The clear night sky full of twinkling stars, this is evidence that we are just a planet orbiting a small star in the vast universe, the revolution of the planet.
From Orion to the Big Dipper, even though humans have been named some constellation of stars, but in reality, the number of stars in the universe of the multitude, unable to name them.
So how much is the number of stars in the universe? How many stars are not completely clear, but it is certainly a lot, a lot of.
various types of galaxies
Search for galaxies
To know the number of stars in the universe, one way is to find out the average number of stars in a typical galaxy, and then multiply it by the number of galaxies in the universe.
According to a new study in October of this year, astronomers using the deep field images from the Harbert Space Telescope found that the number of galaxies in the universe was 10 times that of a total of about 2 trillion galaxies.
In the darkest night, the naked eye can see fewer than ten thousand stars, but according to astronomers' estimates, the average of each galaxy has 100 million stars.
The number is not just by pointing the telescope at the sky, and then counting the number of stars, only the brightest star in the galaxy can be observed by astronomical telescopes.
For example, in 2008, the Sloan Digital Sky Survey (all observable objects covering the sky 1/3) detected approximately 48 million stars, it is estimated that half the number of stars.
If the neighboring Andromeda galaxy in the Milky Way system, there is a bright like the sun and stars, then use the traditional telescope (such as those used by the Sloan Digital Sky Survey) is not observed.
On the contrary, the estimated number of stars in galaxies are galaxies based on the quality of. Because the universe is expanding, and galaxies are far away from each other, so on average, light from other galaxies will appear slightly “ red shifted ” this means that its wavelength is stretched. But due to the rotation of the galaxy, some parts of the galaxy is actually close to the earth movement, which means that some light will appear “ blue shift ”.
By using these optical measurements, astronomers can roughly estimate the rotational speed of the galaxy and then reveal its mass. However, astronomers have to filter out all the dark matter, or the gravitational effect of non reflective material.
The United States from Ithaca College (Ithaca College) astronomer David Kornreich said in a typical galaxy, if by observing the galactic rotation curve (Galaxy of stars, dust and gas velocity changes with the distance from the center of the Galaxy) to measure its quality, the results obtained in the dark matter about accounted for 90%.
The number of galaxies in the universe (roughly 2 trillion) is multiplied by the average number of stars in each galaxy (about 100 million), which can be obtained from the entire universe of about 2 trillion billion stars (i.e., 2 10^20 x stars).
Of course, this is only the estimated number of stars in the universe, how many stars are only one day to know.