NASA videos provide us with all the details of the Moon for 2015

Tuesday, December 9, 2014, 6:59 PM - Pay close attention to our Moon over the course of a year and you'll see plenty of things change, and not just in the phases.

The video above, shared with us by NASA's Goddard Spaceflight Center, gives us a look at the Moon courtesy the high-resolution images taken by the Lunar Reconnaissance Orbiter. This isn't just one cycle of the phases, though. The video presents an hourly time-lapse, as viewed from the Northern Hemisphere, for an entire year, and is specially timed so that it represents an accurate down-to-the-hour viewing guide to the Moon for all of 2015.

There's a lot more going, though. 

The orbit around the Earth has been included in the top left, but seeing as it's fairly small there, NASA's Scientific Visualization Studio has included a larger version, shown below:

Also, even in that larger version, it may be hard to pick out, but the Moon's orbit around the Earth isn't exactly a circle. A 'lunar distance' is typically averaged out to 384,400 km, but the actual distance between Earth and the Moon can vary by over 42,000 km over time - from 363,104 km at the minimum (perigee) to 405,696 km at its maximum (apogee). Watching it as it goes around doesn't make this very clear though. This view, from the side, show it much better:

The angles of the lunar equator and meridian, as well as the subsolar (yellow) and sub-Earth (blue) points - the points directly 'under' the Sun and the Earth, respectively - are shown in this view:

Note the times when the subsolar and sub-Earth points directly line up. Those are nights of a Total Lunar Eclipse somewhere on Earth. Two of those are happening in 2015 - part of a rare 'tetrad' of 2014/2015 lunar elipses - once over the Pacific Ocean on April 4, and again over the western Atlantic and most of North America on Sept 27.

Lastly, as the phases change during the video, you'll notice names popping up along the 'terminator' between day and night. Those are the names of the craters that lie along the terminator at that time.

The 'Rocking' Moon

An added bonus the video highlights, without drawing too much direct attention to it, is a very cool thing called libration.

While the moon is tidally-locked with the Earth, meaning that one side of it is always facing towards us, and we only see half of the Moon at any one time, we're not limited to seeing only 50 per cent of the Moon's surface from here on Earth. In fact, over the course of a month, due to the angle and shape of lunar orbit, we actually get to see more like 59 per cent of it. This is due to libration.

Of course, we've had pictures of the far side of the Moon since the late 1950s, the Apollo 8 astronauts were the first humans to set eyes on it in 1968, and we've had plenty of other lunar missions since (including LRO), but libration gives those of us here on Earth a little 'peek' around the edges, to see features that are hidden to us at other times of the month.

More views, from different perspectives

Are you used to seeing the Moon from the Southern Hemisphere? NASA hasn't left you out. Head to their website (click here) to be treated to a more familiar view of all the videos above.