Cardinal Direction: POLARIS, VENUS & COMPASS

 

Courtesy: wikipedia

A long exposure photo of Polaris and neighbouring stars (exposure time 45 min), taken in Ehrenbürg (Walberla) in 2001.

Cardinal directions are very important factors for Navigation. Ancient mariners took the help of stars and planets for this purpose. In my few previous articles about North and south were discussed. Here also few points are discussed about polaris and venus how they help to find direction. For this article I took the help of wikipedia and other on line sites. You are requested to visit to know more.

Now I shall tell you How i became interested in this subject.nOW I can not exactly remember WHEN MY KHALA(AUNT) SUFIA PRACTICALLY TAUGHT ME CARDINAL DIRECTIONS. however, i had to repeat again again what she had taught me.

IT WAS IN our MOTHER TONGUE bENGALI DIALECT: PURBo (THE EAST), POSCHIM (THE WEST), UTTOR (THE NORTH) AND DOKHIN (tHE SOUTH). tWO OTHER DIRECTIONS WERE ALSO TAUGHT THEY WERE UrDHO (UP) AND ADHO (DOWN). iT WAS THE MATTER OF my PRIMARY OR PRE PRIMARY TIME. MY KHALA WAS A STUDENT OF CLASS FOUR. In bangladesh khala/ fufu are always very ENERGETIC teacher provided they live in the joint family or nearer. i was lucky enough my khala was living nearer to our house in my nanu bari (grand mother’s house).

SO, HER GEOGRAPHICAL KNOWLEDGE THUS she could IMPOSE UPON ME. i REMEMBER SHE TRIED TO SHOW ME DHROB TARA (POLE STAR/ NORTH STAR). MOST PROBABLY SHE ALSO TRIED TO SHOW ME SOKAL BELAR TARA(MORNING STAR) AND SONDHA TARA(EVENING STAR). SOME TIMES I GAZED A BRIGHT STAR OVER THE MOON. iT WAS ACTUALLY EVENING STAR I.E. VENUS PLANET. iN THE BANGLADESH ARMY MY MAIN PROFESSION BECAME teaching of MAP READING subject THAT INCLUDES ASTRO NAVIGATION, air PHOTOGRAPHY etc.  SO, I HAD TO TEACH MY SOLDIER STUDENTS POLARIS AND URSA MAJOR, URSA MINOR, PLOUGH, ‘W’ STAR(CASSIOPEIA) ETC. CONSTELLATIONS. NOW IN MY RETIRED LIFE STILL I TRY TO KEEP CONTACT WITH INSTRUCTORS OF NAVIGATION IN THE CIVIL ARENA.

WE CAN SEE INNUMERABLE STARS IN THE OPEN EYES. bUT ALL ARE NOT IMPORTANT FOR ASTRO NAVIGATIONAL PURPOSE. FOR ALL OTHER THAN NAVIGATORs and astronomers ONLY MENTIONED CONSTELLATIONS AND VENUS MAY BE IMPORTANT TO KNOW TO FIND DIRECTIONS IN THE UNKNOWN PLACES.

iN THE LOCALITY ONE CAN FIND DIRECTIONS FROM MOSQUE, CHURCH, PAGODA, GRAVES ETC BECAUSE OF THEIR SPECIAL CONSTRUCTION THAT MENTION PARTICULAR DIRECTION. bUT IN THE SEA OR ISOLATED AREAS NO SUCH CONSTRUCTION OR LAND MARK mAY BE PRESENT. FOR THEM THIS POST MAY BE HELPFUL.  IT IS WRITTEN BY THE HELP OF WIKIPEDIA AND OTHER ENTRIES OF INTERNET WHAT HAVE RICH CITATIONS:

 

 

ar, α Cas

Courtesy:wikipedia

(Shedar is the α star found at the bottom right of the CONSTELLATION)

“Polaris was used more for navigation than any other star. Just follow the edge of the giant soup ladle four lengths and you find polaris.”

“Polaris determines due north, in its direction, polaris directly above due north, and its angle in the sky can tell you latitude.”

“There is no equivalent naked eye for the southern hemisphere, but southern hemisphere navigators just use constellations reasonably close to due south to identify due south. You can kind of draw a circle using octanus and the southern cross, and use its imaginary center as a south pole star.”

POLE STARS MAY SHOW US TRUE NORTH AND TRUE SOUTH. BUT BY ANOTHER WAY WE MAY KNOW A NORTH. IT IS COMPASS OR MAGNETIC NORTH. BY MODERN COMPASS WE EASILY CAN KNOW ALL THE DIRECTIONS AS THOSE ARE MARKED ON THEM. FOR MORE ACCURACY IN SUCH COMPASSES DEGREES, MINUTES, SECONDS ETC ARE MARKED. IT IS WORTH MENTIONING HERE THAT THERE IS VARIATION BETWEEN THE TRUE AND MAGNETIC NORTH.  THERE ARE FEW IMAGES OF MODERN COMPASSES TAKEN FROM THE WIKIPEDIA.

Courtesy: wikipedia

(A military compass that was used during World War I.)

Courtesy: wikipedia

(Turning the compass scale on the map (D – the local magnetic declination).

 

A Military Compass                                                       (Courtesy: wikipedia)

When the needle is aligned with and superimposed over the outlined orienting arrow on the bottom of the capsule, the degree figure on the compass ring at the direction-of-travel (DOT) indicator gives the magnetic bearing to the target (mountain).

VENUS WAS ALSO HAD SOME NAVIGATIONAL VALUE TO THE ANCIENT MARINERS. BUT BY SUN EAST AND WEST COULD BE ASCERTAINED. SO THAT WAS NOT IN WIDE USE. THERE ARE FEW IMAGES AND INFORMATION GIVEN FROM THE WIKIPEDIA AND OTHER ENTRIES OF INTERNET. THESE MAY HELP THE LEARNERS:

Venus orbits the Sun at an average distance of about 108 million kilometres (about 0.7 AU) and completes an orbit every 224.65 days. Venus is the second planet from the Sun and orbits the Sun approximately 1.6 times (yellow trail) in Earth’s 365 days (blue trail)

Courtesy: wikipedia

Venus as a brilliant “Evening Star” next to crescent moon

“Ancient mariner used to take the help of Venus for their direction finding and hence Asro Navigation.’

“Venus mainly just provides about as much navigation information as the sun does, and you can know with utmost intuition without a doubt where the sun is, even without looking directly at it. Even at night, you can remember from the day which side of the sky the sun set upon.”

“The problem with Venus is it is never far from the sun, so it’s kind of useless to use as a navigational aid when you can just use the sun instead. After the sun has been down for a while Venus goes down too, Likewise in the morning the sun is never far behind it.”

“Venus sometimes appears as an evening star above the western horizon shortly after sunset and sometimes appears as a morning star above the eastern horizon shortly before sunrise.  In primitive times, people regarded the evening and morning stars as two different heavenly bodies but in the sixth century BC, Pythagoras suggested that they might be one and the same body.”

“The Venus tablet of Ammisaduqa (Enuma Anu Enlil Tablet 63) refers to the record of astronomical observations of Venus, as preserved in numerous cuneiformtablets dating from the first millennium BCE. It is believed that this astronomical record was first compiled during the reign of King Ammisaduqa (or Ammizaduga), the fourth ruler after Hammurabi. Thus, the origins of this text should probably be dated to around the mid-seventeenth century BCE.^[1]“

“The tablet recorded the rise times of Venus and its first and last visibility on the horizon before or after sunrise and sunset (the heliacal risings and settings of Venus) in the form of lunar dates. These observations are recorded for a period of 21 years.^[2]“

“On rare occasions, Venus can actually be seen in both the morning (before sunrise) and evening (after sunset) on the same day. This scenario arises when Venus is at its maximum separation from the ecliptic and concomitantly at inferior conjunction; then one hemisphere (Northern or Southern) will be able to see it at both times. This opportunity presented itself most recently for Northern Hemisphere observers within a few days on either side of March 29, 2001, and for those in the Southern Hemisphere, on and around August 19, 1999. These respective events repeat themselves every eight years pursuant to the planet’s synodic cycle.”

VENUS IS NOT ONLY THE MORNING STAR. A LIST OF MORNING STARS IS GIVEN BELOW:

• Morning star, a name for the planet Venus when it appears in the east before sunrise
• Morning star, a name for the star Sirius, which appears in the sky just before sunrise during the Dog Days
• Morning star, a (less common) name for the planet Mercury when it appears in the east before sunrise

(Courtesy:WIKIPEDIA AND OTHER ONLINE ENTRIES. READERS ARE REQUESTED TO VISIT THOSE TO KNOW MORE. In no way this post is enough for military students because to find position, target, route for night marching much complex calculations are required. So, they must follow their own texts. Same case is for the navigators and astronomers.)