Finding your way by using the Southern Cross

Navigating at Night need not be as daunting as it sounds. Provided that the skies are working for you and are not covered in cloud. If you can find the Southern Cross, or ‘Crux’ by its astronomical name, you can easily find the South Celestial Pole (SCP), an imaginary point in the sky directly above south.

Finding your way by using the Southern Cross

Method 1

Imagine a line joining the two stars at the ‘head’ and the ‘foot’ of the cross. Extend the line out another four lengths (x) from the foot of the cross. This will determine the South Celestial Pole (the SCP). Then look straight down from the SCP to the horizon. You’ve found south!

Finding your way by using the Southern Cross

Method 2

Another slighty trickier, but more accurate, way of finding south is to use the Southern Cross and the pointer stars from the neighbouring constellation, Centaurus.

Draw a line through the two stars at the ‘head’ and the ‘foot’ of the cross and extend it to the dark patch of the sky the same way as in the first method (Line 1).

Then join a line between the two pointers (Line 2). Find the middle of Line 2 then draw a perpendicular line down toward Line 1 until the lines meet. The point at which the lines 1 and 3 intersect is the SCP. From there just look straight down to the horizon and you’ve found south.

Even though the Southern Cross moves around the sky during the year, the foot of the cross always points to the SCP, which is very handy if you’ve lost your compass or the sun’s gone down.

Finding your way by the light of the Moon

Finding your way by the light of the Moon

The moon has no light of its own. The light seen from the moon is a reflection of the sun. The shape of the reflected light varies as the Earth orbits around the sun. This can be useful for finding direction at night once you understand how this works. When it is a crescent moon it is really easy.

The moon rises in the east. That means that at midnight, it will be in the north and then set in the west. However, the angle of the moon’s orbit is less reliable than other objects in order to help you navigate.

You can however, use a crescent moon to navigate. If you draw an imaginary line down the side of the crescent moon (from tip-to-tip), that line will point you north (in the southern hemisphere) or south (in the northern hemisphere).

If the moon rises before sunset, the illuminated side of the moon will face west. If the moon rises after midnight, the bright side will face east. The reason this navigational method works is because the sun and moon move across the sky from east to west. Since the moon reflects the sun’s light, its bright side will be ‘pointing’ to the direction of the sun, or approximately east or west.

4 thoughts on “Navigating at Night

  1. Hi Darren,

    Just one point to note above, you have the same 3 pictures, 2 of which show a point which is south whilst the third notes this direction as north. Clearly if you are standing in the same spot looking at that scenery then it cannot be both directions. Whilst your comments are correct, you should definitely use a different photo as your diagrammatic explanation

    1. Hi Stuart. Thanks for your comments can you please elaborate more? The diagrams are correct and represent the related descriptions. Which one is incorrect? The three images are not meant to be viewed in association with earth other. Each image relates to the related description only.

    2. Hi Darren,
      In isolation the pictures are correct, it is simply confusing to see the same picture three times with two of them showing South but the third one showing North. Whilst I understand that “each image relates to the related description only”, the problems exists that they are being depicted in the same article & therefore a natural conclusion is drawn. As I mentioned above, if you are standing in the same spot looking at the scenery as depicted, you cannot have two opposite directions. If these pictures were used in different articles there would be no confusion but sitting directly underneath one another an automatic psychological link is drawn between them. The Moon picture should use a different picture. Just my thoughts

    3. Thanks for your comments Stuart. I have flipped the last image so that the scenery represents the reverse view of the other two images.

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