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Juane 講師的專欄

Where are the Stars?

每週主題: Who loves stargazing here?

2020年11月30日



Our ancestors were very familiar with starry nights, unlike us.

Nowadays, more than half of the world's population lives in urban areas, where light pollution makes it almost impossible to distinguish the Milky Way from background noise. The concepts of "galaxy", "constellation" and "shooting star" have become rather abstract for city residents.

In order to appreciate the vastness of the universe above us, we need to leave the cities and spend the night in a place withouth electrical power or, at least, where there are not so many people using it to illuminate their streets and houses during the night. Any spot in the countryside, away from villages, is usually all right to watch the brightest stars. However, if you want a top-level cosmic performance, there are other factors to take into account.

One of them is altitude. The higher we are in the atmosphere, the smaller the amount of air that light has to cross to reach us and, therefore, the brighter we will perceive stars. Another factor is humidity. Water molecules in the atmosphere absorb light and its absence makes deserts a great place for stargazing. However, if the terrain is snowy in very high altitudes, its brightness will make it more difficult to distinguish faint stars, similarly to what happens in dusty deserts, where dust particles reflect and disperse light, creating a typical reddish glow.

During my lifetime, I have had the privilege to observe the night sky in places like Everest Base Camp at more than 5000m in Nepal, the sand dunes of the Moroccan Sahara, the infinite steppes of Kazakhstan and the shores of Titicaca Lake in Peru. All of them are great spots to understand why the Milky Way is called "milky".

Happy stargazing!

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