你用肉眼所能看到的最暗的星的亮度值大约是第6级(如果是黑夜的话)，而最亮的星的亮度值是0(更有甚者其亮度值为负)。

The faintest star you can see with your unaided eye is about sixth magnitude (from dark skies) whereas the brightest stars are magnitude zero (or even a negative number).

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同时又利用MODIS影像的第1通道和第2通道的亮度值计算出该区域的NDVI值，并将其转化为植被盖度。

At the same time we use the brightness of MODIS band1 and band2 to calculate NDVI of this area, and translate it into coverage of vegetation.

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心大星的亮度在天空中位于第15位。

Antares is the 15th brightest star in the sky.

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