The Backyard Astronomer

Category: Solar System

  • April 2024 – Solar Cycles and Sunspots

    Our Sun, courtesy Mark Johnston, Phoenix Astronomical Society @AZAstroGuy

    Nearly 3,000 years ago, The Chinese Yi Jing or “Book of Changes” documented small, irregular concealments in the surface of the Sun.  By 300 BC, both Eastern and Western cultures were documenting their changing views of our star, and the patterns that would grow and then disappear on its disk.  English Monk John of Worcester is the first known to have captured these obscurations in his drawings dating to 1128, and just a year after Galileo showcased his first optical telescope in 1609, English astronomer Thomas Harriot turned one of these new inventions to the leading lady of our Solar System.  Taking from the work of so may great minds before him, Danish astronomer Christian Horrebow first proposed a regular cycle in 1775, noting, “it appears that after the course of a certain number of years, the appearance of the Sun repeats itself with respect of the number and size of the spots.”  By 1852, Swiss astronomer Rudolf Wolf compiled all the data available to him, finding an approximate 11-year period from one minimum through maximum and back to minimum.  Choosing to begin with the best possible documented records, Wolf denoted February 1755 as the beginning of Solar Cycle 1, with Solar Cycle 25 having begun in December 2019, and estimated to peak during Mid 2024.

    Though I must suppose these early solar astronomers spent much of their later years suffering from poor vision after a lifetime of staring at the Sun, we now have technology allowing anyone to document their own backyard observations of our closest star.  The more complex Hydrogen Alpha (H-Alpha) filters allow an extremely narrow bandwidth of the light spectrum through a lens to the eyepiece of one’s telescope or camera sensor.  The simpler form many of us are familiar with are the cardboard solar glasses you might find at an eclipse or other educational event, with lenses made of thin polymers reducing the sun’s penetrating radiation to the equivalent of shade 14 welding glass.  NASA and the ESA have also provided us with the ability to view the sun remotely in many different wavelengths, courtesy of the Solar and Heliospheric Observatory – or SOHO – launched in 1995.  Continuing to provide valuable observations of the sun nearly 30 years later, the SOHO Viewer app is available on most mobile platforms, allowing backyard astronomers to observe sunspots, prominences, and solar flares in real time. 

    More than just observing dark spots on the Sun, Solar Maximum can have diverse impacts on the environments of the Solar System.  Periods of Solar Maximum may be accompanied by flares and storms, the largest of which are known as CMEs or Coronal Mass Ejections.  In December 2021, Mars suffered a direct hit from a CME, and both orbiting and ground craft there documented how it affected the Martian atmosphere.  Closer to home, 1859’s Carrington Event during Solar Cycle 10 caused Aurorae to be visible from the poles to the equator.  Telegraph operators worldwide experienced electrical shocks, disconnected the power from the equipment, and were still able to send and receive messages, with some operators reporting better transmission for up to two hours, despite not being connected to a power source.  Multiple telegraph offices even reported fires starting from such high electromagnetic activity.

    Check with your local library and the Prescott Astronomy Club for events relating to the April 8th solar eclipse, and use your safe viewing instruments to enjoy this event and document the number of sunspots and prominences you observe during this Solar Maximum.

  • March 2024 – Vernal Equinox and Spring Beehives

    Beehive Cluster, Courtesy Stuart Heggie, NASA JPL.

    Tuesday, 19 March, at exactly 8:06 PM MST, denotes the moment when the Sun will again be directly over Earth’s equator.  As viewed from Central Yavapai County at approximately 34.54° N, we will see the Sun appear to rise and set due East and due West, respectively.  This is the Vernal Equinox, the rebirth of the Northern Spring, and a day celebrated by cultures around the world as an emergence from the long, cold Winter.

    Beehive Cluster, Courtesy Joel Cohen, Prescott Astronomy Club.

    Many ancient cultures began their calendar on the equinox, including Babylon, Persia, and even carries through to modern times with the official government Indian National Calendar or Shaka Calendar.  The Angkor Wat complex of Cambodia was built nearly a millennium ago, with near perfect alignment to the Equinoxes, including the rising and setting of the sun over the central lotus tower on those dates, as well as sculptures and carvings that depict numerical representations of the number of days between each the Summer and Winter Solstices with the central Equinoxes.  Western cultures, heavily influenced by the spread of Christianity, connect the Easter celebration to the equinox.  The Paschal full moon, named from the Aramaic word for Passover, denotes the first full moon proceeding the vernal equinox, which this year will illuminate the night skies on March 25th, after which Easter is celebrated on the following Sunday.  Due to the celestial mechanics of the equinox and the Lunar cycle, this may place Easter as early as March 22nd in some years or as late as April 25th in others.  This pattern of celebrating of death and resurrection is not unique to Christianity and was likewise observed with direct correlation to this celestial event in the Roman festival of Hilaria and the Pagan holiday of Ostara.  And throughout the Arab world, Mother’s Day is commonly celebrated on the spring equinox.

    Beehive Cluster on Vernal Equinox, SkySafari, 3/19/2024.

    The 2024 equinox on March 19th will see the waxing gibbous moon spend the evening in the constellation Cancer, the Crab.  Lying tangent that night to one leg of a triangle connecting the bright stars Regulus, Pollux, and Procyon, the Moon may guide you to the Beehive Cluster, as separated by just a few degrees.  With over 1,000 stars, and one of the closest open clusters to Earth, this is one of the best objects for a backyard astronomer to find with their small telescope or binoculars.  Lying midway between Pollux and Regulus, this stellar nursery was documented by Galileo, Messier, Shur, and many other astronomers over the centuries.  Add yourself to that list of astronomers on this night and count how many stars you can discern in this hive of activity, then revisit the Beehive Cluster later in the month when the bright moon has moved away and see if you are able to resolve more of the bees of the Beehive Cluster.

  • Unicorns and Roses

    Rosette Nebula, Courtesy N.A Sharp, NOIRLab, Wikimedia Commons.

    A lesser-known and relatively modern constellation occupies the void between Orion, Canis Major, Hydra and Gemini, though the stars are difficult to see with the naked eye due to modern light pollution.  Monoceros – mono meaning “one” and ceros meaning “horn” – the Unicorn is a simple 7-point constellation, though only two of the stars are usually discernible without the aid of binoculars or a telescope.  Coined by Dutch cartographer Petrus Plancius in the 17th century, Monoceros contains many intriguing objects for the amateur observer.

    The nose of the unicorn is quite easy to locate.  Start with the bright orange shoulder of Orion, the easily identifiable star Betelgeuse and the dimmer blue star Meissa that marks the Hunter’s head.  Draw a line from Meissa to Betelgeuse, continuing nearly that same distance again to the Southeast of Betelgeuse to find the binary system ε Monocerotis, denoting the nose of the unicorn.  Just a slight look continuing to the east will place the Rosette Nebula in your view.

    Orion and Monoceros, SkySafari, 2/15/2024.

    About 5,200 lightyears distant, the Rosette Nebula takes its name from the stylized floral design, often seen as a textile rose awarded for competitions.  English astronomer John Flamsteed first noted the nebula in 1690, noting its circular shape and dark center, reminiscent of a rose.  Approximately 130 lightyears across, this emission nebula is a star nursery, estimated at a mass of more than 10,000 solar masses, or the equivalent of 10,000 of our suns. The intense radiation of the juvenile stars in this densely packed space excites the molecules in the clouds of gas and dust around them, off putting more and more radiation in a chain of events that continuously sends ever increasing quantities of ultraviolet and x-ray radiation in all directions.  For us, this equates to a beautiful nebula, perfect for our viewing pleasure.  At apparent magnitude of 9.0, even small telescopes can resolve this stellar breeding ground.

    Enjoy the Rosette Nebula, Monoceros, and the Orion constellation in the Southern sky in the early hours of the evening throughout the month of February.  Wishing you clear skies!

  • Dancing Planets

    Jupiter, Courtesy Joel Cohen imaged from Prescott Valley, 2020.

    The planet Mercury is a unique specimen within our solar system.  Orbiting every 88 days, this closest rocky body to our Sun has no geological activity and virtually no atmosphere.  Its surface is pockmarked with testimonies of destruction, and with nothing to erode the signs of billions of years of impact events, making it a dense, grey, blemished world.  The ancients knew of Mercury, and many cultures named it relative to its proximity to the Sun and its quick movements across the sky.  Being so close to the Sun, Mercury is often not visible to terrestrial viewers, however on the morning of January 12th Mercury will be 23.5 degrees from the Sun, its Greatest Western Elongation.  Look to the Eastern Horizon in the hour before sunrise to catch a view of this elusive wanderer.

    Saturn, Courtesy Joel Cohen imaged from Prescott Valley, 2020.

    On the evening of January 14th, Saturn will make a close approach to the Moon in the constellation Aquarius.  To astrologers, this lunar conjunction with the ringed planet may impart a pragmatic and practical approach to financial stability, however, to astronomers it means a fun opportunity to observe the waning crescent moon next to the famous rings of Saturn.  Binoculars or a small telescope is all that you need for this event, with just 40x magnification to resolve the rings separate from the planet.  The waxing crescent phase is also a great time to look at the highlighted craters of the moon. Get out early this evening, as Saturn will begin to set in the Western hills around 8 PM.

    Galilean Moons, SkySafari, 1/18/2024.

    Just a few nights later on the evening of January 18th, Jupiter will make its close approach to the Moon in the constellation Aries.  A first quarter Moon will spend the evening with the King of Planets, and your binoculars or small backyard telescope should be able to resolve the four Galilean moons: Ganymede, Callisto, Europa, and Io.  Those last two, Europa and Io, will be having a conjunction of their own that night, passing extremely close to one another as viewed from Earth.  With larger scopes of 100mm or more, and the blessing of a clear night, you may be able to observe the red and white bands of clouds that circle the planet, as well as its most defining feature – the Great Red Spot.  Like a high-pressure hurricane, this storm averages 1.3x the diameter of Earth, with wind speeds up to 432 km/h or 268 mph.  If early astronomical observations were correctly recorded of the same storm, then it has been in existence since at least 1665.

  • December 2023 – Geminids Meteor Shower

    Meteor showers are generally produced when the Earth passes through the remnant tail of a comet, often long after it has visited our inner Solar System.  July’s Perseids are a gift from Comet Swift Tuttle (last close approach in 1995), the Eta Aquariids in May and Orionids in October come from the path Halley’s Comet (1986), and each November we see the Leonids courtesy of comet Tempel-Tuttle (1998).  Only two major meteor showers are the product of something other than a comet, the Geminids being the most active, and visible throughout mid-December.

    Geminids, Asim Patel, courtesy Wikimedia Commons.

    NASA’s Parker Solar Probe has been studying the sun since 2018 and holds the record of fastest human-made object, with a maximum speed of about 690,000 km/h or 430,000 mph.  Its study of the sun has also provided valuable data on objects that orbit the sun, including the asteroid 3200 Phaeton.  Classified as an Apollo asteroid for its Earth-crossing orbit, it is the largest and most studied asteroid passing closest to our Sun.  The data from the Parker Solar Probe lends credence to the hypothesis that a much larger body was catastrophically torn apart by the Sun’s immense gravity, leaving behind 3200 Phaeton and at least two other large asteroids, and a debris field stretching for millions of miles through space.

    The tails of comets leave behind icy dust particles that may create a meteor shower on Earth.  By comparison, the detritus remaining from the cataclysmic event that created 3200 Phaeton is more rocky and often larger in diameter, offering bright, multi-colored meteoroids for your viewing pleasure.  Peaking on the early morning hours of December 13th through 15th, this rubble collides with our atmosphere at speeds of 35 km/s or 22 miles per second, which while seemingly fast, is slower than many other meteor showers, allowing for long, bright streaks across the sky.  The fireballs will mostly appear to emanate from the Gemini constellation, with this point of origin called the radiant.

    Geminids, 12/14/2023 at 3AM MST, SkySafari.

    Step outside in the early hours of Thursday 14 December.  Look to the South Southwest, find the belt of Orion, and continue up to the bright twins Castor and Pollux.  Bring a blanket for the cool late fall morning, and you could enjoy more than 120 shooting stars per hour on this dark, moonless night.

  • October 2023 – Annular Eclipse

    If you happen to be around the Four Corners area on October 14th, make sure to have your solar eclipse glasses with you.  After that day, you will be able to tell your friends that you saw an eclipse from four different states!  An annular solar eclipse will grace our skies that morning, with the full eclipse beginning around 9:30 MST and lasting for just under 5 minutes.  You may encounter this path of totality along a swath of the United States covering from the coast of Oregon to South Texas on that day.

    Path of Annular Eclipse, courtesy Great American Eclipse.

    An annular eclipse is a type of solar eclipse, where the moon is directly between the Earth and Sun.  When viewing a total solar eclipse, the moon will completely cover the disk of the sun, whereas an annular eclipse only covers the center of the Sun, leaving a slim ring of light visible around the Moon.  This halo is the annulus, from the Latin meaning “little ring”, and mathematically is defined as the area between two concentric circles.  This “little ring” is also where we get the word annual, for the circular nature of the yearly calendar.

    Geometry of an Annular Solar Eclipse, courtesy of NASA.

    The reason we have both total and annular eclipses is due to the non-circular nature of the universe.  Seemingly a contradiction to all of this talk of rings and circles, objects in space are governed by the forces of gravity, and orbit in ellipses rather than true circles.  At some points in the Moon’s orbit, it is closer to the Earth, at which time we experience Supermoons like we did in August.  This closest part of the Moon’s – or any other object’s – orbit is known as perigee.  At other times, the ovular orbit takes the orbiting body further from the primary body, and this more distant point is called apogee.  Likewise, when the moon is at apogee during a solar eclipse, the apparent diameter of the Moon as viewed from Earth is not sufficient to fully cover the Sun, giving us a “ring of fire” eclipse that is quite the sight to behold.

    Ring of Fire Eclipse, by Jerry Shaw.

    Whether total or annular, a solar eclipse happens about twice per year on Earth, though with more than 70% of Earth’s surface covered by water, they are not always visible from terra firma.  In addition, the rotation of the Earth means that these eclipses could happen on any continent, and so are unique events when able to be seen locally.  The path of the annular eclipse is around 120 miles wide in that track across the Western United States, however a viewer hundreds of miles away can still experience a partial eclipse.  Here in Central Yavapai County, we will see approximately 82% coverage of the Sun’s face over the course of the morning. 

    AND DON’T FORGET YOUR SOLAR GLASSES FOR SAFE VIEWING!

  • September 2023 – Archers, Teapots, and the Milky Way

    From double full super moons to ringed giants at opposition, August was full of local events in our Solar System, whereas September takes us back to some amazing deep sky objects.  Many of the best clusters and nebulae lie along the galactic plane, easily identifiable in the sky as the Milky Way.  While one can technically define the Milky Way as everything around us, the vast swath painted across the night sky represents the edge-on view of much of our galaxy, given Earth’s position somewhat centrally located on what we call the Orion Arm of our barred spiral galaxy.  Being in the middle of all the action, looking toward this denser region of stars offers the casual viewer opportunities to pick out many more “faint fuzzies”. 

    The constellation Sagittarius borders the Western edge of the Milky Way, pointing his bow and arrow into this hotbed of stellar activity.  Hundreds of stars inhabit this constellation, with 17 making up the primary outline of the centaur archer.  More easily identifiable are the 8 primary stars that make up the “Teapot” asterism, which defines the torso and bow of the Archer.  Within or abutting the Teapot are five Globular clusters, catalogued by Charles Messier as M22, M28, M54, M69 and M70.  The clusters of stars are only a few light years across yet are packed with thousands or even millions of stars orbiting the galactic center together.  To the naked eye, these may seem like a single star, then binoculars will show the observer a fuzzy cotton-ball like image, and larger telescopes will begin to resolve many of the individual members of these heavenly neighborhoods.  Use your binoculars or a wide-angle eyepiece on your telescope to scan the Teapot and see how many star clusters you can find.

    Globular Cluster, Courtesy Mount Lemmon Steward Observatory.

    The stellar life cycle may begin or end with a large cloud of gas and dust, either coalescing over millions of years into stars and planets, or inversely created when a star runs out of fuel and collapses in on itself, exploding in one of the universe’s greatest displays of light and energy.  These clouds are known as nebulae, Latin for “mist” or “fog”.  As you peruse the Teapot and Milky Way, areas of light and dark gas will highlight against the dark backdrop of space.  The Lagoon Nebula is visible to the naked eye in the darkest skies and is a perfect starting point for the amateur astronomer.  As an emission nebula, it has a pinkish hue created by the ionized particles coming off nearby stars.  Separately, the Trifid Nebula is a combination emission and reflection nebula, appearing both pink and blue as you scan the region.  Also containing an open star cluster, the Trifid Nebula is a late summer favorite among many astronomers.

    Trifid Nebula and Lagoon Nebula, Gary Jones, Wikimedia Commons.

    So, remember to look to the South, for the teapot pouring out the milk, and you will be locked on to some of the greatest views in the Northern Hemisphere summer.

  • August 2023 – Celestial Neighbors

    August hosts a plethora of lunar and planetary events, perfect for the Backyard Astronomer.  Even the most basic binoculars or telescope will allow one to enjoy our celestial neighbors as they put on quite the display this month.

    August 1st starts off the month with a Full Supermoon.  The second Supermoon this year, this event occurs when the Moon appears slightly larger in the sky due to its proximity to Earth in its elliptical orbit.  While there is no strict definition of a Supermoon, it is commonly accepted that the moon be within 90% of perigee, or the closest approach of its orbit to Earth.  By contrast, the furthest part of an elliptical orbit is called the apogee, and the Moon’s distance from Earth can sway from about 405,500 km to as close as 363,400 km, or about 252,000 miles to 225,000 miles.  This full moon was also known in the Great Lakes regions as the Sturgeon Moon, for its timing correlated with the preferred fishing season.

    Supermoon Comparison, Courtesy NASA.

    On August 10th, Mercury will be at greatest Eastern elongation from the Sun, meaning it is as high in the evening sky as we can see it, before it begins to move back around the Sun.  “Eastern Elongation” may seem like a misnomer, referencing where the planets are in relation to each other, however you will look to the Western horizon just after sunset.  This is the best day of the year to catch a glimpse of the elusive owl whom the Maya regarded as a messenger to the underworld.

    In the early hours between August 12th-13th the Earth will pass through the tail of comet Swift-Tuttle.  Having last visited the inner solar system in 1992, and not returning until 2126, the debris cloud of dust and ice particles affords the annual Perseids Meteor Shower, with excellent viewing this year as the moon will only be a crescent.  Enjoy this show after midnight when you may catch upwards of 60 meteors per hour.  

    On August 24th, the bright red head of the Scorpius will be eclipsed by the moon.  This rare event will see the occultation of Antares by the moon, disappearing behind the moon at 6:55 PM MST and reappearing an hour later at 7:55PM.

    Saturn puts on a show on August 27th, at what we call Opposition.  Saturn will be at its closets to Earth on this night, and fully illuminated by the Sun directly opposite it.  Moving through the constellation Aquarius in the Southern sky, a medium sized telescope will allow you to see the rings and maybe even its moon Titan.

    Saturn by Joel Cohen.

    Wrapping up the month of August on the evening of the 31st is the second Supermoon of the month.  When two full moons occur in the same calendar month, we call the second one a Blue Moon.  This Moon won’t really appear blue but is a relatively rare event to have both full moons in a single month be Supermoons.

  • Scorpions and Rabbits

    By Adam England, The Backyard Astronomer

    One of my personal favorite constellations is Scorpius.  It is very easy to identify in the summer months when it rises in the Southeast and sways above the Bradshaw Mountains like the traditional scorpion promenade à deux pairing dance.  The red supergiant Antares defines the head of the Scorpion and is often confused with Mars for its brightness and somewhat ochre coloration. Just one degree westward of Antares is the globular cluster Messier 4 (M4), the first cluster to have individual stars resolved by astronomers in the mid 1700s.  Today, Backyard astronomers can easily locate this cluster with a decent pair of binoculars or a small telescope.

    Antares and Messier 4 – SkySafari

    While the head of the scorpion is dominated by Antares and the five stars making up its head and claws, the tail of the scorpion rises above the mountain tops a litter later in the evening and is defined by its large hook at the tip.  The Hawaiian culture saw these stars as the fishhook of the demigod Maui, calling it Ka Makau Nui o Māui or “The Big Fishhook of Maui”.

    Scorpius – Till Credner, Wikimedia Commons

    Here in Northern Arizona, we certainly have scorpions and will use a fishhook for landing a trout, however the Navajo culture some something different in these stars.  The last four stars in the tail are strikingly similar to the tracks left by a running rabbit, and as such, was known as Gah Haat’e’ii – Rabbit Tracks.  It was the return of the rabbit tracks each year that signified to Navajo hunters that hunting season was over.  During the time this constellation is visible in the night sky is when deer, elk, and other large game have given birth to your young, and these newborns are still reliant on their mothers for sustenance.  When Rabbit Tracks move to the East and is no longer upright in the sky, the young are then old enough to care for themselves, and the hunting season returns.

    Gah Haat-e’ii – Rabbit Tracks – Judy Volker, judy-volker.com

    Due to its placement along the main swath of the Milky Way, Scorpius contains many other deep sky objects, including double stars, nebulae, and both open and globular clusters.  Enjoy the beautiful summer nights of Northern Arizona and get your telescope out to look at this amazing patch of sky.

  • Planetary Demotions

    When I was growing up, we remembered the names of the planets in order with the mnemonic My Very Excellent Mother Just Sent Us Nine Pizzas.  However, on August 24th, 2006, the International Astronomical Union voted on a stricter definition of what it means to be a planet.  You see, Pluto had become a problem – it was discovered by Clyde Tombaugh at Flagstaff, Arizona’s Lowell Observatory in 1930, with nearly a dozen more distant worlds discovered within our solar system in the early 2000s.  Our planetary family was expanding to include at least 9 more, or we needed a better way to classify different types of worlds.  It was decided that a planet must be in orbit around the Sun, large enough that its own gravity creates an essentially spherical shape, and that as the gravitationally dominant body in its orbit it has successfully cleared its neighborhood of other large bodies, excepting its natural satellites or moons.  Pluto did not meet this definition, nor did the recently discovered Eris, Haumea, Makemake, Gonggong, Sedna, or Orcus.   As such, planetary scientist Alan Stern is credited as coining the term Dwarf Planet to classify these worlds that border on the definition.  Pluto lovers worldwide were disheartened as we amended to My Very Excellent Mother Just Sent Us Nachos.

    Ceres as imaged by Hubble, 2004.

    This wasn’t the first time that a planet had been demoted.  On January 1st, 1801, a Catholic priest searching for a dim star from the Academy of Palermo in Sicily found a star that moved from night to night.  First assuming it to be a comet, 24 consecutive observations led Giuseppe Piazzi to conclude, “since its movement is so slow and rather uniform, it has occurred to me several times that it might be something better than a comet.”  Mathematical predictions placed this new object’s orbit as coming back into view on the other side of the sun, and astronomers worldwide looked skyward for its return.  On December 31st of that same year, Ceres orbit was confirmed, and astronomers celebrated the addition of a new planet.  Located partway between the orbits of Mars and Jupiter, Ceres is in the location we now refer to as the Asteroid Belt, so named because of its high concentration of solid bodies, both large and spherical, and small and irregular in shape.  Just 15 months after the discovery of Ceres, Heinrich Olbers found Pallas, and by 1807, Vesta and Juno joined the planetary family.  William Herschel, who discovered Uranus in 1781, suggested the term asteroid for these new worlds, meaning “Star Like.”  By 1868, over 100 asteroids had been discovered, and by 1921, primarily due to the introduction of astrophotography in 1891, the number of asteroids discovered tallied over 1000.  The term asteroid stuck, and we now count around 1 million within our Solar System.

    The Dawn Spacecraft visited Ceres in 2015 for a closer look.

    Ceres is not visible to the naked eye, but a good pair of binoculars or small telescope should allow you to find this dim world, which fluctuates in apparent magnitude from 6.7 to 9.3 throughout its orbit.  At 2.97 AU and just 595 miles in diameter, it represents approximately 25% of the asteroid belt’s total mass.  Look for it this month as it approaches Denebola, the bright star marking the tail of Leo.

    Where to find Ceres in the night sky around April 10th, 2023.