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Offline Dharmansh

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Moon
« on: 05/05/2012 09:44:51 »
How does moon glow?


 

Offline MikeS

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Re: Moon
« Reply #1 on: 05/05/2012 11:25:59 »
It's a photo-luminescent bacteria in the cheese.

Sorry Dharmansh, I just couldn't resist that, somebody had to say it.

Seriously, it's just reflected sunlight.   We normally see the moon when the Earth is in darkness.  The sun illuminates half of the moon (as it's a sphere) and we see the part of the moon that is illuminated as visible from our position on Earth.

If you us a torch to illuminate any spherical object (like an apple or orange) you will see what I mean.
« Last Edit: 05/05/2012 11:39:48 by MikeS »
 

Offline Dharmansh

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Re: Moon
« Reply #2 on: 05/05/2012 11:28:20 »
But earth is between Sun n moon so how can light travel through Earth?
 

Offline CliffordK

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Re: Moon
« Reply #3 on: 05/05/2012 11:31:42 »
The moon glows from reflected light from the sun.

The moon orbits around the Earth in just under a month (27.321 days).  What we see as the moon rising and falling is really the Earth rotating, one rotation per day.

During the period of the month when the sun and moon are on opposite sides of the Earth, we see the moon as a "full moon", with the entire moon illuminated by the sun.

During the period of the month that the moon and sun are on the same side of the Earth, the moon may be faintly visible during the day (perhaps by light from the sun reflecting off the Earth, to the moon, and reflecting back to the Earth).  But, during the "new moon", we have moonless nights which are excellent for star gazing in rural areas.

During other phases, we will see part of the moon from a sliver to an almost full moon depending on the portion of the moon that is illuminated by the sun, and then visible from the Earth.

You might find this photo interesting.
http://www.thenakedscientists.com/forum/index.php?topic=42796.0

Where the moon was displayed near the horizon, but impossibly illuminated from the wrong side, and thus obviously a cut & paste job.
 

Offline MikeS

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Re: Moon
« Reply #4 on: 05/05/2012 11:35:51 »
Sometimes the Earth is between the sun and the moon.  Sometimes the moon is between the sun and the Earth.  They events are called an eclipse.
As both the moon and the Earth are very small in proportion to the distance between them eclipses are infrequent.  Normally the sun illuminates the moon unrestricted by the Earth.  Likewise, the sun illuminates the Earth unrestricted by the moon.
« Last Edit: 05/05/2012 11:37:56 by MikeS »
 

Offline CliffordK

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Re: Moon
« Reply #5 on: 05/05/2012 11:42:04 »
But earth is between Sun n moon so how can light travel through Earth?
While the moon looks somewhat close, it is actually 384,000 km from the Earth.
Earth's diameter is only about 7,926.28 miles (12,756.1 km), or a relatively small fraction of the overall distance to the moon. 

Occasionally the Earth does pass directly between the moon and the sun to create a lunar eclipse (moon darkened).  Or likewise the moon will pass directly between the Earth and sun to create a solar eclipse (earth darkened).  However, for the most part, the moon, earth, and sun are offset slightly so that they don't line up perfectly.

Also, keep in mind that both Earth's axis, and axis of the moon's orbit around the earth are tilted slightly.  Thus, due to the tilt, for much of the year the moon won't be perfectly in line with the sun and Earth.  Eclipses would have to occur near the equinoxes in the spring and fall.
 

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Re: Moon
« Reply #5 on: 05/05/2012 11:42:04 »

 

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