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Martian Analemma (APOD 30 Dec 2006)
Posted: Sat Dec 30, 2006 7:08 am
by rowlfe
OK, so I am a newbie, and an amateur. I wonder why the analemma of Mars is not a figure 8 as the analemma of the Earth. Doesn't Mars have a tipped axis as does the Earth? Wouldn't the tip of the Mars axis cause the same shape analemma as we see here on Earth? This inquiring mind wants to know...
Posted: Sat Dec 30, 2006 4:00 pm
by orin stepanek
http://antwrp.gsfc.nasa.gov/apod/ap061230.html
I too wonder why that would be. Could it have something with the way Mars wobbles as compared to the way Earth wobbles?
Orin
Posted: Sat Dec 30, 2006 4:34 pm
by BMAONE23
Might it have something to do with the latitude at which the images were taken? Does the Analemma here differ near the equater?
professorship/teacher at its finest
Posted: Sat Dec 30, 2006 7:17 pm
by ta152h0
I have always thought dropping hints onto active minds causes discoveries.
good job BM
Posted: Sun Dec 31, 2006 2:38 am
by Dr. Skeptic
BMAONE23 wrote:Might it have something to do with the latitude at which the images were taken? Does the Analemma here differ near the equater?
The answer is no, the properties of the analemma is dependent on the planets orbital inclination and eccentricity. Earth's inclination is about 13° Mars about 1.8°. If an inclination was at 0°, the analemma would be a straight line, adding a pure circular orbit, it would be a single dot.
For those that don't know, "inclination" is the difference between the planet's equatorial and orbital planes.
Posted: Sun Dec 31, 2006 5:28 am
by kovil
so by 'reverse osmosis' ;
if one photo'd the sun every day at the exact same time;
the tilt of the planetary axis,
and the eccentricity of the orbital body
could be deduced from the 365 solar dots?
or however many are in one orbit.
Fascinating!
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Kind of like a gravitational field produces a parabolic curve in a traveling object,
and an acceleration field produces an elliptical curve in a traveling object.
That's how to tell if you are in a box that is not moving and on a planet,
or if you are in an elevator compartment accelerating upward!
Throw something across the room, level, and measure the curve traversed!
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Todays APOD has a much better angle to determine the slope of the crater terrain!!! Thanks APOD photo selection men!!!
There are many 'gullies' along the view. Whatever it is that causes washouts or landslides. It looks more like a liquid event than a dry soil event, by the edges of the gullies.