Mercury and Jupiter
Written by Fraser Cain
Solar System montage
Let's compare and contrast the two most different planets in the Solar System, Mercury and Jupiter. Of course, you probably know that Mercury is the smallest planet in the Solar System while Jupiter is the largest planet in the Solar System.
First, let's just take a look at the physical measurements of Jupiter and Mercury. The diameter of Mercury is 4,879.4 km, while the diameter of Jupiter is 142,984 km. In other words, Jupiter is 29.3 times bigger across than Mercury. In terms of volume, you could fit 24,462 Mercurys inside Jupiter. Jupiter even has 5,750 times more mass than Mercury.
Now let's take a look at their composition. Mercury is a rocky terrestrial planet, with a high density. In fact, the liquid iron core of Mercury accounts for 42% of the planet, and this is surrounded by a mantle and crust of silica. Jupiter in comparison is a relatively less dense gas giant planet; it's made up almost entirely of hydrogen and helium, with a few other trace elements.
Mercury orbits very close to the Sun, with an average orbital distance of 57.9 million kilometers. Because it orbits so close, Mercury completes an orbit around the Sun every 88 days. Jupiter, on the other hand, is located 778.5 million km from the Sun and takes 11.86 years to complete a single year.
Mercury has no moons or rings, while Jupiter has a faint set of rings and 63 named natural satellites so far.
It sounds like Jupiter and Mercury are different in every way, but there's one big similarity. You can see them both with your own eyes. Jupiter is very bright and often very high in the sky. In fact, if you see a really bright star in the sky in the middle of the night, you're probably seeing Jupiter, and not a star at all. Mercury is also possible to see with your own eyes. But since Mercury orbits so close to the Sun, you'll only see it shortly after sunset or before sunrise until the Sun washes out the night sky.
We have written many stories about Mercury here on Universe Today. Here's an article about a the discovery that Mercury's core is liquid. And how Mercury is actually less like the Moon than previously believed.
Want more information on Mercury? Here's a link to NASA's World Book on Mercury, and here's NASA's Solar System Exploration Guide to Mercury.
We have also recorded a whole episode of Astronomy Cast that's just about planet Mercury. Listen to it here, Episode 49: Mercury.
Filed under: Astronomy
