Everyone Knows That Mercury Is Scorchingly Hot. How The Hell Is It So Icy!?

Abdullah Almomtan
2 min readAug 30, 2021

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My Very Excellent Mom Just Served Us Noodles. Using this mnemonic device, I can remember the planets of the solar system in order: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. So, Mercury is the closest planet to the Sun and is naturally the hottest. It’s so hot that it literally can’t form an atmosphere, the atoms can’t sit still enough to form one. But, astronomers have detected signs of huge amounts of water ice there! How is this possible? Well, it seems that it’s because of the scorching Sun that so much ice forms!

COURTESY OF NASA, JOHNS HOPKINS UNIVERSITY APPLIED PHYSICS LABORATORY AND CARNEGIE INSTITUTION OF WASHINGTON

First Things First: Where Did The Water Come From?

As I said, Mercury has no atmosphere. So, It doesn’t have anything to protect it from asteroid and comet collisions; these comets are usually waterlogged. So, a lot of this water pooled and froze in craters around the poles. A similar phenomenon happened to our Moon, except for the fact that it contains less ice, even though the Moon is much colder than Mercury.

Why Does Mercury Have More Ice Than The Moon, Then?

Let’s break water down, shall we? A lot of chemical compounds contain a positive part and a negative part, and so they attract each other. Water’s 2 parts are (H+) ions and (OH-) ions, which combine to form H2O. It so happens that the Sun releases a huge amount of charged particles, called solar wind, and one of those particles is (H+), and the minerals in Mercury contain a lot of (OH-). During the day, those ions separate from the minerals because of the heat (I’m running out of adjectives to describe the intense swelter on Mercury), and collide with the (H+) ions from the solar wind, forming H2O. Some of that water drifts off into space, and some of it reaches the poles, where it’s colder, and freezes.

The Moon also has minerals containing (OH-) ions, but it’s too cold there to free them from those minerals nor to catalyze the reaction between them and the (H+) ions.

Sources

Georgia Institute of Technology. “Mercury’s scorching daytime heat may help it make its own ice at caps.” ScienceDaily. ScienceDaily, 13 March 2020.www.sciencedaily.com/releases/2020/03/200313155329.htm.

“Georgia Institute of Technology.” Georgia Tech’s Research Horizons Magazine, 24 Aug. 2021, rh.gatech.edu/features/mercurys-400oc-heat-may-help-it-make-its-own-ice.

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