The Backyard Astronomer

December 2021
The Subaru Cluster

The dormant volcano Mauna Kea is the highest point of the Hawaiian Islands and the Central Pacific, peaking at 13,803 feet. At that height, the benefits of dry air above the clouds with little to no light pollution make it the preeminent site in the world for astronomical observation, so many large telescopes operate at its summit. One of these is the Subaru telescope of the National Astronomical Observatory of Japan.

Subaru, you say? They sold naming rights of a telescope to a car company? Well, no. The car company and the telescope were both named for the open star cluster Subaru, which graces the fall and winter skies of the Northern Hemisphere. The closest naked-eye star cluster to Earth, the six bright stars of Subaru glow hot blue and are surrounded by beautiful nebulosity that can be seen with even the smallest binoculars or telescopes. This cluster has been clearly recorded in dozens of ancient cultures and even referenced in the bible. The oldest known depiction of the night sky is a bronze disc found in Germany that dates to around 1600 BCE and is believed to include the sun, moon, and the stars of the Subaru cluster.

Fast-forward to 1953, when the Japanese businessman Kenji Kita combined six smaller companies across the manufacturing sector to create Fuji Heavy Industries, producing everything from scooters to cars to buses. Drawing on his love of the sky to characterize the six businesses he brought together as a group, he named his first car the Subaru 1500, its logo a clear representation of the star cluster.

Whoa, whoa, whoa. The brightest and best star cluster, most visible to the naked eye, with visible nebulosity, and you’ve never heard of it? That may be because Western culture traditionally uses ancient Greek and Roman names for the primary constellations, and we know Subaru as The Pleiades.

December3 brings a great opportunity to see the Subaru constellation in person! Findlay Subaru and Manzanita Insurance are sponsoring a Subaru viewing night, with amateur astronomers on hand to point out this and other objects in the night sky. Follow us at for details.

November 2021
M33, The Triangulum Galaxy

In the same patch of sky as Andromeda is possibly the most distant object one can see with the naked eye. In good viewing conditions, with 20/20 vision and without magnification, you may be able to spot the Triangulum Galaxy, or Messier 33. It is sometimes referred to as the Pinwheel Galaxy, however another galaxy is recorded in separate astronomical databases as the Pinwheel, and so, to prevent confusion, we will stick with Triangulum, so named based on the simple triangle its three main stars form. While certainly one of the smallest and simplest of the 48 Ptolemaic constellations, it is a great place to look for deep-sky objects.

The Babylonians referred to this formation of stars as The Plough and recorded it on clay tablets dating back nearly 3,000 years, making it possibly the oldest documented constellation. (This is not to be confused with the UK nickname for Ursa Major, which we usually call the Big Dipper and they call The Plough.) In ancient times this constellation would have risen early in the predawn hours in early spring, signifying the time for the farmers of the Fertile Crescent to begin plowing their fields. The Greeks referred to it as Deltoton for its resemblance to the Greek letter delta, a shape also referenced where the Nile River empties into the Mediterranean, the Nile delta. The Romans had a few names for this triad, one of which was Sicilia, for the roughly triangular shape of the island of Sicily. Roman mythology stated that Ceres, the island’s patron goddess, begged the god Jupiter to place it in the heavens, and so the triangle in the sky came to be. Other names used by ancient Mediterranean cultures almost universally reference the tri- prefix we associate with the number three, including Tricuspis, Triquetrum, Trigonon, Trigonum and eventually Triangulum. The modern International Astronomical Union, which regulates the accepted names of astronomical bodies and objects, assigned the abbreviation “Tri” to this constellation in 1922.

While much smaller than its neighbor, with an apparent size of 70.8 x 41.7arcminutes, we view the Triangulum Galaxy nearly face-on, and as such we can see its features much more clearly defined. It has prominent arms of dust, gas, and stars spiraling out from its center, but it differs from the Milky Way and Andromeda on one major feature, in that it does not have a bulge at its center. Surveys of the galactic center of M33 show the stars there orbit normally, suggesting that it does not have a supermassive black hole like its two larger neighbor sin the Local Group. The future may yet provide it with such a blackhole, as a major collision with either Andromeda, the Milky Way or both is expected to combine all three galaxies into one mega-galaxy in about 2.5 billion years.

If you found Andromeda last month, you’re on the right path. You used the bright star Alpheratz to star hop across the stream of stars to its left. The second star in the stream is Mirach, and the Triangulum Galaxy is approximately the same distance below it as Andromeda is above it. Since it is face-on, the brightness of its stars seems spread over a much larger area, so it can be tough to find the first time with your binoculars or small scope. Look for a fuzzy spot, almost like a smudge on a window, then adjust your focus and play with different eyepieces to resolve more detail.

October 2021

As you’re probably aware, we live on Earth, which orbits the sun every365.256 days as part of our solar system. Our system is one of hundreds of millions of stars and similar systems that orbit the center of our Milky Way galaxy about every 225 million years.

Joel Cohen

We are familiar with the cloudy or “milky” swath above our heads that is visible on moonless nights through much of the year. With advancements in radio astronomy in recent decades, we have been able to peer deeper into the sky and analyze the structure of our galaxy to learn we are on the outskirts of an arm in a giant spiral galaxy, held together by the gravitational pull of dark matter and a massive black hole in the center that we call Sagittarius A*, pronounced ‘Sagittarius A Star.’

For hundreds of years we had to guess what the structure of our galaxy was, as we are inside of it and cannot see it from an outside perspective. Our best approximation comes from looking at our neighboring galaxies, some of which are visible to the naked eye.

Our nearest partner in space is the Andromeda galaxy. Although it hangs out about 2.5 million light-years distant, it is large enough and bright enough to have been documented over a thousand years ago, long before the advent of the telescope. In the tenth century Persian astronomer Abd al-Rahman al-Sufi described Andromeda as a “nebulous smear;” later astronomers used rudimentary telescopes to define the blurry spot in the sky as an “island universe.”

With a diameter more than six times that of the full moon, Andromeda is one of the largest objects that astronomers can see with either the naked eye or simple ground-based equipment, and many astronomers have spent their lives dedicated to researching it. But it was not until Edwin Hubble studied Andromeda in 1925 that we truly understood it was a separate galaxy at such a distance from our own. This realization expanded our understanding of the universe from essentially believing in one galaxy to now knowing there are upward of two trillion separate galaxies in the observable universe.

October is arguably the best month to view Andromeda in the evening sky, reaching the zenith (directly above you) around midnight. On October6 is the new moon, and about an hour after sunset that evening Andromeda will be approximately 30° above the northeast horizon. You can find it by looking for the Great Square of Pegasus — an easily identifiable asterism — with the bright double star Alpheratz forming the northern corner. Two streams of stars seem to pour left from this point, and about 12° from Alpheratz (slightly more than the size of your fist held at arm’s length) and just above the topline of stars will have you looking at a cloudy patch of sky. Bust out the binoculars and you will see this is Andromeda, and then with the telescope you will begin to resolve the bright galactic center and swirls of stars around it. You will see Andromeda just slightly off from edge on, so it should look like a long oval getting brighter and denser toward the center.

September 2021
The Summer Triangle and the Dumbbell Nebula

In July we talked about using the Summer Triangle asterism to locate Messier 57,the Ring Nebula. If you were able to make it to our August Star Party at Pronghorn Park, you most likely were able to view it and the planets Saturn and Jupiter shining bright at opposition. But M57 is just one of the heavenly surprises hiding within the Summer Triangle.

The Dumbbell Nebula (M27) by Joel Cohen

One of the three points of the Summer Triangle is Deneb, the brightest star in the constellation Cygnus, the Swan. The main stars of the Swan make up the Northern Cross, making it easily identifiable to the naked eye just after sunset. Move down from Deneb to about midway between Vega and Altair, and the main body of the Northern Cross is formed with Deneb at the top and Albireo at the bottom. Inversely, the Swan is viewed as diving down, with Deneb at the tail and Albireo the head. Albireo appears as one bright star until a look through your binoculars or telescope reveal it to be a fun double star, with Albireo A being the brighter, yellow star and Albireo B smaller and blue. It is believed that these two stars are not actually a binary system and orbiting each other, as Albireo B is most likely 300 light years further past Albireo B, and just appears to be a neighbor as viewed from Earth.

Another fun object to view in the Summer Triangle is M27, the Dumbbell Nebula. The first planetary nebula to be discovered during Messier’s charting of non-comets, the Dumbbell is much larger and closer than the Ring Nebula and has higher reflectivity. This makes it much easier to find with binoculars, and higher magnification with a telescope reveals a beautiful shape and some color.

The Prescott Astronomy Club is doing a star party at Pronghorn Park in Prescott Valley on the evening of

Saturday, September 11.

August 2021
The Dog Days of Summer and Giants at Opposition

We often hear “the dog days of summer” used to describe a seasonal period of stagnation or inactivity, usually brought on by long days and extreme heat. In the Arizona central highlands, much as our ancient predecessors experienced in Greece and Rome, this time correlates with the beginning of the monsoon season, connected with heat, drought and sudden thunderstorms.

While we may feel like spending this time lying in a backyard kiddie pool with our dogs, the term has absolutely nothing to do with terrestrial canines, and everything to do with astronomy.

The three stars of Orion’s belt point almost directly to the bright star Sirius, which in ancient times returned to view in the northern hemisphere during the hottest phase of summer, just prior to the annual flooding of the Nile River valley. As the brightest star in the sky and part of the constellation Canis Major (“the Greater Dog”), it is often called the Dog Star, and from this reference we still call this time of year the “dog days of summer.”

This year we can experience the opposition of both Saturn and Jupiter during this time, as we reach closest approach to these gas giants on August 2 and 19, respectively. Just a few days on either side of the August 8 new moon s the best opportunity of the year to view details of these planets and their natural satellites.

With the sun giving us the brightest illumination on these evenings, even smaller and medium-sized telescopes can pick out the weather bands of Jupiter, ring divisions around Saturn, and a handful of moons around each.

Specifically with Jupiter, watch over consecutive nights and sketch the locations of the four Galilean moons you see, documenting how they change position during their orbits from evening to evening.

Join us on the evening of August 7 at Pronghorn Park in Prescott Valley for an opportunity to view these and other objects in the night sky!

July 2021
Summer Constellations, Asterisms and the Ring Nebula

The beginning of summer in the northern hemisphere brings warmer nights to the backyard astronomer, a stark contrast from the often freezing viewing sessions of the winter constellations.

The RingNebula (M57) by Joel Cohen; locator by

July offers longer days but also some great stargazing for the moderate-sized telescope. The constellations Aquila the Eagle, Cygnus the Swan and Lyra the Lyre converge directly overhead at solar midnight, with their three brightest stars forming the Summer Triangle. Easily identifiable asterisms such as the Big Dipper, Southern Cross and Summer Triangle have long been a way for the layperson to identify patterns of stars.

The Big Dipper is probably the first asterism kids in North America become familiar with. Popularized as the Drinking Gourd in an African-American folk song in the 1920s, the end stars of the bowl form a line to the bright star Polaris, the one closest to Earth’s celestial north pole, which helped lead escaped slaves north to freedom.

The Southern Cross is a series of four (sometimes five) bright stars visible in the southern hemisphere nearly any time of year. Used in a similar fashion to find the southern celestial pole, everyone from ancient Pacific navigators to Argentine gauchos have used this grouping of stars to navigate vast tracts of land and desolate expanses of ocean.

Used on no less than ten national, regional and organizational flags, Crosby, Stills, Nash and Young spoke of it in their aptly named 1982 hit “Southern Cross,” positing, “When you see the Southern Cross for the first time, you understand now why you came this way.”

The Summer Triangle is formed by the three bright stars Altair, Deneb and Vega, with Vega the brightest of the three. The second star (after the Sun) to be photographed and the first to have its spectrum recorded, Vega is relatively close at just 25 light-years distant, and is the second-brightest star visible in the Northern Hemisphere. Just below Vega, and directly on the leg of the Triangle formed with Altair, is the Ring Nebula, a small planetary nebula formed when a dying star ejects gas in all directions as it runs out of fuel to maintain nuclear fusion. Visible with three-to four-inch telescopes, you can begin to resolve the rings of gas and eventually the central remaining white dwarf star with eight-inch scopes and higher magnification.

June 2021
Mars, Cancer, and the Beehive Cluster

For the past couple of months the scientific community has been intently focused on Mars. 

M44 by Stuart Heggie, NASA-JPL

Every 26 months our planets align in a way that shortens travel time from Earth to Mars to about nine months, and as more countries develop space programs, more robotic explorers are sent to the red planet during this window. In 2021 the UAE orbiter Hope arrived on February 9, China’s Tianwen-1 entered orbit on February 10, and the NASA Perseverance rover touched down on February 18. 

Perseverance carried with it the Ingenuity helicopter, which has spent the last month proving the first powered flight on another world, and on May 14 Tianwen-1 released the Zhurong rover, making China only the second country to successfully land a rover on the Martian surface.

Mars by Joel Cohen

Mars is easily identifiable with the naked eye, its deep red hue due to high levels of oxidized iron in its crust. Basically the whole planet has rusted over the last couple billion years.

The arrivals of the orbiters and landers in February signaled a (relatively) close approach of our two planets. For most of 2021 they have been moving farther from one another, making Mars lower and dimmer in our night sky.

Sinking closer to the setting sun, Mars enters the constellation Cancer on June 8. As the month wanes, you may be able to catch one last conjunction with Mars passing just 0.5 arc-minutes from the Beehive Cluster M44 on June 23, just minutes after sunset, low in the western sky.

The Beehive Cluster – Messier 44 – is one of the nearest open clusters to Earth. Ptolemy referred to it as the “nebulous mass in the breast of Cancer,” proving how easily identifiable it is with the naked eye. Galileo resolved 40 stars within the cluster, though we now count at least 1,000 stars spread across 39 light-years, close enough to be gravitationally bound with one another. At least three exoplanets are known to orbit stars within the Beehive Cluster.

If you are lucky enough to catch the conjunction of this open cluster and our neighboring planet, both should easily fit within the field of view of your telescope or binoculars. With the right magnification, one can resolve some nebulosity from the Beehive Cluster and the Martian polar ice cap.

May 2021
Scorpius, Antares, and Globular Clusters

A quick moral mythology: Orion felt that he was such a great hunter that he once boasted to Artemis, goddess of the Wilderness, that he would kill every animal on earth. Rightfully unsettled by this proclamation, Artemis sent a scorpion to kill Orion before he could make good on his claim. The ensuing battle was epic.

Till Credner,

Zeus, observing all of this from on high, snatched up the two duelists and placed them in the sky as a lesson to mortals forever to curb their pride. It is also said that Orion now hunts across the heavens for the winter months but is chased away every spring by the return of the scorpion.

M4 by Jeff Stillman

As we enter the spring months of 2021, the scorpion is again rising in the eastern sky. This constellation consists of 18 main stars, one clearly outshining the rest. Antares is the 15th-brightest star in the sky, often called the “rival of Mars” from its visibly red hue.

A wide-field view with binoculars reveals a unique ball of light just 1.3 degrees west of Antares, known as Messier 4. M4 is a globular cluster, which initially will appear as a fuzzy cotton ball covering a swath of sky about the size of the Moon.

M4 was the first globular cluster to have individual stars resolved by astronomers in the 18th century. Having spent more than 250 years analyzing this dense gravity well, we now estimate over 20,000 stars are packed into an area just 27 light-years across. 

Once you locate M4 with your wide-field view, switch to a telescope or more magnifying eyepiece and you will begin to resolve some of the outlying stars and see how densely packed the center of this cluster truly is.

From M4, move slightly northwest to find another globular cluster. Messier 80 contains several hundred thousand stars spread across approximately 95 light-years. Despite having many more stars, M80 is less visible through binoculars due to its distance, at 3,200 light-years, as opposed to the much closer M4 at 7,200.

April 2021
The Whirlpool Galaxy

As early telescopes developed beyond Galileo’s rudimentary first models, astronomers around the globe began to make astonishing revelations.

Joel Cohen

Charles Messier initially began sketching and cataloging anything that was not a comet using a four-inch refracting telescope, adopting the Latin word for “cloud,” which he used to classify his objects as either a star cluster or “nebula.” He documented Messier 51 in 1773 as one of these first 110 objects. William Parsons again observed M51 in 1845 with a 72-inch reflecting telescope, resolving what he dubbed the first spiral nebula. His 1845 drawing clearly defines what we now know to be a spiral galaxy, however it was not until the 1920s that Edwin Hubble, using the 100-inch Hooker telescope at Mount Wilson Observatory in Los Angeles, proved that our Milky Way was just one of an untold number of galaxies spinning through the cosmos.

Sketch by William Parsons, 1845

Modern astronomers now use the relationship of M51 and neighboring NGC 5195 to study how galaxies interact. Due to its near-constant observation, three recent supernovae have been observed in M51, in 1994, 2011, and 2019. Just in September 2020 a potential exoplanet was detected in M51 using the eclipsing-transit method for observing distant stars. If confirmed, this would be the first planet discovered outside our galaxy. By way of comparison, all the current exoplanetary candidates in the Milky Way galaxy are within a radial distance of no more than 25,000 light-years. The candidate in the Whirlpool Galaxy is 31 million light-years distant.

Today many amateur astronomers enjoy M51 or the Whirlpool Galaxy as a good place to learn how to hop from star to star in search of other objects in the sky. The basic spiral structure of the galaxy can be seen with a good pair of binoculars or small telescope, and is relatively easy to find through much of the year. Start at the Big Dipper, locating the last two stars in the handle. Moving southwest 3.5 degrees at a near right angle, the Whirlpool Galaxy and its companion galaxy are unmistakable, first as an elongated fuzzy gray ball, then resolving in greater detail with larger scopes.

March 2021
The Northern Equinox

Beginning, middle or end, depending on how you look at it

About 90% of Earth’s population lives in the Northern Hemisphere, so many of our astronomical traditions relate directly to how the sun, moon, and stars move across the northern night skies and northern weather patterns.

A prime example of this is the northern equinox, which we most commonly refer to as the spring or vernal equinox, although if one resides south of the equator, it’s more correctly the fall or autumnal equinox. On this day the center of the sun is directly perpendicular to the equator.

Derived from the Latin aequus (“equal”) and nox (“night”), March 20 and September 23 represent the two points in the year that most closely approximate equal times of day and night across the planet.

Ancient cultures did not recognize the exact angle of the sun relative to the center of the earth, but rather that the sun would rise and set directly east and west. The equinox also became a date for the beginning of many annual calendars and subsequent regional festivals.

The Persian and Indian calendars both begin on the day of or day immediately following the northern equinox, and are still used today in their respective countries. The Babylonians began their calendar on the first new moon following the March equinox, celebrating the return of the goddess Inanna from the underworld. The Jewish Passover and Christian Easter are both calculated based on the first full moon after the vernal equinox. 

The equinox is a perfect time to do home science projects. You can wake up with the sun and measure for yourself the exact hours of daylight. Find a local sundial (Sharlot Hall Museum!) or make one yourself, align it using a compass to magnetic north, and find what the solar time is at your home.

Last but not least, maybe we can bring back broom-balancing and pretend it’s real science!

February 2021
Monoceros and the Christmas Tree Cluster

The hollow between Orion, Canis Major (the Great Dog) and Gemini (the Twins) is a relatively dark area. Though the stars are difficult to see with the naked eye due to modern light pollution, in this void is a less-known and relatively modern constellation.

Image courtesy Joel Cohen, Prescott Valley 2021

Monoceros – ‘mono’ meaning ’one’ and ‘ceros’ meaning ‘horn,’ or the Unicorn — is a simple seven-point constellation, though only two of the stars are usually discernible without the aid of binoculars or telescope. Dutch mapmaker Petrus Plancius first noted the Unicorn in 1612, with others following through the 17th century. With better telescopes William Herschel studied the area in 1781, becoming the first to discover that Beta Monocerotis, the brightest of the constellation’s stars, is actually three separate entities, observed as a curved line of pale blue-yellow stars. He later described this triple-star system as “one of the most beautiful sights in the heavens.”

Using a telescope to starhop around the dark areas among these constellations, you can find a slew of other heavenly surprises. The Rosette Nebula (NGC 2244) is known for its ring shape and dense nebulosity. The open cluster Messier 50 and NGC 2506 will appear as fuzzy cotton balls in the smallest apertures, and larger scopes can begin to define many close stars.The real highlight of Monoceros, though, is NGC 2264, the Cone Nebula. Appearing as though a celestial bowling ball was thrust down a foggy lane, parting the fog around  it, a dark cone imparts densely defined edges to a large diffusion of nebulous clouds. At 2,600 light-years distant it is one of the closer nebulae to Earth, and covers a large swath of space with star-forming elements to create its stellar nursery. Along with the Fox Fur Nebula, this diffuse nebula is often referred to as the Christmas Tree Cluster due to its triangular shape with a star at the apex.

Take your binoculars or telescope out and start at the bright star Betelgeuse in Orion, exploring the area just below and down to the Hunter’s belt. As you scan the sky, moving downward toward the Beta Monocerotis triple-star system, you’ll be surprised at what you find.

January 2021

What do you call it when

      the Moon is directly between the Earth and the Sun? — a solar eclipse.

      the Earth is directly between the Moon and the Sun? — a lunar eclipse.

      the Sun is directly between the Earth and the Moon? — an apocalypse!

The word ‘eclipse’ stems from the Greek ekleipsis, meaning, “failure to appear.” Between two and five times each year the Sun fails to appear, either partially or in full, due to the orbital mechanics of Earth, Sun and Moon. As the Earth swings around the Sun and the Moon spins around the Earth, their orbits periodically line up to where they are on a direct line, causing the Moon’s shadow to cover a small portion of the Earth’s surface.

“Small” is a relative term here, as we experienced on August 21, 2017, when the shadow of the Moon traversed from the Pacific northwest to the southeast United States. Where the shadow completely blocks out light from the sun, we call it ‘totality.’ While the path of totality in 2017 covered thousands of miles and amazed millions of onlookers, we know that the Earth’s surface is mostly uninhabited, covered by dense forest, vast desert, frozen tundra or open ocean. So many eclipses go unseen, able to cross thousands ofmiles of the Pacific Ocean with few if any human viewers.

Eclipse-chasers from around the world reserve hotels and campsites years in advance to get views of these rare events.

In central Yavapai County we were able to observe a partial eclipse in 2017, with the Moon covering at most 76% of the Sun. Sometimes we see partial eclipses where the Moon is slightly farther from Earth in its orbit, causing it to block out the center of the Sun, leaving a ring of light around the Moon. This is called an annular eclipse, such as that seen at the Grand Canyon on May 20, 2012. Also called a Ring of Fire eclipse, these events make for great images, but only with the proper equipment — even the small ring of light radiating from the Sun can damage your eyes. The next annular eclipse visible in our area will come on October 14, 2023.

Just a few months later, a total solar eclipse will once again grace the skies of North America on April 8, 2024. The path of totality will cross Mexico and Texas, continuing over much of the Midwest and almost directly over Indianapolis and Buffalo, then on to northern Maine.

Should you want to travel for a view of totality, book your reservations now! Eclipse-chasers from around the world reserve hotels and campsites years in advance to get views of these rare events. If you don’t intend to travel, mark your calendar to keep an eye out for local events to celebrate with amateur astronomers and skywatchers locally.

December 2020

We know the holiday season is upon us when strands of color light the night. 

Homes, businesses, pets and even an iconic tree along the highway are all adorned with lights representing hues across the spectrum.

At home the celebratory scenes carry over from outside to inside, blanketing every room of our house.  We love this time of year and the joy we receive from all the lights and colors around our community.

One can enjoy these splendid colors gracing the night any time of the year, just by looking to the heavens.  The constellation Orion is full of colors, though you might need a pair of binoculars or a small telescope to define some of them. Deep red/oranges and bright blue/whites are all easily discernible against the inky backdrop.

The easiest grouping of stars to find is the belt of The Hunter. Three stars in a nearly straight line rise almost vertically above the eastern horizon each evening. Just to the lower right of the bottom star in the belt is The Hunter’s sword, a cluster of three more stars that contain the Orion Nebula. Even the smallest viewing instruments can begin the resolve the beautiful colors of this hydrogen-rich star nursery 1,300 light years from earth. Larger and more advanced scopes will often photograph this nebula with various filters to accentuate the variety of elements comprising this massive cloud of star dust.

Working around the perimeter of the constellation, the left shoulder of Orion is Betelgeuse, one of the largest stars visible to the naked eye, apparent by the bright red hues it emits. Continuing clockwise around the belt are Bellatrix, Rigel, and Saiph, each with a cool blue-white tone.

Varying in distance from about 250 to over 2,000 light years, the stars in the Orion constellation give the amateur astronomer the perfect opportunity to learn their new equipment and the sky. Take a few evenings this month and use different eyepieces to look at the stars and nebulae in Orion. There are three nebulae and multiple double-star systems, How many can you find?