[ FirstLight Astronomy Club ] The Skies Above

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Mama Cass and Her Beautiful Daughter

Observing >

Once there was a great king and queen of Ethiopia called Cepheus and Cassiopeia. They had a beautiful daughter named Andromeda.

Now Mama Cass was one proud parent and one fine day she blurted out that her daughter was one beautiful young lady, even more beautiful than the Nereids, those sea nymphs of lore. Bad move.

The offended Nereid went and told old Poseidon, the god of the oceans, who then proceeded to flood the whole kingdom of Cepheus and Cassiopeia, and worse, send a sea monster to bat cleanup. It was quickly decided --- without asking Andromeda apparently --- that Andromeda herself should be sacrificed to the monster to make things all better. Thanks, Mom.

This is when the famous and rugged Perseus flew in and saved the day waving the hideous head of Medusa, herself another tale of beauty gone bad.

Somehow all the actors in this passion play got their own constellation, and in the same part of the skies in the north. But here we focus specifically on Cassiopeia (CAS), the most easily recognized of the bunch.

In the northern skies, on the opposite side of the North Star as the Big Dipper you have undoubtedly seen the Big W (or Big Jagged Number 3 as it looks at this time of the year). That is the reclining Cassiopeia, relaxing on her throne.

Cassiopeia is a great constellation to show you how some stars are named.

There are the common names in CAS, to be sure, like Schedar and Ruchbah and Segin. But often the stars in constellations are named from brightest to dimmest by using the Greek alphabet. The brightest one is the alpha star, then beta, then gamma, etc.

You can impress your friends and family by going out tonight and rattling off the Greek designations for the Big Five stars of Cassiopeia. Just remember BAG-DE; beta, alpha, gamma, delta, and epsilon. At the brighter end of CAS, the top of the 3, is beta Cassiopeia; then alpha Cassiopeia (the brightest star); then gamma, delta, and dimmer epsilon.

Regular readers here will recall that the Greeks and Romans weren't the only ones to have myths and stories and then immortalize them in the skies. Many ethnic groups have their own traditions which reflect their unique culture.

For example the Lapps, a people of northern Scandinavia, who weren't too overly influenced by the Greeks, saw in CAS a moose's antler.

When CAS is shaped as an M, during our winter nights, a group of people in northern Siberia called the Chukchee saw five roaming reindeer.

Some Arab folks in the Middle East placed there the humped back of a camel, a very special and useful beast of burden of their region. The rest of the camel extends down into what we know as Andromeda and Perseus.

Go all the way down into the Marshall Islands of the South Pacific and we see another influential animal given a place of reverence here. To the Marshallese the great W formed the tail fin of a monstrous porpoise. Their starry mammal extends down to the east from Cassiopeia through Andromeda and tiny Triangulum all the way to the porpoise's mouth located at the two brightest stars in Aries. That's nearly 40 degrees across the sky, which is more than both hands fully spanned at arm's length. That's one major mammal.

It's a fascinating learning experience to see how different people see the skies in different ways, reserving there special places for the influential and holy things in their lives.

Questions or suggestions? Write Mark Ritter here.

Posted by Administrator at 2002.09.28 02:28 PM | Comments (0)

The Day (and Night) of Solar Equality

The Calendar >

Tonight we mark the first official moments of fall. Starting Sunday night at precisely 9:56 the leaves will begin to turn colors and fall from the trees. The weather will become suddenly cool and windy. Football games will break out spontaneously in neighborhood parks. Christmas decorations will be out for sale at stores everywhere.

Of course we know that's not what happens when it becomes fall --- except for maybe the Christmas decoration thing. The beginning of fall for most of us passes as just a formality of the calendar and few know why we mark that day in the first place.

There was a time for humans --- and still is for some peoples of this planet --- that this event, the fall equinox, marked the special midpoint between the solstices.

The summer solstice for Northern Hemispherical people was celebrated around June 21. It was when the sun, that great bright ball in the heavens, that mysterious source of light and heat and growth, trekked across the sky on its highest path. It rose northeast on the horizon and set in the northwest. The daytime was the longest of the year; nighttime was at its shortest. Light ruled!

Six months later, around December 21, came the day the sun rose very south of east, barely cut a path much above the horizon during this "shortest day," and then just hours later set in the very southwest. Darkness was king on winter solstice.

Fall equinox, however, was the moderate diem between the two extremes. The sun rose due east, was in the sky for 12 hours --- exactly half the day --- and then set due west. The fact that the sun was up as long as it was down gave us the term equinox, which means "equal night."

People who took the equinox seriously noticed that after this day the sun would be below the horizon longer than above it. Darkness would slowly snuff out the light, until finally the winter solstice came and light would again start to fight its way back to daily supremacy. Spring would not be far off.

There really is an astronomical reason for all this. But fair warning! As usual, the cold steel of science has a way of demythologizing the more poetic and agrarian meanings of the day. Ready?

Our planet has been blessed with a tilt. And therein lies the reason for why the equinox exists. Right now we are tilted over about 23.5 degrees. But tilted compared to what? Not the sun!

Imagine the Earth orbiting around the sun. It draws out a huge near-circular path. This whole path etches out a giant circular plane.

It's like a CD (or vinyl record if you remember those). Imagine a piece of corn stuck in the middle hole. That would be our sun. (Just go with it.) The whole CD is our "orbital plane" a.k.a. the ecliptic. Our planet would be a piece of dust traveling around in a circle on the CD.

We are tilted over a little with respect to this plane. Our poles do not stand straight up at attention, perpendicular to the plane. Our north pole seems to have a mind of its own and points --- all year long --- towards a distant star called Polaris, our North Star.

Sometimes during the year --- specifically during our summer --- we just happen to be tilted toward the sun. And six months later, on the other side of the sun, we are tilted away, during the darker days of winter.

The equinoxes are between those places, where, even as our North Pole is still pining for the North Star, we are not tilted at all with respect to our own star, the sun. The sun will shine on that day from pole to shining pole, hovering directly over our equator, favoring neither hemisphere.

The whole globe during this special day has a twelve-hour day and a twelve-hour night. For every nonpolar person the sun rises due east and sets due west. It's like a Global Solar Equality Day.

Alas! It is only on that day we are all equal. The next day sees the sun rising ever so much later and setting a wee bit sooner. It travels a slightly lower path each day as we move around towards the winter part of our orbit. The shorter days make it progressively cooler. Leaves really do start to change color as trees prepare for winter.

But the beauty of it is that this marvelous cycle just keeps going year after year, giving us season after season. Every year is blessedly the same, every year wonderfully different.

Have a question or comment? Write Mark Ritter here.

Posted by Administrator at 2002.09.21 02:30 PM | Comments (0)

A New Meaning for 'Star FM'

Observing >

There is a whole unsung branch of astronomy filled with men and women who just love radio; they can't get enough of it. I'm not talking about Top 40 or news radio or talk radio. The "radio" I refer to are waves from the cosmos itself and their message is changing the way we look at our universe.

By far the biggest chunk of glory in astronomy has gone to those who have studied what we can see in the visible wavelengths of light. Great telescopes, like at Palomar and Keck, have given us, to be sure, many stunning images of the visible worlds beyond.

But they show us only a small fraction of what is out there.

There are other unseen wavelengths of light, beyond what our eyes are sensitive to, which are trying to show us more of the Big Show. These photons have wavelengths thousands of times longer than the light we see, but can be picked up by special instruments. These are radio waves.

Because radio waves have such long wavelengths, the laws of physics tell us that they can only be efficiently bounced off and focused from huge surfaces like the radio dishes we often see in "alien” movies. Not huge as in a couple feet across. No, huge as in hundreds of feet end to end. Some radio telescopes are so big that several football games could be played on them simultaneously.

Their sole purpose is to collect radio waves from space and reflect them into an antennae suspended high above the dish. Computers can then translate the signals into information that we can "see,” thus telling us even more about the great beyond.

"Looking” at those radio waves we see, for example, our galaxy swimming in a sort of glowing hydrogen gas, pocketed all around in great clumps, future factories of stars.

In the radio we've discovered the center of our galaxy. It couldn't be pinpointed before because its visible radiation gets absorbed by all the dust and crud choking it there. But long radio waves can pass through dust and clouds like they're not even there. Which explains why radio telescopes can work under just about any weather condition here on this planet, even during pouring rain.

Radio astronomy has also revealed great jets of material spewing fast and furiously from the centers of other galaxies, jets which dwarf their entire parent galaxy, jets which are evidence for supermassive blackholes at the centers of those galaxies.

All this is an amazing feat given that the amount of energy we get at the radio end of the spectrum is less than miniscule at best. The entire surface of the Earth gets only a grand total of about a trillionth of a watt of it. Compare that to the 10 million watts we get in the infrared and visible from a single average star!

Moreover, radio astronomers must contend with all the radio radiation coming from ... us! We spew out so much radio energy for communications and other fun things that we actually get interference from our own radio waves bouncing off the Moon!

Which is why, when you see those gargantuan dishes, they are far away, often in valleys, hidden from much of our own interference.

In future articles we'll discuss the importance of the other invisible wavelengths, such as X-ray and ultraviolet and infrared, all of which put a new and different facet on this gem of a universe we live in.

Until next time, clear skies!

Have a question or comment? Write Mark Ritter here.

Posted by Administrator at 2002.09.14 02:32 PM | Comments (0)



Looking for something?	« August 2002 \| Main \| October 2002 » Mama Cass and Her Beautiful Daughter Observing > Once there was a great king and queen of Ethiopia called Cepheus and Cassiopeia. They had a beautiful daughter named Andromeda. Now Mama Cass was one proud parent and one fine day she blurted out that her daughter was one beautiful young lady, even more beautiful than the Nereids, those sea nymphs of lore. Bad move. The offended Nereid went and told old Poseidon, the god of the oceans, who then proceeded to flood the whole kingdom of Cepheus and Cassiopeia, and worse, send a sea monster to bat cleanup. It was quickly decided --- without asking Andromeda apparently --- that Andromeda herself should be sacrificed to the monster to make things all better. Thanks, Mom. This is when the famous and rugged Perseus flew in and saved the day waving the hideous head of Medusa, herself another tale of beauty gone bad. Somehow all the actors in this passion play got their own constellation, and in the same part of the skies in the north. But here we focus specifically on Cassiopeia (CAS), the most easily recognized of the bunch. In the northern skies, on the opposite side of the North Star as the Big Dipper you have undoubtedly seen the Big W (or Big Jagged Number 3 as it looks at this time of the year). That is the reclining Cassiopeia, relaxing on her throne. Cassiopeia is a great constellation to show you how some stars are named. There are the common names in CAS, to be sure, like Schedar and Ruchbah and Segin. But often the stars in constellations are named from brightest to dimmest by using the Greek alphabet. The brightest one is the alpha star, then beta, then gamma, etc. You can impress your friends and family by going out tonight and rattling off the Greek designations for the Big Five stars of Cassiopeia. Just remember BAG-DE; beta, alpha, gamma, delta, and epsilon. At the brighter end of CAS, the top of the 3, is beta Cassiopeia; then alpha Cassiopeia (the brightest star); then gamma, delta, and dimmer epsilon. Regular readers here will recall that the Greeks and Romans weren't the only ones to have myths and stories and then immortalize them in the skies. Many ethnic groups have their own traditions which reflect their unique culture. For example the Lapps, a people of northern Scandinavia, who weren't too overly influenced by the Greeks, saw in CAS a moose's antler. When CAS is shaped as an M, during our winter nights, a group of people in northern Siberia called the Chukchee saw five roaming reindeer. Some Arab folks in the Middle East placed there the humped back of a camel, a very special and useful beast of burden of their region. The rest of the camel extends down into what we know as Andromeda and Perseus. Go all the way down into the Marshall Islands of the South Pacific and we see another influential animal given a place of reverence here. To the Marshallese the great W formed the tail fin of a monstrous porpoise. Their starry mammal extends down to the east from Cassiopeia through Andromeda and tiny Triangulum all the way to the porpoise's mouth located at the two brightest stars in Aries. That's nearly 40 degrees across the sky, which is more than both hands fully spanned at arm's length. That's one major mammal. It's a fascinating learning experience to see how different people see the skies in different ways, reserving there special places for the influential and holy things in their lives. Questions or suggestions? Write Mark Ritter here. Posted by Administrator at 2002.09.28 02:28 PM \| Comments (0) The Day (and Night) of Solar Equality The Calendar > Tonight we mark the first official moments of fall. Starting Sunday night at precisely 9:56 the leaves will begin to turn colors and fall from the trees. The weather will become suddenly cool and windy. Football games will break out spontaneously in neighborhood parks. Christmas decorations will be out for sale at stores everywhere. Of course we know that's not what happens when it becomes fall --- except for maybe the Christmas decoration thing. The beginning of fall for most of us passes as just a formality of the calendar and few know why we mark that day in the first place. There was a time for humans --- and still is for some peoples of this planet --- that this event, the fall equinox, marked the special midpoint between the solstices. The summer solstice for Northern Hemispherical people was celebrated around June 21. It was when the sun, that great bright ball in the heavens, that mysterious source of light and heat and growth, trekked across the sky on its highest path. It rose northeast on the horizon and set in the northwest. The daytime was the longest of the year; nighttime was at its shortest. Light ruled! Six months later, around December 21, came the day the sun rose very south of east, barely cut a path much above the horizon during this "shortest day," and then just hours later set in the very southwest. Darkness was king on winter solstice. Fall equinox, however, was the moderate diem between the two extremes. The sun rose due east, was in the sky for 12 hours --- exactly half the day --- and then set due west. The fact that the sun was up as long as it was down gave us the term equinox, which means "equal night." People who took the equinox seriously noticed that after this day the sun would be below the horizon longer than above it. Darkness would slowly snuff out the light, until finally the winter solstice came and light would again start to fight its way back to daily supremacy. Spring would not be far off. There really is an astronomical reason for all this. But fair warning! As usual, the cold steel of science has a way of demythologizing the more poetic and agrarian meanings of the day. Ready? Our planet has been blessed with a tilt. And therein lies the reason for why the equinox exists. Right now we are tilted over about 23.5 degrees. But tilted compared to what? Not the sun! Imagine the Earth orbiting around the sun. It draws out a huge near-circular path. This whole path etches out a giant circular plane. It's like a CD (or vinyl record if you remember those). Imagine a piece of corn stuck in the middle hole. That would be our sun. (Just go with it.) The whole CD is our "orbital plane" a.k.a. the ecliptic. Our planet would be a piece of dust traveling around in a circle on the CD. We are tilted over a little with respect to this plane. Our poles do not stand straight up at attention, perpendicular to the plane. Our north pole seems to have a mind of its own and points --- all year long --- towards a distant star called Polaris, our North Star. Sometimes during the year --- specifically during our summer --- we just happen to be tilted toward the sun. And six months later, on the other side of the sun, we are tilted away, during the darker days of winter. The equinoxes are between those places, where, even as our North Pole is still pining for the North Star, we are not tilted at all with respect to our own star, the sun. The sun will shine on that day from pole to shining pole, hovering directly over our equator, favoring neither hemisphere. The whole globe during this special day has a twelve-hour day and a twelve-hour night. For every nonpolar person the sun rises due east and sets due west. It's like a Global Solar Equality Day. Alas! It is only on that day we are all equal. The next day sees the sun rising ever so much later and setting a wee bit sooner. It travels a slightly lower path each day as we move around towards the winter part of our orbit. The shorter days make it progressively cooler. Leaves really do start to change color as trees prepare for winter. But the beauty of it is that this marvelous cycle just keeps going year after year, giving us season after season. Every year is blessedly the same, every year wonderfully different. Have a question or comment? Write Mark Ritter here. Posted by Administrator at 2002.09.21 02:30 PM \| Comments (0) A New Meaning for 'Star FM' Observing > There is a whole unsung branch of astronomy filled with men and women who just love radio; they can't get enough of it. I'm not talking about Top 40 or news radio or talk radio. The "radio" I refer to are waves from the cosmos itself and their message is changing the way we look at our universe. By far the biggest chunk of glory in astronomy has gone to those who have studied what we can see in the visible wavelengths of light. Great telescopes, like at Palomar and Keck, have given us, to be sure, many stunning images of the visible worlds beyond. But they show us only a small fraction of what is out there. There are other unseen wavelengths of light, beyond what our eyes are sensitive to, which are trying to show us more of the Big Show. These photons have wavelengths thousands of times longer than the light we see, but can be picked up by special instruments. These are radio waves. Because radio waves have such long wavelengths, the laws of physics tell us that they can only be efficiently bounced off and focused from huge surfaces like the radio dishes we often see in "alien” movies. Not huge as in a couple feet across. No, huge as in hundreds of feet end to end. Some radio telescopes are so big that several football games could be played on them simultaneously. Their sole purpose is to collect radio waves from space and reflect them into an antennae suspended high above the dish. Computers can then translate the signals into information that we can "see,” thus telling us even more about the great beyond. "Looking” at those radio waves we see, for example, our galaxy swimming in a sort of glowing hydrogen gas, pocketed all around in great clumps, future factories of stars. In the radio we've discovered the center of our galaxy. It couldn't be pinpointed before because its visible radiation gets absorbed by all the dust and crud choking it there. But long radio waves can pass through dust and clouds like they're not even there. Which explains why radio telescopes can work under just about any weather condition here on this planet, even during pouring rain. Radio astronomy has also revealed great jets of material spewing fast and furiously from the centers of other galaxies, jets which dwarf their entire parent galaxy, jets which are evidence for supermassive blackholes at the centers of those galaxies. All this is an amazing feat given that the amount of energy we get at the radio end of the spectrum is less than miniscule at best. The entire surface of the Earth gets only a grand total of about a trillionth of a watt of it. Compare that to the 10 million watts we get in the infrared and visible from a single average star! Moreover, radio astronomers must contend with all the radio radiation coming from ... us! We spew out so much radio energy for communications and other fun things that we actually get interference from our own radio waves bouncing off the Moon! Which is why, when you see those gargantuan dishes, they are far away, often in valleys, hidden from much of our own interference. In future articles we'll discuss the importance of the other invisible wavelengths, such as X-ray and ultraviolet and infrared, all of which put a new and different facet on this gem of a universe we live in. Until next time, clear skies! Have a question or comment? Write Mark Ritter here. Posted by Administrator at 2002.09.14 02:32 PM \| Comments (0)
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