Weekly Sky Reports

Late September 09 - Mid January 10

September 28 to October 4, 2009 

In this week that bridges September and October, the evening moon grows from half  full to full. As the week begins, we are viewing half of the moon’s day side and half of its night side. Then as the moon orbits  the Earth, more and more of the moon’s dayside  rolls into our view. On Sunday, October 4th,  we have fall’s first full moon, called the Harvest Moon. A century or more in the past, before there were mechanized farms, farmers continued to work through the dusk and into night to pick their crops, aided by the light of the Harvest Moon. On September 29th, the moon will appear near the very bright planet Jupiter in the southern evening sky. As the moon orbits the Earth, it lines up the bright zodiac groups and planets, usually once in a calendar month. But this is the moon’s second line up with Jupiter, as it appeared near Jupiter on September 2nd. For the moon orbits the Earth every 27 days, so it can line up with a planet or bright star both at the beginning of the month and towards the end of the month.

October 5 to October 11, 2009
   
In this first full week of October, we get extra evening moonlight from the Harvest Moon.  For in early fall, the moon’s orbit is at a low angle to the eastern horizon. As the moon moves along its orbit toward  the East, it moves considerably northward, reducing its usual 50 minute in rising from night to night. On the average the moon rises about an hour later each night due to its eastward motion about the Earth. This delay is reduced to only a half hour for the Harvest Moon, so in the early part of this week (Oct.5,6,7,8), we get extra moonlight in the first half of the evening. While farmers don’t work in the fields at night anymore, we can take advantage of the Harst Moon with Hayrides or walks in the early evening.  There are three planets seen low in the East at 6:30 a.m. dawn, brilliant Venus and  the dimmer planets Saturn and Mercury below. On Thursday at dawn, Mercury and Saturn will be only a half degree apart. Use binoculars to improve your chances to see this line up. Mercury is slightly brighter and to the right.    

October 12 to 18,  2009
    
In this week in the middle of October, the brilliant planet Venus lines up with the planet Saturn low in the eastern dawn on Tuesday, October 13th. Try viewing about 6:30 a.m. from a place with a flat eastern horizon. Venus is about 100 times as bright as Saturn; the two planets will be separated by a half of a degree (one moon width). You may be able to see the planet Mercury below the Venus-Saturn pair. On Friday, October 16th, the crescent moon will appear to the right of both Venus and Saturn. In the evening sky, the bright planet Jupiter blazes low in the Southwest, shining steadily. The two brightest evening stars are golden Capella, flickering in the Northeast and white-blue Vega, sparkling in the Northwest. As the evening hours pass, Capella climbs and Vega descends.

October 19 to October 25, 2009

As we approach the end of October, the moon returns to the western dusk as a thin crescent, barely visible on Tuesday at dusk and quite easily seen on Wednesday. Since the moon is to the east of the sun, it means no interfering moonlight for the Orionid meteor shower in the early morning hours of Wednesday, October 21st  (when its meteors will be at their best). A meteor shower occurs when the Earth crosses the orbit of a comet. The comet for the Orionids is Halley’s Comet, which last visited the sun’s vicinity in 1986. As a comet travels near the sun, it’s outer layers melt, freeing imbedded grit, which line the comet’s orbit. So when we cross Halley’s Orbit twice each year, first in May and then in October, we have a spurt in the number of meteors seen. The comet grit, typically
the size of a pea gets incinerated in the Earth’s upper atmosphere. In a second or so, the grit is heated to thousands of degrees, and is reduced to fine ashes. This meteoric dust dispersed widely across the globe plays a role in the formation of clouds. Each day about 20 tons of meteoric dust is added to the Earth.  The Orionid meteors can be traced back to the star group Orion, famed for his three star belt. You will see the star group Orion in the early morning hours. The meteors may be seen in all directions of the sky. Your best bet to spot meteors is lie upright  in a lounge chair.      

October  26 to November 1, 2009

In this week that bridges October and November, the evening moon grows from just past half full to nearly full on Sunday, November 1st. So early in the week is the best time of the month to view the moon’s craters and flat lava plains with binoculars or a small telescope. On Monday, October 26th, the moon will appear close to the bright planet Jupiter in the southwestern sky in the early evening. So if you are observing the moon with binoculars, try viewing Jupiter (to the right of moon). To the east of Jupiter, you may spot Jupiter’s large moon Callisto while to the West of Jupiter is the moon Ganymede. Even though these moons are each about 3,000 miles wide, they will appear as tiny stars near Jupiter. Because these moons hurtle around Jupiter faster than our moon, they change their positions relative to the planet from night to night. A  small telescope will allow you to see 3 or 4 moons on most nights.

November 2 to 8, 2009

Now that we are on Standard Time, we have more sunlight in the morning hours as sunrise has fallen back from about 7:40 a.m. to 6:40 a.m. But our sunsets are now coming about 5:15 p.m. From many places in this area,  most homes lie in valleys so the sun is hidden behind western hills before 5 p.m. By the time of traditional evening news (usually starts at 6:30 p.m.), the sky is quite dark. On Monday, November 2nd, the moon is full. This is the Hunters’ Moon, a moon that seems to linger in the evening sky for a few extra evenings, as last month’s Harvest Moon. In this first week of November, the actual sun is about 17 minutes ahead of the mean sun (on which we base our clock time).  The mean sun is a fictitious body that moves along the celestial equator a fixed amount each day. By using the mean sun for time keeping, we maintain a  24 hour day. For the actual sun varies in its apparent drift per day due to the Earth’s elliptical orbit. In early July, we are farthest from the sun, so our solar days are shorter than the average. In early January, we are closest to the sun, so our solar days are longer than the average.  This accumulation of differences can add up. This difference between mean sun time and actual sun time is portrayed in the analemmas on globes and sundials.

November  9 to 15, 2009

In this second full week of November, the moon shines in the morning sky, appearing half full on Monday, November 9th. On Thursday, November 12th, the crescent moon appears near the planet Saturn in the  Southeastern dawn sky. Both objects are easily seen at 4 a.m. On Sunday, November 15th, the crescent moon appears to the right and below brilliant Venus in the 6:15 a. m dawn.. In mid  November, this area receives only 10 hours of sunlight a day. With twilight at dawn and dusk both lasting about an hour, that gives us 12 hours of darkness. During the rest of  the year, there will be less than an hour of change in daylight time. On December 21st, we will have the shortest duration of daylight, about 9 hours and 20 minutes. In late January, the daylight duration will creep back to 10 hours.

November 16 to 22, 2009

The moon is New, aligned with the sun on Monday, November 16th.  This means good viewing conditions for the Leonid meteor shower, which peaks early in the morning hours of Tuesday, November 17th.  This shower’s name refers to the meteors seeming to come out of the star group Leo, the Lion. Best time for observing these meteors will be after Leo is well above the eastern horizon in the early morning hours. The Big Dipper’s scoop stars that point left to the North Star, also pointright towards Leo. By Thursday, November 19th, the crescent moon will be easily viewed in the western dusk. Look for Earthshine, the dim illumination of the moon’s night side by the Earth. The bottom edge of the moon will be quite bright but you can see the dim outline of the moon’s dark side. When the moon appears rather thin to us, someone on the moon will see a nearly full Earth. Because of the Earth’s being nearly 4 times as wide as the moon and about four times as reflective, the fullEarth outshines our full moon by a factor of 75 times

November 23 to 29, 2009

This week the sun appears to cross in front of Scorpius, the narrowest star group along the sun’s path. For the sun spends only 6 days in the Scorpion, compared to 45 days for Virgo. The sun takes 19 days to cross Ophiuchus, the little known 13th star group along the sun’s path, not recognized by most astrologers. On Monday, November 23rd, the evening moon appears near the bright planet Jupiter. On the next evening, November 24th, the evening moon appears half full, offering the best views of the moon’s craters and lava plains as seen by binoculars or a  small telescope. For along the moon’s straight edge, the sun there is rising. Craters’ raised rims will catch the sunlight while the craters’ bowls will be in darkness. The moon also has mountain ranges, actually the rims of gigantic craters that were formed by giant asteroid impacts in the moon’s early days. The areas within these gigantic craters were depressed and became filled with lava about 4 billions years ago. These lava plains can be seen by eye as grey patches on the moon.

November 30  to December 6, 2009

The moon is full on Tuesday evening, December 1st.  Below the moon that evening will be Aldebaran, the star that marks the eye of Taurus, the Bull  Below and to  the right of the moon will   be  Orion, the brightest star group seen in the evening sky. Orion resembles a tilted hour glass with a broad top, a slender middle and a broad bottom. In the middle of Orion is his belt of three matched stars in a row.  In the late evening sky, you can view the bright planet Mars low in the East, now on the eastern edge of Leo. Mars is now about as far from the Earth as we are from the sun. On the evening of  January 29th, next year, Mars will be closest  to the Earth, at a distance of 61 million miles. On August 28th of 2003, Mars pulled within 34.4 million miles and briefly outshone the planet Jupiter. This was the closest approach for Mars in historical times and will not be duplicated for thousands of years from now. When you view Mars, late in the evening, see if you can a yellow-orange tint in its light. This is the color of Mars as seen through a telescope.

December 7 to 13,  2009

A week into December, we have our earliest sunsets of the year, about  4:50 p.m. This event doesn’t happen on the shortest day of the year on December 21st, the first day of winter. The shift in earliest sunsets is due to the orbit of the Earth  that takes us closest to the sun in early January and farthest in early July. Our clocks are based on the mean sun, an imaginary sun that drifts eastward along the celestial equator the same amount each day. This insures that our days are all 24 hours in length. Using the mean sun for time keeping allows the real sun to get ahead of the mean sun by as much as 16.3 minutes (in early November). This difference slowly decreases over the next month but is still large enough to cause the sun to have its earliest sunset on December 7th for our latitude. Latest sunrises (by standard time) are similarly offset, occurring about January 4th, when the Earth is closest to the sun for the year. If we just consider clock time, we have the latest sunrises  (about 7:43 a.m.)  on the last day of Daylight Time (October 31st this year)  before we shifted to Standard time.

December 14 to 20, 2009

Early Monday morning, December 14th is the best time to see the Geminid meteor shower. The name comes from the star group Gemini from which the meteors can be traced back to. A very slender crescent moon at dawn will not detract from the meteors. This meteor is associated not with a comet but an Earth crossing asteroid named Phaethon. Year after year, the Geminids are one of the best meteor showers with bright, medium speed flashes or meteors. Dozens may be seen per hour. The crescent moon may be seen on Thursday, December 17th, but more easily on Friday, December 18th low in the western dusk.  The first sighting of the moon in the Middle East will trigger Muslim New Year, A.H. 1431, the years counted from Mohammad’s flight to Medina, 200 miles to the North of Mecca. In the standard calendar, this event happened in 622 CE,  so 622 + 1431 = 2053 . But for every 33 standard years, there are nearly 34 Muslim lunar years, explaining the difference of 44 years.  

December  21 to  27,  2009

December 21st is the first day of winter, the day when our part of the world is tipped farthest from the sun. On this day, the sun rises farthest South and sets farthest South. The sun has its lowest sky path of the year, peaking at 27 degrees above the southern horizon. This date is called the winter solstice, solstice meaning ‘standing still’. For all through the fall, the sun rising point crept a little southward each day. But a few days before December 21st, the sun’s rising point scarcely budged, thus ‘standing still’. In the following days, the sun’s rising point will stay fixed but then gradually will begin to shift a little bit towards the North each day. On Monday, December 21st, the crescent moon will appear near the bright planet Jupiter in the southwestern dusk. On Thursday, December 24th the evening moon will appear half full in front of the dim stars of Pisces. Around the time of Christmas, the brighter stars of Cygnus form an upright cross low in the Northwest about 9 p.m.  This is called the Northern Cross, a larger and better formed figure than the Southern Cross seen from tropics and Southern Hemisphere.

December 28 to January 3, 2010

The moon is full on New Year’s Eve, December 31st. This is the 2nd full moon of the month  so it can be called “A blue moon”. Since the 1940’s, this term has been used to refer to a  second full moon in a month. We have ‘a blue moon’ about once every three years. It is possible that a year can have two blue moons; for example in 1999, there were two full moons in January, no full moon in February and then two full moons in March.  Recent single blue moons have been in 2001, 2004 and 2007.  The New Year of 2010 begins with the bright planet Jupiter low in the southwestern dusk.  Before Jupiter sets, the yellowish planet Mars rises in the East.  Saturn is rising just before midnight in the East. As the sky begins to glow before sunrise, Saturn is in the South and well placed for telescope viewing of its rings.

January 4 to 10, 2010

Here is an overview of the best planet sights in 2010.  Jupiter drops out of evening view in early February. To see Jupiter, now look low in the West as it begins to get dark. In the East, the planet Mars will be closest to the Earth in late January, then rising as the sun sets and hanging in the sky all night long. As Mars fades in early spring, the planet Venus will creep out of the western dusk. Venus will dominate the evening sky in May, June and July. Saturn will appear in the evening sky throughout the spring and summer.  As Venus drops lower in the Western dusk in late summer, the planet Jupiter will again appear low in the East as it gets dark. Jupiter will dominate the evening sky through the end of the year.  

Public Programs at the Frostburg State Planetarium resume on September 6th with “Blue-White Marble and Pale Grey Dot”, a view of the Earth and moon as seen from other planets. To get a free planetarium schedule/bookmark, call (301) 687-7799 and leave your name and mailing address.

By Dr. Bob Doyle

You can contact Dr. Doyle by mail at

Planetarium
Frostburg State University
Frostburg, MD 21532

or by email at rdoyle@frostburg.edu.