How do scientists determine the distance and weight of celestial objects?

Calculate the speed of light of the laser and then find the time it takes for it to reflect back from the Moon.

Trigonometric parallax is the basis of all celestial distance measurements, and more than 10,000 stars have been measured in this method to date. We know that in astrophysics, the mass of an object is a very important indicator that determines a lot of data about an object. Therefore, scientists have been concerned about how to calculate the mass of these objects.

For different stars, scientists have found different methods.

It is estimated that half of the stars in the universe are binary star systems. This is definitely good news for scientists. Just as we calculate the distance between the planets of the solar system and the sun, we can use Kepler's third law to do so.

Kepler's third law, which states that the square of a planet's orbit around the Sun is proportional to the cube of its orbital radius, also applies to stars outside our solar system.

In this case, the distance between the two, the period of time around the center of mass, the gravitational constant, which means that if you know the distance between the two, you can find the sum of the masses. And then based on the ratio of the distance between the two stars and the center of mass or the Doppler effect or something like that (there are many ways to do that anyway), you can calculate their respective masses. So the only thing that is unknown now is the distance between them.

It's not that hard. If two stars are far apart and telescopes can distinguish them, then the data is readily available. If the distance is relatively close, you need to use spectroscopy and other methods to calculate, although it is a bit complicated, but you can also get data.

Of course, half of the stars in the universe are not binary stars, so how do you calculate their mass?

<> through continuous research, scientists have discovered that the delayed mass of a star is directly related to its luminosity, a law known as the mass-light relationship of stars. Using the relationship between luminosity and silver tremor mass, we can calculate its mass. Of course, it is important to note that this method works for ordinary main-sequence stars, but not for red giants or variable stars.

This doesn't matter anymore, because almost 90% of stars can calculate their mass in this way.

The principle of calculating these stellar parameters is the same as that of finding ascending exoplanets, that is, if the distance makes it impossible to measure directly, find other reference objects to assist in the measurement. The best reference is the binary star system. Generally, the noise fluid adopts a variety of noise measurement or quantity and calculation methods such as triangular parallax ranging, angular diameter distance, brightness distance, light travel distance, lateral movement distance, etc.

It must be calculated by scientific means, and the main method is to estimate the mass of celestial bodies by using the laws of gravitation and Newton's laws of motion, to estimate the mass of celestial bodies by using the radius of the celestial body's true reed head and the acceleration of surface gravity, and to estimate the mass of celestial bodies by Kepler's third law of difference.

Newton's formula for gravity f=gmm r 2, where f is the gravitational force, g is the gravitational constant, m and m are the masses of the two objects, and r is the distance between the two objects.

At present, it is common to use the doping effect to measure and then use Hubble's law to calculate the distance. In the past, most of the parallax was used. For example, the "Earth's radius" is used to check the position of the stars at the South and North Poles.

Of course, it doesn't have to be at the North Pole and the South Pole, as long as the two points are connected by the geocentric, and then the distance is calculated by geometric relations. After calculating the stars close to the Earth, we can use one star as a reference and measure the other stars in combination with the radius of the Earth's orbit. These geometric processes are relatively complex, but absolutely doable.

I saw it at the time, but forgot now. Cepheids are a type of star whose brightness changes periodically. American astronomers have discovered the change in the diameter of a Cepheid variable by looking at the side, and can directly calculate its distance from the Earth.

This will help to more precisely measure the distance between each galaxy and the Earth, thus "calibrating" the expansion rate. Cepheid variables have been observed to expand and contract like a "deep breath", producing changes in light. Cepheids' photoperiods are related to their true brightness, so the brightness observed from Earth is related to their distance from Earth.

Parallax method, parallax method is a method of calculating the distance between a planet and the Earth invented by the German astronomer Bessel. His principle is that when the human eye observes a planet about 100 light-years from Earth, the planet will move a certain distance for a planet farther away.

The distance between the Earth and the Sun is an astronomical unit.

When calculating the distance of a certain celestial body to the Sun, the distance between them is very far, much farther than the distance from the Earth to the Sun. So it can be approximated that the distance d is approximately equal to the distance from the Earth to this celestial body. In the figure, when the angle p is the arc second of a triangle, it is a unit of measurement for length in astronomy.

Measuring distances using the parallax method requires a combination of telescopes that can only be accurate when measuring the distance between a planet and Earth within 50 light-years. Knowing the distance between the two stars to the Earth and the angle between them, we can calculate the distance between the two stars. With the increasing number of astronomy enthusiasts, astronomy and geography are no longer a topic of conversation for a few people.

If you are careful enough, you will surely find that when the star being described is not Earth, there is usually a uniform parameter, which is the distance of the star from the Earth. However, this unit of distance is not the kilometer that people often use, but the distance that a beam of light travels on the Earth in a year, i.e., a light year.

Scientists calculate the distance of celestial bodies from the Earth using trigonometric functions and visual gaps. There must be some errors in this, but not by much.

Trigonometric parallax is the most commonly used method of ranging by scientists. Scientists have calculated the results through a large number of actual observation data, combined with relevant theories, although there may be a certain error due to the limitation of the observation level, but on the whole, the data given by scientists is quite reliable. There is an error.

At present, it is generally measured by the doping effect, and then the distance is calculated using Hubble's law.

In the past, most of the parallax used, for example, using the radius of the earth to see the position of the star at the south pole and the position of the star at the north pole, of course, it does not have to be at the north and south poles, as long as the two points are connected by the center of the earth, and then the distance is calculated with geometric relations, after calculating the stars close to the earth, we can use one star as a reference, combined with the radius of the earth's orbit to measure other stars, these geometric processes are relatively complex, but absolutely feasible. I saw it at the time, but now I forgot.

Knowing the distance between the two stars and the Earth and the angle between them, we can calculate the distance between the two stars. With the growing community of astronomy enthusiasts, astronomy and geography are no longer a topic of conversation for a very small number of people. If you are careful enough, you will surely find that when the star being described is not the Earth, a uniform parameter usually appears, which is the distance between the star and the Earth.

However, this unit of distance is not the kilometer that people often use, but the distance traveled by a beam of light in a year on Earth, that is, a light year.

I'm sure no one would think that a light-year is a unit of time. After all, it's 2020, so, do you guys have any questions about how scientists calculate the distance between these stars and the Earth, they are usually billions of light years, I think this distance is very far, are these calculations reliable? We can concretely perceive the answer to this question by the conversion between light years and kilometers, the distance of one light year is actually about 9 7 trillion kilometers, about 6 trillion miles.

Unlike the difficulties we usually encounter when driving at the same speed on the road, light-years have a very high accuracy and can maintain a constant speed in any space of the universe. In a vacuum, light can travel at a speed of 1079252849 kilometers per hour. The distance of a light-year is actually equal to the speed multiplied by the number of hours in a year on Earth.

Conversion: 1079252849 8766 9 5 trillion kilometers or so, or 5878625370000 miles.

A laser ranging method for a planet as close as the moon could accomplish this task. For example, the distances of some planets in the solar system can be calculated according to Kepler's law, and the trigonometric parallax method can be calculated very accurately. Stars that are slightly closer to the Sun can also be calculated using the trigonometric parallax method.

This method can calculate the distance between a planet and the Earth within a few hundred light-years of the Earth, but as the distance increases, the accuracy of the measurement decreases significantly. For more distant objects, scientists have also measured some galaxies according to the circumferential relationship of Cepheid variables, and the distance of star clusters from the Earth, the Andromeda galaxy is the method used to determine the distance. A galaxy a little further away is used in Hubble, where scientists have observed that the galaxy is moving away from us, and this distance causes it to propagate light to Earth.

The red-end shifts that become more and more like spectral lines and the wavelength becomes longer and longer, which is called redshift. Scientists can measure how far away a distant galaxy is from Earth by measuring the redshift of light.

Electromagnetic waves can be emitted by radar, and then calculated based on the time it takes for the electromagnetic waves to come into contact with celestial bodies and reflect back.

Cepheids are a class of high-luminosity periodic pulsating variables, whose brightness changes periodically with time, and the distance of celestial bodies can be determined according to the circumferential light relationship of Cepheids.