How Can Planets Lose Heat Convective Radiation From Within?

The Earth’s internal heat is a result of various processes, including the decay of radioactive elements such as potassium, uranium, and thorium. As the Earth’s size increases, so does its heat loss to space. Convection transports heat as hot material rises and cool material falls, transferring heat from the mantle to the crust and escaping into space through radiation. The rate at which a planetary interior cools depends on its surface-to-volume ratio.

A major source of Earth’s heat is radioactivity, which is released when unstable atoms decay. As Earth’s size increases, increased pressure on its interior causes it to compress and heat up. Heat also comes from friction when melted material is redistributed within Earth, forming the core and mantle.

The Sun generates energy that is transferred through space to the Earth’s atmosphere and surface. Some of this energy warms the atmosphere and surface as heat. There are three ways energy is transferred: convection, radiation, and the surface-to-volume ratio.

Radioactive decay of metals in a planet’s core can generate heat for billions of years, constituting about half of its heat content. Heat content depends on volume, while loss of heat through radiation depends on surface area. Time to cool depends on volume.

Approximately 99 percent of Earth’s internal heat loss at the surface is by conduction through the crust, with mantle convection being the dominant control on heat. In planetary interiors, heat is generated by the decay of radiogenic isotopes 235U, 238U, 237Th, and 40K. Latent heat may also be present.

Earth’s mantle stops convecting once the core has cooled to the point where there is not enough heat transfer to overcome the strength of the rock. Heat transfer shapes planets’ interiors and surfaces, with various sources warming planetary cores.

What are the three sources of heat inside planets?

The deep earth contains three main sources of heat: heat from the planet’s formation and accretion, frictional heating caused by denser core material sinking to the center, and heat from the decay of radioactive elements. Heat moves slowly out of the earth through convective and conductive transport, retaining much of its primordial heat from the first accretion and development of its core. The amount of heat that can arise through simple accretionary processes, bringing small bodies together to form the proto-earth, is large, around 10, 000 kelvins (about 18, 000 degrees Farhenheit).

The key issue is how much energy was deposited into the growing earth and how much was reradiated into space. The current idea for how the moon was formed involves the impact or accretion of a Mars-size object with or by the proto-earth, which could have melted the outermost several thousand kilometers of the planet.

How does the planet lose heat?

Solar energy is absorbed by the Earth and converted into various forms of heat energy. Some of this energy is converted into thermal radiation, which can escape through the atmosphere and contribute to OLR. The rest is transported upwards through various heat transfer mechanisms, resulting in the emission of thermal energy as thermal energy. This energy is then radiated into space in the form of longwave radiation.

The transport of longwave radiation is governed by radiative transfer equations like Schwarzschild’s equation and Kirchhoff’s law of thermal radiation. A one-layer model provides an approximate description of OLR, resulting in temperatures at the surface and the middle of the troposphere that are close to observed average values.

How the Earth’s interior is heated by radiation?

The majority of Earth’s interior heat, up to 90%, is fueled by the decaying of radioactive isotopes like Potassium 40, Uranium 238, 235, and Thorium 232 within the mantle. These isotopes radiate heat as they shed excess energy and move towards stability, causing almost the same amount of heat as the total heat measured from Earth. Radioactivity is present in both the mantle and Earth’s crust, with a 1-kilogram block of granite emitting a tiny amount of heat through radioactive decay.

How do satellites get rid of heat?

The satellite’s heat is transferred between its components through radiation and conduction, and dissipated from its external surfaces through radiation into space. Heat transfer occurs between electronic components and the structures that support them.

How do planets lose their internal heat?

Accrution and differentiation occur when planets were young, with initial internal heat from formation dissipating depending on the size of the planetary body. Smaller bodies like the Moon or Mercury have lesser internal heat than Earth. Convection transports heat as hot material rises and cool material falls, transferring it from the mantle to the crust and escaping into space through radiation. The rate at which a planetary interior cools depends on its surface-to-volume ratio, with larger objects cooling more slowly.

Smaller worlds cool off faster and harden earlier, making the Moon and Mercury geologically “dead” due to their loss of internal heat from formation hundreds of millions of years ago. Earth, on the other hand, has cooled more slowly than smaller terrestrial planets due to the decay of radioactive isotopes, which keeps much of its interior molten and drives plate tectonics that shape and reshape the Earth’s surface.

How did Mars lose its heat?

The transition of Mars from a warm, wet climate to a cold, dry one was largely due to the loss of a significant portion of its atmosphere to space. In contrast, the Earth’s magnetic field, which deflects the solar wind, has allowed the development of life on Earth.

Is the Universe losing heat?

The hypothesis of heat death suggests that if the universe’s curvature is hyperbolic or flat, or dark energy is a positive cosmological constant, it will continue expanding forever, leading to a cooling to equilibrium at a very low temperature. This idea was first proposed by Lord Kelvin in the 1850s, who extrapolated the theory of heat as mechanical energy loss in nature to larger processes on a universal scale. This led to the formulation of the heat death paradox, which disproves an infinitely old universe.

The second law of thermodynamics, which states that entropy tends to increase in isolated systems, supports this hypothesis. It suggests that if the universe lasts long enough, it will asymptotically approach a state where all energy is evenly distributed. This implies that the mechanical movement of the universe will run down as work is converted to heat due to the second law.

What causes internal heating in planets?

The core of a terrestrial planet represents the primary source of internal heat, which is generated by a number of processes, including a hot atmosphere, tidal heating, and radioactive decay of elements. These processes can be significant in terms of their ability to create heat.

How are planetary interiors heated?

Planetary interior refers to the internal structure of a planet, including the mantle and core, where heat is generated and transferred through processes like convection and thermal diffusion. This influences geological phenomena like volcanism, plate tectonics, and magnetic field generation. ScienceDirect uses cookies and holds copyright for text and data mining, AI training, and similar technologies. Open access content is licensed under Creative Commons terms.

How is heat lost in space?

In the vacuum of space, both Earth and the International Space Station (ISS) receive heat from the Sun. However, the transfer of heat is not identical in both cases. The vacuum of space precludes the transfer of heat by conduction and convection, as occurs on Earth and within the ISS. Instead, radiation is the sole means of heat transfer in the vacuum of space.

What are the 3 types of Earth’s internal heat?

Heat transfer is a process that occurs in three main forms: radiation, conduction, and convection. Conduction is the most significant form of heat transfer in solid Earth regions, while thermal convection occurs in the viscoelastic mantle and molten outer core. Access to content on Oxford Academic is typically provided through institutional subscriptions and purchases. Members can access content through IP-based access, which is provided across an institutional network to a range of IP addresses, and through signing in through their institution, which uses Shibboleth/Open Athens technology to provide a single sign-on between their institution’s website and Oxford Academic.