14 Aug 2005
School is back in session, or about to be. And you or your child might be soon hearing the words, “And what did you learn over the summer?”
That Jennifer wants Brad back? Yawn. That gas prices soared. Boring! You need something smart and astronomical to fill this order. Never fear! Here are some quick trivia to impress both teacher and fellow students alike. Read them, know them, and go back to school mentally dressed to impressed! Here goes…
1. You learned that the big star-like object now in the western skies after sunset is Jupiter and it’s bigger than you ever imagined!
Jupiter, the 5th planet out, is so monstrous that it outweighs all the other planets combined! One can mix together all the planets, Mercury to Pluto, and still couldn’t make anything as massive as that Big Guy out there. And yet to see it, that bright lone dot in the sky, gives one an idea of how vast space really is. Our solar system, although huge, is vacuous beyond words. You might say it is nothing more than space, interrupted now and then by a seemingly random rock.
2. You learned that there is a vast reservoir of planet-like things out beyond Pluto!
Most of us learn of the nine planets, and their order, but very few of us are aware that beyond the common planets lies a dispersed collection of crud that extends for billions of miles still. Here are thousands of icy bodies in a donut-like area called the Kuiper Belt. It is here that astronomers working at Palomar have found icy bodies considerably bigger than Pluto! Will they be deemed planets, as well? Or will they keep their present non-poetic names of Kuiper Belt Objects? Will Pluto itself be downgraded to a mere Kuiper Belt Object? Stay tuned, the next year should be a telling time in the planetary sciences.
3. You learned that Mars is rising earlier and earlier in the evening, readying itself for a close approach in October.
As we pass Mars on our inside lane round the sun we will come closer to it, to be sure. It will get brighter and brighter in the night sky, it’s bright pinkish color setting it apart from the background stars. But unlike the internet stories being forwarded all over, the Red Planet will not be as bright and big as the full Moon! Nor will it pass so close that we can see the ice caps and dust storms with the naked eye. We’ll still need a scope to see those – sorry!
4. The whole classroom, the students, the books, the backpacks – even the teacher! – are made of atoms forged in the furnaces of giant stars that lived and died before our sun was even a thought in its parents’ minds.
You may recall from previous columns here that the great giant stars live and die a wild and crazy life. Their immense mass, sometimes a hundred times that of our own star, have such intense gravity that their innards get squished something frightful.
It’s OK! This pressing causes a process called fusion. Fusion “fuses” little hydrogen and helium and carbon atoms into bigger atoms. Fusion lights the great flaming plasma and pushes the gases back against gravity into a bright sphere that we see as a “star.”
But the big stars can only fuse to iron. Once iron is formed the process stops producing energy to balance the mighty crush of gravity. Gravity doesn’t care; it continues to push down anyway. In a complicated set of steps the star’s core collapses and explodes violently.
The violence is so intense that the atoms already there are fused further into essentially the entire Periodic Table, and thrown out into space.
Future star systems collect this debris into new stars and planets.
So, not only is our planet proper made of stardust, so is everything in it. That would include you and your backpack and the classroom hamster, Larry.
There! That should impress the teachers for a while. But don’t stop there! Go and discover more throughout the year, filling yourself not just with knowledge, but with understanding and appreciation for this marvelous universe we’ve been given.
Have a great school year!
07 Aug 2005
One great thing about summer in America is that we get two fireworks shows. Both are exciting and beautiful. Both elicit “ooohs” and “aaahs” from awe-filled spectators. Both take no more effort than to look up and enjoy.
But one is artificial, the other natural. Of course, the 4th of July celebration is the artificial, man-made one. But the other can be seen all over the world in the night skies around the 12th of August.
It is, of course, the Perseid meteor shower, an annual heavenly delight for people everywhere – astronomer or not.
The meteor shower is a friendly reminder that there is not just the sun and the planets in our solar system, but asteroids and comets, as well.
The comets are the main reason for our meteor showers, including this week’s.
Comets travel about the sun on highly elongated orbits, and slough off dust and gases when near the sun. We saw some of this dusty material get exploded into space when NASA’s Deep Impact spacecraft threw a projectile into a comet last month.
But the dusty material stays in pretty much the same very large orbit as the mother comet.
If the comet’s orbit happens to cross ours, our planet inevitably smashes into the dust train. As we do, the comet dust gets thrust into our atmosphere at great speeds, 10-40 miles per second!
When just a random sand grain-sized particle flies through our beefy atmosphere at that speed it lights up from all the friction with our air molecules. That, my friend, is a meteor.
When we hit a swarm of these tiny particles, as what happens when we hit the debris train from a comet, meteors can come fast and furious. That is a meteor shower. Instead of the usual 5-10 random meteors per hour we normally get, a good shower can provide us with hundreds or even thousands per hour.
The Perseids originate from the jetsam of Comet Swift-Tuttle. Its latest fly-by was just over a decade ago, and at the moment it is very, very far away. But although the comet proper is presently way over yon, we are passing through its debris train now!
You may have already seen a Perseid meteor – we are already in the outer edges of the trail of schmutz. But the time to really make time for them is either the night of the 11th or the 12th. It is then that we pass through the thickest parts of the dross, kind of guaranteeing a fairly good fireworks show. But it’s never a sure thing.
The predicted peak is Friday night, a good night since most need not worry about school or work the next day. And, more importantly, the Moon will be setting about midnight, right before Prime Time for Meteors begins. Yes, sorry, I said after midnight.
The reason the best time for meteor showers is after midnight is because that is when our location on earth turns full face into the cloud of crud. Imagine sticking your head out the car window while being driven through a light rain. Face backwards and your face feels nary a drop. But turn around into the direction you’re being driven and, ouch! its full immersion time.
How many you see will also depends on your viewing conditions. Are you in the city? You’ll see the bright ones, but that’s it. Out where its dark with no interfering man-made lights, and with few hills or trees surrounding you? Then you may see one every couple minutes.
Best for all, you need not be an astronomer to enjoy it. You do need a place to observe them; lay down for maximum comfort. You need to smear on the DEET before you go out - West Nile virus is no fun I hear. And even if it’s warm, dress in layers. It will get cold later even on a hot night.
But because the meteors during a shower never hit the ground, you needn’t worry about bringing along one piece of equipment: an umbrella.