For much of the world, the moon and the planet Venus will be closest together for the month before sunrise on June 24, 2014. The second-brightest and third-brightest bodies of the nighttime sky – the moon and Venus – will be beautiful, snuggled up together in the eastern, predawn sky.
You’ll likely be able to see the night side of the slender waning crescent moon softly aglow in earthshine – sunlight that’s reflected from the Earth and back to the moon. The shadow line dividing the lunar night from the lunar day is called the terminator line, and it’s along this lunar terminator that you’ll have the best three-dimensional views of the moon’s terrain through binoculars or a telescope. Another tip if you’re using optical aid: wait until dawn begins to light the sky, so that the contrast between the bright moon and dark sky is least. If you wait, you’ll see more on the moon.
When the moon is waning in Earth’s sky, the terminator line on the moon – line between light and dark – shows you where it’s sunset on the moon.
However, if you were at the moon looking back at Earth, the Earth’s terminator would show you where it’s sunrise on the waxing gibbous Earth.
At any moment, the phase of the moon as seen from Earth is exactly opposite of the phase of Earth as seen from the moon. For instance, as viewed from North America at dawn on June 24, the waning crescent moon will be about 8% illuminated in sunlight and 92% covered over in the moon’s own shadow. However, if you could look back at Earth from the moon, you’d see just the opposite: the Earth 92% illuminated in sunlight and 8% covered over in Earth’s own shadow.
Bottom line: Enjoy the morning tableau from around the world on June 24, 2014 as the waning crescent moon and brightest planet Venus beautify the eastern sky at dawn. Plus … how the moon’s phase as seen from Earth is always opposite of Earth’s phase as seen from the moon.