A week of planets

If you follow science news, you may have noticed some buzz about Mercury’s May 9 solar transit. Because of cosmic geometry, the transit was not visible from a broad swath of the west Pacific. That swath included Saipan. But this week is still a good one to think about planets, so here we go.

Oddly enough, I happened to be at an astronomy gathering during the event, but it wasn’t because of Mercury. Those who observed the transit (I didn’t) saw the teeny-tiny dot of Mercury’s orb crawling in front of the sun. This wasn’t a naked-eye gig. It required some equipment and technique. Photos are all over the Web, and I did look at some of those.

The photos put the sun’s imposing size into perspective. In normal, everyday life, we have no sense of the sun’s scale. Mercury is the smallest planet in our solar system, but it’s still very much a planet, and photos of the transit make it look so fleetingly small against the mighty backdrop of the sun.

Since Mercury is the closet planet to the sun, you’d expect it to be parched, and some of it is, with temperatures that reach 800F. On the other hand, parts of Mercury also get to hundreds of degrees below zero. This wacky hot-or-cold situation is the result of having no atmosphere (well, none worth writing home about, at least), so there’s no gas blanket to smooth out the extremes.

If the weather is lousy, the scenery isn’t much better, either. Its surface is pocked with craters and it looks like the moon. However, it doesn’t even have a moon of its own. Poor Mercury.

And, poor Earth, eventually. Mercury’s barren fate awaits us in one or two billion years. That’s when the sun will succumb to middle-aged bloat. Its expanding belly will boil off the earth’s atmosphere and oceans. I guess we’ll still keep our moon, but there won’t be anyone left to appreciate it.

But here’s something to appreciate: Jupiter. Mercury’s transit may have cold-shouldered Saipan, but Jupiter, big, bright, and fat, more than makes up for it.

Jupiter is hanging high overhead, in a perfect position to be viewed from Saipan. If you take a look at about 9pm this weekend, Jupiter will be about 60 degrees above due west, and it will be the brightest thing in that part of the sky except for the sliver of the Earth’s moon. This is an easy find for everyone on Saipan, even if they live on the east side of the island.

Jupiter is the king of our planets, by far the biggest, and if its moons we’re after, Jupiter has at least 67 of them. The biggest four of those are easily visible through small telescopes, and even a decent pair of binoculars can pick them up. These four moons are called the Galilean moons, having been discovered in 1610 by Galileo Galilei

Believe it or not, a small telescope can even see Jupiter’s upper-level clouds, which appear as broad bands.

Some libraries in the mainland are starting to allow patrons to borrow telescopes. The cases I’m aware of are loaning out 4.5-inch (that’s the diameter) scopes made by an American company called Orion. These scopes should have no problem seeing Jupiter’s cloud bands as long as the local sky, and the telescope, are in decent condition.

As for the Galilean moons, they put on quite a little cosmic ballet because they whirl around Jupiter so rapidly. If you take a couple of glances at them just a few hours apart, you can often notice that their relative positions have changed, or some have dropped out of sight, or some have popped into sight or, of course, some combination thereof. This show never gets old. I try to keep a small telescope at hand (a 4.5-inch Orion, as a matter of fact) so I can enjoy Jupiter without having to haul out my heavier stuff.

Well, we’ve accounted for Mercury and Jupiter this week, but NASA upstaged this action with a big announcement: The agency just unveiled the discovery of 1,284 planets outside of our solar system. Naturally, there’s all sorts of speculation about which planets might be candidates for extra-terrestrial life, so if you’re interested in such things, this is a good time to get an updated look at the science news.

All in all, then, it’s been a good week for planets.