The moon may be a mostly uniform expanse of gray, but if you look closely, you can still find a few nooks and crannies in its surface, from deep trenches to pits and maybe even caves.

Now, researchers at CU Boulder have set out to explore what the environment might be like inside some of these shadowy features—many of which are too dark to see clearly from orbit.

The team's preliminary results suggest that pits and caves on the moon showcase remarkably stable conditions. They don't seem to experience the wild swings in temperature that are common at the moon's surface, said Andrew Wilcoski, a graduate student in the Department of Astrophysical and Planetary Sciences at CU Boulder. He will present the group's initial findings Friday at the American Geophysical Union fall meeting in New Orleans.

"If we're hoping to send people into these caves in the decades ahead, we want to know what they should expect down there," said Wilcoski, a co-author of the new research.

Ready to brave the cold? If you're like us, you haven't wasted an early clear sky morning to get out and see Comet C/2021 A1 Leonard before it heads southward. The coming days offer another early AM celestial sight: the Geminid meteors. To be sure, 2021 sees the Geminid meteors transpire under somewhat challenging conditions. But fear not: With a little planning and patience, you too can witness the "Tears of the Twins."

Circumstances for 2021: First, the bad news: the Geminids peak this year on Tuesday, December 14 at 7:00 Universal Time (UT) or ~2:00 AM EST, just over four days prior to full moon on the 19th. This puts the moon at 80 percent illumination waxing gibbous, meaning there's a narrow window of 'true darkness' between moonset and the beginning of dawn. For example, here in Norfolk, Virginia at latitude 37 degrees north, the moon sets at 2:53 AM EST on the 14th, and dawn begins at 5:37 AM EST just a few hours later.