SiobainVirtual Ranger
Joined: Wed Feb 25, 2009 9:38 pm
Posts: 5264
Location: Johannesburg
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| BEGINNERS' STARGAZING QUIZ (QM) |
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Siobain Virtual Ranger Joined: Wed Feb 25, 2009 9:38 pm Posts: 5264 Location: Johannesburg
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| Fri Dec 16, 2011 9:00 pm |
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| Re: BEGINNERS' STARGAZING QUIZ (QM) |
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onewithnature Distinguished Virtual Ranger Joined: Tue Dec 23, 2008 5:22 am Posts: 19081 Location: Midway between the infinite and the infinitesimal!
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| Sat Dec 17, 2011 8:49 am |
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Okay, let's do some prompting then because the answer is perfectly logical.
 The Sun and Earth are in a line, while the Moon comes in-between the two during New Moon. In other words, Macho Sun is blazing away, but Moody Moon blocks his attentions. Now, if Moody Moon is pretty much the same size as her suitor, why does she not block his loving light from reaching our Earth altogether? You mighty mites have touched on it, but I need you to see the reason why this is so. Logically, if the Moon came between the Sun and the Earth, and both are the same size, it WOULD block out his rays completely, except for one thing. What is that thing? |
| Re: BEGINNERS' STARGAZING QUIZ (QM) |
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Siobain Virtual Ranger Joined: Wed Feb 25, 2009 9:38 pm Posts: 5264 Location: Johannesburg
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| Sat Dec 17, 2011 10:16 am |
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I still stand by my previous answer, but I'll add more detail.
Being logical then, the one thing has to be distance.The moon is 400 times smaller than the sun, but it is also 400 times closer to Earth—so from Earth, the moon and the sun look about the same size. The size of the New Moon shadow differs depending on the distance it is from the Earth. This distance changes month to month, so the further it is from Earth the smaller it's shadow becomes. When the Moon is at it's furthest distance, it's shadow is said to be 14% smaller than when it is closest, so the size of the shadow, and the amount of light visible from the sun will change each month, at New Moon. Ok so if I understand this, once each month, the moon comes all the way around in its orbit so that it is more or less between us and the sun. If it were directly between, a solar eclipse would take place. But that doesn’t happen every month. Instead, in most months, the moon passes above or below the sun as seen from our earthly vantage point. On the day of new moon, the moon rises when the sun rises. It sets when the sun sets. It crosses the sky with the sun during the day. |
| Re: BEGINNERS' STARGAZING QUIZ (QM) |
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ecojunkie Legendary Virtual Ranger Joined: Sat Oct 06, 2007 7:05 am Posts: 6403 Location: Back home - a caravan in Malelane Camp, KNP
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| Sat Dec 17, 2011 10:32 am |
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Yes, I am sure it has to do with the fact that the size only appears the same. Also the fact that the moon revolves the earth, and is closer at some times than others, and the same of the earth revolving round the sun. But how to tie it all together into an explanation - that makes sense - is beyond me!
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| Re: BEGINNERS' STARGAZING QUIZ (QM) |
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onewithnature Distinguished Virtual Ranger Joined: Tue Dec 23, 2008 5:22 am Posts: 19081 Location: Midway between the infinite and the infinitesimal!
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| Wed Dec 21, 2011 11:11 pm |
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Very well done, Siobain.
 That is what I was looking for.  To summarize, the plane of the Moon's orbit is offset from that of the Earth's orbit about the Sun by about 5 degrees. Doesn't sound like much, but because of the large distances involved, this angular difference is enough to prevent the Moon obscuring the Sun. If the Earth-Sun and Earth-Moon orbits were in exactly the same plane in 3D-Space, the Moon would block out the Sun approximately every 29.5 days! |
| Re: BEGINNERS' STARGAZING QUIZ (QM) |
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onewithnature Distinguished Virtual Ranger Joined: Tue Dec 23, 2008 5:22 am Posts: 19081 Location: Midway between the infinite and the infinitesimal!
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| Wed Dec 21, 2011 11:18 pm |
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Now let's see if you understand eclipses.
 Please fill in the four missing words below: At special times during the year, the Earth, Moon, and Sun do in fact line-up as we see it. When the Moon blocks the Sun or a part of it, it's called a ....... eclipse, and it can only happen during the ....... phase of the Moon? Conversely, when the Earth casts a Shadow on the Moon, it's called a ....... eclipse, and can only happen during the ....... phase of the Moon? |
| Re: BEGINNERS' STARGAZING QUIZ (QM) |
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ecojunkie Legendary Virtual Ranger Joined: Sat Oct 06, 2007 7:05 am Posts: 6403 Location: Back home - a caravan in Malelane Camp, KNP
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| Thu Dec 22, 2011 9:25 am |
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solar, new moon, lunar, full moon?
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| Re: BEGINNERS' STARGAZING QUIZ (QM) |
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onewithnature Distinguished Virtual Ranger Joined: Tue Dec 23, 2008 5:22 am Posts: 19081 Location: Midway between the infinite and the infinitesimal!
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| Thu Dec 22, 2011 9:34 am |
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Spot on, EJ.
Yes, a solar eclipse can only take place during New Moon because that is when the Moon is directly between the Earth and the Sun, and so the Moon is able to block out the disc of the Sun. Similarly, a lunar eclipse can only take place during Full Moon because the Earth is between the Sun and the Moon, thereby able to cast her shadow upon her satellite. Neither of these happen every month because of the alignment we discussed in the last question. However, when alignment in the same plane takes place, then we have an eclipse; depending on how flush the alignment is depends on whether we get a total eclipse (the whole of the Sun's or Moon's disc is blocked out) or a partial eclipse (where only a part of the disc disappears in shadow). |
| Re: BEGINNERS' STARGAZING QUIZ (QM) |
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onewithnature Distinguished Virtual Ranger Joined: Tue Dec 23, 2008 5:22 am Posts: 19081 Location: Midway between the infinite and the infinitesimal!
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| Thu Dec 22, 2011 9:39 am |
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Great.
 Can anyone tell me on what dates the next solar and lunar eclipses will take place in Southern Africa, and whether they are partial or total eclipses? |
| Re: BEGINNERS' STARGAZING QUIZ (QM) |
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Siobain Virtual Ranger Joined: Wed Feb 25, 2009 9:38 pm Posts: 5264 Location: Johannesburg
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| Sat Dec 24, 2011 4:26 pm |
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The next Solar eclipse will be a partial eclipse on 13th Sept. 2013
The next lunar eclipse will also be partial and it is on 25th April 2013 |
| Re: BEGINNERS' STARGAZING QUIZ (QM) |
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onewithnature Distinguished Virtual Ranger Joined: Tue Dec 23, 2008 5:22 am Posts: 19081 Location: Midway between the infinite and the infinitesimal!
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| Sun Dec 25, 2011 6:07 pm |
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Spot on, Siobain.
Sadly for Southern Africa, the next total solar eclipse will only take place on Nov 25th 2030, which will cut through Durban, Kroonstad, and part of Kgalagadi, before crossing into the Atlantic. Which means I will have been on the SANParks forum for almost 22 years, when I will be addressing this event! |
| Re: BEGINNERS' STARGAZING QUIZ (QM) |
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H. erectus Junior Virtual Ranger Joined: Fri Dec 25, 2009 5:03 pm Posts: 1206 Location: On my stoep. Sell by date not expired yet!!
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| Sun Dec 25, 2011 6:28 pm |
 That's it, my days are numbered!!!  |
| Re: BEGINNERS' STARGAZING QUIZ (QM) |
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onewithnature Distinguished Virtual Ranger Joined: Tue Dec 23, 2008 5:22 am Posts: 19081 Location: Midway between the infinite and the infinitesimal!
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| Mon Dec 26, 2011 5:58 pm |
 Yes, numbered ... as in 20134, 20135, 20136 ... |
| Re: BEGINNERS' STARGAZING QUIZ (QM) |
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H. erectus Junior Virtual Ranger Joined: Fri Dec 25, 2009 5:03 pm Posts: 1206 Location: On my stoep. Sell by date not expired yet!!
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| Mon Dec 26, 2011 8:44 pm |
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Ok, had enough, will now attempt
to demolish the great wall 'o China using me forehead!!! |
| Re: BEGINNERS' STARGAZING QUIZ (QM) |
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JenB Moderator Joined: Sun Oct 07, 2007 1:41 pm Posts: 17359 Location: Johannesburg - where they cut down trees and name streets after them.
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| Tue Dec 27, 2011 5:28 am |
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I certainly hope I'll still be around on the Nov 25th 2030.
Experiencing a total solar eclipse is such a spiritual experience, makes you realize how small and helpless we really are. That bit of instinctive panic you feel although your mind tells you that all will be fine and that the sun will be out soon again. If I ever win the lotto, I'll become an eclipse chaser for sure! |
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