How many stars have been discovered by scientists so far?

6973 are visible to the naked eye.

There are two main factors that determine whether people observe the stars as light or dark:

One is due to the size of the star's ability to emit light, and the other is the distance between the star and people.

Astronomers usually divide the ability of stars to shine into 25 magnitudes, with the strongest ones being about 10 billion times different from the worst ones.

The brightness of a star is often expressed in terms of magnitude. The brighter the star, the smaller the magnitude. The magnitude measured on Earth is called the apparent magnitude; A magnitude that is attributed to a distance of 10 parsecs from the Earth is called an absolute magnitude.

The magnitude of the same star measured by detection elements that are sensitive to different wavelength bands is generally not equal. One of the most versatile magnitude systems is the U (ultraviolet), B (blue), and V (yellow) trichromatic systems (see Photometric Systems'"class=link> metering system); b and v are close to photographic and visual magnitudes, respectively. The difference between the two is the commonly used color index.

The Sun is of v=equal, the absolute visual magnitude is m=+, the chromatic index is b-v=, u-b=. The color temperature can be determined by the color index.

A star that is close to people has a strong ability to emit light, so people will light up when they see it. However, even if a star is quite capable of emitting light, if it is very far away, then its brightness may not be as bright as that of a star that is tens of thousands of times less capable of emitting light.

Suppose there is a star called Antares that is about 100 million times the size of the Sun and is about 50,000 times more luminous than the Sun, but because it is 410 light-years away from the Earth, one can only see it as a bright star with a red glow. If Antares were to be moved to the position of the sun, the light and heat it emitted would bake the earth into a large stone ball where everything had disappeared.

At present, scientists have discovered more than a billion stars!

How many stars are there in the universe?

There are about 125 billion leaks in the galaxy that have been discovered and observed, and each galaxy has hundreds to trillions of stars like the Sun. Our galaxy is home to about 40 billion planets. So just do a simple math problem and you'll learn that there are many, many stars in the universe we've observed.

The total number of planets in the universe is about 1 trillion (1 followed by 20 zeros).

Zhang Heng, a famous astronomer in the Eastern Han Dynasty, is known as a scientist who counted stars.

Zhang Heng was a great astronomer, mathematician, inventor, geographer, and writer in the Eastern Han Dynasty of China. In his later years, he entered the court as Shangshu due to illness, and died in the fourth year of Yonghe (139) at the age of sixty-two. During the Northern Song Dynasty, he was posthumously named Western Obo.

Zhang Heng's family has been a local surname for generations. His grandfather, Zhang Kan, was known as the Holy Child since he was a child, and once gave millions of his family heirloom to his nephew. After Emperor Guangwu Liu Xiu ascended the throne, Zhang Kan was appointed as the Taishou of Shu County, and made great contributions to the great Sima Wu Han in his crusade against Gongsun Shu, who had seized Yizhou.

During the reign of Emperor Yongyuan of the Han Dynasty (89-105), Zhang Heng was promoted as filial piety, but he did not accept it, and the government did not recruit him several times. At that time, the country was peaceful for a long time, and from the prince down, there was no one who was not extravagant. Zhang Heng then imitated Ban Gu's "Liangdu Fu" and thought hard for ten years before he wrote "Erjing Fu" to satirize the imperial court.

The general Deng Qiu admired Zhang Heng's talent and recruited him many times, but Zhang Heng did not accept his order.

In 100 A.D. (the twelfth year of Yongyuan), Zhang Heng was invited by Nanyang Taishou Baode to be his master bookkeeper and in charge of clerical work. Eight years later, Bao De was transferred to Beijing, and Zhang Heng resigned and stayed at home.

The child who counts the stars - Zhang Heng, a famous astronomer in the Eastern Han Dynasty.

At night, the sky is full of stars shining like pearls. A child sits in the yard, leaning on his grandmother, raising his head and counting the stars into the night sky. One, two, all the way up to hundreds.

Grandma smiled and said, "Silly boy, I'm counting the stars again." There are so many stars, twinkling and moving, and your eyes are dazzling, can you count them? ”

The child said, "Grandma, I can count them." The stars are moving, not moving. You see, this star and that star, always so far away. ”

Grandpa came over and said, "Son, you look very carefully. The stars in the sky are moving, but the distance between them is constant. Our ancestors divided them into groups and gave them back.

They have names. Grandpa paused, pointed to the northern sky, and said, "Look, those seven stars are connected like a spoon, and they are called the Big Dipper." The bright star facing the mouth of the spoon is the North Star. The Big Dipper always revolves around the North Star. ”

Is what Grandpa said true? The child didn't sleep well all night and got up several times to look at the stars. He could see clearly, and the Big Dipper was indeed slowly rotating around the North Star.

This child who counts stars is called Zhang Heng, and he is from the Eastern Han Dynasty. He grew up studying astronomy and became a famous astronomer.

The Earth is no longer the only one? Scientists have discovered 24 planets, which are more suitable for human habitation.

There are no clear figures.

The universe is so big, there are so many planets, it can be described as innumerable.

The Sun is only one of about 300 billion stars in the Milky Way. Astronomers believe that the Milky Way galaxy has about 93 stars with planetary systems, or 280 billion stars. According to conservative estimates, there must be at least 100 billion planets.

There are more than 100 million places in the galaxy that could support complex life. Scientists have investigated more than 1,000 planets and used formulas that take into account planet density, temperature, substrate (liquid, solid, or gas), chemical processes, distance from stars, and age. Using this information, they calculated and came up with the Biological Complexity Index (BCI).

BCI calculations suggest that 1%-2% of planets have a BCI level higher than Jupiter's moon Europa, which is said to have an underground global ocean, or may support the existence of life forms. Considering that there are about 10 billion stars within the Milky Way, the BCI results imply 100 million possible habitable planets.