Последние новости
Flu in five charts - how this year's winter outbreak is different
，更多细节参见WPS下载最新地址
Последние новости，更多细节参见WPS下载最新地址
What are Moon phases?According to NASA, the Moon takes about 29.5 days to orbit the Earth. Over the course of this period, it moves through eight recognisable phases, what we call the lunar cycle. While the same side of the Moon always faces us, the amount of its surface lit by the Sun changes as it continues along its path. The shifts in sunlight create the different appearances we see from Earth, ranging from a fully illuminated Moon to a thin sliver or near darkness. The eight phases are: