You’ve already seen it. You couldn’t help it. There in the west after sunset, two brilliant “stars” grab attention because they’re the brightest things in the whole sky: Venus and Jupiter. Each evening they’re closer together. Now, this weekend, it happens: the best conjunction of the year.
After exploring infinity and the Big Bang and multiverses the past few weeks, it’s great to get away from pure head-stuff and take a refreshing gander at real things in the real sky. No star charts needed. It’s in-your-face stargazing. You don’t even need a telescope.
Also, most of the sky-motion that we see comes from the simple fact of Earth’s quick rotation. Objects rise, march slowly to the right [if you are facing south] and set. So it’s stately – and strangely inspiring – to see changes caused by other planets. Dazzling Venus’ movement is particularly easy, because it travels through space even faster than we do. As we face it in the west each evening from 6:30 to 9 p.m., it’s zooming to the upper left at 22 miles per second. What makes its fast motion obvious is that it’s going to align with giant Jupiter, way off in the distance, which provides a nearly stationary background reference point.
The next clear evening, take a look. Venus is the very-brightest star and Jupiter’s the second-brightest. Each evening you’ll see Venus shift closer to Jupiter. From this Sunday through Tuesday (the 11th to the 13th), they’ll be closest together: a wonderful conjunction that shouldn’t be missed.
This all happens against the inconspicuous stars of the constellation Aries, which looks like a ram only to those who used illegal substances in college. Adding an extra touch, Venus is nearly at its very brightest. If you’re away from all artificial lights and away from town, you can see your shadow cast by Venus-light – if you can find a nice white surface, like snow, to make the shadow stand out. Otherwise, you can spread a sheet.
If you’re pointing out these planets to kids, it’s good to have a dramatic fact about each on hand, as gee-whiz material. For Venus, it’s the fact that, of all the objects in the known universe, this planet comes closest to not spinning at all. It rotates only once every 243 days – so slowly that a person walking along the Equator could keep night from ever falling.
For Jupiter, maybe it’s best to puncture the “almost-a-star” myth that one hears so often. Even if Jupiter had 50 times more mass than it does, pressures at its core wouldn’t reach the point where nuclear fusion could begin. It’s a planet, period – albeit so massive (318 times heavier than Earth) that all the others combined and doubled wouldn’t equal its weight alone.
I also like to visualize Jupiter’s ultra-strong magnetic field that traps and holds lethal radiation belts. This magnetosphere is the largest structure in the solar system. If it were visible to the naked eye, it would appear larger than the Sun. It’s a barrier that discourages salespeople or any other potential visitors from ever paying a personal call.
We can’t touch. But this week we sure can look.