StarWatch for the greater Lehigh Valley
---------------

FEBRUARY  2019

FEBRUARY STAR MAP | MOON PHASE CALENDAR | STARWATCH INDEX | NIGHT SKY NOTEBOOK

Print Large Sky Charts For 9 p.m. EST:   NORTH | EAST | SOUTH | WEST | ZENITH

[Moon Phases]

CURRENT MOON PHASES

Current Solar X-rays:    

Current Geomagnetic Field:    

Status
Status
CURRENT MOON

---------------
1172    FEBRUARY 3, 2019:   Earth's Shadow Games
We just had the opportunity of watching the moon sweep through the Earth’s shadow, a night so cold that my voice froze in midair, and no one heard me until the morning’s thaw. The next chance that we have to see a similar event is on May 15/16, 2022. I can already feel the blush of a verdant, vernal evening. There is also a deep, partial lunar eclipse visible from North America on November 19, 2021, if you like being awake at 4:00 a.m. However, no worries about having to wait that long to see the Earth’s shadow projected into space. There is another very simple way to view the umbra without an eclipse, especially from locales with sweeping western vistas and drier air. The southwestern US is an ideal location. Here the planet’s shadow is projected visibly into space almost every clear evening as a rising, elongated, greyish haze, straddling the opposite horizon to where the sun has set. Its upper boundary may be bathed in a pinkish or lavender hue which represents the reddening sunlight as Sol dips below some far distant horizon below the curvature of the Earth. One of my first experiences with observing this phenomenon happened in 1975 while I was hiking and camping in Arches National Park, located in east-central Utah near the town of Moab. The Earth’s shadow was so distinct against the brighter sky above it that I considered disassembling my telescope because I thought a cloud deck was approaching. In reality, it was the harbinger of one the darkest evenings that I had ever experienced until that time. The problems with seeing Earth’s shadow east of the Mississippi are many. More humid conditions and hazier air normally persist. Then there are buildings, hills, and trees that may also get in the way of a good view opposite to sunset. The last time that I saw Earth’s shadow was on Thursday evening traveling to class at Moravian. A photo is online, snapped on the previous evening when the shadow was also seen. It was not very distinct, blending in with the darkening sky, but it was there. Check online to see how Earth’s shadow appears on a really good evening near Hanksville, Utah. Go to astronomy.org and click on “this week’s StarWatch.” Look below those images, and you’ll see smartphone photos of the total lunar eclipse sent to me by two good friends and former Dieruff Huskies, Adam R. Jones and Jesse Leayman. Jones of Denver, now an IT guru for an international company which employs over 100,000 people worldwide, used his grandfather’s home-built reflector that was constructed shortly after WWII. The eyepieces were machined from wood. Adam handheld his phone, positioning the lens directly over the eye lens of the eyepiece, not an easy feat, especially with older oculars. Posted online are the best four of his 200 pictures. Not to be outdone, Jesse Leayman, master outdoorsman (Wildman) who lives right off Moravian’s main campus, used an Astroscan 2001 telescope and a special device that allowed his smartphone to be attached to the telescope’s eyepiece. The monetary value of each setup was in the phones that were employed. I used several thousand dollars of camera gear to achieve what I considered to be “okay” results. You don’t need a huge investment to take good pictures. Thanks, Jesse and Adam, for proving that, and to all of us, “Keep looking skyward for that elusive Earth’s shadow

[Earth's Shadow Rising]
If you ever see the Earth’s shadow rising above the horizon this distinctly, you know the night is going to be perfect. This image was taken from the Mars Desert Research Station near Hanksville, Utah during the summer of 2012. Note the pinkish hue above the shadow, the projection of the last rays of reddened sunlight as Sol dips below the horizon. MDRS is where Moravian College has its 25 percent timeshare of the MDRS Robotic Observatory. Gary A. Becker image.

[East Coast Earth's Shadow Rising]
The Earth’s shadow rising from an East Coast location is much less spectacular than from the Southwest as seen in the above photo. Here the shadow is more distinct to the left of the road, towards the NE, because the sun is setting to the south of west. This smartphone image was snapped on my way to Moravian College to meet with my Monday/Wednesday astronomy class on January 30. Like the above image, note the pinkish/creamy hue hugging the upper part of the shadow, the projection of the last rays of reddened sunlight as Sol dips below the distant horizon beyond our view due to the curvature of the Earth. Gary A. Becker image from State Street in Coopersburg.

[Jesse Leayman-Total Lunar Eclipse]
Jesse Leayman of Bethlehem used an Astroscan 2001, a short focal length Newtonian reflector, and an adapter which attached onto the eyepiece of his scope and also connected to his smartphone to record these unguided images of the January 20/21 total lunar eclipse. Nice going Jesse.

[Adam R. Jones-Total Lunar Eclipse]
Adam R. Jones used his late grandfather’s Newtonian reflector made mostly of wood, constructed shortly after the Second World War, to record these images of the eclipse. Unlike Jesse, Adam had no adapter which connected his wooden barreled eyepieces to his smartphone and handheld all of the images. He recorded over 200 pictures and considered these to be his best four. Wow!

[Adam R. Jones-Total Lunar Eclipse]
When consideration is given to the photography of Adam R. Jones and Jesse Leayman presented above, it is obvious that smartphone photography has its place in astronomical imaging, especially with brighter objects like the sun, moon, and eclipses. Here are three of my totality images of the January 20/21 total lunar eclipse recorded with a Canon 80D camera and a Canon 70-200 telephoto zoom lens with a Canon 2x extender. All are high quality pieces of optics. The effective focal length was 640 mm at F/5.6. Gary A. Becker images.
 

1173    FEBRUARY 10, 2019:   What’s Your Sign?
A guy cozies up to an attractive young woman sitting at a bar and asks as his pick-up line, “What’s your sign?” The woman looks him squarely in the eye and with one word, “Exit,” sends him on his way. That always gets a laugh from my students, but the concept of signs and the sky dates back thousands of years to the Babylonians. It was perfected by the Greco-Roman mathematician, astronomer, and geographer, Claudius Ptolemy, who reach his greatest epoch of achievements about AD 140 and died around 168. Ptolemy refined the geocentric universe, where the Earth was in the middle and all other objects revolved about it. Ptolemy did not consider his system as reality; it was meant to be a mathematical and aesthetic predictive model for the future and past positions of the sun, moon, and planets. When the Church later turned Ptolemy’s ideas into dogma, causing all kinds of problems for Galileo and others, the immovable Earth was considered to be the cesspool of corruption for a universe that was pure and unchanging surrounding our planet. Ptolemy was simply happy with his predictive model which allowed him to perfect the pseudoscience of astrology, culminating in the rules of its operation with his Tetrabiblos (four books), which still remains the primary source of astrological information today. The sun, moon, and planets all had traits, which heightened or diminished the influence of each other on the human condition (humors) depending upon where these objects were located in the sky. Although completely bogus by today’s scientific standards, about 13 percent of American still believe that astrology is real (Chapman University, 2014). That is “probably down” from 90 percent of Americans, who in a survey published about 30 years ago, believed that astrology had some influence on their lives. There is good science rooted in astrology because the accurate positions of celestial objects need to be known. However, when those objects are given traits and these qualities are related to one’s life, the science departs like a falling lead weight. I try to support this idea to my students because I was born under the sun sign of Gemini. My traits fit Geminis pretty closely. They are smart, witty, and good articulators, but they can also be quick tempered with split personalities. The “smart” and “witty” statements always elicit smiles. I’m actually pretty average. However, here is the rub. If you mock up the date of my birth on a computer, June 10, 1950, you will find that the sun is squarely in the star pattern of Taurus the Bull and not in the constellation of Gemini. The reason for this change is the 26,000-year wobble of the Earth’s axis which moves the star patterns against the yearly position of the sun. Ptolemy was aware of precession, but who cared at a time when everything was in perfect synchronization? How do astrologers account for this discrepancy today? They claim that the birth sign remains the same and remembers the traits, even though it has nothing to do with the true location of the sun in the sky when you were born. My sign is still Gemini even though the sun was in Taurus when I came into this world. Good science, right? WRONG!!! More about precession, without the astrology, next week.
 

1174    FEBRUARY 17, 2019:   Wobbling Earth and the Tropical Year
Astronomers monitor a plethora of different motions of the Earth and many other effects which change the positions of objects in the sky. Two of these motions are fairly obvious—rotation, the spinning of the Earth on its axis in a 23-hour, 56-minute, 4-second period and the revolution of the Earth around the sun in a 365.26-day interval. These times are referred to as the sidereal periods of rotation and revolution and are related to the 24-hour day and the calendar year that we use. The sidereal day brings a star to the same position in the sky, and the sidereal year brings the sun to the same position in the sky with respect to the stars. Each rotation occurs during an interval of time that allows the Earth to orbit the sun by about one degree. The 365-day calendar year is intimately related to the 360 degrees found in a circle. The orbiting Earth shifts the sun about one degree to the east each day after one rotation. We return the sun back to its original location, due south at noon, by adding four minutes to the sidereal day, and all is well. Our 24-hour clocks keep on ticking in relative congruency with what the sun is doing. Unlike one spin period of the Earth, our calendar year does not return the sun back to its original position with the stars, but rather to the intersection point of Sol’s path with the celestial equator, the projection of Earth’s terrestrial equator into space. When the sun crosses this point in the heavens, we call it the first moment of spring, the vernal equinox. That will happen at 5:58 p.m., Wednesday, March 20; but why a calendar year with 365.24 days rather than one full Earth revolution of 365.26 days? It all has to do with the precession of the equinoxes, the conical wobbling of Earth’s axis in a 25,772-year period and keeping the calendar in step with the seasons. The tipped Earth is like a slowly spinning top with the sun trying to pull the Earth’s slightly bulging equator into alignment with the Earth’s orbital plane. Because the Earth is spinning, the action of the sun’s gravitational force causes the axis to pivot at a right angle to Sol’s downward pull, resulting in the wobble. This causes the point of the vernal equinox to slide westward against the stars by 50.287 seconds of arc per year or about 0.013969 degree. “Who cares?” one might quip, but it’s really important to the calendar! Just like we want to the sun to return to the same due south position in a 24-hour period to repeat the day, we want the sun to revisit the same point in the heavens, the vernal equinox, with respect to the start of the seasons to repeat the year. This is called the tropical year as opposed to the sidereal year, a length of time which is about 20 minutes shorter than the actual orbital period of the Earth around the sun. By using the vernal equinox as the marker, we will insure in perpetuity that Christmas will always happen at the beginning of winter when it is cold and that Independence Day will always happen when it is summer. There will be changes, but it will only be in the position of the sun with respect to the stars. Two thousand years ago, I would have been born with the sun in the constellation of Gemini, about 11 days before the summer solstice. Today, because of precession, the sun is in the constellation of Taurus, but babies born on June 10 are still brought into this world 11 days before the summer solstice. Twelve thousand years from now, Christmas will still be celebrated in winter, but with many of the stars we currently view in the summertime gracing our yuletide sky
 

1175    FEBRUARY 24, 2019:   
 

[February Star Map]

[February Moon Phase Calendar]
 

---------------