I’m not talking about the surface, including the atmosphere, but the planet as a whole. Isn’t Earth cooling off, i.e. losing energy to the universe, like other bodies in the universe that don’t have their own sources of heat?
The core of the Earth is slowing cooling down. The flow of heat from the core contributes to the surface temperature, but it’s a small contribution and the actual surface temperature is dominated by the radiation of the Sun and the atmosphere trapping some of that heat.
It should also be noted that (very roughly, with a wide range of uncertainty) about half of the internal heat escaping to the surface is due to radioactive decay within the mantle and crust, and only (roughly) the other half is due to the earth’s original primordial heat. This total amount of heat is completely insignificant compared to the heat we get from the sun.
wolfpup - are you saying that the earth is cooling down by an amount less than what the earth gets from the sun? If so, then is the earth - qua planet - cooling off or not?
Yes, the earth’s interior is very slowly cooling. The amount it emits to the surface is a pittance compared to what we get from the sun, however – about 47 TW from the interior compared to about 173,000 TW received from the sun.
This looks like a Factual Question to me, so I’ve moved it. It certainly doesn’t belong in Cafe Society, which is where I found it. If @CC prefers some other forum, please let the mods know – ideally, a mod of the forum you want it moved to.
Do the moons of gas giants get heated up by the tidal forces their parent planet exerts? And if so, how much heat is generated by the moon tugging on our planet’s core? Obviously significantly less, but the moon is particularly large relative to us, right?
The interior is cooling while the surface is staying warm due to the Sun’s heating. So overall the Earth is cooling while the surface is currently getting warmer.
The surface gets warmer and cooler depending on a lot of things. For most of Earth’s history the surface was slightly warmer than it is now. Humans and most of modern life evolved during an abnormally cool period, and the surface has been slowly warming up for the past 30 million years or so (greatly accelerated here lately due to us pesky humans mucking with things). At one point the Earth’s surface froze solid (glaciers scrape the surface of the Earth as they move, and these scrapes have been found all the way from the poles to the equator) and at another point in time the Earth’s surface got so hot that the polar ice caps melted and most life around the equator died.
The interior has been much more consistent during all that time, just slowly cooling off with a bit of radioactive decay offsetting some of the cooling.
If everything else stayed the same, the interior would slowly cool until all of the molten stuff froze solid. At that point plate tectonics would stop and the continents would no longer move and change over time. The Earth’s magnetic field would disappear as well. However, everything else isn’t going to stay the same. The sun will start to burn out and will obliterate the Earth long before its interior has a chance to freeze solid. But you have a couple of billion years before you need to worry about stuff like that, so no biggie. And even then, statistically, it’s likely that all life on Earth will be wiped out long before then by some chunk of space rock slamming into the Earth at a rather high velocity.
I would say, rather, that overall the planet is warming. We’re currently getting more energy from outside (all of it from the Sun) than we’re releasing to the outside. Within that, heat is being redistributed some, but on net, it’s still an increase.
The moons of Jupiter get heated a LOT by the tidal forces of Jupiter and the other Jovian moons. It’s enough to turn Io into a molten inferno, and to sustain the subsurface ocean of Europa.
I don’t know an exact figure, or even a rough estimate, but I suspect the thermal impact of the tidal interaction of our moon on the Earth is small. Presumably some friction due to the tides sloshing water around and some energy added to rocks as the moon’s orbit varies.
Yep. Many of Jupiter’s moons have icy surfaces with melted water underneath due to tidal heating.
Eh, not much these days. There is some but it’s not that significant overall. The Earth also causes moonquakes and heats up the moon a bit, but not enough to melt anything.
Way back when the Moon was still a new thing, it was much closer to the Earth, and back then its influence was much greater. Tidal forces were larger and heating was more significant. As the moon slowly moved away from the Earth, the tidal forces and heating decreased as well.
I thought I had posted it to “factual questions.” I am looking for a factual answer.
To use an inexact but perhaps entertaining simile- The earth is running a high fever temperature, and the core cooling is like applying a ice cube to the little toe.
Ok, try it like this. If you were several hundred million miles from Earth and could take the temperature of the planet from that distance, would it be higher or lower today than it had been 500 years ago?
Any temperature you could measure would be at the surface, which is definitely, unambiguously, hotter now than it was 500 years ago.
Great! That’s where I moved it. Must have just been a slip of the mouse.
Especially true given that 500 years ago the Earth was in the “little ice age” (roughly 1400s to the mid 1800s).
The measured temperature on the outside of a metal mug (say one of those fancy Yeti or RTIC ones) of coffee and the temperature of the coffee itself will be different. And the effect on the outside of that mug from leaving it outside on a sunny, summer day will be noticeable compared to leaving it in the shade, regardless of the temperature of the coffee inside.
The coffee/mug system (like the earth) is not isolated from external energy.
ETA: likewise, on a sunny, hot summer day, what is the difference in cooling a freshly baked pie in direct sunlight vs cooling one in the shade. They will both cool but at the same rate?
Although we’re significantly further from “normal” now than we were in the Little Ice Age.