To estimate the temperature of a theoretical new planet with similar characteristics to Earth but located between Venus and the Sun, we can examine a few key factors:
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Distance from the Sun: If the new planet is at the same distance from the Sun as Venus, it is approximately 0.72 astronomical units (AU) from the Sun.
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Atmospheric Composition: The atmosphere composed mostly of carbon dioxide (CO₂) and methane (CH₄) would be very effective at trapping heat due to their strong greenhouse gas properties. This would lead to a significant greenhouse effect, resembling the conditions on Venus.
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Solar Heating: The amount of solar energy received is greater at a distance of 0.72 AU than at Earth's 1 AU. The solar constant (solar energy received per square meter) increases as you get closer to the Sun. The solar constant at 0.72 AU can be calculated as follows:
\[ \text{Solar Constant} \approx 1361 , \text{W/m}^2 \times \left( \frac{1}{(0.72)^2} \right) \approx 1361 , \text{W/m}^2 \times 1.93 \approx 2620 , \text{W/m}^2 \]
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Calculating Effective Temperature: In equilibrium, the effective temperature of a planet can be estimated using the Stefan-Boltzmann law, considering the energy received and the assumption of black body radiation.
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Influence of Greenhouse Effect: The greenhouse effect from CO₂ and CH₄ would increase the effective surface temperature significantly above the equilibrium temperature.
Given a similar size and thickness of the atmosphere, the actual surface temperature could be expected to be much higher than the equilibrium temperature due to the intense greenhouse effect, potentially reaching temperatures similar to or higher than Venus (around 467°C or 872°F).
To summarize, if such a planet existed with the specified conditions, it could have a surface temperature similar to or perhaps even higher than that of Venus, likely exceeding 400°C (752°F) due to the combined effects of proximity to the Sun and the potent greenhouse gases in its atmosphere.