Tuesday, December 27, 2011

The Ellensburg sky for the week of 12/31/11

What's up in the sky 12/31/11

Today: Forget about that big bright ball in Times Square. You can mark the start of the new year with one of the sky’s own big bright balls. That perennial favorite New Year’s Day marker, Sirius, the brightest star in the night sky, rises to its highest point in the sky a little after midnight on January 1. Thus, when Sirius starts to “fall”, the new year has begun. Look for Sirius about two and a half fists held upright and at arm’s length above due south at midnight.

Sunday: Today is the day we celebrate the anniversary of something new – a new classification of celestial objects. Giuseppe Piazzi discovered Ceres [pronounced sear’-ease], the first of what are now called “asteroids”, on January 1, 1801. Ceres is the largest asteroid in the belt between Mars and Jupiter. At first, Piazzi thought it was a star that didn’t show up on his charts. But, he noted its position changed with respect to the background stars from night to night. This indicated to him that it had to be orbiting the Sun. In August of 2006, Ceres got promoted to the status of “dwarf planet” by the International Astronomical Union.

Monday: Venus is one fist above the southeast horizon and Jupiter is five fists above the south-southeast horizon at 6 p.m.

Tuesday: Today’s weather forecast: showers. Meteor showers, that is. The Quadrantid meteor shower peaks over the next two nights. Meteor showers are named after the constellation from which the meteors appear to originate. That makes this shower mysterious because there isn’t any constellation with this name now. The shower was named after Quadrans Muralis, an obsolete constellation found in some early 19th century star atlases. These meteors appear to come from a point in the modern constellation Draco the dragon. This point is about three fists held upright and at arm’s length above the northeast horizon at 1 a.m. In good years, careful observers can spot about 100 meteors per hour. This year, the moon will be setting during the peak observation time so some of the dimmer meteors will be obscured by moonlight. Meteors are tiny rocks that hit the Earth and burn up in the atmosphere. Most meteors are associated with the path of a comet. This shower consists of the debris from an asteroid discovered in 2003. Keeping with the comet-origin paradigm, astronomers think the asteroid is actually an “extinct” comet, a comet that lost all of its ice as it passed by the Sun during its many orbits.

Wednesday: If the Sun looks big today, your eyes are not playing tricks on you. The Earth is at perihelion at about 5 p.m. If you dig out your Greek language textbook, you’ll see that peri- means “in close proximity” and helios means “Sun”. So, perihelion is when an object is closest to the Sun in its orbit, about 1.5 million miles closer than its average distance of 93 million miles. Since it is winter in the Northern Hemisphere now, the seasonal temperature changes must not be caused by the Earth getting farther from and closer to the Sun. Otherwise, we’d have summer when the Earth is closest to the Sun. The seasons are caused by the angle of the sunlight hitting the Earth. In the winter, sunlight hits the Earth at a very low angle, an angle far from perpendicular or straight up and down. This means that a given “bundle” of sunlight is spread out over a large area and does not warm the surface as much as the same bundle in the summer.

Thursday: Has it been tough to wake up this past week? It should have been because the sunrise has been getting a little later since summer started. I know. I know. December 22 was the shortest day of the year. But, because the Earth’s orbit around the Sun is elliptical and not circular, the Earth does not travel at a constant speed. It moves faster when it is closer to the Sun and slower when it is farther away. This leads to the latest sunrise occurring in early January, today for 2012, and the earliest sunset occurring in early December, not on the first day of winter, the shortest day of the year. On the first day of winter, however, the interval between sunrise and sunset is the shortest. For more information, go to http://goo.gl/C7Fyz.

Friday: Mercury is less than a half a fist above the southeast horizon and Saturn is three and a half fists above due south at 7 a.m.

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

Wednesday, December 21, 2011

The Ellensburg sky for the week of 12/24/11

What's up in the sky 12/24/11

Today: What would that special someone want to see on the back of Santa’s sleigh when she gets up early Christmas morning to eat one of Santa’s cookies? A fruit cake? No. A barbell? Maybe to work off the fruitcake. A subscription to The Daily Record? Of course. But what she really wants is a ring. And if she looks out a south-facing window, she’ll see her ring. Saturn the ringed planet, that is. Saturn is three and a half fists held upright and at arm’s length above the south horizon at 7 a.m.

Sunday: Where is the one who has been born King of the Jews? We saw Jupiter being eclipsed by the Moon in the east and have come to worship him” (Matthew 2:2, Bruce Palmquist version, informed by Michael Molnar). There are many theories as to the physical explanation of the Star of Bethlehem, the celestial object that guided the wise men to the location of Jesus. Some people think it was a recurring nova, a star that explodes. Some think it was a close alignment of bright planets. Some think it was a miracle that requires no physical explanation. In 1991, astronomer Michael Molnar bought an ancient Roman Empire coin that depicted a ram looking back at a star. Aries the ram was a symbol for Judea, the birthplace of Jesus. The Magi, or “wise men”, who visited the baby Jesus practiced astrology and would have been looking in that region of the sky for the king prophesied in the Old Testament. Molnar, a modern day wise person, used sky simulation software to model the positions of planets and the Moon in the region of Aries. According to his model, Jupiter was eclipsed, or blocked, by the Moon on the morning of April 17, 6 BC. Molnar’s theory is supported by a book written by the astrologer of Constantine the Great in 334 AD. The book describes an eclipse of Jupiter in Aries and notes a man of divine nature born during this time. See http://www.eclipse.net/~molnar/ for more information.
Aries and Jupiter make an appearance in the Christmas sky tonight. At 8 p.m., Jupiter is five fists above the south horizon and the dim constellation Aries is about a fist and a half to the upper left of Jupiter.

Monday: Mercury is about a half a fist above the southeast horizon at 7 a.m.

Tuesday: Columbia the dove, representing the bird Noah sent out to look for dry land as the flood waters receded, is perched just above the ridge south of Ellensburg. Its brightest star Phact is about one fist above due south at 11 p.m.

Wednesday: Venus is about a half a fist above the southwest horizon at 6 p.m.

Thursday: Have you ever looked down on the ground and spotted a penny? In Yakima? While you were standing in Ellensburg? If you have, then you may be able to see the star Hamal as more than just a point of light. It has an angular diameter that can be directly measured from Earth. Hamal, the brightest star in the constellation Aries the ram, has the same angular diameter as a penny 37 miles away. (For comparison, the moon is about half the diameter of a penny held at arm’s length.) Hamal is six and a half fists above due south at 7:45 p.m.

Friday: NASA’s Kepler satellite recently found the first two Earth-sized planets orbiting a star other than the Sun. Don’t expect to travel there soon. For one thing, the star is nearly 1,000 light years away. For another, the two planets orbit extremely close to their star, much closer than Mercury orbits our Sun. The star, called Kepler 20, is in the constellation Lyra the lyre, two and a half fists above the west-northwest horizon. Read the short article in the journal Nature at http://goo.gl/TqdmT for more information.

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

Friday, December 16, 2011

The Ellensburg sky for the week of 12/17/11

What's up in the sky 12/17/11

Today: Listen, do you want to know a secret? Do you promise not to tell? Whoa oh, oh. The Beatles certainly didn’t write this song about the Barringer meteorite crater in Arizona. Astronomers are studying this 50,000-year-old impact to learn more about our planet’s violent history as well as the physics of impacts throughout the solar system. If you’d like to be let in on some of these secrets, go to http://goo.gl/sqbBe.

Sunday: This morning’s Moon is nearly in the third quarter phase, the phase that occurs when the Sun, Earth, and Moon make a right angle and the left side of the Moon appears illuminated. I wrote “nearly” because the three objects make a right angle at 5 p.m. this evening, when the Moon is not even visible in Washington. It is visible about four fists above the southwest horizon at 7 a.m. Mars is one fist above the Moon.

Monday: Venus is one fist above the southwest horizon at 5 p.m.

Tuesday: Jupiter is five fists above due south at 8 p.m.

Wednesday: At 9:30 p.m., the Sun reaches its lowest point in the sky with respect to the background stars. This point is called the Winter Solstice. During the day that the Sun reaches this point, your noon time shadow is longer than any other day of the year. Also, the Sun spends less time in the sky on the day of the Winter Solstice than any other day making this the shortest day of the year. Even though it is the shortest day of the year, it is not the day with the latest sunrise or the earliest sunset. The latest sunrise is during the first week in January and the earliest sunset is during the second week in December. The Sun is at its southernmost point with respect to the background stars on the day of the winter solstice. This means the Sun spends the least amount of time above the horizon on that day. But, the Sun rise and set time depends on more than its apparent vertical motion. It also depends on where the Sun is on the analemma, that skinny figure-8 you see on globes and world maps. During the second week in December, the Sun is not quite to the bottom of the analemma. But, it is on the first part of the analemma to go below the horizon. During the first week in January, it is on the last part of the analemma to rise above the horizon. For more information on this, go to http://goo.gl/wE9nP.

Thursday: I know you’re staying up late to train yourself to wait up for Santa. So look out a south-facing window at 12:45 a.m. and see Sirius, the brightest star in the nighttime sky, as high as it ever gets in the sky. It is two and a half fists above due south.

Friday: Mercury will be as far away from the Sun in the sky as it will get this orbital cycle. This "farthest away" point is known as the planet's greatest elongation. Since Mercury is in morning sky, it is west of the Sun and this occurrence is called the greatest western elongation. This morning and tomorrow morning will be the best mornings to observe Mercury for the next few weeks. Mercury is about a fist above the southeast horizon at 7 a.m. Over the next few weeks, Mercury will move toward the Sun in the sky. By late February, it will be visible in the evening sky.

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

Thursday, December 8, 2011

The Ellensburg sky for the week of 12/10/11

What's up in the sky 12/10/11

Today: “Red Moon, you saw me sleeping alone. Before the Sun rises up. Before I turn on my phone.” Early risers will see a total lunar eclipse this morning, low in the western sky. During a total lunar eclipse, the Moon enters the earth’s shadow. Total lunar eclipses are not as obvious as total solar eclipses because light still reaches the Moon even when it is directly behind the Earth. That is because the Earth’s atmosphere acts like a lens and bends rays of light that would normally miss the Moon such that they hit the Moon. That doesn’t mean the Moon looks the same during a total lunar eclipse as it does during a normal full Moon. Sunlight is white. White light is the sum of all of the colors in the visible spectrum (red, orange, yellow, green, blue, indigo and violet). Our atmosphere scatters the blue component of the Sun’s white light. That is why our sky is blue. When the Sun or Moon is near the horizon, the light passes through a lot of the atmosphere meaning a lot of the blue light is scattered and the Sun or Moon looks redder than when it is high in the sky. During a total lunar eclipse, sunlight passes through a large slice of the Earth’s atmosphere. The remaining light that reaches the Moon is reddish. Thus, the Moon looks red during a total lunar eclipse. From our perspective in Washington, the Moon will start to enter the Earth’s shadow at 4:45 a.m. Totality starts a little after 6 a.m. By 7 a.m., the total eclipse will be over.

Sunday: Jupiter is five fists above due south at 9 p.m.

Monday: The Geminid meteor shower peaks at 10 a.m. tomorrow morning but will remain highly active throughout the next two nights. Meteor showers are named after the constellation from which the meteors appear to originate. These meteors appear to come from a point in Gemini the twins. This point is about three fists held upright and at arm’s length above the east-northeast horizon at 9 p.m. tonight. You can follow this point throughout the night as it will remain near the bright star Castor, the right hand star of the “twin” stars Pollux and Castor. This shower is typically one of the best ones of the year producing bright, medium speed meteors with up to 80 meteors per hour near the peak. Unfortunately, the Moon will be out throughout the night, obscuring most of the meteorites.
Most meteor showers occur when the Earth passes through the orbital trail of a comet. The broken off comet fragments collide with the earth and burn up in the atmosphere. Astronomers had searched for a comet source for this shower since 1862 when the shower was first observed. Finally, in 1983, astronomers discovered the object that created the fragments that cause the meteor shower. To their surprise, it was a dark, rock that looked like an asteroid, not a shiny icy comet. Astronomers named this object Asteroid 3200 Phaethon. But, they still don’t know if it an asteroid or if it is a comet with all of its ice sublimated away by many close passes by the Sun. For more information about 3200 Phaethon, go to http://goo.gl/LuwGW.

Tuesday: On these cold mornings, it is difficult to get going. You just want to plop into a chair and sit still. But, are you really sitting still? You’re moving at about 700 miles per hour due to the rotation of the Earth on its axis and 66,000 miles per hour due to the revolution of the Earth around the Sun. If that’s not enough, the entire solar system is orbiting the center of the galaxy at a whopping 480,000 miles per hour! So while you may be sitting still with respect to your living room (and all of the over achievers in your house), you are NOT sitting still with respect to the center of the galaxy. For more information about this concept, go to http://goo.gl/lPVPS.

Wednesday: Sirius, the brightest star in the night sky, is one fist above due southeast at 10 p.m.

Thursday: Mars is one fist above due east at midnight.

Friday: Regulus is less than a fist to the upper left of the Moon at 11 p.m.

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

Thursday, December 1, 2011

The Ellensburg sky for the week of 12/3/11

What's up in the sky 12/3/11

Today: The earliest sunset of the year occurs this week, about 4:13 p.m. This seems odd because the shortest day of the year, the winter solstice, isn’t for about two more weeks. The Sun is at its southernmost point with respect to the background stars on the day of the winter solstice. This means the Sun spends the least amount of time above the horizon on that day. But, the Sun rise and set time depends on more than its apparent vertical motion. It also depends on where the Sun is on the analemma, that skinny figure-8 you see on globes and world maps. During the second week in December, the Sun is not quite to the bottom of the analemma. But, it is on the leading edge of the analemma, the first section to go below the horizon.

Sunday: Venus, the brightest of the planets in the night sky, is a half a fist above the southwest horizon at 5 p.m.

Monday: Are you cold? Tired of the blowing snow? Then get up this morning and look at Saturn, the bright point of light two and a half fists above the southeast horizon at 6 a.m. Saturn will not make you warmer. But thinking about its ice moon Enceladus might. Enceladus has numerous geysers that spew ice particles with an aggressiveness that makes the Ellensburg wind feel wimpy – up to 1000 miles per hour. To learn more about Enceladus and its geysers, go to http://goo.gl/5J3iv. If you have a small telescope, you may be able to see Enceladus nearly touching the rings of Saturn this morning.

Tuesday: Jupiter is about a half a fist to the lower right of the Moon at 8 p.m.

Wednesday: “Hey baby! What’s your sign?”
“Ophiuchus, of course”
The Sun is in the same part of the sky as the stars of Ophiuchus from about November 29 to December 17. This is what astrologers mean when they say the Sun is “in” a constellation. Thus, if you were born between these dates, you should be an Ophiuchus. The fact that the horoscopes never list Ophiuchus is a major flaw of astrology. Astrology says that some of our characteristics are based on the location of the Sun at our birth. How can astrologers leave out three weeks from their system? That is like a scientist saying she can explain the results of her experiment every month of the year except early December. Ophiuchus was a mythical healer who was a forerunner to Hippocrates. According to myth, he could raise people from the dead. Maybe that is why he is ignored by astrology. Raising people from the dead is much less impressive than giving spot-on advice such as “Today is a good day to watch your finances.”
The bright stars of Ophiuchus rise just before the Sun. Rasalhague (pronounced Ras’-al-hay’-gwee), the brightest star, is about one fist held upright and at arm’s length above the east horizon at 6:30 a.m.

Thursday: When Galileo aimed his telescope towards the sky, he knew of only one Sun-like star: the Sun. By the early twentieth century, Annie Jump Cannon, Williamina Fleming and others had developed a scheme for classifying stars so astronomers could identify other Sun-like stars. But it wasn’t until the last few years that astronomers have discovered planets around Sun-like stars. Some astronomers estimate that one out of every four stars like our Sun may be orbited by Earth-like planets. Of course, the definition of Earth-like typically means a rocky planet about the mass and radius of the Earth orbiting at a distance where they can be liquid water. So don’t start saving up for that interstellar vacation yet. But over the next few years, satellites such as Kepler will start imaging Earth-like planets. Not long after that, astronomers will be able to study the atmospheres of those planets and look for clues that the planet might have life. If you want to find the most Earth-like planet in the solar system, look a half a fist above the east horizon at midnight. There you’ll see Mars. Yes, Mars. It is a rocky planet with a thin atmosphere that has solid water now and almost certainly had liquid water in the past.

Friday: Do you remember the relative positions of the Moon and Jupiter on Tuesday? Tonight at 8 p.m., the bright star Aldebaran is a half a fist to the lower right of the Moon.

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