The bright horizontal line running the full length of the image is the galaxy's main disc - the plane in which the Sun and the Earth also reside.

贯穿整张图片的明亮水平线是银河系的主盘，太阳和地球就处于其中。

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This suggests either that they are happening outside the Milky Way or that they occur in the spherical halo that surrounds its main disc.

ECONOMIST: Astronomy

The minute hand remains but hours are displayed on a main rotating disc.

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James Cook, a year into his circumnavigation of the world, observed the transit of Venus over the Sun's disc, the main purpose of his voyage.

CNN: Tuesday,