30 Oct 2005
After all the internet hype a couple months ago about Mars appearing “as big as the Full Moon,” and then suddenly vanishing, I fear the truth about our Little Red Buddy’s latest close encounter may be a little… uhhh… anticlimatic.
I’ll risk telling you about Mars anyway, without all the urban legend embellishments, and bruit proudly of the truth about that bright pink dot gracing our evening eastern skies.
Mars, as you know, is our fourth rock from the sun. A tiny rocky planet, it is only about half the size of our own.
Of course there are other rocky planets in our neighborhood but they’re tough to examine .
Mercury always hugs the sun, so it’s difficult to see in all the brightness. Venus is big and bright to be sure, but she is cloud-covered all the time.
Mars, on the other hand, has a load of features on its surface, and there is no better time to espy these than now - at opposition.
Opposition is when a planet is on the opposite side of the sky as the sun. As the sun sets, the planet rises and thus stays in the sky all the live-long night. From a big picture view, we in our orbit have finally caught up with Mars in its orbit. Which means not only is the planet up all night, but we are at our closest approach to it, as well.
These are two things that get the astronomer’s heart beating just a wee faster.
And as an added bonus, on this fly-by we are closer to Mars than usual. What do I mean by “usual”?
Mars’ orbit is not exactly a perfect circle. It’s actually rather elliptical, like the rim of a drinking glass seen at an angle. This means that sometimes Mars is close to the sun – what astronomers call perihelion - and sometimes it is far, aphelion.
Well you can imagine then that the best time to be near Mars is when Mars is nearest to the sun. We can just about shake hands as we pass by. It is then we get a fine close-up look at our little friend.
We were just about as close to Mars as we can get the last time we flew by the Red Planet. That was in 2003. But even though we aren’t now at the absolute closest we can get – Mars is just a bit away from perihelion - we are close nevertheless.
What also makes this year’s opposition so good is good position in the sky. Meaning this: We are at the time of the year when the sun is creeping lower across the sky, and the time when the planets at night will do the opposite. They will rise high in the sky. The benefit?
This means a planet will be high above the heat waves, off the horizon. There will be good “seeing” as we say in the biz.
So you will be able to see more clearly all those features that we’ve been watching for the last 400 years.
Get out a scope and scope out for yourself Mars’ polar ice caps. And see the dark areas in contrast to the light areas. When you do so you’ll be seeing history.
For the last part of the 19th century and far into the 20th century many thought that those dark areas were vegetation and that the polar ice caps were made of water. This, together with some vivid imaginations that saw non-existent canals strewn across Mars, made many people think that Mars was filled with… well… Martians!
So grab yourself a scope or get together with an astronomy club and go take a look at the Red Planet in the next couple weeks.
If you’re a glutton for punishment and want to see Mars when it’s at its most distant opposition, you’ll have to wait until the year 2832. March to be exact. Mark your calendar!
Until next time, clear skies!
16 Oct 2005
Quiz Time! The following statements are true or false. Ready?
1. It’s easy to spot Mars in the sky. It’s the only red thing up there!
Mars is known as The Red Planet. And as we’ve seen from all those pictures coming in from those tiny spacecraft traveling about the planet, it does indeed take on a reddish hue. A lot of the surface of Mars is made up of oxides of iron, similar to rust. Hence the ruddy look.
But it isn’t really too red in the sky. In fact, it barely makes pink. But it has enough of a tinge of red that we can still call it the red Planet and not lose sleep about it.
But it’s not the only red thing in the sky. Stars can be red, too! It all depends on their temperatures.
In astronomy really hot stars bleed all the wavelengths of light but really pour out the blue, cooler stars appear white and yellow (like our own), and the coolest stars only get to red.
It’s the small stars, the runts of the cosmic family, that can’t raise their surface temps too high. They can’t fuse a lot of material down in their cores and therefore never really cough up enough energy to heat the place up too much.
But there are monstrously big stars that are red, too. How’s that??? The bigger stars, when they reach the end of their lives, expand to enormous sizes. You may remember from school that when gases expand they cool. As these monsters outmonster themselves, their surfaces cool. As they cool they change color, many eventually reaching redness.
There are several of these “red giants” visible in the skies, one of which is Antares in Scorpius. What an amazing coincidence! Antares means anti-Ares, rival of Ares. Ares was the Greek version of the Roman god Mars. Antares is named so because it is often confused with our friend Mars.
So the original statement is false. Mars isn’t really that red, and there are many other things in the sky that are actually redder.
2. It’s only in the last couple centuries that people have known that the world isn’t flat.
There were these people who lived more than 2000 years ago called the ancient Greeks Some of them liked to sit around all day and think… and think… and then think.
Some of these guys thought about this: Why is the shadow of the earth on the moon always round when there is a lunar eclipse. Well, they thought, what always makes a round shadow? Hmmm…
A sphere of course!
There were a lot of other evidences, too. But the point is, they knew earth was round. They even figured out its circumference, the distance around, without even going around the planet.
Most educated people since those ancient times thought the world was spherical. The uneducated folks often thought the world was flat because… well… it sorta looks that way!
But that we just recently discovered the planet is a big ball is a big myth.
3. The Milky Way we see in the sky and the Milky Way galaxy we live in are the same thing.
Throughout the year, but especially during the summer, there appears in a dark unpolluted sky, a band of light called the Milky Way. It is the source of a thousand myths from peoples all over the world.
But it wasn’t until Galileo’s time that it was discovered that that great band was actually a great field of stars. Peering into the belt with a telescope one can see countless tiny stars of all colors.
And it wasn’t until the beginning of the 20th century that it was discovered that there were other galaxies in the universe, distant monstrous collections of billions of stars each! We were just one galaxy of billions!
It turned out that Great Band of light we called the Milky Way was – ahem - us.
How can it be that we can see countless spiral and elliptical and irregularly-shaped galaxies all over the place filled with billions of bright stars each, but we can only dimly see our own?
To view our place in our great spiral of stars imagine wading in a harbor filled with hundreds of boats. Above you is sky, below you is water. It seems the boats are pretty much limited to a band surrounding you.
In space we have a clear view above the spiral and a clear view below, but in the spiral, where we live, there are literally hundreds of billions of stars, like the boats in the harbor.
Well then, since we are drowning in stars, the whole place should be lit up! Well, there are lots of stars to be sure, but there is also a truckload of dust up there. The dust blocks a lot of the light from ever reaching us.
So, to conclude, the Milky Way we see in the sky and the Milky Way galaxy are the same thing – our amazing home.
How did you do this time? Are there questions you would like to see here? Write me with them!
Until next time, clear skies!
02 Oct 2005
Hurricanes. Can’t live with them, can’t live without them.
Hurricanes have gotten a bad rap lately for obvious reasons. Two big reasons are Katrina and Rita, the two latest hyper-destructive cyclones to hit our country. And more are probably on the way, if not this year, then the next, and the next…
But if we look closer at them, we might come to a conclusion that they really aren’t that bad. Put down those torches and pitchforks! Let me put a positive “spin” on hurricanes…
Our planet spins and spins, all the live-long day. It is because of this spin that we have the giant ocean currents that swirl around the Atlantic, and the overall nice weather that our friends in the south enjoy and which attracts millions of tourists annually.
As the warm waters of the ocean currents around the southern latitudes cycle up toward the north, they can spawn hurricanes. It seems now that the warmer the waters, the faster the currents. And the faster currents lead to more terrifying hurricanes.
It appears that this all occurs in an oscillating kind of way. Meaning that we are in a heavy hurricane period - now. But the 1970’s through the early 1990’s saw lower temps and fewer monster ‘canes. Before that, from about the mid-1920’s to the late 1960’s, it was warmer and nasty hurricanes were more numerous. As far back as we’ve recorded, heavy hurricane decades appear to come and go.
Bottom line for the moment: We are probably in a time of higher hurricane numbers, and they may be bad for some years to come.
So how can any of this hurricane stuff be good? How is it we “can’t live without them”?
Few of us have thought through what it would be like if conditions were not ripe for hurricanes.
For example, what if the world were spinning even faster? What if our day were just a few hours long rather than the 24 hours it is now?
Early on in the history of our planet, we probably had 5-10 hour days. The earth spun quicktime to say the least. Spinning this fast meant that we had winds, severe winds, all the time. And I ain’t talking the wimpy Santa Ana type or even the slightly-less-winpy Katrina kind.
An astrophysicist friend of mine calculates that in those early days the winds swept over at hundreds of miles an hour - if not over a thousand – all the time.
We see tremendous wind speeds like this on the “gas giants” in the outer solar system. Those planets out there, all of them, spin fast. Neptune’s winds average over 2000 miles per hour.
Now, you can fly one mean kite under these conditions, but you will not enjoy life on a planet with winds that can tear your hair off your head.
And the weather patterns on those planets are confined to narrow bands across the face of the planet. This is hardly the lazy ebb and flow of high pressure and low pressure systems we see the local weather guy trying to explain on the 6 o’clock news.
If our spin rate were slower, if our planet took 30-40 hours or more to slooooowly spin around, things don’t get better.
We may avoid ideal hurricane conditions of today, but there would be other, much more severe, things to worry about.
Imagine having the sun up for more than 20 hours at a time, heating the equator and mid-latitudes to a fare-thee-well.
Just as bad, the sun would be gone for about the same amount of time, our stored heat now flowing out into space with nothing to replace it, thus cooling us way, way, down.
Each “day” we would experience extreme temperature fluctuations.
Right now our spin rate allows us a blessed midway between the extremes. Our planet spins just fast enough that weather systems can sweep nicely across the face of continents, delivering alternating times of life-giving rain and sunshine for much of the planet.
Not too fast a spin, not too slow… but just right for a tremendous amount of ideal living space.
And, let’s be honest, hurricanes hardly pop up at random spots over the globe. The real estate they claim for themselves is pretty well established. We know their favorite haunts and, thanks to modern technology, we can track them as they meander across the Gulf. This, ideally, gives people who choose to live in such vulnerable areas ample time to prepare or evacuate.
And lest you think I’m harshly judging the people of the south for choosing to live in a veritable parking lot for hurricanes, I myself have chosen, with full knowledge, and under no duress, to live in a part of the country ripe for earthquakes.
Even though hurricanes seem like natural evils - and to be sure they can bring much pain - I might argue here that they are a relatively minor price to pay in comparison to what “might be.”
A hurricane is, for me, another awesome and terrifying reminder that this planet we live on, this rock we call our home that literally bursts with abundant life, is an amazing work of just-right art.