Busy Solar System 19/3/2006

Comments and questions about the APOD on the main view screen.
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JohnD
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Busy Solar System 19/3/2006

Post by JohnD » Sun Mar 19, 2006 9:52 am

Interesting, but follow the link to the Minor Planets website, and the Earth's Environment animation.
To go direct - http://cfa-www.harvard.edu/iau/Animatio ... eSmall.gif

Oh, Mother! That's scary!

John

l3p3r
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Post by l3p3r » Sun Mar 19, 2006 12:16 pm

I cant see why they posted such an old picture for todays APOD when there is a new one from just a few days ago available...

and yes I agree! It is unnerving just how many pass so close to earth! (though, they cant be *that* close because i notice their paths of travel are not visibly altered by Earth's gravity)

ta152h0
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all those dots

Post by ta152h0 » Mon Mar 20, 2006 1:40 am

the smaller the scale, the more ominous it looks. And how many of those dots are big enough to survive 250000 feet of atmosphere and strike the ground ? :roll:
Wolf Kotenberg

dcmcp
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Post by dcmcp » Mon Mar 20, 2006 1:45 am

l3p3r wrote:It is unnerving just how many pass so close to earth! (though, they cant be *that* close because i notice their paths of travel are not visibly altered by Earth's gravity)
Not close at all. The scale is such that there is a noticeable curve in the Earth's orbit.

[Opinion-guess]At this scale the Earth-moon system resolves to a point. Anything that does not appear to "hit" the Earth is of the order of at least a million kilometers away.[/Opinion-guess]

kovil
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Post by kovil » Mon Mar 20, 2006 3:33 am

Recently crawling around the Astrophysical Journal site, this exact map is on one of their articles, (i saved it too) I am guessing the poster on APOD just lifted that map for here.

Wolf; Every one of those plotted objects is way big enough to do major damage to Earth, that's why they are mapped ! Tho it is 100,000,000 to 1 that any one of them will ever hit earth. So relax and pass me another cold one !!
Besides at their ambient velocity they would pass thru 11 miles of earths atmosphere in one second, and man that's fast ! When I visualize that speed, I can see the atmospheric shock wave easily developing.

One early evening while getting gas for my truck, this very bright light in the low western sky seemed to be getting brighter and closer and it had a growing larger shiney aura behind it. It really caught my attention. As I watched it for another 30 seconds, the aura then suddenly got very wide, very fast. The bright light continued, then diminished and disappeared, leaving a vapor trail that slowly started to get wiggly from the very straight appearance before.
I first thought an airplane was heading for me and was going to crash nearby and I wondered if I should split very quick.
What it actually was, I fully realized after it was over. I had an inkling when the aura got wide very fast.
It was a rocket launch from Vandenberg near Oxnard CA. I was in LA.
This is the only one I ever saw while it was happening. I've seen the trails afterwards many times, with their distinctive wiggly paths.
The main realization that hit me is how thin the atmosphere really is.
When the vapor trail got wide very fast, the rocket was hitting the zone where the stratosphere is, or it was suddenly above the atmosphere at maybe 90,000 feet or something, and the thrust vapors past the nozzle had no atmospheric pressure to hold back its expansion.
There is a visceral realization to watching a rocket go up through this gossamer thin veil of our earthly atmosphere and into space where no restraint to pressurized expansion exists.

It was 1/2 a minute of roller coaster understandings and perplexation.

To see an asteroid transit the atmosphere in one second, 11 miles per second standard incoming velocity, it would make quite a push in the air.