← Back to context

Comment by chungy

2 years ago

Trying your examples, especially considering that the elliptical orbit of the earth likewise causes the Sun's angular diameter change depending on where our orbit is, I found that Units current has a buggy definition of moondist_min and moondist_max. It's defined in the definitions file as 356.371 km and 406.720 km respectively. These should be Mm! (Or remove the period, either will work)

Just to work around the bug, you can use a local definitions file to correct it:

    cat > ~/.units <<EOF
    moondist_min 356.371 Mm
    moondist_max 406.720 Mm
    EOF

5 comments

chungy

Reply
kragen  2 years ago

interesting, looks like an effort to improve the precision resulted in a factor of 1000 error! `help moondist_max` shows me considerably less precise values:

    sundist                 1.0000010178 au # mean earth-sun distance
    moondist                3.844e8 m       # mean earth-moon distance
    sundist_near            1.471e11 m      # earth-sun distance at perihelion
    sundist_far             1.521e11 m      # earth-sun distance at aphelion
    moondist_min            3.564e8 m       # approximate least distance at
                                            #    perigee 1901-2300
    moondist_max            4.067e8 m       # approximate greatest distance at
                                            #    apogee 1901-2300