How humans measure distances between stars

It is understood that measuring the distance between celestial bodies in the universe is complex and generally employed:

First, the trigonometric parallax method. Trigonometric parallax is a method of determining distance using the disparity of different viewpoints to the same object.

Second, according to Hubble's law, the farther away from us a celestial body is, the faster it recedes, and the regression speed can be calculated based on the spectral redshift of the celestial body.

Of course, there are other methods, but they are too complicated for the average person to understand.

Also, it is said that this planet to that planet is calculated in light years. The light-year is a unit that measures the space-time distance between celestial bodies, and is generally used to measure the space-time distance between celestial bodies, which literally refers to the distance that light travels in a straight line in a vacuum for a year, about 9,460.5 billion kilometers, which is calculated from time and the speed of light.

"Year" is a unit of time, but "light year" is not a unit of time, but a unit in astronomy that measures the distance between time and space of celestial bodies. The distance between celestial bodies in the universe is very far, far away, if we use meters and kilometers (kilometers) that we use in our daily life as the unit of measurement, then the number of measuring the distance of celestial bodies is often more than a dozen or dozens of digits, which is very inconvenient. So astronomers created a unit of measurement, the light-year, which is the distance that light travels in a year in a vacuum.

Distance = speed time, the speed of light is about 300,000 kilometers per second (299,792,458 meters per second), and 1 light year is about 9 460 730 472 kilometers.

The details are as follows:

For example, the Earth observes the angle of a star to the Earth at the vernal and autumnal equinoxes, and then calculates its distance from the Earth from the Earth using the radius of its orbit as the baseline.

2.By measuring the closer stars, we can take the diameter of the Earth's orbit around the Sun as a baseline for a known distance.

The time it takes for the Earth to orbit the Sun is one year, and half a circle in half a year. In the two days that were half a year apart, the Earth was exactly at opposite ends of the diameter of the Earth's orbit. When the same star is observed in two days half a year apart, its direction is different, which is its parallax angle.

The distance of the star can be calculated from the parallax angle and the diameter of the Earth's orbit (300 million kilometers). With this method, only the distance of stars within two to three hundred light-years can be measured.

3.Stars farther away, because their parallax angles are too small to be measured, have to look for other methods. One of the famous methods is to use the circumferential relationship of Cepheids to calculate the distances of distant celestial bodies, which has earned Cepheids the nickname "Measuring Ruler".

For example, the Earth observes the angle of a star to the Earth at the vernal and autumnal equinoxes, and then calculates its distance from the Earth from the Earth using the radius of its orbit as the baseline.

4.Spectral redshift ranging method: The popular explanation for spectral redshift is the great cosmological theory.

Hubble pointed out that the redshift of celestial bodies is related to distance: z = h*d c, which is the famous Hubble's law, where z is the redshift; c is the speed of light; d is the distance; h is the Hubble constant, and its value is 50 80 kilometers (seconds·megaseconds).

According to this law, the distance d of the galaxy can be calculated as long as the redshift z of the extragalactic lineage is measured. Distances up to 10 billion light-years can be determined using the redshift method.