|Why is Venus hotter than Mercury if Mercury is
closer to the sun?|
|Question Date: 2013-02-28|
This is a great question! The answer to it
lies in the fact that Venus has a very dense
atmosphere made up of carbon dioxide, nitrogen,
and sulfuric acid, while Mercury has a very thin
atmosphere with various gases, but very little
carbon dioxide. So what's so important about
carbon dioxide? Well, sunlight will pass through
Venus' clouds (which contain mostly carbon
dioxide) and warm the surface of the planet.
Usually, the surface of a planet is warmed
during the day and cools off at night by
releasing infrared radiation (heat) back into
space. But the carbon dioxide in Venus' clouds
absorbs energy from infrared radiation very well
and "traps" the heat on the planet, making it
very warm. This has sometimes been called
a "runaway greenhouse effect." We don't see this
happen on Mercury because its atmosphere is not
thick and does not have much carbon dioxide in
it. I hope this helps!
Venus is hotter than Mercury because it has a
much thicker atmosphere. The atmosphere, the
gaseous layer surrounding a planet, is like a
blanket. Think of two people sitting next to a
campfire one is much closer to the fire while
another is further away. The one that is closer
doesn't have a blanket (Mercury), while the
other further away has a sleeping bag (Venus).
Both persons are getting heat from the fire but
the person with the sleeping bag keeps all the
heat he or she gets. Mercury is closer but
because it has a very thin or no atmosphere at
all the heat goes out into space. Venus on the
other hand with it's much thicker atmosphere
holds all the heat it gets. 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.
Venus is hotter due to the greenhouse effect:
Venus has an atmosphere about ninety times
thicker than that of Earth, and made almost
entirely of carbon dioxide, which is one of the
gasses that causes the greenhouse effect on
Earth. The greenhouse effect on Venus is so
great that it raises the surface temperature on
Venus to, as you say, hotter than that of
Mercury, despite being farther from the sun.
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