In Like A Lion...

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Apollo XX
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In Like A Lion...

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...Out Like A Lamb - at least that's what they say. We'll see, but this winter has been a doozy for the past month and a half, that's for sure. I hope you've still been able to get out observing at least some. In the spirit of positive thinking, I submit to you an observing challenge for March. Dig out those scopes!

Howdy Folks,

For our March Whatzup Challenge, I call your attention to the Moon. The Moon rides nice and high this time of year, and for those who care to put in the time it can be a never-ending source of wonderment and observing challenges. The light that shines upon the Moon never does so quite the same way twice, thus the features you view in one observing session will appear at least somewhat different the next time you go there. The Moon isn’t just for beginners either. There are countless observing projects that will challenge even the most seasoned observer. As we’ll see in this challenge, you’ll be accessing all of your experience to eek out the subtle features discussed in this article.

In the “there’s no need to reinvent the wheel” category, we’re going to use an article published at the Sky and Telescope website that was written by Bob King, aka “Astro Bob”. This article focuses on the observing of some relatively obscure moon features called concentric craters. Concentric craters were unknown to me until I read Bob’s article, and since then I’ve tried to observe a couple, with mixed success.

Concentric craters are challenging primarily because they are small. To get an idea of how small, it helps if we do a little math. We all know that the moon appears to cover about 30 arc minutes on the sky, and that it has a diameter of about 2,160 miles. That means that there are 72 miles of moon in an arc minute, and breaking it down a little more there are about 1.2 miles of moon in an arc second. When we consider that the largest concentric crater on the earth facing side of the moon is 15K (9.3mi) in diameter, we see that it will appear to be about 7.75 arc seconds wide in the eyepiece. This means that aperture and magnification, lots of both, will be very helpful in observing these interesting little features.

To get to Bob’s article on concentric craters, go to http://www.skyandtelescope.com/observin ... s02252015/ Good luck in your quest to conquer the challenge, and if you’re egging for more be sure to check out the link at the end of the article to a list of all known concentric craters on the moon.
"The purpose of life is the investigation of the Sun, the Moon, and the heavens." - Anaxagoras
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Apollo XX
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Re: In Like A Lion...

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So last month I got a look at Hesiodus A, and tonight I tried for Crozier H. No luck. Crozier yes, H no. Needed the terminator to advance a little more and the seeing was abysmal. Maybe tomorrow. Anyone else having a go?
"The purpose of life is the investigation of the Sun, the Moon, and the heavens." - Anaxagoras
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mrgizmo65
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Re: In Like A Lion...

Unread post by mrgizmo65 »

Mike, like O.J.says"I'll take a stab at it" weather I think will start moderating and I'm afraid the ground will be nice and mushy :x at u mass. :x :x
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Apollo XX
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Re: In Like A Lion...

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Hi Jerry, glad to hear you're up for the challenge! I got out again tonight for another go at Crozier H. That sucker is small, I tell you! At just 10K (6.2mi) across, the outer ring of the crater only takes up 5 arc seconds in the eyepiece. I had my 4" refractor up to 250+ trying to resolve that even smaller ring in the middle, but no luck. The seeing wouldn't support the magnification, and it only got worse as the moon lowered toward the western horizon. I'm convinced that this challenge is for boys with big toys. Your 13" should give you a good shot at conquering this challenge. I've got a 10" loaner that I need to go pick up, and this is definitely one of my intended targets when I do.

O/K all you big gun wielders, can you resolve these features - let's see what you've got! :P
"The purpose of life is the investigation of the Sun, the Moon, and the heavens." - Anaxagoras
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