Opto Squad

Vishay's OPTO blog site for the latest in all things OPTO ~ articles, videos, and products

Dark Side of the Moon

Hopefully you had the time, and clear skies, to watch the lunar eclipse that occurred this past Sunday night. The moon was at its perigee, the point in the orbit at which it is nearest to the earth. So it was about 15% brighter than at other times. All this talk about the moon and you invariably hear the expression “the dark side of the moon”.2015-09-27LunarEclipse

Dark Side of the Moon

The far side of the moon is not dark. During a ‘new moon’, the moon is between the Earth and the Sun, and so the side we know is totally dark and the far side will be bright. When the moon is opposite from the Sun, a full moon, the side we know will be totally bright, and the far side will be dark.

Why do we only see one side of the Moon?

We all know that the Earth rotates on its own axis, so theoretically, the Moon should also do the same, allowing us to get a full picture of the planetoid. Why are we limited to seeing only 50 percent? It turns out that the speed at which the Moon rotates has led to this particular phenomenon. Millions of years ago, the Moon spun at a much faster pace than it does now. However, the gravitational influence of the Earth has gradually acted upon the Moon to slow its rotation down, in the same way that the much smaller gravitational influence of the Moon acts upon the Earth to create tides. This influence slowed the rotational period of the Moon to match that of its orbit – about 27.3 days – and it is now “locked in” to this period.

Lunar Reconnaissance Orbiter (LRO) Images

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

Information

This entry was posted on September 30, 2015 by in Articles, on a side note....
THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE. THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000

Enter your email address to follow this blog and receive notifications of new posts by email.

%d bloggers like this: