In both the evening and morning sky, try watching for Earth’s shadow. Earth’s shadow is a deep blue-grey, darker than the twilight sky. The pink band above the shadow – in the east after sunset, or west before dawn – is called the Belt of Venus.

We show a lovely photo of the Earth’s shadow on the chart at the top of this post (image from Woomera missile range in Australia. Used with permission).

Earth’s shadow can be seen any clear evening ascending in the eastern sky at the same rate that the sun sets below the western horizon.

The shadow of the Earth is big. You might have to turn your head to see the whole thing. And the shadow is curved, in just the same way that the whole Earth is curved. Earth’s shadow extends hundreds of thousands of miles into space, so far that it can touch the moon. Whenever that happens, there’s an eclipse of the moon, like the faint penumbral eclipse coming up on September 16.

Check out Earth’s shadow – in the east at sunset or in the west at sunrise – next time you have a clear sky. I often see it while out on the streets of my town as the sun is setting.

By the way, the image at the top of this post shows more or less the same moon phase that you’ll see tonight. It’ll be a waxing gibbous moon that’ll be visible in the east after sunset this evening. The full moon will come on August 18.

Bottom line: Watch for the curved blue-grey line of Earth’s shadow at dawn and dusk. The pink coloration above the shadow is called the Belt of Venus.