As we all know, the Earth is a huge magnet with north and south poles (the north and south poles of the earth are opposite to the magnetic north and south poles), so when the south pole of the magnet in the compass points in a fixed direction, that direction is specified as south. And the same is true for other directions. There is no compass in the universe, so there is no rule that there is east, west, north and south, only up and down, left and right. All positions in the universe are relative, and only by finding a reference object can we determine the direction. Astronauts have a wealth of astronomical knowledge, and they rely on constellations to determine directions, and they are not the only ones who can see constellations on Earth.

In general, the forms of judging directions in the universe are:

1. At great distances, it is very likely that one of these three stars will be obscured by other celestial bodies.

2. Because the massive celestial bodies in the universe will cause light distortions, and the light rays that have traveled long distances will inevitably be distorted, then observers in the distance will not be able to get their true position.

3. The Milky Way is also rotating, and the positions of these three stars are inevitably changing, just like if you rotate the coordinate axis, the near coordinates may change very little, but the changes in the distant coordinates are very large, and even become unusable coordinates, which must be re-measured.

4. If we fly to Planet X 125 million light-years away in a spaceship that can jump, first of all, we will find that we are not located on Planet X, it may be empty space, and it may even crash into other planets. Why? Because we get the information that X was relative to the position of the three stars 125 million years ago. Also, draw a circle on the paper (representing the Milky Way) and make an arrow (representing the coordinates of the 3 stars), the Milky Way rotates once in 250 million years, so when we fly 1.25 light-years away, the 3 stars we see are 125 million light-years ago, just out of position from the actual position! The corresponding coordinates are also completely reversed, and we will think that we have jumped in the opposite direction. I even thought it was a space warp (which was actually just a matter of light). From the above, we can see what a limiting way of three-star positioning! As long as human beings are still using the speed of light to measure position, it is inevitable that they will encounter the problem of the storage time of the coordinate system (such as 3 stars), and the problem of the upper limit of the coordinate value will appear. For example, the upper limit of coordinates in the positioning of 3 stars is 5 billion light years, which is the time of existence of 3 stars. The problem of "lead time" (the measurement position does not match the actual position) is also encountered. A few years later, perhaps humans will be able to discover the true instant mode of transmission, but until then> we can try to use the "long-lived" reference as the coordinate center to expand the scope of this coordinate system as much as possible (the longer the time, the greater the scope of the coordinate system). For example, the Milky Way (which is said to be 13.6 billion years old and has a lifespan of 15 billion years). This coordinate system has a much longer lifespan than a 3-star star, and the position changes between the Milky Way and other galaxies are correspondingly smaller. In addition, the recently estimated age of the universe is about 13 billion ~ 14 billion years, that is, the Milky Way was formed at the beginning of the birth of the universe, so if we use the Milky Way as the coordinates, we can see the Milky Way even if we reach the edge of the universe, provided that we can know what the Milky Way looked like 13 billion years ago...... However, this problem can also be solved, we can jump many times, 1 billion light years, 2 billion light years...... At 13 billion light years, the Milky Way 13 billion years ago can be gradually identified in this way, that is, the juvenile Milky Way can be found and located 13 billion light years away.

The same way you can establish the axes, so that there will be a concept of coordinates.

1. Origin - Take the center of rotation of the Milky Way as the origin

2. Z-axis - the Z-axis is perpendicular to the galactic surface, and the galactic surface rotates clockwise from the positive direction of the Z-axis.

3. X-axis - the projection of the galaxy closest to the Milky Way on the galactic plane is the positive direction of the X-axis.

4. Y-axis - from the X-axis to the Y-axis.

PS: This rule can also be applied to the solar system.

Suppose we have one of the spiral arms of the Milky Way as the positive X-axis. When a spaceship jumps along the X-axis, if the jump distance is not the Milky Way rotation period (250 million years), the people on the spacecraft will find that they are not actually jumping in the X-axis direction, but to an inexplicable position. Especially if the jump is exactly 125 million light-years, you will find yourself jumping in the opposite direction of the Milky Way. Quite simply, because the Milky Way was observed 125 million light-years ago, the Milky Way was actually rotated exactly 180 degrees, and it looked like the spacecraft had jumped in the wrong place. Actually, it's just that the galaxy has turned around. The advantage of using the nearest galaxy in the Milky Way as the positive direction of the X-axis is that you don't have to worry about the ship's "direction" not matching its destination (at least it doesn't seem to match) during multiple jumps. And the most important thing is that you are standing outside the "merry-go-round" of the Milky Way and looking at the Milky Way, rather than sitting on the "merry-go-round" and making your own spinning world. If you use the spiral arm as the X-axis, you will find that you will be faced with very complex calculations, and the most basic concepts will confuse your mind. Of course, usually these troubles will be solved by the computer, but if unfortunately your computer has a small accident...... You still won't be "lost", at the very least, you can jump to the nearest Smart Planet, but the problem is that multiple corrections along the way may make you run out of energy before you fly to the Smart Planet, and that's the real trouble. Now it seems that a relatively complete set of cosmic positioning coordinate system has been completed, but some details still need to be paid attention to. The Sun is moving at a speed of 240 km/s on the "merry-go-round" of the Milky Way. The diameter of the solar system (with Pluto's orbit as the boundary) is 40 astronomical units (about 6 billion kilometers), and it takes about 289 days for the solar system to move a distance equal to its own diameter. However, for objects in high velocity, the "time loss" is also relatively slow, and it feels like it took a year to travel through time and space, which may have been a long time in reality...... So when you come back, you'll find that the solar system has "moved". It takes about five and a half hours to travel 6 billion kilometers at the speed of light, and if the solar system "moves" too far, you may have to spend more than a dozen hours to "travel". Fortunately, this is all time calculated at normal speed, and you flying at the speed of light may feel that it only took more than ten minutes, so people in the future should not have to stay on the train for so long like we did during the Spring Festival. At the very least, it feels less painful......

The center of the coordinate system, the "origin", is the spacecraft itself.

The coordinate system is divided into 6 sectors according to the front, back, left, right, above and below of the spacecraft, and each region is a regular quadrangular pyramid (i.e., pyramidal) with the origin as the fixed point.

The direction of the spacecraft is facing the center of the square underside of the quadrangular pyramid in the area directly ahead.

The individual areas are distinguished by color.

Front area----- SectorGreen (green)

Rear area----- SectorBlue (blue)

Directly above the area----- SectorIndigo (indigo)

Directly below the area----- SectorRed (red)

Sector Yellow (yellow) in the area on the left-----

Right Sector----- Orange

4 divisions of 6 areas

The bottom surface of the square of each region quadrangular pyramid is divided into 4 squares of the same size. With these small squares as the bottom surface and the origin as the vertex, each of them makes a small quadrangular pyramid, and divides the regular quadrangular pyramid into four small quadrangular pyramid-like cells.

The four cells are named A, B, C, and D clockwise from the small quadrangular pyramid in the upper left corner.

In general, in order to facilitate auditory identification, the following words are used instead of the said area.

A－－－－－－－－－－－－－－－－－－－－Alpha

B－－－－－－－－－－－－－－－－－－－－Bravo

C－－－－－－－－－－－－－－－－－－－－Charley

D－－－－－－－－－－－－－－－－－－－－Delta

Quadrangular pyramid square center --- ZeroSector

Similarly, pulsars can also be used as objective anchors in the universe.

German scientists point out that X-rays emitted by three pulsars in the universe can be used for precise interstellar navigation.

Three German space scientists have found a way to use pulsars to navigate the solar system. As they point out in a paper uploaded to the preprint library arXiv, the method relies on at least three pulsars to accomplish triangulation positioning.

The current method of navigating a spacecraft is that the spacecraft sends a radio signal back to Earth, and then scientists calculate the distance based on the time when the signal arrives for positioning, but this method cannot derive the angular position of the spacecraft. Although this is not a big problem at present, in the future, with the increase of space vehicles, the requirements for space navigation accuracy will inevitably increase. This new method, proposed by German scientists, will allow the spacecraft to get rid of dependence on the Earth and navigate autonomously in space.

Pulsars are a type of neutron star that rotates very fast. Because they are constantly rotating, the electromagnetic radiation emitted by the poles sweeps across the earth like a searchlight on a lighthouse, which is where the name pulsars come from. Scientists have wanted to use them as navigation tools for years, but the instruments that can read and interpret pulsar signals are too bulky to be placed on space vehicles. On the other hand, a deeper understanding of pulsars is needed. German scientists say that important advances have been made in both fields of knowledge enough to build a pulsar navigator that can be placed on space vehicles.

Both the radio radiation and X-ray radiation emitted by pulsars are very useful, and the accuracy of the periods of both signals is so high that it is comparable to that of an atomic clock. Scientists say that if the space vehicle used pulsar radiation with a wavelength of 21 centimeters, then the receiving area of the antenna would reach 150 square meters! It's still too big for practical applications. For this reason, they built to use the X-ray signals emitted by pulsars for navigation. In this way, the weight of installing an instrument for listening and deciphering pulsar signals on the aircraft is only 25 kilograms, which has reached a very practical level.

Explanation of the term: pulsar

Pulsar, also known as Pulsar, is a type of neutron star, which is a star that periodically emits pulsed signals, mostly about 20 kilometers in diameter, and rotates extremely fast.

It was first thought that stars were forever immutable. And most stars change so long that people don't even notice it. However, not all stars are so calm. Later, it was discovered that some stars are also "naughty" and changeable. Therefore, those stars that like to change were given special names, called "variable stars". The periodicity of the radio pulses emitted by pulsars is very regular. At first, people were confused about it, and even thought that it might be aliens sending us telegrams. It is said that the first pulsar was once called "Little Green Man One".

After a year of hard work by several astronomers, it was finally confirmed that pulsars are neutron stars that are rotating rapidly. Moreover, it is precisely because of its fast rotation that radio pulses are emitted.

Just as the Earth has a magnetic field, stars also have a magnetic field; Just as the earth rotates, so do the stars; Just like Earth, the direction of the magnetic field of a star is not necessarily in the same straight line as the axis of rotation. In this way, every time a star rotates once, its magnetic field will draw a circle in space and possibly sweep past the Earth once.

Wouldn't all stars be able to pulse? In fact, in order to emit a radio signal like a pulsar, a strong magnetic field is required. And only the smaller and more massive the star, the stronger its magnetic field. Neutron stars are such high-density stars.

On the other hand, when a star is larger and more massive, its rotation period will be longer. We are familiar with the fact that the Earth rotates 24 hours a week. And the rotation period of pulsars is as small as 0.0014 seconds! To reach this speed, not even a white dwarf. This also shows that only neutron stars that rotate at high speed can play the role of pulsars.

Significance of pulsar research

Since pulsars are found in the remains of a shrinking supernovae, they help us understand what happens when a star shrinks. The study of them can also reveal the mysteries of the birth and evolution of the universe. And, over time, the way pulsars behave can change in a variety of ways.

The period of each pulsar is not constant. What we can detect is the rotational energy of a neutron star (the source of electromagnetic radiation). Whenever a pulsar emits electromagnetic radiation, it loses some of its rotational energy and its rotational speed decreases. By measuring their rotational cycles month after month, year after year, we can accurately infer how much their rotational speed has decreased, how much energy they have lost in the process of evolution, and even how long they will survive before they are too low to emit light.

It also turns out that every pulsar is different. Some are extremely bright; Some will have a starquake, which will increase the rotational speed sharply in an instant; Some have companion stars in binary orbits; There are also dozens of pulsars that spin at extremely fast speeds (up to a thousand times per second). Each new discovery brings with it something new and curious, and scientists can use it to help us understand the universe