Can mars or mercury be confused as new moon crescent?

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Shaheed

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<p>Hello:</p><p>I have come across this quote from a group who are saying that mercury or some say the mars sometimes can be confused as a new moon crescent. </p><p>Day before yesterday (Monday evening, 9/29/08) a couple of people from San Diego saw the crescent of the new moon from a hilltop. When this was presented, the other group protested that according to their calculation, the moon cannot be seen from San Diego at that time, and then presented this argument that it must have been confused with either mercury or mars. Can any expert in this field explain what is correct.</p><p>Thank you.</p>
 
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MeteorWayne

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Hello:I have come across this quote from a group who are saying that mercury or some say the mars sometimes can be confused as a new moon crescent. Day before yesterday (Monday evening, 9/29/08) a couple of people from San Diego saw the crescent of the new moon from a hilltop. When this was presented, the other group protested that according to their calculation, the moon cannot be seen from San Diego at that time, and then presented this argument that it must have been confused with either mercury or mars. Can any expert in this field explain what is correct.Thank you. <br />Posted by Shaheed</DIV></p><p>Welcome to Space.com! Hope we can help solve your mystery.<br /><br />Well, Mars is never a crescent. Since it lies further from the sun than us, it is always mostly fully illuminated. When it is at it's greatest distance to the side of the sun, it's not quite fully round, but it never comes close to being a crescent. It is currently behind the sun from us and 99% illuminated.</p><p>Mercury and Venus do become crescent shaped, but they are so small there is no way they ever could be confused with the moon. You really need binoculars to see the crescent shape of either. Some people with very exceptional eyesight can see that&nbsp;Venus is not round when it is a crescent, but would be unable to truly detect the crescent shape without optical aid. It basically looks like a VERY bright star to the unaided eye.</p><p>Having said that, it would have been impossible to see the crescent moon that night. It was basically at the same elevation as the sun, so set at the same time (actually 1 minute and 4 seconds later) so would have been invisible. In addition, at that time it was less than 1 % illuminated so would have been too faint to be seen at that time, with the sun still in the sky only 11 degrees away.</p><p>If the people who thought they saw the crescent moon were using binoculars or a telescope, and were not familiar with how large objects&nbsp;appear through them, Mercury was a thin crescent. It would have been very hard to see Mercury since it set only 21 minutes after the sun; at that time the sun was only 5 degrees below the horizon. It was a very thin crescent. If you had a telescope at exacly the right spot, it&nbsp;MIGHT have been possible, but very difficult in such a bright sky. </p><p>Venus was much better placed, setting almost an hour and 20 minutes after the sun, about 18 degrees higher in the sky. However, it is near superior conjunction now (behind the sun) so is almost fully illuminated at this time. (86%) That means it would look as round as a moon a day or two after full.</p><p>Hopefully with these facts you can figure out what happened.</p><p>Meteor Wayne</p> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>
 
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CalliArcale

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<p>If I might venture a guess, the folks in San Diego who reported viewing the crescent moon may merely have been anxious to end their fasting and get on with feasting.&nbsp; <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-wink.gif" border="0" alt="Wink" title="Wink" />&nbsp; I can imagine that this might make a person a bit overly optimistic in one's observations. </p><p>Ramadan </p><p>&nbsp;</p><p>My personal guess is that either they made it up, or they saw a cloud.&nbsp; Clouds can sometimes appear as crescents.</p> <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>
 
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MeteorWayne

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Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>If I might venture a guess, the folks in San Diego who reported viewing the crescent moon may merely have been anxious to end their fasting and get on with feasting.&nbsp; &nbsp; I can imagine that this might make a person a bit overly optimistic in one's observations. Ramadan &nbsp;My personal guess is that either they made it up, or they saw a cloud.&nbsp; Clouds can sometimes appear as crescents. <br />Posted by CalliArcale</DIV><br /><br />That was also my sucpicion, but I stuck to the facts and gave all the scientific evidence possible. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>
 
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Shaheed

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>That was also my sucpicion, but I stuck to the facts and gave all the scientific evidence possible. <br />Posted by MeteorWayne</DIV><br /><br />I really appreciate the information. However, one thing I wanted to know more about is that moons calculation can vary right (for example if you change the&nbsp;reference point). So in that case, how would you be sure and saying with 100% certainly that moon can not be seen. It actually did happen a couple years back when an organization changed their reference point in the calculation, for which they had to change their already published calender, on a few dates.</p><p>Also, we know that every scientific theory is based on a probabilistic model for its accuracy or occurrence. That is why every single scientific theory, when it is proposed, is verified with model studies or model fit with real life data. Only after that, the theory is published. Typically from what I have experienced and heard, scientific journal and the scientific community will not value much a theory, when presented just as a theory. Only after extensive validation, the theory gains credibility. And on top, even after extensive validation, no one denies that the basis is still on a probabilistic model. Meaning, a scientific theory does not confirm with 100% certainty. It could be say 99% probability of occurrence, but that 1% chance still remains. On top, that 1% chance really does not mean that out of 100 times, only 1 chance of odd can happen. Rather, that 1 chance can happen even in the very next occurrence, and much more, can happen again consecutively on two occurrances. I am not sure if I am able to explain well here. For an example, although unrelated, we had two 50 year rain events in San Diego on two consecutive years, a couple years back. It does not mean that the 50 year flood calculation is wrong, however, it also does not mean that the calculation is decisive. What is decisive is a real life event, in this example, it was the actual rain that was observed and measured. To make the analogy complete, in this case, isnt an actual visual sighting a confirmation with 100% certainty, which may actually happen based on the above discussion&nbsp;(I am assuming the person who said he saw the moon did not lie, because that will end the discussion right there).</p><p><img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-smile.gif" border="0" alt="Smile" title="Smile" />&nbsp;It is hard to believe that a person after fasting for 29 days, cannot fast one more day.</p><p>Oh, I also found a beautiful photograph taken by an amature astrophotographer, which shows the moon crescent, venus and mercury (the one on the left of the chimney about mid height, you really need to zoom up to see it). I though I'd share it here.</p><p><br /><img src="http://sitelife.space.com/ver1.0/Content/images/store/6/11/46ad1fd8-d74d-4bab-bb24-95831d26fadf.Medium.jpg" alt="" /></p>
 
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MeteorWayne

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I really appreciate the information. However, one thing I wanted to know more about is that moons calculation can vary right (for example if you change the&nbsp;reference point). So in that case, how would you be sure and saying with 100% certainly that moon can not be seen. It actually did happen a couple years back when an organization changed their reference point in the calculation, for which they had to change their already published calender, on a few dates.Also, we know that every scientific theory is based on a probabilistic model for its accuracy or occurrence. That is why every single scientific theory, when it is proposed, is verified with model studies or model fit with real life data. Only after that, the theory is published. Typically from what I have experienced and heard, scientific journal and the scientific community will not value much a theory, when presented just as a theory. Only after extensive validation, the theory gains credibility. And on top, even after extensive validation, no one denies that the basis is still on a probabilistic model. Meaning, a scientific theory does not confirm with 100% certainty. It could be say 99% probability of occurrence, but that 1% chance still remains. On top, that 1% chance really does not mean that out of 100 times, only 1 chance of odd can happen. Rather, that 1 chance can happen even in the very next occurrence, and much more, can happen again consecutively on two occurrances. I am not sure if I am able to explain well here. For an example, although unrelated, we had two 50 year rain events in San Diego on two consecutive years, a couple years back. It does not mean that the 50 year flood calculation is wrong, however, it also does not mean that the calculation is decisive. What is decisive is a real life event, in this example, it was the actual rain that was observed and measured. To make the analogy complete, in this case, isnt an actual visual sighting a confirmation with 100% certainty, which may actually happen based on the above discussion&nbsp;(I am assuming the person who said he saw the moon did not lie, because that will end the discussion right there).&nbsp;It is hard to believe that a person after fasting for 29 days, cannot fast one more day.Oh, I also found a beautiful photograph taken by an amature astrophotographer, which shows the moon crescent, venus and mercury (the one on the left of the chimney about mid height, you really need to zoom up to see it). I though I'd share it here. <br />Posted by Shaheed</DIV><br /><br />My calculations were based on San Diego on the night in question. My astronomy program allows me to set the location and time easily.</p><p>In this case, it is not theory, but easily reproducable calculations of the positions of astronomical bodies. They are extremely precise. Not perfect, but good enough that any difference would be too small to see witrh the eye or ordinary telescopes. I can say with 100% assurance&nbsp;that what I posted is correct.</p><p>Weather is much different. It is a chaotic process, based on using models whose input is imperfect to begin with. It's a much more difficult problem, and the output from the models are quite imperfect as well. Odds are very important in weather forecasts since it is an imprecise process.</p><p>That is not the case for the motion of the planets or the moon for periods up to hundreds or thousands of years.</p><p>If you go to millions of years in the future or past, the tiny&nbsp;measurement uncertainty&nbsp;that exist can make a measurable difference.</p> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>
 
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Shaheed

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Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>My calculations were based on San Diego on the night in question. My astronomy program allows me to set the location and time easily.In this case, it is not theory, but easily reproducable calculations of the positions of astronomical bodies. They are extremely precise. Not perfect, but good enough that any difference would be too small to see witrh the eye or ordinary telescopes. I can say with 100% assurance&nbsp;that what I posted is correct.Weather is much different. It is a chaotic process, based on using models whose input is imperfect to begin with. It's a much more difficult problem, and the output from the models are quite imperfect as well. Odds are very important in weather forecasts since it is an imprecise process.That is not the case for the motion of the planets or the moon for periods up to hundreds or thousands of years.If you go to millions of years in the future or past, the tiny&nbsp;measurement uncertainty&nbsp;that exist can make a measurable difference. <br />Posted by MeteorWayne</DIV><br /><br />Thanks for the information.
 
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CalliArcale

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Thanks for the information. <br /> Posted by Shaheed</DIV></p><p>It really is quite impressive to hear about religious authorities attempting to be the first to sight the new moon.&nbsp; The Jewish and Muslim calendars depend heavily on sightings of the Moon, and these can be influenced by local conditions.&nbsp; If it's cloudy, spotting the Moon may even be impossible, and of course the first sighting of the Moon will depend on one's position on the Earth.&nbsp; (The near side of the Moon will become sunlit at the same time for everybody, but only half of the world will be able to see it.&nbsp; For the rest of the world, the Moon will not have risen yet.)&nbsp; So you get constrained by weather and geography. </p><p>But as MeteorWayne said, it's all stuff that can be calculated ahead of time (apart from the weather, which is sometimes a crapshoot).&nbsp; It is possible to predict the moment of new moon to the second.&nbsp; It is a matter of&nbsp; the Moon's rotation, the Moon's libration (it appears to "wobble" in as it goes around the Earth, because its orbit is not perfectly circular), the Earth's rotation, and the motion of both Earth and Moon around the Sun.</p><p>Even outside of religious circles, secular stargazers make something of a sport out of viewing the new moon.&nbsp; It's a challenge to see who can spot (and, ideally, photograph) the youngest moon.&nbsp; I think the record currently is something like twelve hours, which required a telescope. </p><p>One secular source, the US Naval Observatory, has a nice brief primer on&nbsp; viewing very thin crescent moons.</p> <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>
 
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CalliArcale

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I found a page with some nice pictures of the Moon, including one barely a day old. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>
 
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MeteorWayne

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>It really is quite impressive to hear about religious authorities attempting to be the first to sight the new moon.&nbsp; The Jewish and Muslim calendars depend heavily on sightings of the Moon, and these can be influenced by local conditions.&nbsp; If it's cloudy, spotting the Moon may even be impossible, and of course the first sighting of the Moon will depend on one's position on the Earth.&nbsp; (The near side of the Moon will become sunlit at the same time for everybody, but only half of the world will be able to see it.&nbsp; For the rest of the world, the Moon will not have risen yet.)&nbsp; So you get constrained by weather and geography. But as MeteorWayne said, it's all stuff that can be calculated ahead of time (apart from the weather, which is sometimes a crapshoot).&nbsp; It is possible to predict the moment of new moon to the second.&nbsp; It is a matter of&nbsp; the Moon's rotation, the Moon's libration (it appears to "wobble" in as it goes around the Earth, because its orbit is not perfectly circular), the Earth's rotation, and the motion of both Earth and Moon around the Sun.Even outside of religious circles, secular stargazers make something of a sport out of viewing the new moon.&nbsp; It's a challenge to see who can spot (and, ideally, photograph) the youngest moon.&nbsp; I think the record currently is something like twelve hours, which required a telescope. One secular source, the US Naval Observatory, has a nice brief primer on&nbsp; viewing very thin crescent moons. <br />Posted by CalliArcale</DIV></p><p>I should point out that "early" (less than 1 day moons) can only be seen when the moon is positioned above the sun, so it sets later (making a "U" shape). In this case the moon was at the same elevation as the sun (a reverse "C" shape) so seeing it with such a thin crescent would have been impossible.</p><p>Either S&T or Astronomy does an annual article about the upcoming opportunities to see a very young moon during the year. It is dependant on the alignment of the moon and sun (which is different every month) and precise timing between the new moon and sunset at any particular longitude. I'll see if any of those article are online.</p><p>&nbsp;</p> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>
 
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