19 Oct 2008
You have probably noticed in the last several weeks a bright "star" in the western skies as the sun sets. That is our old friend, Venus, presenting herself as the Evening Star. There is no need to rush to see the dazzling planet; Venus will be hanging around in that part of the sky well into next year.
The reason I bring it up now is because it was this week, 28 years ago, that a spacecraft landed there and snapped the first pictures of the Venusian surface, an amazing feat of engineering and perseverance. Why? I thought you'd never ask!
First, sending a spacecraft anywhere is an awesome accomplishment. It has become pretty commonplace now with missions currently to Mercury, Mars, Jupiter, Saturn, and even tiny Pluto, so we take it almost for granted. But putting a car-sized laboratory on a rocket and firing it into space at exactly the right speed and direction to arrive at a place millions or billions of miles away, months or years later, and land in exactly the right spot - that is worthy of more than a pat on the back.
But a trip to Venus has its own extra bucket of angst. Not only do you have to get there perfectly, you have to land on its surface. And Venus' surface is nothing like what we have here or even on tiny Mars. It is hellish.
In the days of old - early last century - it was believed that the surface of Venus might be paradisiacal. The planet was covered with clouds, so there must be water there - probably oceans! And of course, in the eyes of many even today, water on a rocky planet means life.
Well, it turned out the paradise was more like a purgatory. Those clouds turned out not to be water, but sulfuric acid, the stuff of battery acid. And the atmospheric pressures below the cloud cover ballooned to about 90 atmospheres, which means about 90 times what we have on earth's surface. You know how diving to the bottom of a pool makes your ears hurt from the pressure of the water? Imagine diving over a half mile deep into the ocean. Those are the pressures you get on Venus just by standing on the surface.
And it turned out the temperature was not just toasty warm, it was hot enough, at over 800 degrees Fahrenheit, to melt lead. So attempting to land anything on Venus meant battling corrosive acids, crushing pressures and metal-melting temperatures. No easy task.
But those competitive friends of ours from the Soviet Union took on that task in a series of missions spanning over two decades, from the early 60's to the 80's, in a program called Venera.
Those of us growing up during that time know that we were competing with them in everything, including any type of space flight, manned or not. They won many of the competitions, including first spacecraft in orbit and first human in orbit. We stole the show with the first man on the moon in 1969.
But the Venera program gave the Soviets several other "firsts." The Venera missions alone were first to enter another planet's atmosphere, first to land safely on another planet, and, in the event we mark here in this week's column, the first to send back pictures from another planet.
It was Venera 9 that sent back a few black-and-white pictures of the scorched surface of Venus before the spacecraft itself was consumed by the heat and pressure less than an hour after it landed. A belated congratulations to the Soviet engineers on a job well done!
Plans to revisit the Venusian surface are in the works but launch dates are unknown. Right now it is "study from above," in orbit around the planet and safe from ungodly conditions below.
Next time you see Venus - like on the 31st when it is near the crescent Moon - take in its dazzling beauty. But also give thanks that you are seeing it from the surface of an amazingly gifted - and safe - planet.
05 Oct 2008
Eighty five years ago, on the 5th of October, 1923, a cosmic discovery was made from nearby Mt . Wilson Observatory. It was the finding of just a single star in a distant galaxy, but it was a sighting that would forever change the way we'd see our place in the universe.
For as long as man has looked up into the skies it had always appeared that we were at the center of all there was. It wasn't for some self-centered reasons that we came to that conclusion; it was because it really looks that way. We on earth feel no movement, but we see everything seemingly moving around us. We must, therefore, be at the center of a giant sphere of starry hosts.
That belief took a big hit in the 16th and 17th centuries when our worldview changed to one in which our planet, and all other planets and stars, orbit around something else - our sun. This was the great time of Copernicus, Kepler, and Galileo.
Time continues on, and with the invention and improvement of the telescope it was revealed that there are countless stars out there in all directions. Gradually, after decades of refining and reinterpreting our observations, it became the accepted view that our galaxy, our island universe, was all there was. We were a planet orbiting a star, and our star was a mere grain of sand in a giant starry sandbox.
And that was it. Beyond our sandbox was the void.
By the end of the 19th century, people started seeing things in their telescopes which were curiously like miniature versions of what we thought the entire Galaxy might look like. Were these spiral-shaped clouds - called nebulae - merely new stars being born, or were they distant galaxies like our own? If new stars, then our view of the galaxy remains safe. If distant galaxies, then a new paradigm shift awaits offstage ready for an entrance that will put a whole new plot twist in the Grand Scheme of Things.
You see, if they are distant galaxies then the universe is unimaginably bigger than anyone ever thought, and our galaxy would be just one of innumerable other galaxies. For some this would have deep philosophical implications.
If there was just some way to see more detail in those "nebulae" this problem would have an answer. As scopes were getting bigger, more detail could be seen, and some astronomers swore they saw stars in the swirls which would reckon them as distant galaxies, not local clouds.
It wasn't until Edwin Hubble came along that this debate was put to rest. Eighty-five years ago, using the 100-inch telescope at Mt Wilson, he photographed a minuscule pulsating star called a Cepheid variable in the Andromeda Nebula.
A Cepheid variable is a star that pulsates in brightness with great regularity. To make a long story short, knowing the pulse rate of a Cepheid can tell us how bright it should be. When we see how bright it appears to our eyes, and see how much it has dimmed with distance, we can use simple laws of physics to determine how far away it is.
Hubble used his calculations to show the world that the Andromeda nebula was nowhere within our galaxy, that it was at least a million light years away. It was no cloud, it was the Andromeda Galaxy.
Suddenly, overnight, the entire universe was seen to be immense, larger than anyone had ever dreamed, and strewn throughout not with just billions of local stars, but billions of other galaxies. We were a mere speck in a boundless landscape.
Not to despair! Although some now took the view that our new size relative to the new universe made us insignificant, that view has been changing over the last decades.
We now see that the universe must be the size it is, must be as dense as it is, must have as many stars and galaxies and voids as it does - no more, no less - for us to have life on this tiny little planet of ours. Why? Sorry, that is a discussion for another day.
Want to read a great book on the fascinating history of astronomy from Aristotle to modern day? Pick up Timothy Ferris' Coming of Age in the Milky Way.
Until next time, clear skies!