We got this question:
Which phase of the moon would be best for stargazing, and why?
And the answer is … it depends on what you want to do. Some people enjoy watching the moon itself, as it waxes and wanes in our sky. Some enjoy the fact that the moon appears near bright stars and planets at certain times of the month. For instance, you can use the waning crescent moon tomorrow morning (May 23, 2017) to help guide you to the planet Mercury, as displayed on the sky chart below. However, the Southern Hemisphere is now enjoying a fine morning apparition of Mercury (whereas the Northern Hemisphere is not).
The moon is now a thin waning crescent moon. Waning means the illuminated part is diminishing, whereas crescent means the moon is less than half-illuminated. The moon climbs over the eastern horizon shortly before sunrise right now, meaning that the night is virtually moon-free. New moon will occur on May 25.
Moon-free nights enable astronomers to look at deep-sky objects, such as galaxies, star clusters and nebulae, so they like it when the moon is at or near new phase. It’s best to look at these faint fuzzies in a night sky with little or no light. The next new moon happens on May 25.
People using telescopes try to avoid the moon, because its glare interferes with the telescopic views of deep-sky objects. Especially around full moon, the moon casts a lot of light, washing out many nighttime treasures. At new moon, the moon is up during the day, not the nighttime. Around then, you won’t see the moon at all – unless you’re on just the right spot on Earth to watch a solar eclipse. But the last solar eclipse happened with the March 9 new moon, and the next solar eclipse won’t take place until September 1.
Bottom line: The best phase of the moon for stargazing depends on what you want to do. Some enjoy watching the moon itself. On the other hand, people using telescopes avoid the moon because its glare interferes with deep-sky objects.