How do scientists know the diameters and volumes of other planets, and what can be used to measure the size of the universe?

- -! I'm speechless. No one knows the true method of measuring stars and planets that are N light-years away. They are all just trying to make up the numbers!

Let me talk about it briefly. The first thing to measure is the star, and the measurement of the star is based on the infrared rays radiating from its surface, because any object in the universe will radiate infrared microwaves. , and infrared rays have the longest wavelength and are least likely to be blocked by objects, so as long as different types of infrared microwaves are detected, stars can be detected.

The distance to detect stars is determined by the red shift of the rays.

First of all, let me tell you some common sense about rays.

Everyone should know that rays are divided into three categories, namely infrared rays with the longest wavelength, and visible light visible to the human eye, that is, ultraviolet rays with the shortest wavelength.

The method of judging red shift is based on the speed of an object itself and the shift of the spectral position of the rays it radiates, to judge whether the object is moving away from us or approaching us, and based on the change of the spectrum frequency to determine its distance from us.

This is the famous Doppler effect. Through this detection and calculation, the position, direction and speed of a star can be determined.

After measuring the star, if you want to measure whether it has planets, you have to go through a series of elimination methods, detection methods, and probability calculations to barely determine whether there are planets. As for wanting to know There are a few, and the current technology may not have reached such a level of detection.

I can also briefly talk about the role of the elimination method in planet detection. For example, if it is a double star or a multiple star, the probability of having a planet is almost zero, because in double stars and multiple stars Under the influence of gravity, planets have no chance to form. There are also blue and red supergiants without planets, because the light and heat released by the blue supergiant are enough to vaporize almost everything in the universe within its gravitational range, so it is impossible for planetary bodies to appear. A supergiant star is the opposite. It is a star similar to the sun that has entered the aging stage and has changed from hydrogen fusion to helium fusion. Therefore, it expands rapidly, causing everything within its gravitational range to suffer a devastating blow!