to folks from India and British Columbia, place looked like it was infested with high end telescopes and home made contraptions.
GKELL1 says:
May 20, 2012 at 4:48 am
Reply to Smoking Frog in response to the lunar orbital cycle of the Earth
Smoking Frog says “Are you serious? If it didn’t rotate, we would see all sides”
The issue of carbon dioxide and human control over the planet’s climate is just one in a series of ill-conceived conclusions while the idea of a spinning moon is also in the same category as it defies common sense.It would not normally dignify a response as a person walking/orbiting a central object with an outstretched arm pointing at that object is imitating the orbital behavior of the moon as it makes a circuit of the Earth and why we see the same face constantly.
An object only rotates or non-rotates relative to something. The moon non-rotates relative to every observer who, in a month, traverses any “circular” path whose center is coincident with the earth’s center, and whose radius or extension thereof intersects the center of the moon. Relative to every observer otherwise situated, it rotates. Obviously, it rotates relative to a person standing anywhere on the earth’s surface.
Smoking Frog says: “Obviously, it rotates relative to a person standing anywhere on the earth’s surface.”
I wouldn’t dream of convincing you that the moon doesn’t spin as a separate motion to its lunar orbital circuit of the Earth,in older scientific circles it was seen as a lost cause should a person adopt an unreasonable assertion and try to plug in details to support that view.Again,most notably Galileo’s comment on reckless assertions which climatological,astronomical or bottom line –
” I know; such men do not deduce their conclusion from its premises or
establish it by reason, but they accommodate (I should have said
discommode and distort) the premises and reasons to a conclusion which
for them is already established and nailed down. No good can come of
dealing with such people, especially to the extent that their company
may be not only unpleasant but dangerous.” Galileo
The older scientists who relied on a balance between interpretation and speculation had a clear sense that dynamical inputs were primarily responsible for terrestrial effects and especially tidal fluctuations and temperature fluctuations.It is a less aggressive approach than modelers today have it insofar as the original Royal Society scientists were adept at taking in considerations from all angles to account for experiences rather than having a fixed conclusion and distorting data or taking shortcuts to suit that conclusion.In the instance of lunar motion and tidal fluctuations,these guys discounted lunar rotation and treated the moon the way it should- as a separate astronomical object with its own traits and motions.Try the letter from John Wallis to Robert Boyle in 1666 and you may see a lot of material that we ascribed to other people –
http://rstl.royalsocietypublishing.org/content/1/1-22/263.full.pdf+html
This is the 21st century where men have already set foot on the moon and who can look out at a rotating Earth from a non rotating moon and if they so choose,can hop into the lunar buggy and drive around the the opposite side of the moon that never rotates to the Earth.The meaningless idea of lunar rotation is distracting from the orbital trait of the Earth’s orbital motion around the Sun and the explanation of the polar day/night cycle and at lower latitudes ,where it mixes with daily rotation,we know as the seasons.