Some stars being watched have very variable brightness. That is confusing for computers, but for human eyes is less of a problem.

一些观测中的恒星亮度变化较大，这对于计算机来说难以把握，但是对于人眼却不成问题。

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Cepheid variable stars are stars whose brightness changes at regular periods.

VOA: special.2009.04.29

In addition, star colour is simulated for noticeably red, blue and yellow stars, along with the changing brightness of three variable stars Algol, Mira and Delta Cephei.

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"This object was changing its brightness by a factor of three or four -- it was just enormously variable, " Tholen said.

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