The Jovian Opposition Shows Scars

Yes, we know, with a title like that, you’re probably expecting something about an obscure political party. Fortunately for you, what we’ve got is much much more interesting. Jupiter is at its brightest for about the next thirteen months, as the Earth is nearly directly between it and the Sun. While Jupiter doesn’t go through phases, since it’s in a superior (farther out) orbit, this means that we’re effectively at ‘Jupiter as close to being ‘full’ as it gets.

When you look out on the ecliptic, you’ll spot Jupiter in late evening, shining like a very bright star. A small pair of binoculars will quickly resolve it as a disk, and if you watch long enough, you can see the banding of the atmosphere, including the Great Red Spot, and the Galilean moons.

Right now, Io (the inner most moon, and the most volcanic body in the Solar System) is eclipsed by Jupiter, but by the 15th (the night of the opposition) it will be out from behind the planet. Europa (the moon that’s a cracked billiard ball and likely covered by a hidden ocean of water) is also coming out of her eclipse by Jupiter.

Shortly after Jupiter becomes visible, the Great Red Spot will become visible near the equator; this giant weather feature (which is undergoing interesting changes) is several hundred times the size of the Earth. Near the southern pole of Jupiter is the latest feature, the Wesley Impact Scar. This is the remnant of a cometary impact on Jupiter, and is a string of impacts. Interestingly enough, the Wesley impactor hit 15 years to the day of the anniversary of Shoemaker-Levy-9, and the impact released nearly15x the annual energy output of the planet Earth.

In our Solar System, Jupiter is so massive compared to the other bodies that it sweeps up a lot of debris from the formation of the solar system, comets and stray bits of matter. It also causes ripples in orbits of comets that come near it (to a lesser extent, the Earth does as well, as does any other body in the Solar System). The difference is that Jupiter is so much more massive that it does this much more frequently than anything else in the solar system.

If you want to catch the Wesley Impact Scar, you’ll need a fairly large scope and good seeing conditions; Jupiter being in opposition will help, but you’ll want at least a 10″ scope and good viewing conditions. It’s worth looking at – it’s an impact scar that’s larger than the planet you’re standing on, and should reinforce even more than the latest Hollywood blockbuster just how Titanic astronomical impacts really are.