The moon shines close to the planet Saturn and is in a more easterly location relative to the stars and planets tonight (Monday, July 7) than it was last night. Of course it is! The moon moves continually toward the east in its orbit around Earth. Note the wonderful contrast of color between sparkling blue-white Spica, the red planet Mars and the golden planet Saturn. Although you might be able to see these colors with the eye alone, binoculars make the color contrast more apparent.
This evening’s moon is a waxing gibbous moon, which is more than half-illuminated but less than full illuminated in sunshine. The moon reached its half-lit first quarter phase on July 5. The waxing moon will finally reach full phase on the night of July 11-12.
We got this comment from an online friend:
I was driving down a lonely stretch of dark Georgia highway the other night heading west. This gave me plenty of hours and miles to contemplate the moon . . . Is there a formal name for the border of lunar night and day?
There is indeed a name for this demarcation between light and dark on the moon. When you look at the moon in any phase other than full, you are in fact seeing portions of both the day side and night side of the moon. The name for this border between lunar night and day is the terminator line.
If you’re using a telescope or binoculars, and want to observe features on the moon’s surface, one trick is to look along the terminator line. There, shadows are causing lunar craters and mountains to stand out in stark relief in contrast to the surrounding plains. This is, after all, the line of lunar sunrise, and in some ways it’s similar to the long shadows we see on Earth at sunrise or sunset.
If you were standing at the location of that line on the moon’s surface, you’d be standing at the edge of day, or night. A similar line on Earth’s surface passes over you each day at sunset and sunrise. But there is one major difference. On the moon, there’s no dusk or dawn, because the moon doesn’t have any air to disperse sunlight, and to create the twilight that we see on Earth.
That’s at nightfall and evening on this Monday night, July 7, 2014: The waxing gibbous moon near the planet Saturn.