[ FirstLight Astronomy Club ] The Skies Above

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The Active Sun

The Solar System >

Do you remember in school seeing those pictures of the sun with little spots?

Those spots, cleverly called "sunspots," are actually big enough to cram an Earth or two into. They are cooler areas of the sun’s surface where stressed-out lines of magnetism are snaking in and out.

During times of high solar activity - called Solar Max - there are a lot more of these spots than when the sun is more relaxed and laid-back.

This is a Solar Max year and, as expected, there are a load of spots.

But wait! There’s more!

During Solar Max there is also an increased amount of "flares," gargantuan explosions on the sun’s surface which spew particles and radiation out into space.

These flares seem to be related to the latest and most exciting discovery in solar activities called Coronal Mass Ejections (CME). These are solar burps belching prolific amounts of energy and particles. But these burps are so big and magnificent as to defy description; you‘ll have to see one to to even begin to imagine their size (see below for websites).

When the radiation and particles crash into our atmosphere, they do al kinds of interesting things. They fire up aurorae - the Northern Lights. They interfere with radio communications of all types. They break up cellphone conversations. They cause annoying noise on your AM-FM radio. They destroy satellite computer circuitry rendering them useless. They may actually set off an automatic garage door opener!

And the pesky radiation actually heats the upper atmosphere enough to expand it so that low-altitude satellites, normally free from the drag of air molecules, are slowed a little and run the risk of crashing back into earth.

NASA has to be extra aware of the activity on the sun during Solar Max when planning and launching the Shuttle for all those reasons.

Want to see spectacular images of all these solar phenomena and more? The SOHO satellite website has up-to-the-moment images of the sun as seen in visible and x-ray and ultraviolet, and some stunning movies of the CMEs. You can also get a nifty solar screensaver!

Until next time, clear skies!

Mark Ritter is a high school astronomy instructor and can be reached at ritter@firstlightastro.com.

Posted by Administrator at 2000.06.25 09:29 AM | Comments (0)

The Solstice and Tilt of the Earth

The Earth >

For thousands of years, people have practiced rituals which got their cues from the heavens: cues like the rising and setting of the sun and stars, eclipses, planetary alignments, comets, moon phases, and meteor showers.

One pattern the ancients would notice was that every year, during the winter months, the sun would start rising and setting farther north each day and traverse across the sky higher and higher. Daylight would last longer and the days would get warmer.

But this pattern would mysteriously stop after several months. For some reason that day would come when the sun would not rise and set any farther north nor sweep any higher overhead in the sky. On the contrary, it would reverse its daily trend into wintertime, when the whole cycle started all over again.

A special name was given to the day when the sun hit its high mark in the sky. It was christened "solstice," which loosely translated means "the sun has stopped." Early astronomers/astrologers - back then they were one and the same - noticed that the solstice always happened when the sun was vacationing in the constellation Cancer the Crab. (Now it occurs when the sun is in Taurus.)

People who happened to be about 23 degrees north of the equator on the summer solstice - like in ancient Syene, Egypt - would discover that they were standing directly over their shadow. The sun was directly overhead.

This special latitude on Earth, 23.5 degrees N, was given the name Tropic of Cancer. Anyone living north of this imaginary line would never see the sun directly overhead because for some reason the sun never traveled that far north.

Now fast-forward to the present.

We now know that the sun teases us this way because Earth is a little tipsy - it’s tilted over by about 23.5 degrees. (This is the reason those globes in stores are always tipped to one side.)

We in North America are tilted most toward the sun on June 20, so the sun rises as high above our heads as it can on that day. Take the family outside around noon on that day and see what’s left of your shadow. It won’t be getting any shorter.

The Tilt is one of those classic taken-for-granted things about our planet. Our perfect tilt allows a massive amount of earth’s surface to get some nice, moderate year-round temperatures - not too hot, not too cold. There is a huge area of comfortable living space available.

If we weren’t tilted at all, the only comfortable places to live would be near the equator. The frozen Arctic Zones, north and south, would be much bigger.

If we were tilted more, our summers would be more severe, our winters more treacherous and, again, the best places to live would be near the equator.

In a cosmic version of The Three Bears, we might say with Goldilocks that our tilt is not too great, not too small: it appears our tilt is just right.

Until next time, clear skies and sunny solstice!

Posted by Administrator at 2000.06.11 09:31 AM | Comments (0)



Looking for something?	« May 2000 \| Main \| July 2000 » The Active Sun The Solar System > Do you remember in school seeing those pictures of the sun with little spots? Those spots, cleverly called "sunspots," are actually big enough to cram an Earth or two into. They are cooler areas of the sun’s surface where stressed-out lines of magnetism are snaking in and out. During times of high solar activity - called Solar Max - there are a lot more of these spots than when the sun is more relaxed and laid-back. This is a Solar Max year and, as expected, there are a load of spots. But wait! There’s more! During Solar Max there is also an increased amount of "flares," gargantuan explosions on the sun’s surface which spew particles and radiation out into space. These flares seem to be related to the latest and most exciting discovery in solar activities called Coronal Mass Ejections (CME). These are solar burps belching prolific amounts of energy and particles. But these burps are so big and magnificent as to defy description; you‘ll have to see one to to even begin to imagine their size (see below for websites). When the radiation and particles crash into our atmosphere, they do al kinds of interesting things. They fire up aurorae - the Northern Lights. They interfere with radio communications of all types. They break up cellphone conversations. They cause annoying noise on your AM-FM radio. They destroy satellite computer circuitry rendering them useless. They may actually set off an automatic garage door opener! And the pesky radiation actually heats the upper atmosphere enough to expand it so that low-altitude satellites, normally free from the drag of air molecules, are slowed a little and run the risk of crashing back into earth. NASA has to be extra aware of the activity on the sun during Solar Max when planning and launching the Shuttle for all those reasons. Want to see spectacular images of all these solar phenomena and more? The SOHO satellite website has up-to-the-moment images of the sun as seen in visible and x-ray and ultraviolet, and some stunning movies of the CMEs. You can also get a nifty solar screensaver! Until next time, clear skies! Mark Ritter is a high school astronomy instructor and can be reached at ritter@firstlightastro.com. Posted by Administrator at 2000.06.25 09:29 AM \| Comments (0) The Solstice and Tilt of the Earth The Earth > For thousands of years, people have practiced rituals which got their cues from the heavens: cues like the rising and setting of the sun and stars, eclipses, planetary alignments, comets, moon phases, and meteor showers. One pattern the ancients would notice was that every year, during the winter months, the sun would start rising and setting farther north each day and traverse across the sky higher and higher. Daylight would last longer and the days would get warmer. But this pattern would mysteriously stop after several months. For some reason that day would come when the sun would not rise and set any farther north nor sweep any higher overhead in the sky. On the contrary, it would reverse its daily trend into wintertime, when the whole cycle started all over again. A special name was given to the day when the sun hit its high mark in the sky. It was christened "solstice," which loosely translated means "the sun has stopped." Early astronomers/astrologers - back then they were one and the same - noticed that the solstice always happened when the sun was vacationing in the constellation Cancer the Crab. (Now it occurs when the sun is in Taurus.) People who happened to be about 23 degrees north of the equator on the summer solstice - like in ancient Syene, Egypt - would discover that they were standing directly over their shadow. The sun was directly overhead. This special latitude on Earth, 23.5 degrees N, was given the name Tropic of Cancer. Anyone living north of this imaginary line would never see the sun directly overhead because for some reason the sun never traveled that far north. Now fast-forward to the present. We now know that the sun teases us this way because Earth is a little tipsy - it’s tilted over by about 23.5 degrees. (This is the reason those globes in stores are always tipped to one side.) We in North America are tilted most toward the sun on June 20, so the sun rises as high above our heads as it can on that day. Take the family outside around noon on that day and see what’s left of your shadow. It won’t be getting any shorter. The Tilt is one of those classic taken-for-granted things about our planet. Our perfect tilt allows a massive amount of earth’s surface to get some nice, moderate year-round temperatures - not too hot, not too cold. There is a huge area of comfortable living space available. If we weren’t tilted at all, the only comfortable places to live would be near the equator. The frozen Arctic Zones, north and south, would be much bigger. If we were tilted more, our summers would be more severe, our winters more treacherous and, again, the best places to live would be near the equator. In a cosmic version of The Three Bears, we might say with Goldilocks that our tilt is not too great, not too small: it appears our tilt is just right. Until next time, clear skies and sunny solstice! Posted by Administrator at 2000.06.11 09:31 AM \| Comments (0)
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