The stars are so bright that even the howling wind cannot hide the brilliance of the stars. They shine brightly in the dark night, guiding all lost travelers.
Following the direction of Bi Fang's finger, everyone was fascinated.
Someone once took a time-lapse exposure photo in the northern hemisphere starry sky. As the stars move, due to the rotation of the earth, the tracks of stars in the sky form concentric circles one after another.
Only the star in the center of the circle remains unchanged in the field of view because it is located on the extension of the Earth's axis.
This star is called Polaris, and it is also an old friend of everyone.
To observers in the Northern Hemisphere, Polaris remains stationary and other stars rotate around it.
etc......
Northern Hemisphere observer?
Some spectators smacked their mouths, wondering what was wrong.
After a while, someone suddenly realized that Fang Shen was in the southern hemisphere, wasn't he?
[Can Polaris be seen in the southern hemisphere? 】
[I slowly typed a question mark]
[Damn it, I just turned the corner. Isn’t it that I’m in the southern hemisphere? How can I see the North Star? 】
"When did I say this was the North Star?" Bi Fang laughed twice, "I never said this was the North Star."
"I just used Polaris as an example because the underlying logic is the same and everyone is familiar with Polaris. I think it might be easier for everyone to understand."
【I am silly】
[False shot]
【biubiubiu】
[Sorry, I can’t understand what kind of star you get. 】
【So what kind of star is this?】
[So the Southern Hemisphere is the South Pole Star?]
"There is no so-called South Pole Star. This star is actually the center point of the Southern Cross constellation,"
"Polaris is located on the extension line of the earth's axis, and is very, very far away from the earth, so far that the radius of the earth can be ignored in comparison."
"So, when observing the direction of Polaris from a certain location on the earth's surface, this line of sight is parallel to the earth's axis. Then, the angle between this line of sight and the horizon, that is, the elevation angle of Polaris in the field of view, is equal to the latitude of the location."
"That is to say, if you look for Polaris in your field of vision and find that it is directly above your head, that is, the elevation angle is 90 degrees, it means that your latitude is 90 degrees, and you are stepping on the North Pole."
"If you look for Polaris in your field of vision and find it at the horizon with an elevation angle of 0, it means that your latitude is 0 degrees and you are sailing on the equator. If the elevation angle is 30 degrees, it means that your current location is 30 degrees north latitude.
"
[I mentioned this last time, I remember you can use a sextant]
[Fang Shen Sextant is ready, right?]
[That one just now was a sextant, right?]
The audience remembered the strange thing made of several thin wooden sticks that Bifang took out before he started to calculate, and immediately understood its purpose.
Bi Fang did not deny it.
These simple gadgets were not lost in previous adventures, which can be considered a blessing among misfortunes.
"This is the process of determining northern latitude. Although there is no corresponding South Pole star for southern latitude, we found that the center point of the Southern Cross constellation can approximately play the role of the South Pole star."
"Although such observations are not accurate enough, they are sufficient for navigation positioning."
Bi Fang pointed to the starlight in the night sky. After careful observation, everyone found that this star was indeed quite different from Polaris. Although it was also very bright, there was a lot of brightness around it.
Due to the existence of the North Star and the Southern Cross constellations, experienced navigators can easily determine their latitude with the help of suitable measuring instruments, but measuring longitude is much more difficult.
"Latitude is a series of parallel lines, while longitude is a series of lines that intersect at the poles."
"The earth rotates in the east-west direction. There is no east pole or west pole, so there is no east pole star or west pole star."
"However, the navigators still discovered a pattern. This pattern has nothing to do with the starry sky and everything to do with time."
"We clearly know the concept of time zones. For example, it is 2 a.m. Chinese time and 1 noon Eastern Time. If I know that the current Chinese time is 2 a.m. and the current local time is 1 noon,
So, can I deduce that the time zone I am in now is the Eastern Time Zone?"
"Then, I can know that the longitude where I am is the longitude of the eastern part of the country. Therefore, the problem of measuring longitude is transformed into the problem of measuring the time of the known position and the time of the current position."
[I can’t stand it anymore, my head hurts]
[Master Fang, don’t say it anymore, don’t say it anymore]
[Dream back to high school geography class]
[If you learn nothing, you will learn nothing]
Bi Fang followed up with a series of analyses, with the charcoal pen not stopping, both as an explanation and as if he was sorting out his own thoughts.
"The Earth's rotation period is 24 hours, that is, it rotates 360 degrees in 24 hours, 15 degrees every hour, and 1 degree every 4 minutes."
"If the departure port is used as a reference point, such as departing from London, Greenwich Time is used as the standard time, and the longitude of Greenwich is used as the 0-degree longitude."
"Later, at a certain position during the voyage, Greenwich time was 1 a.m., and the local time was 9 a.m., a difference of 8 hours. That is, the difference between this position and Greenwich was 8 times 15, which equals 120 degrees.
, that is, the current location is 120 degrees east longitude."
"But there is a crucial question here. How to determine Greenwich Mean Time and local time in the vast ocean?"
【Corona Bar】
【Clock?】
"It's a sundial."
The crew would get a sundial on the deck and use the direction of the sun's shadow to determine the time.
The ups and downs of the ship have a greater impact on the length of the shadow, but have little effect on the tilt direction.
Greenwich Mean Time is determined by clocks. When setting off from London, set the clock to Greenwich Mean Time and never adjust it again.
[Sounds like it’s a little simpler than Lao Fang’s calculation last time?]
[I don’t know, I don’t know any of them anyway, just listen and that’s it]
[I picked up a pen in class, and I never understood Fang Shen’s problem-solving ideas again]
Bi Fang shook his head again.
"It's easy to say, but it's more difficult to actually implement it. Because this method relies heavily on an accurate and reliable clock, otherwise, the effect will be greatly reduced. Although the ancient Greeks invented the longitude theory, it was restricted by
The craftsmanship of clocks and clocks made it impossible for navigators to accurately measure their own longitude until the 18th century.”
"Before this, there was even a law on maritime navigation. Soldiers who casually told the captain about the route would be executed immediately.
Because they could not determine their own route at that time, they relied entirely on the captain’s experience and intuition. They only knew their latitude but not their longitude until reliable clocks were invented later.”
[Hiss, it all depends on Meng, right?]
[Actually, navigation does not necessarily require accurate knowledge of one's longitude and latitude. Lao Fang has special needs. People at that time just had to keep their heads down and move forward as long as they were heading in the right direction. There were also surfaces along the way, such as islands and so on.]
[Indeed, there is nothing on the surface that Nemo points to, which is the most disturbing thing]
"For this reason, the commonly used method for a period of time was the lunar distance method, which calculates universal time by measuring the angular distance between the moon and the stars. In addition, there are the Davis quadrant, the star board and the sextant, which are all
The way to solve one’s own position at that time.”
"This is also why many famous watches today have nautical models. Due to the inconvenience of longitude measurement, navigators came up with an approximate measurement method, which is to look at distance, which is the so-called nautical mile..."
"Many people may wonder why sailing distances are not measured in kilometers or miles, which are common units, but nautical miles are used, as if to make things difficult for others. The sailing speed must also be measured in knots. In fact, this is all for the convenience of determining the position, because
The arc length of 1 nautical mile corresponds to 1 minute of the central angle of the Earth.”
【Hey, is that so? 】
[When I did similar math problems before, I felt that the things in the sea were anti-human. Why do we need to specially create a unit for distance and speed in navigation? Is this the reason?]
【I gained more knowledge.】
"Each nautical mile sailing in the north-south direction means that the latitude changes by 1 point; every 1 nautical mile sailing in the east-west direction on the equator means that the longitude changes by 1 point; if sailing in the east-west direction on the non-equator, it needs to be multiplied by the reciprocal of the latitude cos as a correction
coefficient."
"The speed unit "knot" also comes from this, 1 knot is equal to 1 nautical mile per hour."
"So, as long as we know the distance we are sailing..."
Bi Fang explained carefully, without stopping the movement of his hand, rubbing the black charcoal pen on the wooden board, leaving behind a dark charcoal ash.
The torch on the bow of the ship swayed in the wind, and the figures flickered.
Of course, the distance calculation cannot be accurate. In fact, the positioning accuracy in the sailing era is enough to be tens or hundreds of kilometers.
Coupled with the mixed use of several methods, mutual comparison and correction, although it is not as good as GPS, it is enough to allow Bi Fang to accurately reach his destination.
Although Point Nemo is a point, it does not mean that Bifang has to sail exactly through this point to be considered a successful crossing.
As long as you are in its vicinity, this mission can be considered a success.
It doesn't even matter where you go next, whether it's going back or moving forward to the next island.
Through various calculations and steps, a big mathematical problem seemed to be solved on the wooden board, and even small serial numbers were marked on it.
Each serial number represents a calculation method used by Bi Fang to find the location.
When three coordinates appeared, Bi Fang listed them, then confirmed each other, and finally breathed a sigh of relief.
He shook the wooden board in his hand in front of everyone, circled a coordinate, then threw down the charcoal, lay down in the Viking, looked up at the night sky, and sounded extremely sad.
"My luck finally got better."
"Point Nemo, right at our feet."
Nemo Point... right at your feet!?
The audience was stunned for a while.
Is this it?
Everyone who originally thought that there was still at least some distance to go never expected that the mission was actually completed like this?
Bi Fang put his arms under his head, feeling indescribably relaxed, and in an instant the world became wider.
The moment the longitude and latitude came out, the mission finally changed on the blue fluorescent system panel, showing a semi-completed status above Point Nemo.
At the moment when his body and mind were completely relaxed, Bifang's eyelids suddenly became extremely heavy, and he could not open his eyes for a while.
The audience in the live broadcast room undoubtedly fell into cheers again. The barrages appeared rapidly and swept across the entire screen. For a while, the actual picture could not be seen, but soon, some viewers heard some in the wind.
Other voices.
When the heat subsided a little, I could finally see clearly the countless people in the picture who were speechless.
Bi Fang actually fell asleep like this.
...
Putting aside how lively the Internet is, these are all Bi Fang's routine operations. When he woke up the next day, Bi Fang felt that his energy was more energetic than ever, and even the soreness in his muscles seemed to be relieved a lot.
.
It is only the seventeenth day since Bifang set off from Easter Island, and the speed can be said to be extremely fast.
Bi Fang did not relax his vigilance. Although the most critical part of the mission had been completed, there was still a typhoon chasing behind him. Now was not the time to stop.
During this period, Typhoon Harold also made landfall in Vanuatu as predicted, causing extremely serious disasters.
Although there are several relatively powerful storms in the South Pacific every summer during the tropical cyclone active season, it is relatively rare for a strong storm to hit a country at its strongest like this year. This may mean that the climate model in the Pacific is at a critical stage.
in an abnormal state.
Therefore, for the sake of safety, Bi Fang did not choose to return the same way as it would have been too dangerous to get close to the typhoon, so he chose to continue moving forward.
Among the three islands closest to Point Nemo, Desi Island and Easter Island are very close to each other, while Mahe Island is too close to the Antarctic.
"This star really wants to retire"
Going to Antarctica, although we were far away from the typhoon, the temperature would continue to drop, and Bifang did not bring enough warm clothing.
Therefore, after careful consideration, Bi Fang chose to head directly towards South America, which was further away but more convenient.
There were not many accidents during this period. On the 31st day, some fish finally appeared in the ocean, which alleviated Bifang's food crisis at that time.
On the thirty-fourth day, the first island appeared in front of Bi Fang, symbolizing the perfect ending of this crossing.
Looking at the island in front of him, Bi Fang gave up everything, no longer rowing, no longer controlling the sail, and felt passionate in his heart.
Bi Fang truly achieved something unprecedented!
The opening remarks are no longer just empty words, but everything he has experienced!
"Generation after generation of human beings, just like this, got into canoes, carrying fish hooks and lines, carrying bananas, cassava, coconuts and other fruits, taking their chickens, pigs and dogs, and carrying their boats made of obsidian
Tools, bid farewell to my homeland and sailed towards the vast sea without hesitation."
"Every time we discover a new island, we stop development temporarily. When the time is right, we use it as a base to embark on a new journey."
“We don’t know how many people were swallowed by the stormy waves, we don’t know how many people still failed to reach the other shore after exhausting the last food and water, we don’t know how many people were attacked and killed by ferocious sharks... But one thing is certain
Yes, mankind has never surrendered, and mankind has never stopped."
"This is the story of us, humanity. We should never be forgotten at any time or anywhere. Although we are fragile and small, we are still strong and great."