Why is the Milky Way most obvious only in summer?

The Milky Way, also known as Tianhe Han Yun in ancient China, is a milky bright belt across the starry sky. The Milky Way intersects the celestial equator in Aquila and is located in the northern hemisphere. The milky way draws a band with different widths on the celestial sphere, which is called the galactic band. Its widest place is 30, and its narrowest place is only 4 ~ 5, with an average of about 20, which is only a part of the Milky Way.

The Milky Way occupies a very important position in the culture of China, and there is a famous myth and legend of the Han nationality. The Milky Way can only be seen on a clear night, which is caused by the light of countless dark stars. The Milky Way is not the Milky Way, but a part of it. The Milky Way contains hundreds of billions of stars, with a total mass of about 600 billion to 3 trillion times that of the sun and a diameter of about 654.38+ million light years. You can refer to the "Galaxy" entry to distinguish the two.

On summer nights, the bright band of light we look up to is called "the Milky Way". It is the central part of the galaxy. The radius of the Milky Way is about 50,000 light years (the latest data may be 60,000-63,000 light years), and the solar system is about 26,000 light years away from the center of the Milky Way, which is about 50% of the radius. The density of stars in the center of the Milky Way is high, and the stars in the outer edge are sparse, so the brightness in the center is high.

When the earth moves between the sun and the center of the Milky Way, if we look up at night, at this time, we turn our backs on the sun and see the bright center of the Milky Way. This is the so-called "Milky Way". It's just summer in the northern hemisphere.

The cycle of the sun's revolution around the Milky Way is about 200 million years. According to this calculation, after 65.438 billion years, the sun will move to the other side of the Milky Way. At that time, people in the northern hemisphere of the earth will see the Milky Way on winter nights. Therefore, the accurate statement should be: the moment when we see the Milky Way happens to be a summer night in the northern hemisphere.