Glad to see this article - one or two points I’ve never seen before. It did, however, fail to mention what would happen if the moon was too large. Then the Earth’s rotation would synchronize with the moon’s rotation and we’d have long, extremely cold, nights and long, extremely hot, days - probably any life would have to be deep* underground.
Do the people discovering all these new planets have the capability (meaning sensitivity of equipment) of detecting moons around these planets? Is anyone doing work on the likelihood of such moons existing? If our Earth-Moon combination is unique, we will never find habitable planets outside our Solar System.
*I’m not just referring to conduction of heat. The expansion and contraction due to temperature change would cause large cracks - even worse than our roads here in Northern Ohio.
The article repeats the usual mis-understanding that the Moon causes the tides.
The reality is the moon creates only some of the tides. The Sun is also a major tide generator though not as much as the moon. We see this in the four major components of tides
M2 Principal Lunar 12.42h
K1 Luni-solar durnal 23.92h
S2 Principal Solar 12.00
O1 Principal lunar diurnal 25.82h
The effect of the Sun and Moon generating the tides together is the 14 day cycle of spring and neap tides
If there was no moon we’d have a two tides a day roughly conciding with the Sun position. We’d have no noticeable spring and neap tides (there actually will be some variation due to all sorts of other effects from the earth’s orbit). So we’d probably wind up with different types or specialisations of inter-tidal species
The Moon does cause tides. The article is about the Moon. He doesn’t need to mention that the Sun also contributes a smaller amount.
Plus, you’re missing the larger point. Cecil wrote
Tides were very much larger in the past, and that may have been instrumental in helping life appear. The Moon was around half as far away when life first appeared, so the lunar tides would have been around eight times stronger than they are now. Instead of the solar tides being half as large as those from the Moon, they would then have been only 1/16th as large.
Perelandra (the planet) is Venus, as Malacandra is Mars and Thulcandra is Earth. Some old British paperbacks of Perelandra were actually retitled Voyage to Venus.
But plenty of writers have presented Venus as inhabited. Golden- and silver-age DC comics pretty much assumed that all planets were inhabited, and Edgar Rice Burroughs set an entire series on “Amtor” (Venus), though it is far less popular than his novels of “Barsoom” (Mars).
That falls into the realm of idle speculation, not facts, and strays into the realm of completely at odds with observed facts.
As it happens I live very close to a whole bunch of stromatoiltes who survive in lakes that have almost zero tidal range. There are also nearby stromatolites who survive in a limited tidal range. I have not yet seen stromatolites that live in what could be called a high tidal range.
Given stromatolites are the earliest recorded life-forms it would seem likely that high tidal range was more of an impediment than a benefit.
This is a really bizarre response. Are you seriously claiming that tides were not much larger in the past? Something like “Stromatolites lived 3.5 billion years ago, stromatolites can’t live in high tidal areas, so the tides must not have been large”? Your complaint about Cecil’s description of the Moon’s contribution to tides is what I was responding to.
Otherwise, I have no idea why you’re talking about stromatolites; your response is a complete non-sequitur from what you originally said, and what I was responding to. You weren’t complaining about Cecil’s statements regarding evolution of life, you were talking about tides. I guess you’re trying to change the subject.
Whatever, here’s a cite that scientists consider that tides were an important benefit. Perhaps you can provide a cite for your last paragraph that high tides are instead an impediment to the formation and early evolution of life. Also, a cite that my statement quoted above is “completely at odds with observed facts.” Or are those just idle speculation?
No. I’m asserting that stromatolites live in areas of low tidal range. Back X million or billion years ago there were also areas of low tidal range.
I assume you are unaware that the earth presently has a huge variation in tidal range entirely dependent on local geomorphology and hydrography. In some places the tidal range is close to zero.
The same principle applied however long ago and it’s certain there were areas then of low tidal range that would suit stromatolites.
Getting back to my original point, the geological evidence shows the earliest life was in stromatolites that were no different to modern stromatolites. Modern stromatolites live in areas of low tidal range. There is no reason to believe ancient stromatolites were any different. ergo ancient high tidal range was not a factor in development of life.
Stromatolites are not living things. They are mineral deposits produced by cyanobacteria.
While stromatolites are remnants of very early life, they not the earliest (that would be graphite, produced by the Archaean bacteria)
Regarding the importance of tides, all the literature I’ve read mentions that the important thing is that there were any tides at all. There is only speculation as to what would have happened if the tides were greater or less than what they were.
<rant>
It makes me happy to see “Earth” capitalized in the title of this thread.
All the other planets get a capital letter at the front of their name. Always. The word “earth” is funny though, because it can mean dirt or it can refer to the planet. If you’re talking about the planet, then it should get a capital letter just like all the other planets get capital letters. But if you’re talking about dirt, it doesn’t get a capital letter. Yeah, I know it’s common practice that lots of people everywhere spell the planet Earth with a lowercase “e”. But I’m saying they should stop doing it. The argument in favor of using an uppercase E is that it’s logically consistent with how we spell the names of the other seven planets. The argument in favor of using a lowercase e is that we can get away with it. That’s a weak argument right there.
</rant>
This was a really good column about the moon’s influence, but I have another item to add.
When we look up at the sky at night, there are some interesting things that we notice. For example, the entire night sky seems to pinwheel around in unison, with seven exceptions: the sun, the moon, and five visible “wanderers” (planets). There are two more planets that you can only see with a telescope, but that’s not important for what I’m saying here. Another interesting thing is that, in the northern hemisphere, all the stars pinwheel around a point which happens to be centered very close to a bright star, Polaris. Another interesting thing is that the moon and the sun appear to be almost exactly the same size, so that one can just about perfectly cover up the other when they happen to be in the same spot in the sky. So we get solar eclipses but they are rare, rare enough to tease us into wondering when the next one will happen, encouraging us to discover mathematics in order to make predictions about it.
Things haven’t always been so interesting in the night sky. Sometimes the imaginary spot around which the stars pinwheel isn’t anywhere close to a bright star. For most of Earth’s history, the moon loomed much larger in the sky, and solar eclipses were much more common.
My point is that the fact that the moon right now is almost exactly the same apparent size as the sun may be partly responsible for us developing curiosity, math, astronomy, and science itself.
One of the problems is that the set of planets with life consists of a single example. I can imagine an alien civilization on the other side of the galaxy where their Cecil explains how if their planet had a large moon orbiting it, they would be subject to extremely large tides, and a rotation stuck in a single plain while everyone knows that if a planet wobbles through its rotation, it provides a much wider range of environments required by evolution.
So you figure Krypton didn’t have a large moon? (All known Kryptonians are thought to have that ability.)
As far as an inhabitable Venus in SF, pretty much every SF writer up until the early 60s had that in one story or another. Then the results from Mariner 2 (1962) came in showing the real conditions there and suddenly inhabitable-Venus stories pretty much vanished. One notable exception to this is Zelazny’s “The Doors of His Face, The Lamps of His Mouth”, which was published in 1964. I’m not sure if that story was written earlier, or was some kind of homage or tribute or something to the earlier stories, or perhaps Zelazny just hadn’t gotten the memo.
From Cecil’s column:
This is pretty much nonsense at the moment. We don’t know of any extra-solar moons (although there are a couple searches underway) so it’s impossible to prioritize planets with them. Perhaps in the future when lots of Earth-sized planets, some with large moons, are known, then such prioritizing will make sense.
I was just poke to the original post where the poster asked if we would have developed x-ray vision if we didn’t have a large moon. However, Krypton may have not have had a moon, and that could explain it. I don’t think the comic book made any reference to their moon.
Speaking about habitable planets…
Scientific American published a story of super habitable planets – after discussing how Earth may be past its prime, and not really all that great a place to live after all.
The article focused on super Earths (about twice the mass of Earth) planets orbiting small dwarf stars. Such stars are cooler, but also have a much longer lifespans than a star like the Sun (The sun will survive about 15 billion years, but will probably make Earth uninhabitable after another 2 to 4 billion years). These small dwarf stars can last around 100 billion years and are more stable. A planet twice the size of Earth will retain its internal heat that much longer, and be more likely to have plate tectonics.
Of course, no one has found such a planet, so we’re not moving anytime soon. Besides, the rent on those places is really expensive.