dipper@utastro.UUCP (Debbie Byrd) (08/11/84)
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dipper@utastro.UUCP (Debbie Byrd) (10/31/84)
The first quarter moon will illuminate the sky this Halloween evening. More -- right after this. October 3l Halloween A first quarter moon will be shining down on trick-or-treaters on Halloween night -- a moon dead overhead when evening begins -- bound to illuminate the landscape as well as any neighborhood streetlight. This happens to be the second first quarter moon for this month -- possible because the moon takes slightly less than a month to go through all its phases. If you're out there trick-or-treating tonight, you might let the moon remind you that Halloween is really an astronomical holiday. It's the fourth and final cross-quarter day for the year. Cross-quarter days lie about midway between a solstice and an equinox. In the case of Halloween, and the other cross-quarter days, the dates aren't exact -- since people used to be less precise than we are about the dates for the solstices and equinoxes. The other cross-quarter days are Candlemas, February 2nd, called Groundhog Day in America -- May l, or May Day -- and August l, with its early harvest festival called Lammas. Halloween is the most sinister of the four cross-quarter days. That's got to be because the days are now growing shorter and the nights longer -- with no relief in sight until the solstice on December 2l -- the day the sun makes its lowest arc across the sky visible from the northern hemisphere. On Halloween, witches and ghosts supposedly prowl around until midnight -- when good spirits arrive to get rid of them. Script by Deborah Byrd. (c) Copyright 1983, 1984 McDonald Observatory, University of Texas at Austin
dipper@utastro.UUCP (Debbie Byrd) (11/08/84)
(c) Copyright 1983, 1984 McDonald Observatory, University of Texas at Austin
dipper@utastro.UUCP (Debbie Byrd) (03/13/85)
This is the anniversary of the discovery of the planet Uranus. More -- after this. March l3: The Discovery of Uranus On this date in the year 1781, the known size of the solar system doubled. With a homemade six-inch telescope, William Herschel discovered the first new planet in recorded history --the planet Uranus. Uranus orbits the sun some 800 million miles farther away than Saturn, which was then thought to mark the outermost limits of the solar system. In 1781, new planets were so unexpected that even Herschel didn't think he'd found one. Instead, he believed he'd discovered a comet. When he began to suspect that the greenish disk of Uranus was a planet after all, he suggested that we name it the latin equivalent for George's Star, for the current king of England. The British Nautical Almanac listed the planet as the Georgium until 1850. But everywhere else the planet came to be called Uranus, for the mythological father of Saturn, who in turn was the father of Jupiter. Jupiter--Saturn--Uranus--these faraway worlds were blurry disks through telescopes to astronomers only two hundred years ago. We today have seen the planets at close range--because we are the first to have spaceships which travel through the solar system. The Voyager spacecraft have now swept past Jupiter and Saturn. Voyager 1 is on its way out of the solar system -- but Voyager 2 is due to encounter mysterious Uranus less than a year from now -- to give us our first close-up look at it in early 1986. Uranus is four times larger than the Earth -- we know it has thin rings -- and that it spins on its axis sideways with respect to the other planets. Script by Deborah Byrd. (c) Copyright 1984, 1985 McDonald Observatory, University of Texas at Austin
dipper@utastro.UUCP (Debbie Byrd) (04/01/85)
April Fool's Day may have come about in celebration of the vernal equinox. We'll talk more about it -- after this. April l Fooling the Fish Day Would you believe us if we said that the moon will really is made of green cheese?! Of course not -- because today is April Fools Day. No one is really sure how April Fools Day got started. There've been many different explanations -- but some may be as fanciful as April Fools jokes themselves! Still, in countries as far apart as France and India, festivals of merriment and foolishness have arisen -- possibly in connection with the vernal equinox. In our country, the tradition of April Fools Day probably stems from England, Scotland and France -- where the most popular form of April fooling was to send someone on a "fool's errand," for example to buy some pigeon's milk or a stick with one end. Scholars have noticed the similarity of this custom to one that used to be popular in India. There, people celebrated an ancient fertility rite at the equinox, or beginning of spring. On the last day of the celebration, March 31, people in India would also be sent on fool's errands. The similarity of April fooling in the east and west makes some scholars believe that the custom has a very ancient origin -- one tied to the beginning of spring. Whatever its origin, the aim of April fooling has always been to play a joke on an unsuspecting person who hasn't noticed what day it is. What you might not know is that in some places, April fooling has to be carried out before noon. Otherwise, it's traditional to call the person playing the joke an "April fool" for having tried his tricks too late. Script mostly by Diana Hadley. (joke by Joel Block) (c) Copyright 1984, 1985 McDonald Observatory, University of Texas at Austin
dipper@utastro.UUCP (Debbie Byrd) (07/23/85)
The Earth has earthquakes -- and the moon has moonquakes. More about them -- right after this. May 23: Moonquakes When NASA's Apollo astronauts went to the moon, they came back minus some instruments. These instruments were left behind to study lunar phenomena from Earth -- long after the astronauts had returned. One type of instrument was a seismograph, the same device use on Earth to measure the intensity of eathquakes. During the years it was operational, the seismograph let us listen to vibrations in the body of the moon. The vibrations had a variety of sources. Some came from our own spacecraft landing and taking off. Some resulted when meteorites struck the moon. And still other came from moonquakes. Moonquakes are similar to earthquakes -- but they're generally much milder, and they occur less often. Earth spawns more than a million earthquakes each year, while the moon has only a few hundred moonquakes. The moon is far less geologically active than Earth. Its most recent active period probably occurred billions of years ago. The seismograph also revealed a surprising fact about the crust of the moon, which is the layer of rocks that extends down about 40 miles. This layer was found to vibrate extensively -- to ring like a bell for several hours, after such small blows as those from spacecraft deliberately impacted onto the moon. The Earth can also vibrate in this way, but it does so to a much lesser degree. It's thought that the moon rings because its surface crust is thicker and more rigid than Earth's. Script by Deborah Byrd. (c) Copyright 1984, 1985 McDonald Observatory, University of Texas at Austin
dipper@utastro.UUCP (Debbie Byrd) (10/31/85)
Happy Halloween! We'll tell you why Halloween is an astronomical holiday-- right after this. October 3l Halloween Believe it or not, our celebration of Halloween has its origins in astronomy -- in the movement of the Earth around the sun. Halloween is the fourth and final cross-quarter day for the year. These are days that lie about midway between a solstice and an equinox. In the case of Halloween, and the other cross-quarter days, the dates aren't exact -- since people used to be less precise than we are about the dates for the solstices and equinoxes. There are three other cross-quarter days -- all associated with holidays. The first one is Candlemas, February 2nd -- called Groundhog Day in America. The second is May l, or May Day. The third is August l, with its early harvest festival called Lammas. The most sinister of the four cross-quarter days is Halloween. That's got to be because the days are now growing shorter and the nights longer -- with no relief in sight until the solstice on December 2l -- the day the sun makes its lowest arc across the sky visible from the northern hemisphere. On Halloween, witches and ghosts supposedly prowl around until midnight -- when good spirits arrive to get rid of them. The moon is a few days past full now -- and it won't rise until mid-to-late-evening. So if you're out prowling about early this evening -- you'll have a dark night for it. The brightest light in the sky will be the planet Jupiter -- until moonrise. Script by Deborah Byrd. (c) Copyright 1984, 1985 McDonald Observatory, University of Texas at Austin
dipper@utastro.UUCP (Debbie Byrd) (11/19/85)
Today is the anniversary of the second time people walked on the moon. More -- in a moment. November l9 Apollo Twelve On today's date in the year l969 we landed on the moon for the second time. Four months after the first astronauts visited the moon, Pete Conrad and Alan Bean became the third and fourth people to walk on another world. The two astronauts spent more than thirty-one hours on the surface -- while Richard Gordon orbited above in the command module called the Yankee Clipper. The lunar lander -- called the Intrepid -- made a pinpoint landing in an ancient lunar lava bed with the romantic name the Ocean of Storms. Two hundred yards away, the unmanned probe Suveyor Three had set down two and half years earlier. Conrad and Bean visited the older spacecraft while out walking on the moon. They brought back to Earth pieces of the Surveyor -- so that scientists could learn what effect being on the moon had on the metal of the spacecraft. The astronauts also collected moon rocks -- rocks that were redder and younger than the samples from the first Apollo mission -- which had set down in the lunar Sea of Tranquility. Six scientific experiments were deployed -- including a seismometer used to measure earthquakes -- or in this case -- moonquakes. After Conrad and Bean rejoined Gordon in the command module, the separate lander, Intrepid, was deliberately crashed into the moon. The vibrations from the impact continued for almost an hour -- providing, through the seismometers, new information about the inside of the moon. The Apollo Twelve mission proved that Apollo Eleven hadn't been a fluke -- that people could travel to the moon and return safely. Script by Diana Hadley. (c) Copyright 1984, 1985 McDonald Observatory, University of Texas at Austin
dipper@utastro.UUCP (Debbie Byrd) (03/22/86)
Invisible potholes may have formed galaxies and influenced their behavior. We'll tell you how -- after this. March 6 The Birth of the Galaxies The vast size of a galaxy is difficult to comprehend. Some, including our own Milky Way, are hundreds of thousands of light-years across. But it's even more mind-boggling to reflect on the countless billions of galaxies in our universe. Galaxies generally come in clusters. Clusters of galaxies group together on the scale of the whole universe to create a spectacular cosmic tapestry. We can observe galaxies -- but no one is sure how they came to be. Galaxy formation has always been a puzzle. But recently advances have been made toward a solution to the puzzle. In one current model, the universe started out with 90 per cent cold, dark, invisible matter and l0 per cent ordinary matter. The cold, dark matter contained locations of high density which may have acted as gravitational potholes to trap ordinary matter. Ordinary matter -- heated in the potholes -- may have evolved into galaxies. The new model suggests that the potholes tended to move towards each other and merge. Those formed early in the history of the universe were shallow -- and their galaxies merged quickly into larger structures. Later, deeper potholes formed which moved more slowly towards each other. Developing galaxies therefore had more time to cool and condense before collisions occurred. The result was not a merger but a dense clustering of galaxies. This speculation may explain why certain kinds of galaxies appear more often in dense clusters and why other kinds are more likely to be found with fewer neighbors nearby. Script by Holly Clark. (c) Copyright 1985, 1986 McDonald Observatory, University of Texas at Austin