Moon and Antares

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Nutritionists tell us to avoid high-sodium foods and instead eat foods that are high in potassium, such as orange juice and bananas. But that can be a challenge -- a challenge that comes from the stars, because they've made a lot more sodium than potassium.

Both elements are what chemists call alkali metals. They're in the first column of the periodic table. Sodium is atomic number 11, which means every sodium atom has 11 protons. Sodium is one of the ingredients in sodium chloride -- table salt. Consuming too much of it can raise your blood pressure.

Potassium, which is one row below sodium in the periodic table, helps regulate activity in muscles and nerves.

Both elements owe their existence to massive stars -- stars like one that's in good view tonight: Antares, the brightest star in Scorpius. It's to the left of the Moon at nightfall.

Stars like Antares are chemical factories -- they combine lightweight elements to make heavier ones, like sodium. At the ends of their lives, the stars explode as supernovae. During the explosion, oxygen atoms smash together to create a little bit of potassium.

Unfortunately, heavy stars make a lot more of the bad element -- sodium -- than the good one -- potassium. In fact, for every potassium atom in the universe, there are about 16 sodium atoms. That makes it a little tougher to avoid the salt.

So, as William Shakespeare might have said, the fault is not in us, but in our stars.

Script by Ken Croswell, Copyright 2008

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