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Robbery In Progress

The Galaxy >

There is a robbery going down. The Little Dipper is a victim of stolen identity. Often I have seen people look up into the winter sky, point to a little cluster of stars in Taurus that looks "dippery," and say something like, "Isn't the Little Dipper so pretty?"

Well, the pretty little cluster that sort of looks like a dipper is actually the Pleiades, the Seven Sisters, and very often it mistakenly gets tagged as the Little Dipper. The real Little Dipper is just a little turn of the head over there in the north, near its big brother the Big Dipper, just waiting to be properly recognized.

Let's take a little dip into that pool of stars over there and investigate the real Little Dipper.

The Little Dipper is not hard to find in skies that aren't bleached out in our light pollution. Go out tonight and seek out the Big Dipper in the northwest skies. At around 9 p.m., it's low in the sky, just hours from ploughing into the horizon. Follow the two pointer stars at the end of the bowl of the dipper to the North Star, Polaris. Unknown to most, the North Star --- one of the most famous and easily identified stars in the sky --- is actually the brightest star of the Little Dipper. It is the end of the handle.

If you have nice, clear, dark skies you can find the rest of the Little Dipper, but you may have needs of an imagination, too. (I have a star chart ready for you.) Using Polaris as a starting point, in your mind's eye imagine a curved line gently taking you up and over to the tip of the handle of the Big Dipper. It is along this sweeping curve that the rest of the Little Dipper is positioned, with the bowl of the Little Dipper situated about half the way to the Big Dipper's handle.

During this time of the year the little guy is high in the sky making it easier to see, but also upside down, thus awkward to imagine. Actually to me, it looks more like a meat cleaver in the hand of a butcher, lifted high over his head, about to plunge down and do its cleaving business.

You'll notice that I haven't referred to the Little Dipper as a constellation. Neither Dippers are. They are just parts of constellations. The Big Dipper is the torso and tail of Ursa Major, the Great Bear. The Little Dipper is torso and tail of Ursa Minor, the Little Bear.

Star patterns that are just parts of full-blown constellations, but have easily recognized patterns themselves, are called asterisms. The Dippers actually look like dippers, but the bigger Ursas only kinda-sorta look like bears. Another asterism rising in the northwest in the constellation Pegasus is called the Great Square of Pegasus. You'll never guess what shape it takes.

Of course, other cultures see different things in our star-spangled skies. The Little Dipper real estate is no different. Ancient Egyptians portrayed the asterism as a hippopotamus on the planisphere at their Temple of Denderah. Why a hippo? Here's one possible line of reasoning.

Earth spins on an axis. The North Star is directly above our axis, and so acts like the pivot point around which all the stars seem to revolve through the night. So, the stars in the very northern skies and the constellations they are a part of have tight turns around Polaris and don't actually set, that is, go below the horizon.

Since these stars never really set, Egyptian beliefs led them to believe some of those stars were evil. Hence, the necessity of the Hippo. The hippopotamus is not the cute little ballet star of Disney films that many of us know. It is a big brute of a beast, one to be reckoned with. This behemoth was greatly feared and respected and was there in the sky to keep those evil stars in line.

Other cultures have seen there a fish, a dog's tail, the daughters of Atlas, the Lesser Wagon (compared to the Great Wagon of the Big Dipper), a hunting horn, and --- I kid you not --- a giant piece of edible fruit called the myrobalan.

Be that as it may, you can help the Little Dipper overcome the identity crisis it is suffering through in our own culture. Next time you hear someone incorrectly point out a faux Little Dipper in some other part of the sky, take that person --- with gentleness and respect --- on a little tour through the northern lights and set them straight.

Mark Ritter teaches astronomy at Temecula Valley High School and can be reached at mritter@firstlightastro.com.

Posted by Administrator at 2004.08.21 12:19 PM | Comments (0)

The Boys of Summer Are Back

Comets >

Time for the annual fireworks show! Only this one takes place on no holiday, comes with no explosive noises, and is completely au naturel.

This week you are invited to the annual Perseid meteor shower. It is actually taking place now but the peak of the show will flare up late Wednesday night, early Thursday morning.

Now if you have not experienced a Perseid shower consider doing so this week. For one thing, they are one of the more reliable showers of the year; you are practically guaranteed to see fiery streaks. But this year circumstances make it a little more tempting than usual.

This year there will be no big, bright, sky-bleaching moon to mess things up --- which is actually a double blessing. Not only do the meteors show up brighter and in more detail, but the rest of the glorious summer sky is there in all its sparkling beauty.

You may remember that comets shed tons and tons of dusty material as they pass through the inner solar system.

The dust spreads out a wee bit, but for a while maintains the same basic orbit as the parent comet. If our orbit happens to cross the orbit of this dust train, we'll have us a cosmic collision --- and we win.

During the second week of August, Earth crosses the orbit of Comet Swift-Tuttle, a comet about the size of the one that exterminated the dinosaurs. Of course, the comet is far away from us at the moment, but its dust still lingers in that orbit. It is these tiny particles, no bigger than a grain of sand, that suffer an incandescent fate.

We crash into them at tens of miles per second. As they hit us, like bugs on a windshield of a speeding car, they meet a fiery demise in our thick atmosphere and then qualify for the well-known moniker "shooting stars." They are no more, but their deaths provide us with those luminous slashes across the canopy of the sky.

How does one suitably set up for a shooting-star soiree? First, make sure you get a good nap the day of the event because the best time to see a shower is very late at night. Many people are disappointed during a shower because they look up in the early evening skies when the meteors are few and far between --- too early for the good part of the show. But why is late night best?

If you want to see bugs smack into your moving car you don't stare at the rear window, you keep your eyes on the windshield. We on Earth spin into the oncoming stream only after our local midnight. Until then, it's like staring at the rear window --- nothing much happens. So if you want to really enjoy this thing, with all those wee beasties hitting us head-on, the best time is between about 1 AM and the rising of the sun.

And it is this easy: Smear on the mosquito repellant, dress warmly, go outside somewhere where there is little or no light, lie down, and look up. No telescopes required.

Here are some things to look for. You'll notice that the meteors are not flying about randomly; they seem to be coming out of one area of the sky. Actually, because of the way we hit the stream of debris, they appear to be coming from a part of the sky in the northeast where the constellation Perseus resides. Hence, the name "Perseid meteor shower."

In the moments between strikes, take in the grandeur of the cosmos above. Over your head will be the faint white band of light, starting in the south and arching over into the north, a veil composed of countless millions of stars. That is the Milky Way, our home galaxy, as seen edge on.

If you are in the preferred dark countryside setting, you'll notice patches of blackness in the Milky Way. Those are clouds of dust and gas blocking the light from more distant stars.

Ignoring the sleep deprivation, meteor showers like the Perseids are really win-win situations. You get to witness the combined aesthetic beauty of dozens of shooting stars in the throes of death, played out on a backdrop that includes the overwhelming glory of the starry heavens.

Mark Ritter teaches astronomy at Temecula Valley High School and can be reached at mritter@firstlightastro.com.

Posted by Administrator at 2004.08. 7 12:21 PM | Comments (0)



Looking for something?	« July 2004 \| Main \| September 2004 » Robbery In Progress The Galaxy > There is a robbery going down. The Little Dipper is a victim of stolen identity. Often I have seen people look up into the winter sky, point to a little cluster of stars in Taurus that looks "dippery," and say something like, "Isn't the Little Dipper so pretty?" Well, the pretty little cluster that sort of looks like a dipper is actually the Pleiades, the Seven Sisters, and very often it mistakenly gets tagged as the Little Dipper. The real Little Dipper is just a little turn of the head over there in the north, near its big brother the Big Dipper, just waiting to be properly recognized. Let's take a little dip into that pool of stars over there and investigate the real Little Dipper. The Little Dipper is not hard to find in skies that aren't bleached out in our light pollution. Go out tonight and seek out the Big Dipper in the northwest skies. At around 9 p.m., it's low in the sky, just hours from ploughing into the horizon. Follow the two pointer stars at the end of the bowl of the dipper to the North Star, Polaris. Unknown to most, the North Star --- one of the most famous and easily identified stars in the sky --- is actually the brightest star of the Little Dipper. It is the end of the handle. If you have nice, clear, dark skies you can find the rest of the Little Dipper, but you may have needs of an imagination, too. (I have a star chart ready for you.) Using Polaris as a starting point, in your mind's eye imagine a curved line gently taking you up and over to the tip of the handle of the Big Dipper. It is along this sweeping curve that the rest of the Little Dipper is positioned, with the bowl of the Little Dipper situated about half the way to the Big Dipper's handle. During this time of the year the little guy is high in the sky making it easier to see, but also upside down, thus awkward to imagine. Actually to me, it looks more like a meat cleaver in the hand of a butcher, lifted high over his head, about to plunge down and do its cleaving business. You'll notice that I haven't referred to the Little Dipper as a constellation. Neither Dippers are. They are just parts of constellations. The Big Dipper is the torso and tail of Ursa Major, the Great Bear. The Little Dipper is torso and tail of Ursa Minor, the Little Bear. Star patterns that are just parts of full-blown constellations, but have easily recognized patterns themselves, are called asterisms. The Dippers actually look like dippers, but the bigger Ursas only kinda-sorta look like bears. Another asterism rising in the northwest in the constellation Pegasus is called the Great Square of Pegasus. You'll never guess what shape it takes. Of course, other cultures see different things in our star-spangled skies. The Little Dipper real estate is no different. Ancient Egyptians portrayed the asterism as a hippopotamus on the planisphere at their Temple of Denderah. Why a hippo? Here's one possible line of reasoning. Earth spins on an axis. The North Star is directly above our axis, and so acts like the pivot point around which all the stars seem to revolve through the night. So, the stars in the very northern skies and the constellations they are a part of have tight turns around Polaris and don't actually set, that is, go below the horizon. Since these stars never really set, Egyptian beliefs led them to believe some of those stars were evil. Hence, the necessity of the Hippo. The hippopotamus is not the cute little ballet star of Disney films that many of us know. It is a big brute of a beast, one to be reckoned with. This behemoth was greatly feared and respected and was there in the sky to keep those evil stars in line. Other cultures have seen there a fish, a dog's tail, the daughters of Atlas, the Lesser Wagon (compared to the Great Wagon of the Big Dipper), a hunting horn, and --- I kid you not --- a giant piece of edible fruit called the myrobalan. Be that as it may, you can help the Little Dipper overcome the identity crisis it is suffering through in our own culture. Next time you hear someone incorrectly point out a faux Little Dipper in some other part of the sky, take that person --- with gentleness and respect --- on a little tour through the northern lights and set them straight. Mark Ritter teaches astronomy at Temecula Valley High School and can be reached at mritter@firstlightastro.com. Posted by Administrator at 2004.08.21 12:19 PM \| Comments (0) The Boys of Summer Are Back Comets > Time for the annual fireworks show! Only this one takes place on no holiday, comes with no explosive noises, and is completely au naturel. This week you are invited to the annual Perseid meteor shower. It is actually taking place now but the peak of the show will flare up late Wednesday night, early Thursday morning. Now if you have not experienced a Perseid shower consider doing so this week. For one thing, they are one of the more reliable showers of the year; you are practically guaranteed to see fiery streaks. But this year circumstances make it a little more tempting than usual. This year there will be no big, bright, sky-bleaching moon to mess things up --- which is actually a double blessing. Not only do the meteors show up brighter and in more detail, but the rest of the glorious summer sky is there in all its sparkling beauty. You may remember that comets shed tons and tons of dusty material as they pass through the inner solar system. The dust spreads out a wee bit, but for a while maintains the same basic orbit as the parent comet. If our orbit happens to cross the orbit of this dust train, we'll have us a cosmic collision --- and we win. During the second week of August, Earth crosses the orbit of Comet Swift-Tuttle, a comet about the size of the one that exterminated the dinosaurs. Of course, the comet is far away from us at the moment, but its dust still lingers in that orbit. It is these tiny particles, no bigger than a grain of sand, that suffer an incandescent fate. We crash into them at tens of miles per second. As they hit us, like bugs on a windshield of a speeding car, they meet a fiery demise in our thick atmosphere and then qualify for the well-known moniker "shooting stars." They are no more, but their deaths provide us with those luminous slashes across the canopy of the sky. How does one suitably set up for a shooting-star soiree? First, make sure you get a good nap the day of the event because the best time to see a shower is very late at night. Many people are disappointed during a shower because they look up in the early evening skies when the meteors are few and far between --- too early for the good part of the show. But why is late night best? If you want to see bugs smack into your moving car you don't stare at the rear window, you keep your eyes on the windshield. We on Earth spin into the oncoming stream only after our local midnight. Until then, it's like staring at the rear window --- nothing much happens. So if you want to really enjoy this thing, with all those wee beasties hitting us head-on, the best time is between about 1 AM and the rising of the sun. And it is this easy: Smear on the mosquito repellant, dress warmly, go outside somewhere where there is little or no light, lie down, and look up. No telescopes required. Here are some things to look for. You'll notice that the meteors are not flying about randomly; they seem to be coming out of one area of the sky. Actually, because of the way we hit the stream of debris, they appear to be coming from a part of the sky in the northeast where the constellation Perseus resides. Hence, the name "Perseid meteor shower." In the moments between strikes, take in the grandeur of the cosmos above. Over your head will be the faint white band of light, starting in the south and arching over into the north, a veil composed of countless millions of stars. That is the Milky Way, our home galaxy, as seen edge on. If you are in the preferred dark countryside setting, you'll notice patches of blackness in the Milky Way. Those are clouds of dust and gas blocking the light from more distant stars. Ignoring the sleep deprivation, meteor showers like the Perseids are really win-win situations. You get to witness the combined aesthetic beauty of dozens of shooting stars in the throes of death, played out on a backdrop that includes the overwhelming glory of the starry heavens. Mark Ritter teaches astronomy at Temecula Valley High School and can be reached at mritter@firstlightastro.com. Posted by Administrator at 2004.08. 7 12:21 PM \| Comments (0)
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