19 Oct 2009
This week in history - long ago in the year 2137 BC - the earliest known solar eclipse recorded by humans took place. Of course, solar eclipses had been a mainstay on planet Earth for b-zillions of years before that; this one was the first recorded.
But it wasn't recorded by ancient Europeans, and many of us might first guess. This event is found in a book called Classic of History, a Chinese book.
Not many of us are aware of the fact that other people groups outside of the west were heavily engaged in astronomy for eons. The Chinese were one of those people.
One of the main purposes for their observations - the same purpose for a lot of people - was to keep time, of course. Knowing when to plant and reap, and the ability to plan important annual events are important human activities. And the Chinese, like many people, studied the stars not just for telling time but for astrological purposes, for divining what might be coming up in the near future for whomever was in power at the time.
The Chinese contributed a lot to astronomy over the millennia. Centuries before Christ, Chinese astronomers were working out how to predict solar and lunar eclipses. And for thousands of years the Chinese have been cataloging the skies with elaborate star charts and collections of constellations.
While Europe was wallowing about in astronomy before and during the Middle Ages, contributing next to nothing, the Chinese were going strong. As just one example, it was they who saw and recorded a great heavenly event in the year 1054, somehow missed in Europe.
A Chinese document records this: "In the 1st year of the period Chih-ho, the 5th moon, the day chi-ch'ou, a guest star appeared... After more than a year it gradually became invisible..."
It turns out this "guest star" was nothing less than a supernova, the death of a giant star. The faint remnants of the explosion can still be seen in a backyard telescope as the Crab Nebula in Taurus.
One of the oldest observatories in the world was built in Beijing in the 15th century as Europe was beginning to awake from slumber. Built before the invention of the telescope, it sported the latest in observational equipment, including an armillary, a quadrant, and a theodolite.
The contributions of the Chinese are many and could never be satisfactorily covered here. Were the Chinese perfect in their predictions and theories and overall views of the cosmos? Of course not. Like the Arabs, and later, the Europeans, there was plenty of contribution, but also a fair share of miscalculation and misinterpretation. But they were on the A-list of astronomical contributors for literally millennia.
05 Oct 2009
Ever look up in the evening skies just staring at the constellations, and suddenly notice a tiny illuminated dot floating gently across the expanse only to vanish into nowhere seconds later? That may have been the kin of an object launched into space over 50 years ago, a manmade satellite called Sputnik.
It was 52 years ago this week that the Soviet Union surprised us all by launching the first artificial satellite into orbit around our planet. Just a faint, almost invisible speck in the night sky, it collected data on the atmosphere and launched something of its own, namely the Space Race which ultimately led to our landing on the Moon.
Presently there are literally thousands of tiny manmade objects floating around up there. But doing what exactly? And how do we see one in action?
Satellites are used for a multitude of things. We addicts of Google Earth know that some satellites are up there taking a lot of high resolution, close up and personal pictures of our planet. For some, too personal. And people with GPS devices in their cell phones absolutely depend on satellites to get around.
Speaking of cell phones, there are also instruments in orbit for phone communications, and television, and radio.
Scientists use special instruments onboard satellites to see parts of the electromagnetic spectrum we cannot see. For example, with infrared detectors we can "see" the temperatures of landforms and ocean surfaces.
And of course, there are satellites not looking down on us, but looking up, out into the universe, like the legendary Hubble Space Telescope.
If you have never seen one with the naked eye, here's how.
After the sun sets, when the sky is finally dark enough to see a lot of stars, just go out in your yard, lay down and look up. That's all there is to it. Occasionally you may see a tiny fleck of light moving slowly but deliberately across the starry sphere. You will not see the red and green lights of an airplane, just that white dot.
Why early in the evening? Because it is then that the sun's light is gone for us, but not for a shiny satellite a couple hundred miles above Earth. They continue to reflect the light long after we on the surface are in the dark.
In fact, you may notice a satellite vanishing suddenly, before it gets anywhere near the horizon. That's because it is orbiting into the Earth's giant shadow. Unable to reflect the light of the sun, it fades to black.
Don't expect to see Sputnik up there. It burned up on reentry just months after its famous launch. Such is the eventual fate for most satellites.
Until next time, clear skies!