NEW PROJECTS FOR FALL AND WINTER UNDER CONSTRUCTION



PROJECT: SATURN PROGRADE MOVEMENT
 

What's that bright star up there? Often it is one of the five bright, easily seen, planets (Mercury, Venus, Mars, Jupiter and Saturn. At present, that bright “star” is the beautiful planet Saturn up there in the early evening sky of the spring 2011. It shines brightly just east of Porrima (Gamma Virginis). Saturn will remain in our sky throughout the summer and most of the fall when it will be joined by Jupiter. The figure below shows Saturn’s movement from late May until early October. Saturn is just at the western extent of its “retrograde motion” which it will reach about June 14, 2011. From then through the remaining time in our 2011 sky, Saturn will reverse its movement and travel eastward, closing the distance and passing 51 Theta Virginis around October 4, 2011. You can watch its progress using this star chart.

Often it is one of the five bright, easily seen, planets (Mercury, Venus, Mars, Jupiter and Saturn. At present, that bright “star” is the beautiful planet Saturn up there in the early evening sky of the spring 2011. It shines brightly just east of Porrima (). Saturn will remain in our sky throughout the summer and most of the fall when it will be joined by Jupiter. The figure below shows Saturn’s movement from late May until early October. Saturn is just at the western extent of its “retrograde motion” which it will reach about June 14, 2011. From then through the remaining time in our 2011 sky, Saturn will reverse its movement and travel eastward, closing the distance and passing 51 around October 4, 2011. You can watch its progress using this star chart.

 

This project is simply taking a look at Saturn on a regular basis and noting its position relative to Porrima and Theta Virginis.   

  ZODIACAL CONSTELLATIONS

Many of the constellations that will be discussed in these “Backyard Projects” are “zodiacal” constellations. Perhaps we should begin with some definition of what these are. First, we need to distinguish between astrology and astronomy that are two very different things. Astronomy is a science, based on the tenets of scientific inquiry and testable hypotheses. On the other hand, astrology is a “belief system” that attempts to predict personality traits and futures from the date and time of one’s birth and how that is associated with the positions of the Sun, Moon, and the planets. While astrology has a legitimate history, it is not a science and the two should not be confused.

The locations of the Sun, Moon and planets in our solar system are a matter of natural law; that is, they may be observed in these positions on a regular basis and/or we may predict where they will be at any given time. More importantly we are concerned about where the solar system objects are positioned from our terrestrial point of view and relative to the celestial background.

The “zodiac” is simply that section of the sky where we find the Sun, Moon, and planets. It is a band sixteen degrees wide with eight degrees on either side of the path the Sun takes through the stars; the “Ecliptic”. This wide band passes through 24 constellations and we could talk about “Moon Signs” or specific “Planetary Signs” depending on the path described by those objects.

The twelve “Sun Signs” are the twelve “zodiacal” constellations through which the narrow ecliptic passes. In reality, the constellation Ophiuchus should be included as a “zodiacal” constellation because it lies across the ecliptic. The reasons for its exclusion are not our concern here although squeezing the astrological “zodiac” into twelve rather than thirteen does change your “astrological sign”. George Armstrong Custer, Winston Spencer Churchill and I are really Ophiuchans and therefore have “no personality”.

Here is how the Sun travels around the sky. At the autumnal equinox (September 21), the Sun is in the constellation Virgo and we see Pisces and Aquarius rising in our evening sky. At the winter solstice (December 21), the Sun is in the constellation Sagittarius and Gemini occupies our evening sky. At the vernal equinox (March 21), the Sun is in the constellation Pisces and we see Virgo rising in the evening sky. Finally, at the summer solstice (June 21), the Sun is in the constellation Gemini and we have Sagittarius in our summer sky. 

CELESTIAL NAMES AND CATALOGUES

Perhaps you have heard or seen various names, numbers, and letter designations referring to stars or celestial objects bantered about at star parties or astronomy club meetings (e.g., M31, NGC 6231, IC 2165, etc.).  And, maybe you have also wondered what these “names” really mean.  Here is a brief, hopefully helpful, explanation of a rather broad topic.

 

One of mankind’s inherent qualities is to observe, name, and categorize things we encounter in our surroundings. The heavens certainly have not gone without notice. The first known star catalogues were those of Hipparchus who recorded the naked-eye objects he observed in the sky from the Greek island of Rhodes in the Aegean Sea between 146 and 127 B. C., and Ptolemy who observed from Canopus in Egypt from A. D. 127 to 151. Since then and with the invention of the telescope, our understanding of the universe has changed and many more catalogues of celestial objects have been compiled by prominent astronomers of the time.

 

One of the most commonly used catalogues is that compiled by Charles Messier (1730-1817). Like many others at the time, he was interested in finding comets and his published catalogue(s) was of fuzzy “comet look-alikes” in the sky.  The purpose of his catalogue(s) was to help others not waste time observing things that were not comets. His telescopes were rather crude by comparison to modern scopes, but the 110 bright objects he identified and catalogued are among some of the most interesting objects in the sky. All of these objects carry the “M” designation. It is possible on or near the vernal or autumnal equinoxes (12 hour nights) to observe all 110 of Messier’s objects in one night; the Messier Marathon.

 

In the nineteenth century, William Herschel and his sister Caroline, working with much improved telescopes, systematically catalogued thousands of deep space objects. John Herschel continued his father’s work by observing objects in the southern sky from Cape Town, South Africa.  He published a catalogue of over 5,000 objects most of which were observed by the Herschels. Herschel objects are identified with a Roman numeral and Arabic number designation indicating the type of object; Herschel numbers (e.g., H III 476, H VII 43, etc.) may still be found in some listings.

 

By 1886, there were so many catalogues and different designations that the Royal Astronomical Society of Great Britain decided to merge all of the existing lists into one master list; the New General Catalogue (NGC).  Soon after the NGC was published it required revision and subsequently Supplementary Index Catalogues (IC) were published.  These catalogues account for most of the objects most amateur astronomers observe. However, there are many specialized catalogues aimed at specific kinds of objects, many with magnitudes much fainter than can easily be seen.

 

Stars themselves may have strange names (e.g., Antares, Schedar, Ras Algethi) reflecting their original Greek or Latin names or those translated into Arabic, Chinese or some others from our vast cultural heritage. A legacy of this historic application of various names and designations is that a star may have a number of names; Vega, for example, has over 40 different names.

The Bayer designation is a stellar classification in which stars are identified with a Greek letter followed by the genitive form of the parent constellation’s Latin name. Most of the brighter stars were assigned their first systematic names by Johann Bayer (1572-1625), a German astronomer, in 1603 in his Uranometria. He attempted to assign these names on a descending order of brightness. Alpha is the brightest star in the constellation, the second brightest being Beta, then Gamma and so on. For example the star Antares in the constellation Scorpius has a Bayer Classification of Alpha Scorpii. The limitation of this classification is that the Greek alphabet has only 24 letters. Bayer utilized upper-case Greek letters but these are rarely used nowadays.

 

Another classification that is often used in combination with Bayer’s designations is the Flamsteed Classification. This system was designed by John Flamsteed (1646-1719), an English astronomer. It is a numeric classification applied in a manner to give the star’s relative location (west to east) within the parent constellation. For example, 1 Lyrae would be the western-most star in Lyra; 2 Lyrae the next and so on (Vega is 3 Lyrae).

 

Many stars are classified in the modern Smithsonian Astrophysical Observatory Catalogue, initially published in 1966, and have SAO designations. This catalogue which is continually revised is also a comprehensive compilation of many previous star lists. Other specialized lists contain collections of double, multiple or variable stars.

PROJECT: OPHIUCHUS AND THE SUMMER GLOBULAR CLUSTERS

This project is an early summer project that will last through the summer and into the fall. It concerns the study of the constellation Ophiuchus, the Serpent Bearer or God of Medicine. Actually, there are two constellations in three parts; Ophiuchus is the central constellation. He is facing us (the original depiction) grasping the head of the serpent, Serpens Caput, in his left hand (Yed Prior and Yed Posterior) and the serpent’s tail, Serpens Cauda, in his right hand. Serpens is the only constellation out of 88 that is divided. In mythology, Chiron, the Centaur, was a mentor to Ophiuchus.

These constellations were among the 48 recognized by the astronomer Ptolemy in the First century. Although Ophiuchus is truly a zodiacal constellation (the Sun passes through the lower portions of it between November 30 and December 17), it has been left out of the modern twelve for reasons too detailed to discuss here; a Google search will yield many interesting discussions of mythology and astrology (not to be confused with the Science of Astronomy).

It is always a pleasure to see Ophiuchus (aka Asclepius, the Healer) and his magical snake as they usher in the wonders of the summer sky and Milky Way. One of the largest constellations, Ophiuchus/Serpens occupies a huge quadrangle of the sky bounded by four prominent stars; Arcturus (Boötes) and Vega (Lyra) across the top and Antares (Scorpius) and Altair (Aquila) along the bottom. The Serpent Bearer stands with his left foot (just above the bright red star, Antares) toward the galactic fields of Virgo and the spring sky and his right foot in the dense star field of the Summer Milky Way. The constellation is studded with an array of bright to dim globular clusters (dense packed balls of ancient stars). Several attractive open clusters (loose and irregular-shaped groups of young stars) shine over his right shoulder (beta Ophiuchi).

Most of the stars of Ophiuchus are in the mid-range of naked-eye viewing (magnitude 3-4) and it warrants some preliminary study before we delve into its treasures. Ophiuchus is best viewed on a dark moonless night, preferably from a dark sky location. If your back yard is in the city you should give him a chance to rise well above the horizon. By mid June Ophiuchus will be well positioned just east of the meridian (north-south line) around 9:00 PM; feel free to catch him on the rise earlier in the month. Let your eyes become dark adapted so you will be able to view these dimmer stars. Also remember to avert your vision (look to the side rather than straight on) if you are having trouble seeing. Finally, remember the reward of finding these challenging objects is that “once you have seen them, they become easier to see”.

We will begin by finding Serpens Caput, the head and fore body of the snake. By now you should be familiar with the constellations Boötes, Corona Borealis, and Hercules. While we haven’t studied Scorpius yet (coming in July), the bright red alpha star Antares is shown in the star charts below. There is a broken, but rather straight line of stars running from just below Corona Borealis down toward Antares. You will notice there are two pairs of stars along this line. This forms the body of the snake. As your eyes adjust you should see the triangular head of the snake just below Corona Borealis. Retrace the neck region back down to delta Serpentis (mag. 4); here the body bends sharply downward to alpha Serpentis (mag. 2.6), a reddish star at the top of the first pair of stars. The second pair of stars, both reddish, will be found about the same distance on down the body of the snake. These two stars are delta and epsilon Ophiuchi or Yed Prior (mag. 2.7) and Yed Posterior (mag. 3.2), respectively. These two stars form the left hand of Ophiuchus that grasps the snake. Thus, Serpens Caput forms the western sector of Ophiuchus. 

Next let’s trace the head, shoulders, and torso of the Serpent Bearer. From delta Ophiuchi move upward to lambda Ophiuchi (mag. 4), then continue upward to kappa Ophiuchi, a reddish star (mag. 3) that has a small companion (mag. 4.4). Now, you should see a rather bright star above and a bit to the northeast of kappa Ophiuchi. This is alpha Ophiuchi (mag. 2), Ras Alhague (Arabic for “head of the snake collector”). Just above Ras Alhague is the alpha Herculis (mag. 3.5), Ras Algethi (Arabic for “head of the kneeler”, the original name for the constellation Hercules). Now, we will travel down the right (east) side of Ophiuchus. Drop down to beta Ophiuchi, a reddish star (mag. 2.8). Make a long drop down to eta Ophiuchi (mag. 2.4) passing through a small dim star (mag. 4.5) about half way down. Complete the circuit by traveling westward across the bottom of the constellation, passing through zeta Ophiuchi (mag. 2.5) to Yed Posterior. We have just outlined an asterism, sometimes referred to as “the coffin”. Serpens Cauda passes northeastly from eta Ophiuchi to xi Serpentis (mag. 3.5), omicron Serpentis (mag. 4.2), eta Serpentis (mag. 3.2), to theta Serpentis (mag. 4.6).

Now we will look for the marvels of this constellation. We will begin by searching for M5, a tightly packed globular cluster of about 500,000 stars located about 27,000 lys from Earth; it is about 100 lys diameter. It is a fine binocular target shining at magnitude 6. Project a line south from delta Serpentis about the same distance from beta Serpentis to delta Serpentis. Form a triangle of sorts with another line of about the same length from epsilon Serpentis. This should put you in the neighborhood. You should see M5 by scanning the area and using averted vision. If the sky is dark enough, you might be able to see M5 with the naked-eye.

 

There are two globulars, M12 and M10 in the lower middle portion of “the coffin” asterism; both are mag. 6. From delta Ophiuchi (aka Yed Prior) move northward to lambda Ophiuchi, a small star about halfway to kappa Ophiuchi. Project a line eastward at a right angle to the line between delta and lambda Ophiuchi. M12 will be found in this vicinity. Continue the line eastward to an intersection with another line projected north from xi Ophiuchi. Here you should find M10. These two are found “side by side” along the top of a box formed by xi, delta, and lambda Ophiuchi with M10 roughly at the corner opposite of delta Ophiuchi.

 

 

 

 

 

Scan southward from xi Ophiuchi to find M107 which is smaller and slightly dimmer at mag. 7.8. It may be difficult to find if sky conditions are not dark. M107 is fairly easy to locate as it is just half a binocular field south-southwest of zeta Ophiuchi (Mag. 2.5). It will be a tiny round glow directly below a small right triangle of stars. M9 also shares a binocular field with a fairly bright star. If you place eta Ophiuchi at about 1 o'clock in the field, M9 should appear at about 7 o'clock in the field of view. It too does not have that striking fuzziness of most globulars. With averted vision, you should be able to see it. These two globulars are a challendge to find but can offer some entertainment on a warm summer evening of viewing.

 

 

 

 

 

 

M14 is in the expanse of sky just east of a line projected from beta Ophiuchi to eta Ophiuchi. If you divide the above line into thirds, M14 is just east of the end of the first third.

I will bring in three easy to find Open Clusters just east of Serpens/Ophiuchus. The first of these is one of my favorites M11, the “Wild Duck Cluster” because the peripheral clumps of stars look like the “V” flights of ducks; I have never been able to see those even with the big telescope. It still is a beautiful sight on a warm summer night. On the figure, I show a line projected from Altair (53-alpha Aquilae) through delta Aquilae on to M11. An alternative path is to just follow the line of stars gamma, delta, and lambda Aquilae to M11. If you continue scanning southward from M11 you should encounter M26 a slightly smaller and dimmer M26 (mag. 8). Be careful here because you may very well find NGC 6664, another pretty little Open Cluster just east of alpha Scuti (aka SAO 142408; mag. 7.8). M26 is just east of NGC 6664. You may have to hunt around a bit. Notice that you are hunting on the background of the thick star field of the Milky Way Galaxy where there are loads of celestial objects.

 
  This concludes the Ophiuchus Project.

PROJECT: SCORPIUS AND THE FALSE COMET

The constellation Scorpius is a hallmark of our summer sky and is one of my favorites because it is rich in celestial objects. These include double stars and many star clusters most of which are easy naked-eye or binocular targets for an evening of viewing out on the front patio. It also contains an unusual object called the “False Comet”.

Scorpius is embedded in one of the richest parts of the Milky Way Galaxy with expansive gas and dust clouds of active star formation. Since ancient Greek times, the bright stars of this constellation have usually been associated with the form of a scorpion. The stars of the constellation Libra formed the "Chelae Scorpionis" (meaning “claws of the scorpion”). Indeed, alpha Librae (aka Zuben Elgenubi, the “Southern Claw”) and beta Librae (aka Zuben Eschamali, the “Northern Claw) retain their Arabic names within Libra. In Roman times, Libra was split off from Scorpius as the “Scales of Justice” held aloft by the Emperor Julius Caesar. In modern times, Libra has since been reduced to just the scales. There have been a few other instances where Scorpius has been split; the tail region sometimes referred to as a “Fishhook” and the body as a snake. In mythology, Scorpius is known as the “Slayer of Orion” and these two constellations continue their struggle on opposite ends of the sky.

The “Heart of the Scorpion” is alpha Scorpii (aka Antares), a bright red (class M) supergiant that is about 800 times the size of the Sun; it is also a binary star system with a hot blue comanion star, Antares B. Antares (meaning “Rival of Aries” or Mars) is the 15th brightest star in the sky and about 520 lys away. The planet Mars and the star Antares are both located on the ecliptic and occasionally Mars passes near its namesake. The last Antares/Mars conjunction was November 2010 and the next one will be in October 2012. It is worth noting that the red color of Antares, the star, is because it is a swollen “Red Giant” whereas the red color of Mars is the result of reflected sunlight off of the reddish color of the surface of the planet.

 

Scorpius is home to a number of binary, “double star”, systems. We begin with a naked-eye binary omega 1&2 Scorpii located just under beta Scorpii, itself another quintuple star system. Omega Scorpii consists of blue-white star and a yellow giant that are easily separated with binoculars. These two are about the same distance apart as Mizar-Alcor in Ursa Major. Beta Scorpii is another surprising star system with a white primary star with a blue to blue-green companion. In reality, this system is made up of five stars. Below Antares and about half way down the body of the scorpion is an optical double, mu Scorpii. These two stars do not have a gravitational relationship as found in true binary systems. Zeta 1 & 2 Scorpii are a similar optical double also called the Cat’s Eyes. They form the head or Coma of the “False Comet”. Lambda Scorpii (aka Shaula) and nu Scorpii (aka Lesath) are often called the “Stinger Stars” but may also be known as another “Cat’s Eye” optical pair.

Scorpius is home to two Messier globular clusters. M4 is perhaps the easiest to find being located in the same field of view just west of Antares. M80, a tiny, tight packed globular, may be found about halfway along a line drawn between Antares and beta Scorpii (aka Acrab Graffias). M19 and M62 are actually in the constellation Ophiuchus but sit very near the border with Scorpius. Look for M19 along a line projected from Antares to theta Ophiuchi. M62 can be found by scanning along another line projected from epsilon Scorpii and theta Ophiuchi. Both of these globulars are small but well worth the effort to find. 

 

 

 

 

 

 

 

 

 

 

Now let’s find the two beautiful open clusters near the stinger stars of Scorpius. M7 is the first of these and is just east and slightly above lambda Scorpii (Shaula) in the tail of the scorpion. M6, the other open cluster can be in the same field of view depending on the optical power of your binoculars; both are naked-eye objects under dark skies. M7 is about 25 lys across and contains about 100 stars. It is about 200 million years old and located about 1000 lys away. M6 (aka “The Butterfly Cluster”) is about 1,600 lys away and about 12 lys in diameter. With a telescope, you can imagine wings and the “V” antenna of the butterfly.

 

I have saved the best for last—the “False Comet”.  Zeta 1 & 2 Scorpii form the head or coma of the “False Comet” which is a composite object. These two stars are sometimes called the Cat’s Eyes (not to be confused with the Cat’s Eyes near the stinger stars). The tail of the “comet” is made up of several open clusters and the nebulosity of IC 4628. NGC 6231 is an attractive open cluster just above zeta 1 & 2. Above NGC is a collection of overlapping clusters and nebulosity. Collinder 316 is a large open cluster with Trumpler 24 in its northeastern portion; the nebulosity of IC 4628 runs north of these two inseparable clusters. The comet-like appearance of this object can best be seen with the naked-eye but binoculars really bring out the beauty of the “False Comet”.

This concludes the Scorpius project--Enjoy.