What is a sextant? Detailed answer

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What is a sextant? Detailed answer

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What is a sextant?

When traveling the earth, you will not get lost if you know where the road you are walking leads to. Yes, and traveling by ship, if you can see the coast, you can easily determine your location, recognizing the hills, rivers, mountains, forests, beaches, and so on. In ancient times, sailors preferred to stay about three or four kilometers from the shore, so that they could always see the land. People who ventured into the open ocean were at great risk because they did not have a reliable way to determine their location. Later, such a method was found, and the sailors were able to determine where they were, learning the latitude and longitude of this place.

Latitude tells you how far north or south of the equator a place is.

Longitude indicates how far east or west it is of an imaginary line through Greenwich. These readings are measured in degrees. To determine latitude and longitude at sea, the navigator looks at the positions of the stars and the sun. During the day, he learns the latitude by determining how high the Sun rises at noon. At night, he does this by determining the height of the night luminaries. Longitude is determined by comparing the time on board with the time in Greenwich, England. If the time on the ship is earlier, this means that you are west of Greenwich; if later - means, to the east. Each hour of time difference equals fifteen degrees west or east.

A sextant is an instrument used by a navigator to determine the position of the sun, moon, planets, and some stars. The sextant is shaped like a piece of a round pie, with a graduated scale on its rounded part. One end of the pointer is attached to the top of the sextant, just like a movable mirror. The other end points to the scale. Also attached to the sextant is a telescope and mirror glass in front of it. The navigator looks at the horizon through a telescope and this mirror and moves the mirror until the reflection of the observed star hits it, as if touching the horizon. The free end of the arrow will indicate on the scale the height of the observed luminary.

Author: Likum A.

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Optimists are not afraid of a heart attack 21.07.2013

Cheerful people are much less likely to suffer a heart attack and die less often from sudden heart failure, according to a new study by scientists at Johns Hopkins University (USA).

Previous studies have already shown that depression and anxiety can trigger a heart attack. But researchers at Hopkins University have confirmed that it is important to stay healthy not just not to become discouraged, but to be cheerful and energetic. The happier a person is, the happier he feels, the lower the likelihood of developing coronary heart disease.

According to scientists, optimists are more likely to live a long and happy life. The feeling of happiness, good mood and cheerfulness have a positive effect on the state of our body and allow us to stay healthy longer. At the same time, scientists warn that this is more likely not about an artificial attempt to force oneself to look at the world positively, but about innate cheerfulness. That is, if a person is lucky to be born an optimist, then his health is at less risk. If a person, on the contrary, is a pessimist, he will not be able to improve his health even with the best mood.

So far, researchers have no explanation for the mechanism that allows optimists to stay healthy for longer. However, statistics show that the risk of heart attack in cheerful people is still less.

Scientists analyzed data on patients with cases of coronary heart disease in the family. The study was carried out for 25 years. All this time, 1483 people were observed by doctors, whose brothers or sisters under the age of 60 suffered a heart attack (as a rule, such people are at risk for developing heart diseases, in particular coronary heart disease).

Especially for this study, patients filled out a questionnaire describing their mood, the presence or absence of anxiety, the level of life satisfaction, etc. During the 25-year follow-up, 208 cases of coronary heart disease occurred in patients - heart attacks, sudden death, acute coronary syndrome. In addition, some patients needed stenting and bypass surgery.

The researchers found that in the group of optimistic participants, heart disease occurred a third less often. And among those optimists who were at high risk for developing cardiovascular disease, the decline was about 50%.

To test their findings, the researchers looked at other people's data. They looked at the medical records of 5992 people. The history of the 16-year follow-up suggests that in this case, too, optimists were much less likely (13%) to suffer from coronary heart disease.

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