Moon phases on other side of Earth

02 April, 2009

Photograph of Moon at Full phase
Source: Museum Victoria

Question: If it is a full moon in Australia, is it also a full moon on the other side of the world?

Answer: The phases of the Moon are the same all around the world. Any two places that can see the Moon at the same time will see the same phase.

Each Moon phase happens at a precise point in the Moon's orbit around the Earth, and hence at a precise moment in time. This is the same moment all over the world, but will be a different local time for every time zone in the world.

For example, the first full moon of the 21st century occurred at 8:24pm on 9 January 2001, Universal Time. In Melbourne this moment was 7:24am on 10 January 2001, Australian Eastern Summer Time.

Of course opposite sides of the world will not be able to see the Moon at the same time. Only one half of the world will be able to see the moon when it is precisely at one of the phases. For the example I gave above, that Full Moon was visible from the United Kingdom, but not from Australia. The Moon had set in the west around two hours before it became full. However since the appearance of the Moon’s phase does not change very quickly, the Moon would have looked very full when it set.

Your comments

Brunswick East Primary School We are studying Space in our classroom this term. After reading this article, here are some questions from our class. What Colour is the moon? Josh, Grade 2 How many different phases of the moon are there? Imogen, Grade 2 When you have a crescent moon, why can't you see the whole moon? Leila, Grade 1 How wide is the moon? Sam, Grade 2 How high up is the moon? Alycia, Grade 3 Does the moon have a moon of its own? Obi, Grade 3 Thanks, 1/2/3 Brunswick East Primary School

01/05/2009 01:06 PM

Discovery Centre

Hi Josh, Imogen, Leila, Sam, Alycia and Obi,

The colour of the Moon is very subtle: it has soft shades of grey, black and white, and regions of browns, blues and yellows. We generally say there are four phases of the Moon. New, First Quarter, Full, and Last Quarter. See the Moon Phases page of our website.

It is actually possible to see the whole Moon during the crescent moon phase. Sometimes there is so much light reflected from the Earth (Earthshine), that it lights up the part of the Moon that is not lit up by the Sun: we see the bright crescent Moon as well as the pale remainder of the Moon. As the Moon phase moves towards the Full moon, the Moon is so bright you can no longer see the arthshine on the Moon. The Moon has to be in the right position for the Earth to reflect the Sun's light onto the Moon's night side; this only happens just after the New Moon. This is called the Da Vinci Glow. You can find out more about it on the NASA website.

The diameter (width) of the moon is 3475.6 km (0.272 x that of Earth). The moon is (on average) 384 400 km from the Earth. The Moon does not have a moon of its own. You can learn more about The Moon on our website.

09/05/2009 10:52 AM

Moon phases on other side of Earth

02 April, 2009

Your comments

Post a comment

Image Gallery