November 2003Your monthly dose of the Sun, Moon, and Stars... |
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In this month's issue... |
Featured articles...A Little Halloween Astronomy...The Perseus Supercluster This X-Ray image taken from the Chandra X-Ray Observatory (discussed in the September issue of the Skyline) looks like an eerie skull in space. This is actually a picture of the X-Ray emissions from thousands of galaxies. It is likely that somewhere near the "nose" in the picture is a supermassive black hole, possibly large enough to gobble up an entire galaxy. The skull above is a region of space at least 100,000 light years across. The Chandra Observatory folks have made it so that you can send your friends Halloween Astronomy greetings! An Oversight From Last Month...Last month featured films documenting space related topics. As it turns out, I missed a very
important story...
First of all -- credit where credit is due -- I have to thank loyal Skyline regular Bill Yermal for bringing this film to my attention. Thanks, Bill! Now it's my turn to bring it to everyone else... The Dish is the true story of the only radio telescope in the Southern Hemisphere powerful enough to receive the television signal of Neil Armstrong's first steps on the moon. In Parkes, Australia there is an observatory which continues a close relationship with NASA to this day. The movie has an uncanny collection of likeable characters. The characters have tremendous depth, which contributes to the impressive tension and excitement of the film. It does an impressive job of recreating the excitement and anxiety of the first moon landing for those of us who were not in attendance at the actual historic occasion. It provides us with an entirely different viewpoint of the event. This is a historic, funny, dramatic, and at times romantic film. I can't recommend it enough. A Primer on the Sun
So far, I have mainly discussed 'night time' objects in the Skyline. This month I'm going to spend a moment with a day time astronomical object: The Sun! Even though it appears as the brightest star in the sky, the sun is really an average star... in color, size, age, and temperature it is not significant in any real way. The sun is our star, so I don't want to belittle it! We love the sun! It gives us the light and heat we need to live here on Earth. In order to learn about stars that are trillions and quadrillions of miles away, we study the star that is a little closer to us. The Sun is less than 100 million miles away. Sure, it sounds like a tremendous amount, but it's a nice comfortable viewing distance -- as long as you have the right equipment. Remember, don't ever look directly at the sun! The sun has been in the news this past week. There have been a couple tremendous Coronal Mass Ejections (or CME's) that have thrown matter at the Earth. That is good news, and bad news. First, the bad news: the energy and matter thrown at the Earth can damage satellites and electrical equipment here on Earth. The good news: This can trigger auroras, beautiful glowing curtains of color, in the atmosphere. Since people have been discussing the sun, I just wanted to take a few moments to talk about some features of our hometown star!
Sunspots are the dark,
cool regions of the sun. They only get up to a few thousand degrees -- about half the average temperature of the sun. The smaller sunspots
only last a few hours, but larger ones and large groups of sunspots can last for a month or more. These spots are incredible strong
magnetic fields on the surface of the sun, many times stronger than the entire magnetic field of the Earth. Usually, they appear in pairs
-- one having the positive (north pole) charge, and the other having the negative (south pole) charge.
The sun has much to teach us. The sun causes weather here on Earth, and weather throughout the space in the Solar System. It is the star we can study in the most detail, so that we can learn about other stars deeper in space. It is a giant nuclear reactor, and can tell us how to harness its energy, or how to create our own. The sun has much to teach us about space! Planetary UpdateAs we speed past Mars in our orbit, he fades out just a bit. But it is still the first night sky object you will see. Still, only the moon outshines Mars in the first hours of night. As soon as the sun has set, the bright orange object in the southern sky will be Mars, our next door neighbor. Mars will be fading out throughout this month -- right now it is about 58 million miles away, but by the end of the month, that distance will have extended to nearly 80 million miles. As Mars gets left behind, Saturn is an adequate replacement. Saturn rises around 8:00 pm (EST) at the beginning of the month (it clears the treeline about an hour after that). It hangs out right amidst Gemini, the Twins. Gemini is described below, in the Constellation of the Month feature, and there is a picture showing where Saturn can be found. Saturn is a great telescope object -- even a modest backyard telescope will be able to see those great rings. Jupiter is drifting into the scene, as well, but you'll have to stay up late. He doesn't rise until around 2 o'clock in the morning. Jupiter is quite a bit brighter than Mars, and as we get deeper into the winter months, it will dominate the night sky. Jupiter is hanging right below Leo right now... and, as always, is another great telscope object, showing a striped surface, and at least 4 of its moons. Mercury and Venus will make a very brief appearance in the western evening sky towards the end of the month... but wait until December to see them both a little easier. Venus will be quite bright, but very low in the west as the sun sets -- if you live at a high altitude, or in a place with few trees, you will probably see its impressive glow for a few minutes as the sun's light fades away.
Constellation of the MonthThis month we will take a closer look at the bright brothers: this month's featured constellation is GEMINI! [This is a reprint of a Constellation of the Month from December 2002. Since Saturn is in the neighborhood, I wanted to remind you of this great constellation!] The sign of Gemini, the twins, is a well known constellation, but not often identified in the sky. The twins of Gemini linger above a much more widely recognized constellation: Orion the hunter. If you know the hourglass-shape of Orion, right above and to the left of Orion are two VERY bright stars: they represent the heads of the two brothers, Pollux and Castor, and they are named as such: the star on the left is Pollux, and to its immediate right is Castor. Saturn will be right in the middle of this constellation this month (roll your mouse over the picture below to see where!).
Pollux is slightly brighter, and has a definite orange tint (this color is more easily seen from a dark locale, letting your eyes adjust to the darkness for at least 15 minutes). Castor certainly appears to be a plain, white, slightly dimmer companion. In defiance of this plain appearance, the star Castor is a true marvel -- not a single star at all. With a backyard telescope, Castor will actually appear as TWO stars; a TWIN within the constellation of the TWINS! As science has peered at Castor with more powerful imaging telescopes, we've seen that each of these are THEMSELVES twin stars -- a twin of twins!! What's even more miraculous is that there is another, quite dim, pair of stars nearby!!! As you peer at Castor, imagine this one point of light as SIX stars all spinning around each other in 3 dancing pairs. Castor is really a double-double-double star. The Mythology surrounding Gemini is complex -- I will try to sort out their lineage for you. There are some real odd elements to this story, as there are in many of the myths, though for me, some of the details are truly bizarre, even when compared to other myths. Here goes: Our story opens to a mortal couple, the beautiful Leda and her husband Tyndareus. Zeus, king of all the gods (and who seems to be a star of infidelity in many of our stories!), found Leda to be one of the most beautiful mortals, and coveted her relationship with Tyndareus. He learned long ago how his affairs of the past angered his wife, Hera, and did not care to call upon her wrath again. So, he decided to court Leda in the utmost secrecy. He descended to Earth in the form of a swan, and managed to place himself near Leda whenever he could. After a few visits, Leda noticed the handsome swan that lingered wherever she was. She noticed the wisdom in its eyes, and began to speak to it whenever it was around. She told it her secrets and worries without thinking that it could actually understand what she was saying, as one might speak to a pet. But Zeus certainly understood, and the more he learned about her, the more he yearned to be with her. After a time, he could stand it no longer, and showed himself to her. He used much of the knowledge he had gleaned as a swan to woo her, and they ended up spending some serious time together. A number of months later, Leda gave birth (here's where it gets rather odd), to two eggs. Each held a pair of twins. The first egg contained Castor and Clytemnestra, who, it is said, were the mortal children of Leda and her husband, Tyndareus. The second egg contained Pollux and Helen, and these were accepted as the immortal children of the union between Zeus and Leda. (The beautiful Helen grew up to become the famous Helen of Troy.) Castor and Pollux were the best of brothers -- growing and learning and playing together always. Though they did not emerge from the same egg, so they were not truly twins, they did tend to resemble each other as twins. They embarked on many adventures together, and during one, they met the beautiful sisters: Hilaeira and Phoebe. Each brother fell in love with one of the sisters, and their adoration was returned. The problem: Hilaeira and Pheobe were already betrothed to other men. So, Castor and Pollux asked the sisters to run off with them -- and they agreed. Before they were able to escape, the men to whom the ladies were betrothed got wind of the plan, and tried to stop the eloping couples. In the escape attempt and subsequent fight, Castor was killed. Pollux fell, stricken with grief, and wept over his brother's body. Zeus was touched by this show of brotherhood, and allowed Pollux to share his immortality with Castor, if he wished. Of course, there is always a price: both Castor and Pollux could be immortal, but they would need to leave the Earthly realm, and remain in the heavens. Pollux accepted the offer, and Castor and Pollux remain in the heavens today as the constellation we know as Gemini. The brothers are known to be ones who watch over the sea. The phenomenon we now refer to as St. Elmo's Fire, (electrical discharges over the masts of ships as they approach a storm), were thought to be the brothers Gemini warning sailors of dangerous seas.
The MoonWell, we certainly have something to discuss this month. A TOTAL LUNAR ECLIPSE is in store!! This is our second this year (the last one was back in May), though the last one was obscured by clouds. Get ready to sit outside on November 8. Put on a warm jacket. Pop some popcorn. Brew up some hot chocolate. (The choice of snack and beverage can be varied according to taste -- it will have no impact on the eclipse itself.) The show begins around 6:30 pm (EST) as the rusty shadow of the Earth begins to cross the face of the moon. The moon falls totally within the shadow at around 8:05 pm, and remains there until about 8:30 pm. By 11:20 the moon has swung back out of the Earth's shadow. There is also a total solar eclipse in store this month -- on November 23. Notice that the provious sentence contains no shouting or excitement. This is due to the fact that the only people who will be able to view it are those few that will be stationed in Antarctica; it will not be visible to those of us in the Northern hemisphere at all. But the lunar eclipse on the night of November 8 will still be a great sight! Here are the phases for this month:
Website of the MonthOur ever-evolving Digital Skyline has a new feature! Each month, I will be pointing you to a website that has information on astronomy-related topics. So, now you can browse around and learn more in the time between Digital Skylines!! The month I will feature the website called Astronomy Daily!
Astronomy Daily is a great place to start your night-sky viewing. It shows highlights for the evening, and ones which will be coming soon, in an easy-to-read calendar list. There's a variety of charts to help you view constellations, planets, and deep-sky objects. There's frequently asked questions, discussion groups, an index, and a search tool to help answer any question you may have related to astronomy. Astronomy Daily is good for amateurs or professionals, allowing you to take the hobby of stargazing as far as you like! From just
standing at night looking up, to building your own telescope from scratch, Astronomy Daily is a great web-based resource.
Until next month.... Enjoy the skies! Please come and enjoy one of our monthly programs at the Planetarium! If you would like to receive this newsletter in your own e-mail box at the beginning of every month by simply send a note requesting subscription to "The Digital Skyline". Your e-mail address remains private and secure - we shall never provide your e-mail address to any other party. You will simply receive the Digital Skyline at the beginning of every month, and occassional reminders of some significant sky event (such as a meteor shower or eclipse). The Digital Skyline may be freely distributed. The Digital Skyline content and banner logo: ©2002-2003, Chris Fenwick, Astronomer, County College of Morris
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Website of the Month
The Dish
CORONA -- This is the outermost edge of the Sun's atmosphere. It is a thin, hot layer of gas. The corona can get up to a
million degrees. The corona can only be seen during a solar eclipse, when the main body of the sun is blocked by the moon.
Scientists can use a coronagraph to study the corona -- it is a dark disk which blocks the main body of the sun, basically
simulating an eclipse. The corona emits a constant flow of charged particles away from the sun... this is called the Solar Wind,
and is discussed below.
CORONAL MASS EJECTION (CME) -- The sun is a violent place! It is basically a
precarious balance of extreme nuclear explosions in its center trying to blow the sun apart and gravity holding it together. One of the
most violent eruptions from the sun is a Coronal Mass Ejection, or CME. These are exploding bubbles of magnetically charged gas that
ferociously blast out from the corona of the sun. The explosion can take a few hours. Matter and energy is expelled at incredible speeds,
and, if pointed in the appropriate direction, can hit the Earth, disrupting electrical equipment. CME's are not fully understood;
sometimes there is a Solar Flare or Solar Prominence (described below) in that region of the sun which is associated with the CME, but
just as often it is not.
SOLAR FLARE -- Relatively small, quick, superheated, explosions near the
'surface' of the sun are called Solar Flares. They usually last a few minutes, and can get as hot as many millions of degrees during that time.
The blast is equivalent to something in the neighborhood of a billion megatons of TNT. A Solar Flare tosses matter up into the Corona of the sun,
and sometimes seems to lead to Corona Mass Ejections (see above).
SOLAR PROMINENCE -- Matter can be suspended above the surface of
the sun by the variety of its magnetic fields -- this suspended matter is called a Solar Prominence. You can almost think
of a Solar Prominence as the sun's equivalent of a cloud. These can last as little as a few minutes, or as long as a few weeks.
SOLAR WIND -- All of the explosions bubbling up to the surface
of the sun push matter into the hot atmosphere of the sun. It radiates out from the Corona of the sun at an average of a
million miles an hour. The Solar Wind radiates in all directions, permeating the entire solar system. Even at its impressive
speed, it takes nearly a year for the Solar Wind to reach Pluto.
SUNSPOTS -- Sunspots are a feature of the sun that can be
seen by a casual observer! NEVER look at the sun without the right equipment, but there are very easy ways to
First Quarter: November 1
Full Moon: November 9
Last Quarter: November 17
New Moon: November 23