Astronomy/Moon on it's back


Yes, I read your answer, but the question really was : Is it a WINTER phenomenon in the hemisphere over Ireland , or can we have a "moon on it's back" in summer time? I've often seen the moon in this phase, but does it ONLY appear as such in winter. Further, as we see the moon in this part of Europe in it's "on it's back" do you see the same in the USA, and likewise in Japan, Australia, or elsewhere at the same time of the year ?
Thank you,
Aidan Colgan #Ireland#


What you have uncovered is the role of latitude in relation to the observer's 3D orientation, i.e. from a position on the surface of the Earth in relation to the Sun and Moon, and the latter going through its phases. This is a difficult concept to convey verbally, and is perhaps best illustrated by using a 3D model such as this one (featured at

Basically, yes, *how* you observe the Moon - say 'lying on its back' will differ to how someone observes it from perhaps Trinidad or Guyana. Thus, an observer's 'attitude' (3D orientation) in relation to the moon changes as the observer shifts latitude from north to south. For instance, since Melbourne, FL (28 N) is further south than Burlington, Vermont (45 N), the moon will appear more on its side in Melbourne FL than Burlington. (Of course, the converse can also be true at other times, i.e. Moon on its side seen from Vermont, but at right angles seen from FL)

But there is really no way to satisfy yourself of this unless you actually use some kind of #D model to demosntrate that this is so.

Hence, the one noted above which I have also used in giving basic astronomy courses, as in the Caribbean.


All Answers

Answers by Expert:

Ask Experts


Philip Stahl


I have more than forty years of experience in Astronomy, specifically solar and space physics. My specialties include the physics of solar flares, sunspots, including their effects on Earth and statistics pertaining to sunspot morphology and flare geo-effectiveness.


Astronomy: Worked at university observatory in college, doing astrographic measurements. Developed first ever astronomy curriculum for secondary schools in Caribbean. Gave workshops in astrophysics and astronomical measurements at Harry Bayley Observatory, Barbados. M.Phil. degree in Physics/Solar Physics and more than twenty years as researcher with discovery of SID flares. Developed of first ever consistent magnetic arcade model for solar flares incorporating energy dissipation and accumulation. Develop first ever loop solar flare model using double layers and incorporating cavity resonators.

American Astronomical Society (Solar Physics and Dynamical Astronomy divisions), American Mathematical Society, American Geophysical Union.

Solar Physics (journal), The Journal of the Royal Astronomical Society of Canada, The Proceedings of the Meudon Solar Flare Workshop (1986), The Proceedings of the Caribbean Physics Conference (1985). Books: 'Selected Analyses in Solar Flare Plasma Dynamics', 'Physics Notes for Advanced Level'. 'Astronomy and Astrophysics: Notes, Problems and Solutions'.

B.A. Astronomy, M. Phil. Physics

Awards and Honors
American Astronomical Society Studentship Award (1984), Barbados Government Award for Solar Research (1980), Barbados Astronomical Society Award for Service as Journal Editor (1977-91)

Past/Present Clients
Caribbean Examinations Council, Barbados Astronomical Society, Trinidad & Tobago Astronomical Society.

©2016 All rights reserved.