Thursday, September 1, 2011

Basic night navigation: finding Qiblah direction at night using Stars

Allah SWT, Says in Surat Al-Nahl (The Bee):
"And landmarks. And by the stars they are [also] guided." [16:16]


Allah SWT, with His Bounties, made from the stars a way for us to find our directions. We shall discuss in the following entry, few stars that would help us get our direction (for Northern Hemisphere only)

During the course of the night, the stars are not staying in one place, they move as the earth rotates. This is valid for most of the stars to the exception of one of them: Polaris...

Polaris is the North Star, it stays almost at the same place all night long and this is why it is so important for navigation:

This long-exposure photograph shows the Delicate Arch, a rock formation in Utah, silhouetted against the night sky, which is filled with the trails of stars. The brightest and innermost trail, seen at the centre of the arch, was made by Polaris, the North Star or Pole Star. This is the closest of the naked-eye stars to the earth’s north celestial pole. The direction of the rotational axis of the earth slowly changes, so every few thousand years a different star serves as the North Star.
Encarta Encyclopedia
David Nunuk/Photo Researchers, Inc
Image Source: wikipedia.org

The bright innermost circle is created by Polaris.
If Polaris stays at the same place during all night, you then have a fixed reliable point for you to refer and to guide yourself.

How to find Polaris:

Two main constellations are used to help find Polaris: Ursa Major (also known as Great Bear and also known as Big Dipper) and Cassiopeia. Both of these will be found the northern part of the night sky, so they indicate by themselves the North direction without having to go into details of the true North.

Two main advantages that these constellations have: they are visible during all seasons and they appear almost all night long.


The Great Bear (Big Dipper shape) and Cassiopeia (W shape) constellations will rotate during the night around one point: Polaris. This could be seen in the following animation

Image source: Wikipedia.org

According to where you live, Polaris will be found at different altitudes. The higher the Latitude of your place, the higher in the sky you would see it.
People in Equator would see Polaris right above the horizon, while someone sitting right at the North Pole would see it exactly on top of his head. Polaris altitude (height above horizon) gives you your Latitude.


Take a note: If you live in a city, you might not be able to observe all of this, because the city lights are contaminating the light from the stars..
  • If you are living in Mecca, you are on Latitude 21deg N, you would see Polaris at same altitude, 21deg N.
  • If you are living in Medina, Polaris altitude = Latitude = 24 deg
  • If you are living in Singapore, Polaris altitude = Latitude = 1 deg (very difficult to see, right above horizon)
  • If you are living  in Kuala Lumpur, Polaris altitude = Latitude = 3 deg (difficult to see also)
  • If you are living  in Virginia Beach or Algiers, Polaris altitude = Latitude = 37 deg
  • If you are living in Aberdeen, it is higher in the sky, Polaris altitude = Latitude = 57 deg
Using the Big Dipper & Cassiopeia: (You may click on the pictures to have clearer view)
Ursa Major Constellation - بنات نعش 
Finding Polaris using Cassiopeia / Ursa major/ "The One with a Chair"
 
Cassiopeia - ذات الكرسي

Finding Polaris using Cassiopeia






What Ursa Major and Cassiopeia look like in the sky:

I know it might be a bit difficult to spot these constellations, especially if we live in a city where lights interfere with good observation...however, I wanted to post these pictures showing how they would look like in the sky..

Ursa Major - Source Google Images


Photo: Noel Carboni

Cassiopeia - Source Google Images
Cassiopeia and its famous "W" shape

Good to know:


One person lost his boat at sea and managed to drop into a raft before the boat sank. He managed to stay in the same maritime route by keeping his raft at the same Latitude. He managed to do this by using a pencil he had with him !!...he would locate Polaris at night and made sure that it would always be at the same height using his pen while laying on his back in the raft. He was able to steer his raft to stay always within that same Latitude....He eventually managed to get rescued by a passing boat after days spent in the open ocean...

So one can never know, Polaris = Latitude, keep this in mind and it might save your life one day...


What about Southern Hemisphere?
People in the Southern Hemisphere, like Australians, Brazilians etc will not be able to see the same stars than in the Northern Hemisphere. There is no equivalent to a Polaris for the South, they use Crux, or Southern Cross, to find South.


Articles referenced from Wikipedia.org:
Contrary to popular belief, Crux is not opposite to Ursa Major. In fact, in tropical regions both Crux (low in the south) and Ursa Major (low in the north) can be seen in the sky from April to June. Crux is exactly opposite to Cassiopeia on the celestial sphere, and therefore it cannot be in the sky with the latter at the same time.


The brightest stars of Crux appear on the flags ofAustraliaBrazilNew ZealandPapua New Guinea and Samoa. They also appear on the flags of the Australian state of Victoria, the Australian Capital Territory, the Northern Territory, as well as the flag of Magallanes Region of Chile, the flag of Londrina (Brazil) and several Argentine provincial flags and emblems (for example,, Tierra del Fuego and Santa Cruz). The flag of the Mercosur trading zone displays the four brightest stars. Crux also appears on the Brazilian coat of arms.



Related Posts Plugin for WordPress, Blogger...