# What would happen to Earth if it were eclipsed for nearly 10 days?

What would be the major changes that could happen if Earth experienced a solar eclipse caused by a fictional planet for a minimum of 10 days? Mainly what would happen to the oceans and flora in such circumstances.

And what would happen if eclipse may take for more than a month?

• I don’t think there’s any conceivable way that another planet could eclipse the Sun from the Earth for anything like ten days, let alone a month. Orbital mechanics doesn’t work that way. All planets are always moving relative to each other, so your planet would soon move out of the direct line between the Earth and Sun. – Mike Scott Nov 18 '17 at 19:52
• The only conceivable way you can have a planet-wide, very long eclipses is to place it in L2 of a gas giant. Unfortunately that position is unstable so there's no natural way to keep that alignment. – ZioByte Nov 18 '17 at 19:57
• @ZioByte But a satellite of a gas giant at L2 would be permanently eclipsed. The eclipse would never end (until the inherent instability of the L2 position caused the satellite to drift away from the L2 point). – Mike Scott Nov 18 '17 at 20:01
• It would have to be a very, very, very big planet very, very, very close to the earth. In which case, the gravitational force would probably make earth a moon of it. – Justin Thyme Nov 18 '17 at 22:02
• Does the entire eclipse (transition & totality) take 10 days; or, does totality take 10 days and the transition normmal or comparatively longer? – KareemElashmawy Nov 19 '17 at 3:40

Typically the temperature difference between day and night is 10 C. So at first approximation, it drops 1 C/hour.

So if you started at a middle of the road temp, of 20 C, you'd be down to freezing in a day.

Wait:

As the temp drops, clouds form. This slows down the heat loss to something like half to 1/3 of the previous rate.

Since it doesn't rain every night, it takes more than a day for this to happen. So continueing with the furious handwaving: Temp drops 1 C/hour for 10 hours. Clouds form, and it drops for 1/2 C until it gets to freezing. So at 30 hours we are at freezing.

At this point another effect comes in: Latent heat of water Cooling is going to essentially stop while the top foot of ground freezes, and most of the moisture comes out of the atmosphere. This will take at least two full days, more in wet climates (more water in the soil) So at the end of day 3 we are at something like -5 at temperate latitudes.

Now we get some differential effects. Areas near very large lakes and oceans will be warmed by the these bodies of water that take a long time to cool. However continential interiors will continue to cool. Once the air is dry, it will go back to that 1 C/hour, -- call it 20 C/day. The air itself won't chill that fast, and you will end up with layers of very cold dense air near ground level with a temperature inversion above that. This may foster cloud formation again, and limit the heat loss. So, wind it back to 10C/day.

That cold air will flow down hill. Coasts will have a land breeze of cold air flowing off the continent onto the ocean. Oceans will heat it up and humid air will move inland somewhat, producing heavy snow.

At some point the oceans start to freeze at the edges. Places that have ocean currents off shore will last longer. Bays, lakes, and places isolated from currents will freeze as soon as the water temp drops to zero. This is largely a function of water depth. In Alberta it takes a good month of cold weather before even a 10 foot deep slough is safe for skating (4" thick ice)

There is enough heat transfer between equator and poles that even during a 6 month full dark at the south pole temps only get down to the -120s F (-85 C)

Much of that will be the thermal inertia of the ice itself -- which isn't much better than rock. (Ice has a specific heat half that of liquid water)

So overall: Killing frosts. This would likely kill most land based plants (Even plants that can survive a -50 winter can't do so if it catches them during the growing season. They need to adapt slowly.

• "Even plants that can survive a -50 winter can't do so if it catches them during the growing season." In which case, the timing of the eclipse will matter. If it is winter in the Northern Hemisphere (where most high latitude landmass that sustain some life is), then the most cold-resistant species will have a chance to survive. – Luís Henrique Nov 20 '17 at 13:31
• ah, but the equator does not get much heat any more either. Will we get to oxygen rain within a month? – Henning M. Nov 20 '17 at 23:37
• @HenningM. I don't think so. The Antarctic doesn't even get to the point where CO2 hoar frost forms. And there the amount of water vapour in the air is nil. There's not a lot of air exchange either. Cold air flows off the plateau, creating a surface high pressure and a high altitude low. The polar vortex forms from air at height moving in. As long as the oceans have open water, you will have a BIG temperature difference, which will keep pumping water vapour into the air to create insulating clouds. – Sherwood Botsford Nov 21 '17 at 15:51

Lets assume that the eclipse is formed by something else - say some shade squares an ancient civilization left over from when they were building a dyson ring - and for some reason it causes a (hopefully one off) planet wide eclipse for ten days.

The most vital thing the sun gives out planet is heat. Enormous amounts of it. Up to 1kw/m^2 If you withdraw the heat, things start cooling. You know how much colder night is compared to day? Imagine if the earth kept cooling for more than the 12 hours the sun was hidden - and that it didn't get heat transferred from it's other side. Now the Earth does have a significant thermal mass, but over a week much of that heat will have gone (from the surface at least. Further down the core will be fine for a couple million years). Summer and winter are caused by Earths tilt reducing the amount of heat the sun gives a small part of Earth. We're going far worse than that. The poles are the only place that see extended darkness, and they change by about 20 degrees summer vs winter. Given that that is months of darkness, but is offset by the fact that other parts of Earth are still heated, it at least gives us an order of magnitude.

So let's say that over a week of complete Earthwide darkness, the global temperature drops 20 degrees. What happens? The poles get down to -60 degrees, and in some places, CO2 may start condensing out of the atmosphere. Ice starts forming just about everywhere other than the equators - and even there I'd expect to have very low air temperatures. The seas probably don't freeze after only a week, but most overland transport will halt due to icy conditions. Thousands die as diesel solidifies inside generator tanks, hydrodams freeze, and gas in gas tanks refuses to de-liquify. Coal still burns, as does wood (probably).

If the worldwide eclipse persists more than a month or two, the planets atmosphere is solid, and anything that doesn't live underground near a volcanic vent has died.

Of course, if it's not planet-wide, then you won't get more than a few degrees temperature drop in a localised area - but that's far less entertaining.

• 1. OP didn't ask for a reason for the eclipse (it's irrelevant). 2. The rate of air temperature changes is during eclipses is not as similar to nighttime as you propose. During totality the temperature ceases to drop (eclipse2017.nasa.gov/temperature-change-during-totality). During the transition though, the temperature drops uniformly by as much as 28F (space.com/37201-solar-eclipse-temperature-drop.html). During night time, the air temperature changes sinusodially (geography.name/daily-and-annual-cycles-of-air-temperature) and is dependent on thermal capacity. – KareemElashmawy Nov 19 '17 at 3:48
• 1. I just liked to mention that a 10 day eclipse is not possible with normal orbital systems. 2. Hmm. Interesting. Can you suggest another model for predicting temperature drop under planet-wide eclipse? – sdfgeoff Nov 19 '17 at 6:32
• How many days it may take for oceans to freeze out? if so what would be the consequences of it? – Peaceman Nov 19 '17 at 10:31
• The oceans will take a long time to freeze because the surface will form a crust of ice that helps protect the rest of the water. I suspect a long time (decades or centuries of planet-wide eclipse) before all of the water on Earth is frozen, and by that stage the atmosphere will be a layer of liquid nitrogen on the surface. For an example, see Enceladus (Saturn's moon). The surface temperature is −198°C (nitrogen is a liquid), but it has liquid water underground. Unscientifically, I'd guess at 1–2 months until there is no (human breathable) on the planet, and 5–6 to have ice at the poles. – sdfgeoff Nov 19 '17 at 16:48
• +1 for starting with a more plausible reason for the eclipse. – JDługosz Nov 19 '17 at 19:00

Perhaps one could get a decent approximation of the effects by considering the arctic winter, or temperate latitudes where photosynthesis basically shuts down during winter.

So the effects would depend on what time of year the 10-day blackout happened, and what latitude you're looking at. Say it happens in mid-January. Northern temperate and arctic latitudes aren't really going to be affected much, because everything is already in winter dormancy. Southern temperate latitudes will see most plants killed, as by a sudden unseasonal frost, but they will eventually recover from buried seeds, tubers, and re-sprouting from roots.

Tropical areas would likely be hardest hit, as the plants don't generally have adaptions to cold temperatures. You'd probably see a lot of extinctions of tropical species, and eventual dispersion from the temperate lattitudes.

Of course this applies only to land species. My guess is that because the ocean holds so much latent heat, marine species wouldn't feel much effect in just 10 days.

• While plants would be killed, many seeds would not. – Sherwood Botsford Nov 21 '17 at 15:52
• @ Sherwood Botsford: I don't know enough about tropical plants to know whether or not seeds would be killed by sub-freezing temperatures. I'm guessing that at least some wouldn't. You'd get basically all the plants killed, so whatever seeds (or roots, bulbs &c) did make it through would have to start an ecology from scratch – jamesqf Nov 22 '17 at 2:24

Well, If the planet has any significant mass, then it will disrupt our planets' orbit and send us on a trip to the unknown. If it does not have any significant mass, then it will fly away. So only possible way how to do this is MAGIC. Now that we have our 42 on the table lets see... Just darkness by itself would bring the temperature down, just as +sdfgeoff mentioned. But a planet would also influence ocean tides, animal and insect behavior, plant growth. Some people could experience nausea or encounter other health problems. depending on how far from earth the planet will be the Moon would not reflect the sunlight at all, or it would be red or blue (look for lunar eclipse) Religious people would obviously react to this in their specific way and less religious people would start their own riots. Calm people,survivalist types, would quickly try to stock up on resources and stay away from the other two types.

After the eclypse ends most people will think "illuminati did it" and the surviving life would return to its normal state and continue.

It is possible for this to happen, but you need some significant handwaving.

Ordinary planetary orbits will not achieve any long occultation, but you can get it with a sizeable body in Sun-Planet first Lagrangian point. In the case of Sun and Earth, we know that an object the size of the Moon at the distance of the Moon is eclipse capable; this object is about four times as far as the Moon, so it needs only be four times smaller (in radius), which works out as one sixty-fourth the mass.

The need for handwaving is that orbits around L1 are unstable, and require station-keeping. It just might happen that a body is captured every so many years and briefly stations at L1 before proceeding at higher speed on its way (an orbit inside that of Earth is faster than Earth's). Something very vaguely analogous happens with Earth's "second moon" Cruithne.

But especially if the object is larger than the minimum, it could block enough of the Sun's light to give effective birth to a ten day eclipse (it would be more a shadow dancing around the Sun, gradually covering it more and more over three to four days, followed by four-five days of totality, and then spinning away again).

You can expect temperature drops similar to what happens at the Poles between summer and winter, but not so extreme; probably enough to get surface freezing on most bodies of water, assuming the starting temperature is around 20 °C, but not much more. Over a month, it would grow wondrous cold, but again within the limits of an Arctic winter. An abundance of water with its latent heat would help. Far from the oceans, in the middle of a continent, you'd get very harsh conditions - think a Siberian winter.

Provided the eclipses don't come too often, at least in those areas where the temperature drops are not too extreme the ecosystem should recover and even not suffer too much, and possibly some adaptations would evolve - assuming this unstable configuration can hold over evolutionarily significant periods - such as a deep slumber, half-way to hibernation, that organisms can enter with very little forewarning; or the need to accumulate body fat and reserves.

Over the long period, most species (especially vegetable) unable to cope with flash freezes would die out. Possible adaptations are gluey sap with antifreeze properties, thick bark, possibly leaves capable of folding, and a drive to produce year-round tubers capable of surviving both the darkness, the cold and the grazing of herbivores dealing with an increased need for fuel.