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Dubai, a paradise built in the middle of the desert, where the air is filled with rich breath. It is a place of intoxication and soul-searching. The world's tallest building, Burj Khalifa, is located here.

In addition to its frightening height of 828 meters, the Burj Khalifa has another wonder: you can see the sunset twice a day.

First, on the first floor of Burj Khalifa, see the sun slope westward until it sets, then dash straight to the elevator and go up to the highest floor in one breath. You'll be amazed to find that the sun reappears and you'll be able to enjoy the sun going down one more time.

So, how did this spectacle come about?

Actually, the time to see the sunset is different at different altitudes in the same location, the lower the altitude, the earlier the sunset time, the higher the altitude, the later the sunset time.

There is an angle gap between the sun at the ground level of Burj Khalifa and the observation deck view. When the sun sets at the ground level, the sun is actually just about to set at the observation deck view, so if you reach the observation deck fast enough, you will be able to see the sunset for the second time.

So, theoretically speaking, as long as there are fewer obstacles, different latitudes can achieve to see the sunset twice, or even multiple sunsets, as long as they reach a specific height. However, it needs to be calculated more precisely. Those who are not interested in mathematics can ignore it.

The general calculation: 24 hours a day, 60 minutes an hour, 1140 minutes a day. The apparent path of the sun in the sky can be considered as a circle, and a circle is 360 degrees, so the apparent speed of the sun in the sky is about 0.316 degrees per minute.

If the visual diameter of the sun is known without taking into account factors such as light refraction, the exact sunset speed can be calculated.

The difference between the sunset on the first floor of Burj Khalifa and the sunset at the observation deck is about 5 minutes, so if you can take the sightseeing elevator with a speed of 10 meters per second, you will just be able to enjoy the second sunset. Of course, if the building is higher later on, you can even see the sunset three times.

Since you can see the sunset twice, you can also see the sunrise twice. Only the order is reversed, the first sunrise is seen at the observation deck first, then quickly rush to the ground to see the second sunrise.