On Mar 20, 4:56*am, Tudor Hughes wrote:
On Mar 19, 10:12*pm, Yokel wrote:







There are both real and psychological effects.

The moon's orbit is distinctly elliptical, so the moon's distance varies
significantly as it goes round. *This can be shown by looking at solar
eclipses, which vary from the moon being large enough to completely
cover the sun for about 7 minutes at any given point, to "annular"
eclipses when even at mid-eclipse a ring of sunlight is left around the
moon's disk. *Of course, the moon passes through "perigee" every month,
but it is only really noticeable when it occurs at full moon and our
satellite is displayed in full sunlit glory.

The shape of the moon's orbit also varies slightly due to gravitational
effects from the changing geometry of earth, moon and sun. *This has
resulted in the orbit currently becoming slightly more elliptical than
normal, hence the slightly closer approach highlighted for tonight. *The
earth's orbit and angle of the rotation axis also change in this way
over long timescales - these variations affect the distribution of solar
heating over the globe and a gentleman called Milankovitch showed how,
together with "feedback" effects, these variations could partly explain
the pattern of ice ages and interglacials.

The very real psychological effect is that the brain uses various cues
to estimate the size of objects very far away. *Experiments with pairs
of drawings have shown that the brain can be "fooled" by a surprising
amount *- an object seen close to the horizon providing a "scale" for it
seems larger than one high in the sky. *And there have been any number
of incidents which demonstrate beyond all reasonable doubt that people
will believe almost any old tosh - and judge what they see and hear on
this basis - if they do not know or cannot understand the truth.

--
- Yokel -

Yokel posts via a spam-trap account which is not read.

* * The moon is always closer to the earth than average at new moon
and full moon, slightly more so in the latter case, so the closest
perigees always occur near full moon. *This current one is nothing
very special - the moon was closer in 1992, 1993 and 2008 by a few
tens of km. *I have never been able to look at the moon and discern
whether it is at apogee or perigee even though the size varies by
±7%. *The altitude illusion easily swamps any such change. *The moon
is actually measurably *larger* when high in the sky compared with
when on the horizon by a maximum of about 1.6% in these latitudes
because you are then closer to it by a large fraction of the earth's
radius, which is about 1/60th of the distance to the moon.
* * *This full moon, although bright because of the closeness, is not
especially so, the moon being 5.00 degrees from the ecliptic (near the
maximum) and the increase in brightness at full phase is surprisingly
large due to the direct reflection effect.

Tudor Hughes, Warlingham, Surrey.- Hide quoted text -

- Show quoted text -

Thanks both of you. Interesting. we had a veil of high cloud at 9pm
when I looked, so the size was hard to judge. There was a spectacular
halo though.