This month also marks the 40th anniversary of mankind’s first steps on the Moon.  On July 20, 1969, Neil Armstrong and Edwin (Buzz) Aldrin landed a tiny tin-can of a spacecraft on the southwestern edge of the Sea of Tranquility and went on a 2-hour walkabout.  It was an amazing achievement.

*** From One-Minute Astronomer ***

Tired of just reading about the stars?  Stargazing for Beginners takes you on an easy-to-follow tour of the stars and main constellations.  No telescope required!  Click here to learn more…

Celestial Events in July

Moon, Jupiter, and Neptune. The moon and Jupiter play tag on July 9 and 10.  Jupiter is just east of the moon on the 9th, and just west on the 10th.  And on the 11th, the 5-th magnitude star µ Capricorn sits just 17′ (about 1/4 degree) NNW of Jupiter, and Neptune sits another 17′ NNW of that.  This is  a great chance to spot 8th-magnitude Neptune without too much effort.

The Aquariids. See if you can spot the Aquariids meteor shower.  Active from July 25-31, it’s best seen from the southern hemisphere. You might see 15-20 meteors an hour, all tracing their apparent direction back to a point in the constellation Aquarius.

Solar Eclipse. By far the biggest event this month is the total eclipse of the sun on July 22.  The path of totality lies across parts of India, China, and the Pacific Ocean.  If you’re traveling to see the eclipse, we wish you clear skies and safe travels.  And please send us an email to let us know your impressions.  For the those of us who aren’t going, here’s what it will look like, taken from a video of the 2006 total eclipse as it was seen in Turkey.

Planets This Month

Mercury. Mercury will disappear behind the sun early this month, then swing around the other side to reappear in the evening sky.  You might spot it just above the western horizon close to a thin crescent moon on July 23-24.

Venus and Mars. Venus is the belle of the ball this month in the eastern morning sky.  It’s unmistakably bright, hanging in Taurus by mid month.  You’ll find Mars a little higher, above the V-shaped Hyades star cluster and just below the Pleiades.  Mars and Aldebaran both have a similar color; Mars is the one that twinkles the least.

Venus and Mars near the Hyades and Pleiades before dawn on July 17-19.

Jupiter and Neptune. Jupiter and Neptune sit close together in Capricorn.  Although low in the southeast for northern observers, Jupiter always puts on a good show.  As mentioned above, the two planets are within 0.5 degrees of each other on July 11.

Uranus. Also in the southeast sky, Uranus moves slowly through the circlet of Pisces this month.

What to See

The constellation Sagittarius, visible in near the southern horizon from the northern hemisphere and nearly overhead in the southern hemisphere, holds so many sights it’s hard to know which to choose.  Perhaps we’ll cover a few later this month.  But you can’t go wrong just sweeping this part of the sky with binoculars to get a view of the grand spectacle of a major spiral arm of our galaxy.

Finally, no time to write a haiku this month (at least not a good one).  So here’s one from a master:

Summer moon–
Clapping hands,
I herald dawn
-Basho

The Basics

• Like the name suggests, an alt-azimuth mount moves in two directions: altitude (perpendicular to the horizon), and azimuth (parallel to the horizon). With these two motions, you can point a telescope on such a mount to any object in the sky.

• But an “alt-az” does not follow the natural motion of the sky. Stars and planets appear to move around the sky in circles centered about an imaginary line through the north and south celestial poles. The stars rise and set at an angle to the horizon equal to 90 degrees minus your latitude. And they follow a path in the sky that’s a combination of altitude and azimuth. So to keep an alt-az-mounted scope centered on a celestial object, you’ll have to move the scope in both axes, which is bothersome for visual observing and completely unacceptable for photography.

A “rocker box” altazimuth mount for a Dobsonian telescope

A Deeper Look

• For amateur telescopes, alt-az mounts come in two basic configurations. Long Newtonian reflectors are usually mounted on a fork-type alt-az mount called a “rocker box”. You give them a push in one or both axes to point the telescope. In many cases, the telescope is held in place by the mount’s friction.

• For shorter telescopes, some modern alt-az mounts have two moving joints connected together, like a camera tripod. The telescope is fixed to the mount by means of a saddle that holds a dovetail bar that’s fixed to the telescope. There are locking screws and perhaps controls for fine adjustment of the mount’s position.

• Equatorial mounts, which we’ll cover in a future issue, solve this problem because they follow the path of the stars with the motion of a single axis. Equatorial mounts require fairly precise alignment with the pole, and this takes time. Alt-az mounts require no alignment… just plop them down and you’re ready to go.

Good To Know

Modern electronics and electric motors make it possible for an onboard computer to control the motion of each axis of an alt-azimuth mount to automatically track the motion of the sky. The computer needs to know your latitude and may require the mount to sit on a level surface to accurately track. This is great for visual observing. But it won’t work for long-exposure photography because the field of view undergoes an apparent rotation that will ruin an astrophoto.

Personal View

With little time for visual observing and no time for fancy astrophotography, I only use an alta-zimuth mount. It takes me just minutes to grab the mount and scope and start looking. Superb for one-minute astronomy.

** Highly Recommended **

Lunar Phase Pro is the “ultimate lunar observer’s toolkit“.  Detailed 2D and 3D lunar maps (including dark side and polar regions).  Predictions of phases, dynamic simulations, and more.  A great learning and planning tool.  Instant download.  Click here to learn more…

The Basics

• To review: for mid-sized star like our sun, the end comes after helium burns by nuclear fusion into carbon in the core.  When the helium runs out, the star can’t compress itself any further to get hot enough to burn carbon into heavier elements.  The core settles down to become a carbon-rich white dwarf… a large glowing diamond in space.

• But for larger stars, the core gets hot enough for carbon to fuse itself in more complex reactions into heavier elements like oxygen, neon, and magnesium.  The star expands into a red supergiant… it gets cooler and redder, but not much brighter than it already was.  So it moves to the right in the HR diagram.

• What happens next depends very much on the star’s mass.  If the core is not too large, the neon or magnesium becomes dense and holds itself up with the pressure of electrons.  When it gets squashed by the surrounding layers of star, the core ignites it does so violently, like the “helium flash” we mentioned in the last article.  But an oxygen or neon flash is catastrophic… it blows the star apart, and may leave behind a white dwarf made of oxygen, magnesium, or neon.

The “onion-like” layers of nuclear fusion of light elements into heavy elements in a massive star

A Deeper Look

• For more massive stars (say more than 5 solar masses), the core is so hot that it never gets dense enough to flash and blow itself apart.  Every time light elements run out, heavier elements ignite and hold the star up.  So neon, magnesium, silicon, and other elements are created in the core.  In some cases, heavier elements burn in the center, and lighter elements burn in shells around the core, like layers of an onion (see the above drawing).

• This complex nuclear dance comes to an end when lighter elements fuse into iron and nickel, because these elements cannot burn into heavier elements.  At this point, the game is up: there’s no more energy to hold up the star.  The core collapses to become a neutron star or black hole, and the outer layers are violently ejected in a supernova explosion.

• How massive does a star have to be to burn all the way to iron in the core and die as a supernova?  It all depends on mass loss.  The outer layers of a star of are ejected into space in mechanisms that aren’t well understood.  So a star 5x the mass of the sun may eject enough material to end up as a white dwarf rather than blow up as a supernova.  These details occupy professional astronomers today.

Good To Know

The fusion of light elements into heavier elements in the core of the star is a key source of such elements in the galaxy.  Some of the oxygen you are breathing right now, and most of the iron in your blood, were created in the cores of heavy stars that blew up as supernovae.

*** From One-Minute Astronomer ***

Tired of just reading about the stars?  Stargazing For Beginners takes you on an easy-to-follow tour of the stars and main constellations.  No telescope required!  Click here to learn more…

A Quick Review…

• On maps of the Earth, latitude measures how far north or south of the equator a place lies.  By convention, the equator has a latitude of zero degrees, the north and south poles have a latitude of 90° North and 90° South, respectively.  Chicago has a latitude of 41.8° North; Sydney, Australia has a latitude of about 34° South.

• Longitude measures how far east and west a place lies on the Earth’s surface.  But how far east and west of what?  By convention, the reference point of longitude is the great circle running through the earth’s poles and the Royal Greenwich Observatory in London, U.K.   So Greenwich is at zero degrees longitude.  Chicago, west of Greenwich, has a longitude of 88° West.  Sydney, east of London, is at a longitude of 151° East.

The celestial sphere, showing the poles, equator, and celestial coordinates

Celestial Latitude: Declination

• Now imagine the lines of latitude and longitude projected onto the sky.  The celestial equator lies directly above the Earth’s equator, and the north and south celestial poles are above the Earth’s poles.

• Imaginary lines of latitude and longitude are there as well.  But in the sky, latitude is called declination.  By convention, the celestial equator has a declination of 0 degrees.  North and south of the celestial equator, declination is marked with a “plus” and “minus” sign.  The star Vega, for example, has a declination of +39°.  The southern star Achernar has a declination of about -57°.

• Each degree is split into 60 smaller units called “minutes of arc”, marked by a ‘, and each minute is split into 60 “seconds of arc”, marked by a “.  So the more precise declination of Achernar is -57° 14′ 12″.  And Vega is at +38° 47′ 01″.   (See Measuring the Sky)

Celestial Longitude: Right Ascension

• The celestial equivalent to longitude is called right ascension.  It’s measured not in degrees but in “hours”, from 0h to 24h.  Astronomers cooked up this arrangement long ago because the celestial sphere appears to turn once every 24 hours.   With 24 hours in the full 360 degrees of sky, each hour corresponds to 15 degrees of angular distance.  Like degrees, each hour is split into 60 minutes, and each minute into 60 seconds.

• The right ascension of Achernar, for example, is 01h 37m 43s; Vega is at right ascension 18h 36m 56s.

• By convention, the great circle with right ascension of 0 hours runs through a point in the constellation Pisces at which the ecliptic crosses the celestial equator, and right ascension increases going eastward.

Good To Know

The right ascension and declination of each star are fixed from day to day and year to year.  But because the Earth is wobbling in space because of the gravitational influence of the Moon and Sun, the coordinates of celestial objects change over the course of decades.  Every 50 years or so, star maps and star coordinates are updated.  Current star maps are accurate as of the year 2000.

To be honest, almost every telescope available today is just as good or better than the offerings of 30-40 years ago.  And the prices in real dollars are much lower.  But it’s still fun to look back and consider how far the tools of amateur astronomers advanced over the last 30-40 years.   Thousands of these old telescopes are still in use today.

Unitron Refractors

There’s nothing like the look and feel of a fine refractor.  Long, sleek, and serious, a refractor LOOKS like a real telescope.  Today, refractors are back in style.  But in the 1970’s, Unitron was one of the few and certainly the preeminent maker of well-engineered refractors, many of which bristled with eyepieces, finders, and guidescopes for astrophotography.  These telescopes mesmerized solar system observers and hardcore optical purists.

Questar

Questar was the Rolls-Royce of telescopes.  First introduced in 1952, they merged art and fine engineering to produce a 3.5″ and later 7″ Maksutov-Cassegrains with tack-sharp optics and Swiss-watch mechanics.  These scopes were used by astronomers, National Geographic photographers, and even NASA engineers.  Questar was for those who wanted and could afford the best: the 3.5″ model sold for almost $6,000 in today’s dollars!

Celestron

Celestron has changed ownership over the years, but they’re still going strong.  In 1971 they became the first to mass-market Schmidt-Cassegrains, which put compact large-aperture scopes into the hands of thousands of ambitious amateurs.  In the ’70’s, Celestron was known for its trademark orange tubes on its 5″, 8″, and 14″ Schmidt-Cassegrains.  But in the 1960’s, Celestrons built white-tube SCT’s for universities and professional observatories, in sizes from 6″ to 22″.

RV-6 Dynascope

We move downmarket now, but to a no less venerable telescope.  The Criterion RV-6 Dynascope was for serious amateurs with limited budgets, and more sold than almost any other scope of the time.  The optics were sharp, the mount solid, and the clock drive smooth and reliable.  This scope, along with its 8-inch sibling, sold well through the late ’50’s to the mid ’70’s.  Criterion then made a major blunder with the Dynascope, its 8-inch Celestron SCT wannabe which featured lousy optics and a shaky mount.  The product killed the company.

Coulter Dobs

After the SCT craze of the 1970’s, an obscure ex-monk named John Dobson brought aperture to the masses by creating a telescope that combined large optics with a cheap and simple altazimuth mount.  The Dobsonian telescope was born.  But Dobson was no capitalist.  It fell to a company called Coulter Optical to build and market a 13.1″ scope that sold for less than an 8″ SCT.  Dobsonians remain an immensely popular design to this day.  They sell for $50-$100/inch of aperture, half the price of an SCT and 1/10 the price of a top-notch refractor.  A perfect telescope for the visual observer.

The Basics

• The Blue Planetary lies in a rich star field in the constellation Centaurus, just 2.5 degrees NW of delta Crucis in the Southern Cross (RA 11h50m, Dec -57d11m)

• It was first recorded in 1834 by John Herschel, whose father William, coined the term “planetary nebula” because of the resemblance of some of these objects to Uranus, which he discovered.

• The hot core of the central star of the nebula, which is about to become a white dwarf, is too faint to see with a small scope.

A Deeper Look

• Like most small planetaries, NGC 3918 can take a lot of magnification… try at least 150x or so to bring out the bright disk.  It’s about 10″ across; magnitude 8.0  The trick is to use magnification low enough to find it, and high enough to resolve it into a disk.  Try an OIII filter too.

•The nebula lies about 3,000 ly away from us and spans 0.2 light years… roughly 12x the diameter of Pluto’s orbit!

• NGC 7662 in Andromeda is another blue-green planetary.  It’s well positioned for northern observers in autumn.  Most planetaries emit blue-green light, but some are particularly bright at this wavelength.

Good To Know

The blue-green color of this planetary nebula comes from doubly-ionized oxygen atoms that emit light at a wavelength of 500 nm, which is almost the color light reflected from of sea water in a shallow tropical bay.

Bonus Object

NGC 3960, a faint open cluster just 1.5 degrees north of the Blue Planetary at RA  11h 51 min Dec  – 55° 41′.  It’s a pleasant cluster, not terribly bright at magnitude 8.3, but easily visible in a small telescope.  The cluster formed about 0.8 billion years ago.  That’s old for a cluster; it’s about the same age at M44.  NGC 3960 lies in a rich background of stars along this part of the Milky Way, but only about 45 stars belong to the cluster.

For observers in the northern hemisphere, the sun lies high in the sky during the day and not far below the horizon at night, which makes for long twilight and short nights.   Summer arrives at 5:46 GMT on June 21.   But the days now– slowly at first– start getting shorter.  (Of course, it’s the other way around for observers in the southern hemisphere).

Life is busy, I know.  But try to get out to enjoy a few moments of stargazing.  Let a few rays of ancient starlight strike your eye and incite your imagination.

Celestial Events in June

Moon occults Antares. In the evening of June 6, in the Caribbean, northern parts of Latin America, and all but northeastern and far western North America, the nearly-full Moon occults the bright supergiant star Antares in Scorpius. It should be quite a show.  This month, you can see the dramatic rise of Scorpius in the late evening as it lurches over the south-eastern horizon, claws first, looking for its prey.

Io and Ganymede cast shadows simultaneously on the face of Jupiter from 8:06 to 10:16 Greenwich Mean Time (GMT) on June 9.  A small telescope at 100x or more should give you a good view.  Click here to translate Greenwich Mean Time to the time in your area. The event will look a little like this…

Pluto lies directly opposite the Sun this month in northern Sagittarius.  At 14th magnitude, it lies beyond the sight of all but the most determined stargazers.

Moon and Planets

The Moon. Full on June 7; new again on June 22.  On June 19, as a thin waning crescent, the Moon is just 6-7 degrees above Venus and Mars in the pre-dawn sky.

Venus. The beautiful planet wheels away from the Earth and dims slightly in the morning sky.  On June 6, the Sun illuminates only half of the face of Venus as seen from the Earth.

Mars. Lies about 10 degrees above the eastern horizon early in the month, rising a little higher towards the end.

Saturn follows Leo into the southwest after sunset.  But it’s still putting on a good show.  The rings tilt just 3 degrees from edge on.  Regulus lies west of Saturn and Spica lies further east.  Saturn is the one that doesn’t twinkle.

Jupiter. The king of planets lies in eastern Capricorn, low in the sky for northern observers again this year.  Observe it carefully on nights with steady seeing, when the image of the planet doesn’t seem to “boil” in your field of view.  As mentioned above, in a telescope, you can see a double shadow on the planet on the morning of June 9.

Neptune. Fairly dim at 8th magnitude.  Even a good-sized telescope will struggle to show Neptune’s disk, which is only 2.3″ across.  But the outer planet is less than 0.5 degrees from Jupiter all month, so you can see them in a single low-power field of view.

Uranus rises a couple hours after midnight.  It’s in Pisces, near the “circlet” of stars that makes up the head of the western “fish”.  It’s visible in a telescope before the sun rises.

Deep-Sky Sights

The fine double star Izar (epsilon Bootis) is well worth a look.  Separated by just 3″, you’ll need decent seeing and a magnification of 100x or so to resolve the pair.  The reward for your effort is the sight of a splendid contrast of color and brightness.  The brighter star has exhausted its fuel and become a bright red-orange giant; the fainter is a bright white main sequence star which still burns hydrogen in its core.  The pair lies about 200 light years away and takes more than 1,000 years to revolve around each other.

The double star Izar (left center) in the constellation Bootes (click to enlarge)

For southern observers, try Acrux (alpha Crucis), the magnificent double star at the foot of the Southern Cross.  Acrux is actually a triple. The main pair, stars A and B, are brilliant blue-white, and separated by 4″.  C is nearly 5th magnitude some 90″ away. The widely separated A and C components are visible in 10×50 binoculars, and a 3-inch scope shows the A-B pairing at 70x or more.

And finally, June’s Astronomy Haiku…

Darkness falls later,
Testing stargazers’ patience:
The summer solstice

The Basics

• A white dwarf is essentially a stellar cinder; it produces no heat of its own, but radiates away residual heat from the star’s core over many billions of years. White dwarfs have a temperature of 5,000-40,000 degrees, but they have a low surface brightness.

• Typical white dwarfs have a mass near that of the Sun, but a radius of the Earth.  So a white dwarf is very dense: 1 cubic centimeter has a mass of 1,000 kg!

• A thin skin of gaseous hydrogen or helium surrounds each white dwarf.  Light passing through this hot gas allows astronomers to figure out the temperature, composition, and even the magnetic field strength of a white dwarf.

A Deeper Look

• The electrons in a white dwarf are stripped from the carbon atoms and tightly squeezed together.  When this happens, they exhibit a strange quantum-mechanical effect called “degeneracy pressure” that holds the star up against the crushing pull of its own gravity.

• But there’s a limit to how much the electron pressure can withstand.  If the mass of the white dwarf exceeds about 1.4x the mass of our Sun, the star will continue to collapse further into an even stranger body called a “neutron star”.  This upper mass limit is called the “Chandrasekhar Limit” after the brilliant Indian physicist who discovered it when he was only 21 years old.

• Eventually, every white dwarf will radiate away its residual energy and become a “black dwarf”.  This takes billions of years, however, and the universe is not yet old enough to contain any black dwarf stars.

An image of Sirius A and B (from McDonald Observatory).  The light spikes are instrumental artifacts.

Good To Know

Sirius, the “Dog Star”, has a companion star called Sirius B.  Also known as the “Pup”, Sirius B is the brightest white dwarf in the sky.  The Pup was first spotted by Alvan Clark in 1862.

Personal View

Because Sirius B is so close to the dazzling Sirius A, it’s extremely hard to see in normal conditions, even though it’s fairly bright at magnitude 8.6.  Here’s one trick to see Sirius B that’s worked for me… look for the Pup using high magnification at twilight before the glare of Sirius A overwhelms its faint companion.  The stars lie about 8″ apart right now, and will get as far as 11″ apart by 2025.  That’s far enough apart for most telescopes to resolve.  But bright Sirius overwhelms the Pup, so it’s still tricky to see.   Try to see the Pup for yourself when Sirius becomes visible again in the early morning sky in August or September.

** Highly Recommended **

Pocket Stars gives you 2D and 3D star charts of the solar system and deep sky from anywhere on Earth, for any time and date. For PC, PDA, and smart phones. Winner Best Software Awards, 2007-2008. Get the universe in your pocket.   Click here to learn more…

The Basics

* What you’ve learned already: stars on the main sequence fuse hydrogen into helium in their cores, releasing heat and light for tens of millions to billions of years. Massive stars burn fast, hot, and blue; less massive stars burn slow, cool, and white or yellow or red. Eventually, all but the smallest stars run out of hydrogen, and that’s when they start burning heavier elements in the core and quickly evolve off the main sequence.

* After 5-10 billion years, when a mid-sized star like our Sun runs low on hydrogen, nuclear fusion in the core slows. With less light to push back against gravity, the star contracts and heats the helium-rich core, re-igniting a thin shell of hydrogen, which pushes out the star’s atmosphere.

* The star cools and swells by 50-100 times, becoming a red giant. It moves to the right and upwards on the HR diagram. Planets closest to the star may get swallowed up. This fate awaits Mercury and Venus. Earth may be spared, but the Sun will expand to fill much of our sky.

* In some cases, depending on the star’s mass, the helium core will be squeezed enough to suddenly ignite in what’s called the “helium flash“. This expels as much energy as 100,000,000 Suns. But the flash is brief, and the released energy does not disturb the outer layers of the star.

A Deeper Look

* After helium starts burning, the hydrogen shell around the core expands and cools, which means the outer layers of the star contract again. The star shrinks and moves to the left and downwards on the HR diagram, but does not return to the main sequence.

* Helium burning is notoriously unstable, so the star begins to pulsate irregularly. Mira is an example of a star in this late phase of life. The outer layers are expelled as a planetary nebula.  Once the helium is finished burning, the core becomes rich in carbon and oxygen. The core collapses again, but this time it doesn’t get hot enough to continue burning. What’s left of the core become a white dwarf, which we’ll cover in the next issue.

* The sun has enough hydrogen fuel to burn for 5 billion more years before it enters the red giant stage. But here’s the kicker… as the hydrogen burns, the Sun slowly contracts and becomes too hot to comfortably sustain life on Earth. This will happen not in 5 billion years, but just 500 million years. So plan accordingly.

Good To Know

A word about classification. On the main sequence, in the prime of life, a star has a luminosity class of “V” (five). So the sun is a G2V star, and Sirius is a B3V star. When mid-sized stars become red giants, they have luminosity class III (three) or IV (four). Aldebaran in the constellation Taurus, for example, is a K5III star, which means it’s become a red giant.

Personal View

A little knowledge of star types will help you better understand what you see in the sky. For example, go out on a fine spring night and find Arcturus in the constellation Bootes. It’s a red giant star, type K2III, and it’s at this very moment burning a shell of hydrogen near its core; our Sun will look very much like this in some 6 -7 billion years. Now you know why.

(Note… these last three issues were for northerners only.  We haven’t forgotten about you in the southern hemisphere… we’ll tour a patch of southern sky in the near future.)

—– Highly Recommended —–

Use a videocam to image the deep sky, moon, and planets.  Deepsky Imaging software helps you capture video CCD images, and enhance them to bring out maximum detail and color.  Works with most commercial video CCD cameras.  Click here to learn more…

Messier 101

• Pierre Mechain discovered this galaxy in 1781 and suggested Charles Messier include it in his famed catalog.  While it was discovered with a modest telescope by today’s standards,  M101 is hard for most modern stargazers to find.  It shines at magnitude 7.7, which is quite bright, but its light is spread over an area as large as the full moon.  So its surface brightness is quite low.  If you live in the city, you may not see M101 at all, no matter how big your telescope, because the background sky is brighter than the galaxy itself.

• In long-exposure images, M101 is a dazzler.  It’s one of three galaxies, along with M99 and M33, that’s referred to as the “Pinwheel” galaxy, since we view this spiral galaxy face on.   It’s some 17 million light years away.

• The position of M101 is easy enough to locate: it makes an equilateral triangle with Mizar and Alkaid, the last two stars in the Dipper’s handle.  See the map here. And yes, M101 is OVER the Dipper’s handle, but it’s a fine object and a good test of your observing skills.

Messier 106

• Unlike the nearly-symmetrical M101, M106 is a wracked mess of a galaxy, torn and misshapen by violent upheaval like the nearby M82.  It’s dimmer than M101.  But it’s a little easier to see since it has a smaller apparent surface area.  You’ll find it under the handle, about halfway between the star Chara in Canes Venatici and Phad in the Dipper’s bowl.  It’s coordinates are RA12h19m, Dec+47d18m.

• M106 is a Seyfert galaxy, which means it has unusual emission of intense X-rays and light at other wavelengths.  M106 hosts a black hole that emits high-intensity radio waves as it gobbles up stars near its core.

• M106 also contains a naturally occurring “water maser”, which is essentially a laser that emits microwaves instead of visible light.  This is one strange galaxy.

Good To Know

If you can see M101, I have good news… you’ve also seen M102.  A duplicate observation of M101 led to an incorrect entry in Messier’s catalog.  They are really the same galaxy.

Personal View

From my near-urban backyard, I can’t see M101 no matter how hard I try.  The sky is just too bright.  But it’s easy enough with a 4-inch scope from nearby rural sky.