What s in the stars in the sky Please, 3Q

6,973 stars visible to the naked eye There are two main factors that determine whether people observe 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. Wish.

Stars are made of substance, and I didn't learn that, but I know it.

It is a celestial body in the universe that is visible to the naked eye. Celestial bodies look like stars because they are so far away from the Earth, and the reflection of sunlight makes them look shiny. Stars can be broadly divided into planets, stars, comets, white dwarfs, etc.

The Earth is also a celestial body in the universe. The Earth is the third planet in the solar system from the inside to the outside, the largest terrestrial planet in the solar system in terms of diameter, mass and density, and the only celestial body in the universe known to humans to have life, about 100 million kilometers away from the sun.

People always say that the stars in the sky are innumerable, but in fact, all the stars that can be seen with the naked eye can still be counted. Astronomers divide the stars in the sky into 88 constellations according to their regions. Among them, the northern sky (bounded by the celestial equator) has 29 constellations; There are 46 constellations in the southern sky and 13 constellations in the north and south of the celestial equator.

As long as we have the heart to destroy it, we can count the stars in a constellation, and then count the next constellation, we can count the stars that can be seen with the naked eye. According to the calculations of astronomers: 6 stars of magnitude 0; 14 stars of 1st magnitude; 46 stars of 2nd magnitude; 134 stars of 3rd magnitude; 458 stars of 4th magnitude; 1476 stars of 5th magnitude; 4,840 ...... of 6th magnitudeNo more than 7,000 in total.

If we use a telescope, the situation is different, and even with a small astronomical telescope, more than 50,000 stars can be seen. The largest modern astronomical telescope can see more than 1 billion stars. In fact, the number of stars in the sky is much more than that.

The universe is endless, and what modern astronomers see is nothing more than a tiny, tiny part of the universe. Sleepy guess.

Don't ask me how many stars there are, I'll tell you many, many

How many stars are there in the sky? Nature: 30000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000

How many stars are there in the sky? The 1st issue of the journal Nature gives the answer: about 3 followed by 23 zeros.

For those who like to look up at the stars, counting the stars will be a lot of work. Peter Van Dowquin, an astronomer at Yale University in the United States, and Charlie Conroy, an astrophysicist at Harvard University, analyzed the intensity of light from galaxies and concluded that the number of red dwarfs in galaxies was far greater than previously thought. Previously, astronomers estimated that the number of stars in galaxies was about a trillion times that of 100 billion.

This theory is based on the work of Carl Sagan, an astronomer at Cornell University in the United States. Sagan once wrote a best-selling book called "A Hundred Billions of Billions." He believes that there are 100 billion galaxies in the universe, and each galaxy has 100 billion stars.

After observing distant galaxies in Hawaii with the help of electron astronomical telescopes, Van Dokun and his team found that the stars of these distant galaxies were many times or even tens of times larger than previously thought. "We see 10 to 20 times as many red dwarfs as we do," Van Dokun said. Conroy said that 3 is followed by 23 zeros, which is an astronomical number even for astronomers who calculate distances in light years.

To illustrate the size of the number 23 zeros after 3, Conroy said that each person has about 50 trillion human cells, and there are about 6 billion people on the earth, and the product of the two is exactly 23 zeros after 3. In other words, the stars in the sky are comparable to the total number of human cells on earth. In addition, Van Doquin and Conroy found that only one-third of galaxies are elliptical like the Milky Way. Oh.