Starship Asterisk*

by **Beyond** » Sun Mar 20, 2011 2:44 pm

JohnD wrote:That was the Sloop JohnB.
But your remark makes me think we are same generation!

John

JohnB??? GADS! I must be 'older' than i thought

I hope the Beach Boys don't find out i changed the name of their song. They might throw me overboard

by **JohnD** » Sun Mar 20, 2011 11:24 am

That was the Sloop JohnB.
But your remark makes me think we are same generation!

John

by **Beyond** » Mon Mar 14, 2011 12:17 am

JohnD wrote:Beyond,
Look around for other pics of the Messier pair. They are near the edge of the Moon as seen from Earth, so you are looking at them, and the 'normal' craters around at a significant angle. Look in the Mare Fecunditatis on this APOD: http://apod.nasa.gov/apod/ap110303.html
So the normal, circular craters look oval. Oval, not oblong!

John

Ok JohnD, after comparing oblong and oval pictures, i can see that the craters are not quite long or narrow enough to make it to oblong shape, so they are ovals.
My bad! I should have used the 'shorter' word. In school i was only 'average' in English.
Say, does JohnD have anything to do with the Beach Boys song?

by **JohnD** » Sun Mar 13, 2011 9:05 pm

Beyond,
Look around for other pics of the Messier pair. They are near the edge of the Moon as seen from Earth, so you are looking at them, and the 'normal' craters around at a significant angle. Look in the Mare Fecunditatis on this APOD: http://apod.nasa.gov/apod/ap110303.html
So the normal, circular craters look oval. Oval, not oblong!

John

by **DavidLeodis** » Sun Mar 13, 2011 8:26 pm

In the information in the image data with the image that is brought up through the "full resolution mosaic" link in the explanation it states "Time (DOY:001) 2010-01-01T00:00:00". I'm confused about that

Does it mean the image data was acquired in the first second of January 1st 2010 or is it phrasing used when the actual date/time is not known

I've done a search and found that DOY will be Day of Year. Thanks for any help.

by **Beyond** » Sun Mar 13, 2011 6:53 pm

JohnD wrote:Oblong craters?
Where?

In the url you posted. I see five surrounding the two big ones, one of which has the 'rays'. http://www.astronet.ru:8104/db/varstars/msg/1200372

by **JohnD** » Sun Mar 13, 2011 12:02 pm

garry,
It very much fits with theory.
See: http://lroc.sese.asu.edu/news/index.php ... tatis.html
And: http://www.lpi.usra.edu/nlsi/training/illustrations/ which includes information specifically about M.Orientalis.

And there is an interesting explanation of "Crater morphology" on this site: http://passc.net/EarthImpactDatabase/In ... pacts.html
It shows the changing shape of impact craters as the size of the impactor increases, and uses Orientale as the top end example.

Briefly, a small crater's walls remain until weathering or further impacts break them down. In an enormous crater the surrounding rocks have insufficient strength to maintain its shape and they slump into the void, moving in a roughly radial direction to form the circumferential ridges.

John

by **garry** » Sun Mar 13, 2011 10:28 am

If the crater was caused by an impact, why then are there 3 concentric rings forming terraces? This not does not fit in with standard impact theory.

by **JohnD** » Sun Mar 13, 2011 10:25 am

Oblong craters?
Where?

The rectilinear structure in M.Orientale, at about seven o'clock in the APOD image is, I think, a graben, where parallel faults have allowed a block of ground to sink down.

John

by **Beyond** » Sun Mar 13, 2011 2:31 am

There seems to be a few more oblong craters in that area. Maybe a meteor shower??

by **JohnD** » Sat Mar 12, 2011 11:40 pm

Phil T, Sweden wrote:Why is it that from whichever direction one looks there are very few craters which look like a glancing blow ? How come all the impacts look perpendicular to the plane of the Moon's surface ?

Phil,
This was discussed in the recent Nearside thread: http://asterisk.apod.com/viewtopic.php?f=9&t=23063

As I suggested there, look for "Messier" a double crater that is the result of an impact by something that nearly skimmed the surface and missed, but didn't. The main crater is just off circular. See: http://www.astronet.ru:8104/db/varstars/msg/1200372

John

by **bystander** » Sat Mar 12, 2011 9:34 pm

The plural of maria is "Maria Maria"

Click to play embedded YouTube video.

by **neufer** » Sat Mar 12, 2011 9:28 pm

owlice wrote:
salmo italian wrote:
Plural of "mare" is "mari", not "maria".
In Latin, the plural of mare is maria.

Click to play embedded YouTube video.

by **owlice** » Sat Mar 12, 2011 7:30 pm

salmo italian wrote:Plural of "mare" is "mari", not "maria".

In Latin, the plural of mare is maria.

by **salmo italian** » Sat Mar 12, 2011 7:22 pm

Plural of "mare" is "mari", not "maria".

by **johnniem** » Sat Mar 12, 2011 6:54 pm

What are the small square black overlays? at first i thought they were metrics in the system for measuring... but too random for that, i think

by **Chris Peterson** » Sat Mar 12, 2011 6:17 pm

Phil T, Sweden wrote:Why is it that from whichever direction one looks there are very few craters which look like a glancing blow ? How come all the impacts look perpendicular to the plane of the Moon's surface ?

Because craters are always round, except for extremely angled impacts- less than 10 or 15 degrees. And there are a small percentage of oblong or chained crater structures to account for the small number of glancing impacts.

by **Phil T, Sweden** » Sat Mar 12, 2011 6:05 pm

Why is it that from whichever direction one looks there are very few craters which look like a glancing blow ? How come all the impacts look perpendicular to the plane of the Moon's surface ?

by **Chris Peterson** » Sat Mar 12, 2011 4:49 pm

biddie67 wrote:Could an impact on the moon like this have possibly knocked the moon out of its orbit, either into the
Earth or free it completely from its orbit around the Earth?

Not even close.

Could any of that impact effect the oceans on Earth?

An impact like that would definitely have produced debris that reached the Earth as lunar meteorites. I doubt the effect was significant, either on the land or the oceans.

by **biddie67** » Sat Mar 12, 2011 4:46 pm

Could an impact on the moon like this have possibly knocked the moon out of its orbit, either into the
Earth or free it completely from its orbit around the Earth?

Could any of that impact affect the oceans on Earth?

by **KenS** » Sat Mar 12, 2011 3:30 pm

It looks like the asteroid exposed multiple cycles of layering of material deposited on the moon's surface, either by volcanic periods or sequential solidification of different minerals.

by **Chris Peterson** » Sat Mar 12, 2011 3:21 pm

KennyB wrote:What happens to all the debris from an impact like this. Wouldn't there be some huge dust clouds that would be seen?

Yeah... if anybody was watching three billion years ago! Much younger craters do show evidence of impact ejected debris around them. But most of the craters on the Moon are billions of years old, and any structure in ejected material has long since eroded away (yes- there is erosion on the Moon, it's just a very slow process).

by **KennyB** » Sat Mar 12, 2011 2:53 pm

What happens to all the debris from an impact like this. Wouldn't there be some huge dust clouds that would be seen?

by **neufer** » Sat Mar 12, 2011 2:50 pm

orin stepanek wrote:
Smooth surface; might make a good landing site.

The best landing sites (e.g., the Sea of Tranquility) are also the most boring.

by **orin stepanek** » Sat Mar 12, 2011 2:37 pm

Smooth surface; might make a good landing site.

Starship Asterisk*

APOD: Mare Orientale (2011 Mar 12)

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