Hi there! I'm Dr. Stella, a planetary scientist with a focus on the inner solar system. I've dedicated my career to studying the rocky planets, including Mercury and Venus, and I'm thrilled to share my expertise with you.

You've posed a fascinating question: which planet is hotter, Mercury or Venus? It's a common misconception that Mercury, being closest to the sun, holds the title for the hottest planet. However, the reality is much more intriguing.

While proximity to the sun plays a significant role in a planet's temperature, it's not the only factor at play. The <span style="color:red">atmospheric composition</span> and its ability to trap heat, a phenomenon known as the <span style="color:red">greenhouse effect</span>, is crucial in determining a planet's surface temperature.

Let's delve into the specifics of Mercury and Venus:

Mercury:

* Proximity to the Sun: Being the closest planet to the sun, Mercury receives the most intense solar radiation.
* Lack of Atmosphere: Mercury has an extremely thin atmosphere, almost negligible, referred to as an <span style="color:red">exosphere</span>. This means it lacks the capacity to trap heat.
* Temperature Fluctuations: Due to its proximity to the sun and lack of a substantial atmosphere, Mercury experiences drastic temperature variations between day and night. Daytime temperatures can soar to a scorching 800 degrees Fahrenheit (430 degrees Celsius), while nighttime temperatures plummet to a frigid -290 degrees Fahrenheit (-180 degrees Celsius).

Venus:

* Distance from the Sun: While Venus is farther from the sun than Mercury, its dense atmosphere creates a unique situation.
* Dense Atmosphere: Venus boasts an incredibly dense atmosphere composed primarily of carbon dioxide (CO2). This thick CO2 blanket traps heat from the sun, leading to a runaway greenhouse effect.
* Extreme Temperatures: The runaway greenhouse effect on Venus results in a scorching average surface temperature of around 867 degrees Fahrenheit (464 degrees Celsius). This extreme heat makes Venus the hottest planet in our solar system.

The Verdict:

Despite being farther from the sun, Venus wins the title of the hottest planet in our solar system. Its incredibly dense, CO2-rich atmosphere and the resulting runaway greenhouse effect trap heat far more effectively than Mercury's thin exosphere.

It's a fascinating example of how atmospheric composition plays a critical role in shaping a planet's climate and habitability, reminding us that proximity to the sun is only one piece of the planetary puzzle.
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Venus is hotter than Mercury because it has a much thicker atmosphere. ... The heat the atmosphere traps is called the greenhouse effect. If Venus did not have an atmosphere the surface would be -128 degrees Fahrenheit much colder than 333 degrees Fahrenheit, the average temperature of Mercury.read more >>