On Lunar Peregrinations

Sitting observing the Easter full moon, I was reminded of something that hit me in the process of perpetual re-reading. Something about the moon was very wrong.

Now authors are not meant to be experts on everything but sometimes bits of text jar horribly, especially to someone who has dabbled in astronomy over several decades. We know that Safehold’s moon is slightly different from that of Earth but some things remain essentially the same, particularly in terms of orbital period or the approximate plane of the orbit in relation to that of Safehold around its star.

This is not the first time I have seen something wrong. Even Tolkien got it wrong on at least one occasion in The Lord of the Rings. Here is what I noticed, on page 169 of LAMA, hardback edition:

“His gunners were sufficiently well trained to assuage any worries he might have felt on that score, and the moon would be rising within the hour. Not that it would be much help; they were just past the new moon, and the waxing crescent was little more than a nail paring.”

The problem is that any moon that rises during the night is waning and is past the full. A brand new moon with a very thin crescent is already in the sky at sunset and sets soon afterward. As the moon waxes, the setting time gets later in the night until at full moon, it rises roughly at sunset and sets roughly at sunrise. Then, the waning moon rises later every night until a very old moon, once again being a very thin crescent, is rising not long before the sun. At new moon, the invisible moon is relatively close to the sun and travels through the sky in close company.

I hope that this will be of assistance for future reference for any author and anyone reading text that mentions the placement of the moon!

Actually, this indicates that the moon in question is in a retrograde orbit.

At least that's what I have assumed every time I've read that passage

wingfield wrote:Sitting observing the Easter full moon, I was reminded of something that hit me in the process of perpetual re-reading. Something about the moon was very wrong.

Now authors are not meant to be experts on everything but sometimes bits of text jar horribly, especially to someone who has dabbled in astronomy over several decades. We know that Safehold’s moon is slightly different from that of Earth but some things remain essentially the same, particularly in terms of orbital period or the approximate plane of the orbit in relation to that of Safehold around its star.

This is not the first time I have seen something wrong. Even Tolkien got it wrong on at least one occasion in The Lord of the Rings. Here is what I noticed, on page 169 of LAMA, hardback edition:

“His gunners were sufficiently well trained to assuage any worries he might have felt on that score, and the moon would be rising within the hour. Not that it would be much help; they were just past the new moon, and the waxing crescent was little more than a nail paring.”

The problem is that any moon that rises during the night is waning and is past the full. A brand new moon with a very thin crescent is already in the sky at sunset and sets soon afterward. As the moon waxes, the setting time gets later in the night until at full moon, it rises roughly at sunset and sets roughly at sunrise. Then, the waning moon rises later every night until a very old moon, once again being a very thin crescent, is rising not long before the sun. At new moon, the invisible moon is relatively close to the sun and travels through the sky in close company.

I hope that this will be of assistance for future reference for any author and anyone reading text that mentions the placement of the moon!

Louis R wrote:Actually, this indicates that the moon in question is in a retrograde orbit.

At least that's what I have assumed every time I've read that passage

That could be, but I would say that is unlikely. Such orbits are inherently unstable.

Isilith wrote:

Louis R wrote:Actually, this indicates that the moon in question is in a retrograde orbit.

At least that's what I have assumed every time I've read that passage

That could be, but I would say that is unlikely. Such orbits are inherently unstable.

Triton is in an retrograde orbit around Neptune and astronomers believe that it is slowly decaying (it will take over a billion years to reach the Roche limit).

I want to take a moment to say that this is literally why I have never tried my hand at writing

Isilith wrote:

Louis R wrote:Actually, this indicates that the moon in question is in a retrograde orbit.

At least that's what I have assumed every time I've read that passage

That could be, but I would say that is unlikely. Such orbits are inherently unstable.

Retrograde orbits are much more plausible when something like a gas giant captures another satellite.

To return to the subject of my discussion, expecting moonrise for a brand new moon in a retrograde orbit would mean waiting until very late in the night (not long before the dawn - the sky would be growing light). The entire action that followed that night took place in full dark, with the little surprise of the illumination ordered by Hanth as the Desnairians charged.

RFC does not appear to have mentioned that the moon is in a retrograde orbit.

I agree with wingfield, Moon is not available in the orbit.

Andriarivera wrote:I agree with wingfield, Moon is not available in the orbit.

A few years back, one dreadful boy ran up to me and said, “Mr. Bradbury?”

“Yes?” I said.

“That book of yours, The Martian Chronicles?” he said.

“Yes,” I said.

“On page 92 where you have the moons of Mars rising in the east?”

“Yeah,” I said.

“Nah,” he said.

So I hit him. [attributed to Ray Bradbury himself]

Not something I would have noticed. I noticed no RFC comments.