Tuesday, September 28, 2010

The Ellensburg sky for the week of 10/2/10

Saturday: Mnemonics are helpful for remembering astronomy facts. (Similarly, “Johnny Mnemonic”, the 1995 cyberpunk film, was helpful in getting Keanu Reeves’ career going.) After all, school children all around the country are learning the order of the planets by remembering, “My very excellent mother just served us nine….” Oops, I guess that one needs updating. Well, here’s one that will not need updating for nearly 100,000 years: the order of the stars in the Big Dipper. Because the nighttime stars are so far away from us, their actual motion through the sky, called their “proper motion” is not noticeable over even thousands of years. That is why the constellations have remained the same since ancient times. But two stars in the Big Dipper have a proper motion large enough such than in 100,000 years, the stars will no longer make a dipper shape. Until then, you can remember the names of the seven dipper stars in order from handle to cup by remembering “morning, morning, evening, death” or “amampmd”. The stars are Alkaid, Mizar, Alioth, Megrez, Phad, Merek, and Duhbe. Morning, morning, evening, death is one fist held upright and at arm’s length above the north horizon at 11 p.m.

Sunday: Astronomers, philosophers, and smart children have been contemplating the fate of the universe for centuries. Galileo, arguably the first modern astronomer, did not start that endeavor. But by turning his telescope toward the night sky, he opened a new source of evidence for determining that fate. To honor Galileo’s contribution to this question, the International year of Astronomy Hot Topic for October is “What is the fate of the universe?”. For more information, go to http://astronomy2009.nasa.gov/topics_oct.htm.

Monday: For the first time in months, the evening sky has only one naked eye planet. But, what a planet it is. Jupiter, the king of planets, is three fists above the southeast horizon at 10 p.m. But don’t sit at home and look at it alone. Go to the CWU Astronomy Club’s First Monday Astronomy Event from 8:00 to 10:00 pm. We will meet in Lind Hall, room 215 for a brief introduction to the night sky. There will be numerous telescopes in use to view Jupiter and other interesting celestial objects. Dress warm. If the sky is overcast, come anyway to hear a presentation about the Solar System. Lind Hall is on the corner of Chestnut Street and University Way. There is ample close free parking near Lind Hall at this time of night.

Tuesday: Mercury is less than a half a fist above due east at 6:30 a.m.

Wednesday: Fomalhaut, the southernmost of the bright stars, is a little more than a fist above the south horizon at 10:30. It is in the constellation Piscis Austrinus or the southern fish.

Thursday: The Draconid meteor shower peaks tonight and tomorrow night. The meteors appear to come from a point in the head of Draco, the dragon constellation. This point is about five fists above the northwest horizon at 10 p.m. tonight. This point remains near the trapezoid-shaped head of Draco throughout the night. Typically, this is a minor shower. However, Draconid meteors are slow moving which means you will have a easy time differentiating true Draconid meteors, from Comet 21P/Giacobini-Zinner, from stray grains of dust that happen to enter the Earth’s atmosphere near where we see the constellation Draco. As your Mother might say, dress warm and sit in a comfortable chair for maximum enjoyment.

Friday: The bright star Arcturus is about two fists above the west horizon at 8 p.m. Some people may mistake it for a planet because it is bright and it is low in the western sky near sunset. But, you are not “some people”…. You are the one person who actually reads this column.

The positional information in this column about stars and planets is typically accurate for the entire week.

Wednesday, September 22, 2010

The Ellensburg sky for the week of 9/25/10

Saturday: “You know Aries and Cancer and Draco and Libra. Leo and Pisces and Virgo and Hydra. But, do you recall, the pointiest asterism of all? Triangulum, the three sided asterism, had a very pointy edge….” Sorry. Some stores have started putting up their Christmas decorations and that has put me in the mood to modify some Christmas songs. Anyway, Triangulum is a small constellation between the more prominent Andromeda and Aries. Its main feature is a skinny triangle oriented parallel to and nearly four fists held upright and at arm’s length above the east horizon at 10 p.m.

Sunday: Venus will really be negative for the next few nights. But, don’t feel bad for Venus. It is okay for a celestial object to be negative as long as we are referring only to its magnitude. The ancient Greek astronomer Hipparchus developed a system for rating the apparent brightness of stars and planets in which lower numbers refer to brighter stars and planets. In his initial scheme, all points of light in the night sky were classified from first magnitude, meaning bright, to sixth magnitude, meaning very dim. Modern day astronomers have made this scale more quantitative. Tonight and tomorrow, Venus has a magnitude, or apparent brightness rating, of -4.6. Sirius, the brightest star in the night sky, has a brightness rating of -1.5. Venus will barely be visible right after sunset very low in the southwest sky. Sirius is two and a half fists above the south-southeast horizon at 6 a.m.

Monday: Did you time the exact length of the day and night last Wednesday on the first day of autumn? They were not equal in duration. Many people think that the day and night are the same duration on the autumnal equinox. The day is a little longer than the night for two reasons. First, the Sun is an extended object so even when the middle part has set, the upper half is still above the horizon lighting the sky. The second, and more influential reason, is that the atmosphere acts like a lens, bending light from the Sun above the horizon when the Sun is really still below the horizon. Day and night are closest in duration today.

Tuesday: Sometimes you find spare change in a chair or an old candy bar in your backpack. Last month, astronomers announced that they found 14 trans-Neptunian objects in old Hubble telescope data. While trans-Neptunian objects will not help you satisfy your hunger, they offer astronomers clues to the origin of the solar system. Pluto is the most well-known trans-Neptunian object. For more information, go to http://www.universetoday.com/73501/astronomers-find-14-new-trans-neptunian-objects-hiding-in-hubble-data/.

Wednesday: The International Year of Astronomy (IYA) is winding down. But the size of the objects being featured is not getting any smaller. This month’s Go Observe is the Andromeda Galaxy. On Saturday, I had you look for Triangulum. About one fist above Triangulum is a star twice as bright as the brightest star in Triangulum. From that star, hop about a half a fist up to a star that is about one fourth as bright as the bright star you just found. Less than another half fist in the same direction is a fuzzy oval patch of light called the Andromeda Galaxy. The galaxy is impressive to see in binoculars. It consists of about 400 billion stars and is 2.2 million light years away. For more information about the Andromeda Galaxy, go to http://astronomy2009.nasa.gov/observe_oct.htm.

Thursday: Jupiter is three fists above the southeast horizon at 10 p.m.

Friday: Astronomers, philosophers, and smart children have been contemplating the fate of the universe for centuries. Galileo did not start that trend. But by turning his telescope toward the night sky, he opened a new source of evidence for determining that fate. To honor Galileo’s contribution to this question, the IYA Hot Topic for October is “What is the fate of the universe?”. For more information, go to http://astronomy2009.nasa.gov/topics_oct.htm.

The positional information in this column about stars and planets is typically accurate for the entire week.

Tuesday, September 14, 2010

The Ellensburg sky for the week of 9/18/10

Saturday: Last Sunday, I gave you a very brief overview of how to use the Big Dipper as a clock. But, my explanation was helpful only for a late evening in the autumn or spring. Some of you go out other times of the year and need a way to tell time then. First, find the two stars at the far end of the Big Dipper cup, the stars that do not touch the handle. Draw an imaginary line segment starting at the North Star and passing through the two Big Dipper cup stars. Now, draw a big circle around the North Star. Your circle is a 24-hour clock. Number the circle from 0 hours at the top, counterclockwise to 12 hours at the bottom of the circle, and back up to 24 hours at the top. (O hours and 24 hours are the same on this clock because the day is 24 hours long.) The hour number on the big circle closest to where your imaginary line intersects this circle is called your raw time. Due to the location of the Big Dipper compared to the rest of the stars, the time nearest the intersection (the raw time) is correct for March 6. For any other night, subtract two times the number of months the current date is after March 6 from the raw time. For example, let’s say the imaginary line between the North Star and the Dipper stars is pointed to the right. That means the raw time is 18 hours or 6 p.m. If you made this observation on October 6, which is seven months after March 6, you would subtract two times seven or 14 hours from the raw time. Thus, the time for November 6 is 18 hours minus 14 hours or 4 hours. In other words, 4 a.m. Don’t forget to convert for daylight savings time if needed. For a more complete set of instructions, go to http://prdupl02.ynet.co.il/ForumFiles_2/24505461.pdf. There is a simple “star clock” template and instructions at http://www.skyandtelescope.com/letsgo/familyfun/Make_a_Star_Clock.html. Use this paper star clock whenever you watch is broken.

Sunday: Let me tell you the story of the ghostly white figure that rises early in the morning around Halloween. It appears to be a huge dim glow of white light that rises up from the east in the pre-dawn sky. No, I’m not writing about the ROTC student who has her first early morning physical training. I’m describing an effect called the zodiacal light. This light comes from sunlight reflecting off dust grains in our solar system. The effect is the most visible when the band of constellations called the zodiac makes a steep angle with the horizon. You need a clear sky with no haze or light pollution to see the zodiacal light which will be visible for the next week or so. At its brightest, the zodiacal light rivals the light of the central Milky Way.

Monday: Mercury is about a half a fist above the east horizon at 6 a.m.

Tuesday: Jupiter and Uranus are both in opposition tonight. No, that doesn’t mean they will disagree with everything you say. (You: “My, the sky is a pretty blue today.” Jupiter: “No, it’s a pretty yellow.” Uranus: “No, it’s a pretty red.”) Opposition means that a planet is on the opposite side of the Earth as the Sun. An object is in opposition when it is due south 12 hours after the Sun. When an object is in opposition, it is at its highest point in the sky during the darkest time of the night. A planet in opposition shines brighter and appears larger in a telescope than any other night of its orbital cycle. Jupiter and Uranus are four fists above due south at 1 a.m. daylight savings time which is midnight standard time. If you’d rather not stay up so late,

Wednesday: At precisely 8:13 p.m. the center of the Sun crosses the celestial equator and passes into the southern sky. The celestial equator is an imaginary line that divides the sky into a northern and southern half. When the Sun is in the southern half of the sky, it appears to take a shorter path from rising to setting. It also does not get as high in the sky at noon. This leads to shorter days and longer nights. Since the Sun crosses the celestial equator today, there is an instant when it is equally in the northern and southern sky, called the north and south celestial hemispheres. This so-called “equal night” is given by the Latin word equinox. Thus, today is known as the Autumnal Equinox. However, the day and night are not of equal duration today. The sun rises at 6:45 a.m. and sets at 7:03 p.m. Day and night are of equal duration next Monday.

Thursday: If Venus was not the brightest planet, you’d have no hope of seeing it with the naked eye for a few weeks. Look for it this week just above the southwest horizon within 45 minutes after sunset. By next week, it will be lost in the glare of the Sun.

Friday: Christmas Eve is three months away which means it is time to start making your wish list of gifts and recipients. Perhaps someone on your list (maybe you?) wants a telescope. The Sky & Telescope website has a good article on choosing your first telescope. Thanks to improved materials, you can buy a high quality starter scope for under $250. People never outgrow their first small telescope if it is well made. Even people who own giant telescopes or have their own observatory sometimes only want to spend five minutes setting up a telescope to show the neighbor kids Jupiter’s moons. Go to http://www.skyandtelescope.com/equipment/basics/12511616.html for more information.

The positional information in this column about stars and planets is typically accurate for the entire week.

Thursday, September 9, 2010

The Ellensburg sky for the week of 9/11/10

Saturday: Orion's the hunter. Searching for love in these lonely skies again. (Apologies to my favorite 1980s heavy metal band, Dokken.) Orion is such a prominent constellation, there are many myths about it. Nearly all Greco-Roman myths involve Orion getting killed. In one myth, he is accidentally killed by his girlfriend Diana, the goddess of the moon and of hunting. She felt so guilty that she repaid her debt by pulling him across the sky each night in her moon chariot. In another myth, Orion is killed by the bite of Scorpius, the scorpion. Obviously, Orion wants to avoid Scorpius in the night sky so he does not get bit again. That is one story of why Orion sets just as Scorpius rises.
Notice that both of these stories have an element of truth. Orion really does cross the sky each night. Orion really does set as Scorpius rises. Many people think a myth is simply a fake story. Instead, a myth is a story used to communicate a message. Myths always have some truth in them. Try to create your own myth about Orion as you see its belt three and a half fists held upright and at arm’s length above the southeast horizon at 5:30 a.m. The bright reddish star four fists held upright and at arm’s length above the southeast horizon is Betelgeuse (pronounced Bet'-el-jews). The bright bluish star three fists above the south-southeast horizon is Rigel.

Sunday: You can use the position of the Big Dipper as a clock. During the late evening in the autumn, the Big Dipper cup is facing up to hold water. During the late evening in the spring, the Big Dipper cup is facing down to produce those spring showers. The water-holding Big Dipper is one fist above the north horizon at 11 p.m.

Monday: Science is Central! This week, faculty, staff, and students in the College of the Sciences at CWU will kick off the start of the academic year by hosting a series of evening science lectures and demonstrations geared for all ages. All events are taking place on the CWU Ellensburg campus and all are free. The week kicks off tonight with Bruce Palmquist and Michael Braunstein from the Department of Physics presenting a night sky lecture from 6:30 – 7:30 pm in Lind Hall room 215 followed by a guided tour of the night sky with several telescopes. Check http://www.cwu.edu/~web/cwu_news/News.php?ArticleID=2760 for information about events for the rest of the week.

Tuesday: Tonight’s first quarter Moon is in the constellation Ophiuchus (pronounced O-fee-u’-kus) the serpent-bearer. The Sun actually spends more days in line with Ophiuchus than with Scorpius the scorpion making Ophiuchus the thirteenth Zodiac constellation.

Wednesday: Astronomy is a field of science where amateurs can make a significant contribution. Amateur astronomer John Dobson is such a person. He developed a way to make the low-cost, easy-to-use, large aperture telescopes that millions of sky watchers around the world use to study and enjoy the nighttime sky. These devises, called Dobsonian telescopes by everyone but Dobson himself, are the best entry-level telescopes. John Dobson turns 95 years old today.

Thursday: Jupiter is two and a half fists above the southeast horizon at 10 p.m. It is the brightest point of light in the sky at that time and very easy to see. The planet Uranus typically is not easy to find. But this week and next, Uranus is right above Jupiter in the sky. They are less than a pinky width apart in the sky and even close together in binoculars.

Friday: When you look up into the night sky and see all of those stars, you’ve got to ask yourself one question: “Do I feel lucky?” Well, do ya punk? You would if you looked at the lucky stars in the constellation Aquarius. The two brightest stars are called Sadalmelik, the lucky stars of the king, and Sadalsuud, the luckiest of the lucky. Another star in the constellation is called Sadachbia meaning lucky stars of the tents. Sadalmelik is four fists above the south horizon at 11 p.m. Sadachbia is to the lower left of Sadalmelik. Sadalsuud is three and a half fist above due south at this time.

The positional information in this column about stars and planets is typically accurate for the entire week.