What would be the effects of an Earth-like planet with a longer year and longer lunar orbit? I have a planet with 432 days in a year and a lunar cycle of 36 days, with 12 months at 36 days each. The planet is very much like Earth in the inhabitable zone of the Solar System. Assume the density and mass of the Sun and planet and moon adjust proportionally to allow for these orbits. The axial tilt of Earth is the same at 23.5 degrees and the orbit is the same.

The lunar orbit is needed to create extreme tides like Perigean tides. Im talking like the Bay of Fundy if not more. I need the tide to recede by 200 feet.

How would this impact other things on the planet? Changes in the weather? (I'm wanting occurrence of lots of natural disasters of all types). Flora? Fauna? Migration patterns of animals? Anything else that I might be missing?

EDIT: refine questioned to a few topics.

  • 1
    $\begingroup$ Welcome to the site, Dynas. You've got a good premise, but the "Anything else" in your question suggests that your question is currently too broad to be effectively answerable using our format. You can get more info about questions on the help center. In the meantime, I would suggest narrowing your question to a handful (1-4) of areas that you want to see the impact on. $\endgroup$
    – Frostfyre
    Commented Aug 3, 2015 at 16:45
  • $\begingroup$ A more distant moon would make smaller average tides, as would the more distant sun. The large tides in the bay of Fundy is due to the shape of the bay, not astronomical effects. $\endgroup$
    – Oldcat
    Commented Aug 3, 2015 at 17:59
  • $\begingroup$ Well the moon may be more distant at certain times; I'm thinking a more elliptical orbit where you get really flat tides when the moon is further away and really strong tides as it gets closer. $\endgroup$
    – Dynas
    Commented Aug 3, 2015 at 18:07

2 Answers 2


A longer year means longer seasons. Depending on how hot and cold the winters are, that could create hardships. A long winter means that people have to store up more food during the growing season to sustain them through the winter. Depending on other factors, this might mean multiple growing seasons during the spring and summer. If not, that could make it difficult to grow enough crops during the summer to make it through the winter.

Tougher still for wild animals. A longer winter means more plants die during the winter, so there's less food for the animals. You could, of course, postulate hardier plants. I suppose an evolutionist would say that such plants would evolve, a creationist would say that a God who created such a world would create plants that can survive it, or if we're supposing the world was terraformed by advanced beings, they would create plants that can survive it.

Longer seasons likely means greater extremes of heat and cold. Not only more hardship on people and animals, but would cause rocks to crack and create more erosion, glaciers to have more extreme ranges, etc.

Rivers would have greater extremes of depth. They'd be more likely to dry up in the summer, and then overflow in the spring thaws. You'd have more "wadis" like you see in the Middle-East: water beds that are dry much of the year but wet in the spring (and during rainstorms).

Of course these and any other factors someone might think of could be affected by other factors. Like issues caused by long seasons could be mitigated if the planet has less axial tilt and so the seasons are less extreme.

  • $\begingroup$ Would an oasis do the same things as the Wadis? $\endgroup$
    – Dynas
    Commented Aug 10, 2015 at 16:16
  • $\begingroup$ @dynas Hmm, an oasis normally gets its water from springs, i.e. underground water sources. Would these dry up in a long summer? I don't really know. Anybody more knowledgeable on this, please chime in. $\endgroup$
    – Jay
    Commented Aug 10, 2015 at 16:54

To have a longer year you will have to move the planet away from the sun (just slightly), or have a slightly more eccentric orbit. This will increase the extremes of hot/cold, wet/dry. This will make it harder for life to develop on the planet. Once life is established, it will adapt to new conditions.

To get greater tides, move the moon closer or make it more massive. With greater mass it will move more water. If you move the moon closer it will have to orbit faster. Thus the tides will come in and go out more rapidly.

You can make the planet uninhabitable, but that is no fun. You could have most life in the oceans. With extremes, and tsunamis twice a day land life may be limited to algae and moss. Everything else gets smashed on the rocks. As you back off from OMG plants can develop. With high winds plants will remain stunted, and no flying animals will evolve. Backing off more will increase the size of plants and animals and at some point flight will no longer be suicidal.

Of course life could be engineered/designed. It would also be possible that a friendly planet was shifted in orbit by a wandering star/planet. Most life died in the shift, but not all.

I suppose building codes would change with weekly hurricane force winds scouring the landscape.

Ice tides. Every lunar cycle a single wave of ice breaks on the shore. It is a wall of ice meters high that is pulled from the ocean. It is sort of like an instant glacier.

With the moon closer, you might end up with more volcanic activity. This would result in more dust in the air. Organisms might develop more nose hair and better mucus membranes to remove the particulates.

With a very difficult planet, you might need special locations or periodic intervals where things are a bit more friendly.

If Earth shifted orbit tomorrow, our current topology would allow for some sheltered areas. Small valleys that are protected. The isolated pockets of life would become very strange places. Think New Zealand to the European explorers who found it. However, mostly all the soil would be blown off and end up at the bottom of the oceans. The silt load will kill most ocean animals, though some would survive. The oceans would remain turbid because the silt cannot settle. Larger particles of soil would end up in the deep trenches, and the average ocean depth would decline. A rise in sea level would kill off a few more of the isolated pockets of life.

The ash spewed forth by volcanic activity would act as an abrasive. The wind and ash would grind mountains to dust. The world would become much flatter after a few thousands of years. The quiet habitable valleys would also be great places for ash to settle out. This could be a fertilizer boon for those that can handle breathing more silica.


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