----- Original Message ----
> From: luzius.thuerlemann <[email protected]>
>
> Hello there,
I have a new problem concerning horizon creation.
A few
> months ago, I took the time when the Moon was just over the top of a
> mountain.
> Then I calculated the Moon's altitude and created the horizon at this point -
> I
> realised that it's only possible to simulate complete degrees instead of
> minutes
> and even seconds (at least minutes would be nice since it is possible to
> calculate the horizon really accurate with this
> Moon-fully-above-horizon-method).
Ok, two days ago, I measured the time when
> the Moon was just below the horizon - this mountain was as high as the one
> where
> I took the first measurement a few months ago which is why the Moon should be
> displayed at the same altitude above the mathematical horizon.
If this is a different mountain, were you the same distance from it, so the
angle would be the same?
And if this is a different mountain, were you in a different location? If so,
did you change your location in the program? That would affect where CdC
expects the moon to appear.
> When I looked at
> the Moon's altitude in CdC (2.76c) I saw that he was displayed significantly
> nearer to the mathematical horizon than the first measurement was. I thought
> about a wrong first calculation. So I measured yesterday evening when the
> Moon
> was just above the first mountain-horizon again. Just by checking the
> altitude
> in CdC I could see that the first measurement was correct.
> I then saw that
> there must be something wrong with the alignment of the whole sky because the
> ecliptic was significantly not mirror-symmetric when measured in the
> meridian.
The ecliptic is not parallel to the earth's equator or the sky's equatorial
coordinate system, so why would you expect the ecliptic to appear
mirror-symmetric with respect to the meridian?
The earth's equator (and compass directions on the ground) and the sky's
equatorial coordinate system are based on the earth's rotation axis. The
ecliptic is based on the earth's orbit (and the axis of that orbit). But the
earth's axis is tilted 23 degrees relative to its "orbit axis".
> The ecliptic rises above horizon in north-east and falls below the horizon in
> south-west.
Depending on the date, time, and location, that's entirely normal.
-John
