Moon phase and libration, from the other side

A number of people who've seen the annual lunar phase and libration videos have asked what the other side of the Moon looks like, the side that can't be seen from the Earth. This video answers that question.

Just like the near side, the far side goes through a complete cycle of phases. But the terrain of the far side is quite different. It lacks the large dark spots, called maria, that make up the familiar Man in the Moon on the near side. Instead, craters of all sizes crowd together over the entire far side. The far side is also home to one of the largest and oldest impact features in the solar system, the South Pole-Aitken basin, visible here as a slightly darker bruise covering the bottom third of the disk.

The far side was first seen in a handful of grainy images returned by the Soviet Luna 3 probe, which swung around the Moon in October, 1959. Lunar Reconnaissance Orbiter was launched fifty years later, and since then it has returned hundreds of terabytes of data, allowing LRO scientists to create extremely detailed and accurate maps of the far side. Those maps were used to create the imagery seen here.

This narrated video introduces two views of the Moon's far side.

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Image: ESA's SMART-1 revealing unknown regions of the moon

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Citation: Moon phase and libration, from the other side (2015, February 9) retrieved 16 September 2019 from https://phys.org/news/2015-02-moon-phase-libration-side.html
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Feb 09, 2015
When are we going to put some radio telescopes in orbit around the Moon? We have a few in orbit around Earth, right, so why not the moon for maximum view angle to increase resolution?

I'd like perhaps 3 orbiting the Moon: one orbiting on each plane so that as the Moon orbits Earth and Earth orbits the Sun, you always have the best orientation to view potential objects of interest.

It would also be useful in my view to have optical telescopes and x-ray telescopes there.

A wider simultaneous viewing angle provides better depth perception for more precise distance measurements and more precise estimates of velocity and mass of objects, as well as better resolution in general.

Example:
More precise measure of Betelgeuse distance, mass, and size.

There are also some nearby star systems with planetary rings and dust belts which would be interesting to study under higher resolution available.

Better measure of nearby objects improves farther objects.

Feb 09, 2015
We have a few in orbit around Earth, right, so why not the moon for maximum view angle to increase resolution?

"Maxium view angle to increase resiolution"? That gets my vote for most nonsensical techno-gibberish of the year.

And you are aware the shooting stuff into lunar orbit is a tiiiiny bit more expensive than getting it into Earth orbit? Also a bit of an issue with serviceability.


Feb 09, 2015
We can do it around the Earth, but Earth has more interference from the man-made communications.

The two things that affect resolution are the size of the array and the number of nodes in the array. For an orbital array the size is the maximum distance from the orbits of the satellites to one another.

3 nodes, one on each plane, would be the bare minimum. I'd like to see 6 nodes, or two on each orbital plane, in a 2:3 resonance so that their relative positions actually change. The reason for this is synchronized orbits sometimes results in a maximum of 5 viewing the same object, while 1:2 or 2:3 resonance allows timing windows when all 6 nodes can view the same object. Moreover, with 6 orbiters you maximize the time when at least 3 can view any one intended target.

You'd combine GPS technology and some tracking/reference lasers so their exact distance to one another is always known each time they take an exposure.

Feb 09, 2015
And if the cloud bursts, thunder in your ear
You shout and no one seems to hear.
And if the band you're in starts playing different tunes
I'll see you on the dark side of the moon.

Feb 09, 2015
Okay, this was awesome.

http://popularsci...ant.html

Imagine modding this for the next Titan mission? You could planets with atmospheres with incredible ability, provided you could make it able to survive the extreme conditions of freezing rain and cryogenic temperatures.

Feb 09, 2015
The Moon has an advantage over Earth for Parallax measures because the Moon orbits Earth about every Moon, or about 13 times per year.

The farther apart your observations in space, the more precise your estimate of the angle is, but the closer together the observations in time the better because the object moves less from one observation to the next. Therefore having a lunar observatory allows you to have a very wide viewing angle combined with Earth, and observations made only seconds apart instead of minutes, hours, days, or seasons. This precision will reduce margin of error for close and medium range stars, which will in turn refine measure for other stars.

Betelgeuse is an important star for stellar life cycle understanding, but measures of the star are believed to be 25% to 50% margin of error, which makes it very difficult to apply practically to other objects.

Feb 09, 2015
@Returners, The Moon parallax measurements wouldn't be much better than what they get on earth. They measure parallax from earth by measuring 6 months apart when the earth is on opposite sides of the sun. Adding an extra 384,400 km * 2 (earth to moon) won't make much difference to the 149,600,000 km * 2 (earth to sun) that they are already getting, thats only a ~0.5% increase.

Feb 09, 2015
@Returners, The Moon parallax measurements wouldn't be much better than what they get on earth. They measure parallax from earth by measuring 6 months apart when the earth is on opposite sides of the sun. Adding an extra 384,400 km * 2 (earth to moon) won't make much difference to the 149,600,000 km * 2 (earth to sun) that they are already getting, thats only a ~0.5% increase.
Just to bring some people up to date on that: There is a spaceship named Gaia that is already hard at work mapping 1 billion stars in our region of the galaxy; a radius of 30000 lys spanning from beyond the nucleus to the outskirt of the Milky way. It is in position at Lagrange 2 and doing this task using the parallax measurement method. http://www.space-...aia.html

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