How many stars can you see with the naked eye?

How many stars can ordinary people see with the naked eye? Let's count together. Don't think that this is an impossible task, as long as the method is proper, it can still be counted. The ancient Greek astronomer Alba Gu divided the stars into different grades according to their brightness. The very bright star is rated as 1, the second star is rated as 2, and the star that is almost invisible to the naked eye is rated as 6, and the darker star is invisible to the human eye alone.

In this way, we only need to record how many stars there are in each magnitude, so we can know how many stars can be seen by the naked eye. Astronomers have completed this work: 1 magnitude 20, 2-magnitude 46, 3-star 134, 4-star 458, 5-star 1476, 6-star 4840, 1 magnitude 6974 * *.

These nearly 7000 stars are all the stars visible to the naked eye on the whole celestial sphere. However, when we look at it from the ground, only about half of the stars are on the horizon and the other half are under the ground. Near the horizon, the starlight is even weaker because it passes through the dense atmosphere, so it is difficult to see the stars at low altitude near the horizon. In this way, only about 3000 stars "survived".

In actual observation, due to the influence of many observation conditions such as moonlight interference, poor atmospheric transparency and personal vision difference, the number of stars that people generally see is even less than 3,000. The ancient Greek astronomer Ibagu is said to have excellent eyesight, and the number of stars in his catalog based on observations is only 1000. So when we see the stars in the sky, count them carefully, and there are not as many as we think.

What? You've only seen a dozen stars at night. No wonder the city is developing rapidly now, the night sky is affected by lights, and the background brightness is gradually improving. In today's big cities, stars darker than level 3 are submerged in the bright night sky background. If you remove the stars that sink below the horizon, you can only see twenty or thirty stars even if the weather is fine.

Why are there 88 constellations in the sky?

The clear night sky is full of stars. After long-term observation, ancient humans found that the pattern of stars was constant, and only a few bright stars (planets) wandered among stars. In order to distinguish and address these stars, people grouped them and gave them special names. Different nationalities have different combinations and different names. Modern international constellation division can be traced back to Babylon. Babylon had the earliest constellation name as early as 5000 years ago. In 13 century BC, there were 12 constellations on the ecliptic, which were called "Zodiac", meaning 12 in the solar year. Later, it gradually expanded and named more constellations. In the 2nd century AD, Ptolemy, an ancient Greek astronomer, compiled a table containing 48 constellations on the basis of summarizing previous knowledge. 16/kloc-the great discovery of European geography in the 0/7th century, and some southern constellations were added. At this time, the concept of constellation is only a combination of some bright stars visible to the naked eye, and there is no clear boundary between constellation and constellation. With the development of astronomical telescope technology, more and more dark stars have been discovered and deeply studied, but it is difficult to know which constellation they belong to and how to label and address them.

1928, in order to meet the needs of astronomical research, the General Assembly of the International Astronomical Union held in Leiden, the Netherlands, clearly divided the whole sky into 88 constellation areas, divided along the right latitude and right longitude of the celestial equator coordinate system, kept the traditional constellation names, specified their scientific names in Latin, and clearly formed their abbreviation symbols with three capital letters, which were used uniformly all over the world. Later, the Chinese Astronomical Society confirmed the Chinese translation of the constellation and became the official academic name.

Other civilizations also have their own methods of dividing and naming stars. For example, the starry sky in ancient China was divided into three walls, four images and twenty-eight nights, which played a great role in history and culture, and was similar to the popular constellations in the west in function.