Celestia Forums

In the latest SVN (r4533) the Earth is invisible after "1386809 Feb 14 03:08:34 UTC" (Julian Date: 508242690.63095) and before "-1372739 Aug 05 02:11:04 UTC" (Julian Date: -499671645.40897). I think, that the source of the problem is the new "CustomRotation" for Earth: "earth-p03lp". It probably works only between these two moments of time, that I wrote. There is a primitive solution to that problem. One can modify Earth with the timeline:



However, the rotation of the Earth is then not continuous between phases. The Earth immediately jumps to extremaly different orientation! To avoid it, one should change properly "Inclination" and "MeridianAngle" in the first and the last phase. I haven't tried it yet.
Does anyone know a better solution to this bug?

Paul

StandardModel,

Do you really believe that human beings still exist on Earth
in the year 1 386 809, Feb 14 03:08:34 UTC


Fridger

t00fri wrote:StandardModel,

Do you really believe that human beings still exist on Earth
in the year 1 386 809, Feb 14 03:08:34 UTC


Fridger

Fridger,

No, I don't believe in that. I just wrote exact moments of time to make it easy to check the bug .

Paul

The earth is gone but the rest of the planets are there. Maybe we will learn how to blow up planets by then and blow it up.
cartrite

cartrite wrote:The earth is gone but the rest of the planets are there. Maybe we will learn how to blow up planets by then and blow it up.
cartrite

hi hi... cartrite original sound

Cheers,
Fridger

cartrite wrote:The earth is gone but the rest of the planets are there. Maybe we will learn how to blow up planets by then and blow it up.
cartrite

Cartrite,

I hope, you don't mean the LHC

More seriously:

I remind you that the bug is also related to the past. For example, I have an addon, which shows different continents in the distant past. It hadn't work properly before I partially fixed the bug.

Paul

Maybe the invisible earth is what killed the dinosaurs. Being unable to see where they were placing their feet, they all fell over and died of fatal accidents.

Since the earth is also going to become invisible in the future, we need to take steps to prevent humans from meeting the same fate.

I found the source of this problem: the new long-term precession model for the Earth contains polynomials that diverge at dates in the distant past and future. The researcher who derived the expression remarks that it may be used "for any instant in the scale of up to [a] million years". If I clamp time to +/- 500,000 years from 1 Jan 2000, there is no longer any problem with the Earth disappearing or wobbling unrealistically at dates in the distant past or future. With clamping, the Earth's precession does stop abruptly in the year 502,000, but this is reasonable given the limitations of the precession model and our ability to model the behavior of the solar system over very long time periods.

--Chris

chris wrote:I found the source of this problem: the new long-term precession model for the Earth contains polynomials that diverge at dates in the distant past and future. The researcher who derived the expression remarks that it may be used "for any instant in the scale of up to [a] million years". If I clamp time to +/- 500,000 years from 1 Jan 2000, there is no longer any problem with the Earth disappearing or wobbling unrealistically at dates in the distant past or future. With clamping, the Earth's precession does stop abruptly in the year 502,000, but this is reasonable given the limitations of the precession model and our ability to model the behavior of the solar system over very long time periods.

--Chris

Chris,

I think, that such a clamping is a very good idea. Thank you very much for the explanation and for taking this thread more siriously, than others, who posted here.

Paul

Chris,

Thank you for fixing the bug in r4555. I've just checked, that your fix really works and I don't have to use timeline anymore.

Much appreciated

Paul

SU(3)xSU(2)xU(1) wrote:Chris,

Thank you for fixing the bug in r4555. I've just checked, that your fix really works and I don't have to use timeline anymore.

Much appreciated

Great to hear it--thanks for the confirmation that the problem is fixed.

--Chris