The Sky This Week, November 14 – 21, 2017 !

The Sky This Week, 2017 November 14 – 21

The Seven Sisters on the rise
Messier 45, the Pleiades Star Cluster
imaged 2016 December 31 from Mollusk, VA by Geoff Chester
with an Explore Scientific AR102 4-inch f/6.5 refractor
and Canon EOS Rebel T2i DSLR.

The Moon spends most of the week in the glow of morning and evening twilight. New Moon occurs on the 18th at 6:42 am Eastern Standard Time. Luna may be found as a waning crescent in the company of the planets Mars, Jupiter, and Venus in the pre-dawn hours of the 15th, 16th, and 17th. She returns to the evening sky by the evening of the 20th, when you’ll find her low in the southwest as evening twilight fades.

The sky in the middle of November is one of transition between the setting stars of summer and the rising stars of winter. On the whole there aren’t that many bright stars above the horizon during the mid-evening hours. The solitary first-magnitude star among the autumnal constellations crosses the meridian at around 7:30 pm, low in the southern reaches of the sky. This solitary star is Fomalhaut, the brightest and only prominent star in the obscure constellation of Pisces Austrinus, the Southern Fish. It is one of the closer stars to the Sun at a distance of about 23 light years, but somehow its isolated place in the sky makes it seem much more remote. Fomalhaut transits the meridian just before the westernmost stars in the Great Square of Pegasus, the “signature” constellation of the seasonal sky.

High in the east during the later evening hours is a small knot of stars that have probably garnered more attention in skylore that the rest of the constellations combined. Urban skywatchers can see the group as a small fuzzy grouping on clear nights, and as you move farther from the middle of the city the group begins to come into better focus under darker skies. Viewers in the suburbs should be able to see around half a dozen stars in a pattern that resembles a small measuring spoon, while those graces with dark country skies can easily seven or more stars. The group goes by as many names as there are colloquial legends of the sky, and we call the group The Pleiades or The Seven Sisters. In Greek mythology they were the daughters of Atlas and half-sisters of the nearby Hyades, which surround the bright star Aldebaran. Since very ancient times the risings and settings of the Pleiades have dictated agricultural activities, and in the Mediterranean region they were seen as harbingers of stormy weather that comes with the arrival of winter. The vast pre-Columbian city of Teotihaucan, which was 1000 years old when the Aztecs ruled Mexico, has all of its major streets and its largest temple, the so-called “Pyramid of the Sun”, laid out in alignment with the setting of the Seven Sisters. The stars have even found their way into the mythology of J.R.R. Tolkien’s Middle Earth, where Hobbits, Elves, and Men knew them as Remmirath, “the Netted Stars”. The group is a true star cluster, one of the closest to the Earth, about 440 light-years away. Keen-eyed observers under very dark skies may be able to see up to a dozen of its components, while binoculars will reveal several dozen. Astronomers have counted about a thousand total cluster members. The brightest members are energetic young blue stars that have luminosities that are thousands of times that of the Sun.

Try to catch a last glimpse of Saturn in twilight on the evening of the 20th. On that night the slender waxing crescent Moon will be located about two degrees north of the ringed plane. Both objects will be low in the southeastern sky, and you’ll probably need binoculars to see Saturn in the relatively bright sky.

Mars may be found about five degrees above the waning crescent Moon before dawn on the 15th. He’s also fairly close to the bright star Spica, but you should be able to distinguish him by his ruddy tint, which contrasts nicely with the ice-blue of the star.

Venus starts the week close to Jupiter, and as the week passes the dazzling planet leaves Old Jove in her wake. Look for the pair in bright twilight, low in the east about half an hour before sunrise.


The Sky This Week, November 7 – 14, 2017 !

The Sky This Week, 2017 November 7 – 14

Gems in the autumn sky
Messier 31, the Andromeda Galaxy
imaged 2017 October 20 from Great Meadow, VA by Geoff Chester
with an Explore Scientific AR102 4-inch f/6.5 refractor
and Canon EOS Rebel T2i DSLR.

The Moon wanes in the late evening and morning skies this week, passing through the rising constellations of winter and spring.  Last Quarter occurs on the 10th at 3:36 pm Eastern Standard Time.  Look for Luna near the bright star Regulus in the constellation Leo on the morning of the 11th.  By the end of the week the Moon will be near ruddy Mars.  She’ll be just over three degrees east of the red planet before sunrise on the 15th.

The change back to Standard Time now pushes the onset of night an hour earlier.  You can still see the stars of the Summer Triangle in the hours after sunset, and from a dark location the summer Milky Way is still prominent as evening twilight ends.  The densest part of the home galaxy is now setting on the southwest, but the prominent star clouds and dark rifts still split the three stars Vega, Deneb, and Altair.  Its brightness slowly wanes as you look toward the northeast, but the number of bright stars begins to concentrate with the rising constellations of Cassiopeia and Perseus.  These two constellations are wonderful places to explore with binoculars or a small telescope, with dozens of star clusters scattered among their brighter stars.  One of my favorite objects in this area lies in the middle of the Milky Way between the two constellations.  The “Double Cluster” can be seen with the naked eye from a dark location, and its stellar nature is revealed with only slight optical aid.  My favorite views come with my 3- and 4-inch refractors using a low-power eyepiece.  These clusters each contain some of the most intrinsically bright stars in the sky, with luminosities over 100,000 times that of our Sun.  Looking south at around 8:00 pm, you’ll find a relatively sparse sky that’s dominated by a large square of second-magnitude stars that marks the constellation of Pegasus.  The upper left star of this square is Apheratz, shared by Pegasus and Andromeda.  Under dark skies you’ll notice two diverging “chains” of stars pointing toward Perseus.  Go to the second star in the brighter chain, then hop up two fainter stars to spot a small, fuzzy “cloud” that looks like a detached piece of the Milky Way.  Binoculars will reveal an elongated streak of light that refuses to resolve into stars in all but the largest telescopes.  This is the famous Andromeda Galaxy, Messier 31, the largest member of our Local Group of island universes.  At a distance of 2.5 million light years, this is the most distant object you can see with your unaided eye.  It’s estimated that this galaxy contains some 400 billion stars.  The Milky Way and M31 are approaching each other at a speed of about 110 kilometers (68 miles) per second.  It will collide with us in about 4 billion years!

Saturn still lingers in the southwestern sky, visible for a short time after the end of evening twilight before setting at around 7:00 pm.  His low altitude means that detailed views of his rings will be quite distorted by turbulence in our atmosphere.

You’ll find Mars rising in the hours before dawn.  The red planet begins the week just under two degrees south of the second-magnitude close double star Porrima in Virgo.  He continues to trek eastward toward the bright star Spica and is joined by the waning crescent Moon as the week ends.

Venus is now only visible in the brightening morning twilight, rising about an hour before the Sun.  You should be able to spot her if you have a low eastern horizon.  If you’re lucky and have a clear sky on the morning of the 12th look for Jupiter just a quarter of a degree from Venus in the brightening sky.  They will be in bright twilight but should be easy to spot in binoculars half an hour before sunrise.

The Sky This Week, October 31 – November 7, 2017 !

The Sky This Week, 2017 October 31 – November 7

Fall back after the Hunter’s Moon.
The Hunter’s Moon, 2016 October 16
imaged from Alexandria, VA by Geoff Chester
with an Explore Scientific AR102 4-inch f/6.5 refractor
and Canon EOS Rebel T2i DSLR.

The Moon brightens the sky for Halloween’s ghosts and goblins, then waxes to Full Moon on November 4th at 1:23 am Eastern Daylight Time. This Full Moon is popularly known as the Hunter’s Moon thanks to nearly the same orbital geometry as last month’s Harvest Moon. The times of successive moonrises around the time of Full Moon differ by about 35 to 40 minutes, adding a little extra light to the twilight hours. In bygone times this allowed hunters to have a little more time to chase game over the stubble of the harvested fields. In Native American skylore this was also known as the Beaver Moon, since this was the time of year when these industrious rodents were busily preparing for the coming of winter. During the week Luna moves through the faint autumnal constellations, ending the week in the middle of the rising stars of winter. On the evening of the 5th, watch the bright star Aldebaran slip behind the Moon at 7:59 pm Eastern Standard Time, shortly after moonrise. The star will reappear from behind Luna’s slender dark limb at 8:53 pm.

Remember to set your clocks back one hour as you turn in for the night on the evening of the 4th. Technically you should perform this annual ritual at 2:00 am on the morning of the 5th, according to U.S. Code. The subject of Daylight Time and clock-changing has long been a bone of contention ever since it was first legislated in 1918. It was initially adopted as a means to promote the tending of “victory gardens” during World War I, a concept which satisfied factory workers who wanted a little extra food on the table. Within year, though, the law was repealed and Daylight Time became a matter for states and local municipalities to decide. During World War II Daylight Time was observed continuously from February 9, 1942 until September 30, 1945, when once again it became a matter of local choice. It wasn’t until 1966 that a Federal statute was once again passed by Congress as the Uniform Standard Time Act. Under these rules Daylight Time began on the last Sunday in April and lasted until the first Sunday in October. Our current system, with Daylight Time in force from the third Sunday in March to the first Sunday in November, is the result of the Energy Policy Act of 2005. Since these rules are specified in the law of the land they are enforced by a civilian agency, so if you don’t like the current system please call the Office of General Counsel at the Department of Transportation. The Time Service Department here at the Naval Observatory is responsible for producing a uniform time scale, Coordinated Universal Time (UTC); we don’t tell people what to do with it! That said, at least we’ll get back the hour that we lost way back in March.

You will still find Saturn lingering in the southwestern sky as evening twilight begins to darken the sky. The ringed planet’s current tenure in the evening sky is rapidly coming to a close. He sets an hour after the end of evening twilight, and by the end of November you’ll be hard-pressed to spot him at all in the twilight glow.

The next bright planet to grace the sky is Mars, but you’ll have to either be a night owl or a very early riser to catch him. He rises shortly before 5:00 am EDT among the stars of Virgo and spends the week drifting between the third-magnitude star Zaniah and second-magnitude Porrima. His ruddy disc is currently a miniscule 4 arcseconds across, but he will become a great telescopic target when he reaches opposition in late July next year.

Brilliant Venus is now rising at the beginning of morning twilight. She hangs low above the eastern horizon as the sky brightens, so you’ll need to have a good eastern exposure to see her. By the end of the year she will be lost in the solar glare and won’t emerge in the evening sky until early 2018.

The Sky This Week, October 24 – 31, 2017 !

The Sky This Week, 2017 October 24 – 31

A great week to observe the Moon!
The Moon at First Quarter, 2016 NOV 7, 22:42 UT
imaged from the U.S. Naval Observatory, Washington, DC by Geoff Chester
with the 30.5-cm (12-inch) f/15 Clark/Saegmüller refractor
and Canon EOS Rebel T2i DSLR.

The Moon waxes in the evening sky this week, reaching the First Quarter phase on the 27th at 6:22 pm Eastern Daylight Time. Luna begins the week just east of Saturn, then ventures into the dim stars of the autumnal constellations.

The evening of the 28th has been designated as “International Observe the Moon Night”, an evening devoted to exploring the myriad features of our only natural satellite. The Moon will be on the meridian at around 8:00 pm, and the terminator (the line dividing day from night on the lunar sphere) will be ideally placed to reveal some of the Moon’s most famous features. Organized public observing events in the Washington metro area include viewings at the Phoebe Wasserman Haas Public Observatory at the National Air & Space Museum on the Mall. Amateur astronomers will also be convening at Fort Washington National Park with telescopes to share the view. If you happen to have a telescope, set it up on Saturday evening and share the view with your friends and neighbors. Luna’s surface, just under a quarter of a million miles away, is the only place in our universe other than the earth where you will find human footprints. While you won’t see the Apollo landing sites through any terrestrial telescope, you can nonetheless explore the barren beauty of the Moon’s many varied landscapes with very modest optical aid. While these features have remained essentially unchanged for the duration of human history, they always present a slight difference in lighting and detail from lunation to lunation. The Moon is often “looked over, then overlooked” by astronomers, yet it remains the single easiest celestial object to observe, as visible to city-bound telescopes as it is to those on remote mountain peaks. Visit the event’s website for resources, including a map of Luna’s basic features that will be visible on the 28th.

October 31st marks one of my favorite annual observances, Halloween. It seems that each year the decorations that people put up for this event get more elaborate, and the number of ghosts, goblins, and other masked young revelers seems to grow exponentially. Whether they realize it or not, people are actually observing an astronomical event known as a “cross-quarter” day, one that marks the halfway point between astronomical seasonal dates of solstices and equinoxes. These dates have been observed in many traditions for centuries, and have gradually been assimilated into modern popular culture. Halloween was derived from an ancient Celtic pagan ritual observance of the end of the harvest season and the beginning of the dark days of winter. At this time it was believed that the boundary with the underworld became more transparent, allowing departed spirits to invade the conscious world. Under the influence of Christianity it became a feast observing the passing of saints, martyrs, and others who died in the faith, rewarding their souls with sustenance for the coming year. This year we can extend the spirit of Observe the Moon Night; set your telescope up and offer a view of the Moon as one of your treats for the roving spirits.

Saturn will still be visible for early trick-or-treaters, so you might want to get him in the eyepiece before the ringed planet settles toward the horizon. He sets just over an hour after the end of evening twilight.

You’ll have to wait until the pre-dawn hours to find another bright planet. Ruddy Mars rises at around 5:00 am while Venus comes up about an hour later. Mars should be relatively easy to spot once Venus crests the horizon. The red planet will be about 12 degrees above Venus as the week begins. Venus will add another four degrees of separation between the two by the week’s end.

The Sky This Week, October 17 – 24, 2017 !

The Sky This Week, 2017 October 17 – 24

Tour the sky at the NOVAC Star Gaze!
Messier 15, Globular Star Cluster in Pegasus
imaged 2017 September 24 from the U.S. Naval Observatory, Washington, DC
by Geoff Chester with an Explore Scientific AR102 4-inch f/6.5 refractor
and Canon EOS Rebel T2i DSLR.

The Moon wanes returns to the evening sky this week, passing through New Moon on the 19th at 3:12 pm Eastern Daylight Time. You can spot her low in the southwestern sky at dusk on the 21st, and she will pass by Saturn on the evenings of the 23rd and 24th.

For most of the week bright moonlight won’t interfere with overnight skywatching activities. That means that conditions are just about ideal for viewing the annual Orionids meteor shower. The tiny bits of cosmic fluff that leave streaks of light in the sky when they hit Earth’s atmosphere originate from debris sputtered off of Halley’s Comet. The Orionids peak on the morning of the 22nd, but the shower itself is active throughout the month. The shower’s “radiant”, the point in the sky from where the meteors appear to originate, is just to the east of the “club” of Orion. It rises at around 10:00 pm, but the best activity will take place after midnight. A single observer at a dark location can expect to see around 25 “shooting stars” per hour, but the shower has shown bursts of activity that seem to have a period of 10 to 12 years. The last outburst occurred in 2006, when observers saw over 50 per hour, so it’s worth watching to see if a similar event occurs this year. Orionids are fairly swift, and the peak rates occur for a few nights before and after the optimal morning of the 22nd.

Hopefully fine autumn weather will hold for the 35th annual Star Gaze, sponsored by the Northern Virginia Astronomy Club. If you’ve ever wondered about what amateur astronomy can offer as a hobby, this is your chance to experience the many different facets that the sky can offer. The program runs from 3:00 – 11:00 pm at C.M. Crockett Park in Midland, Virginia in western Prince William County. The event features a number of talks and activities, safe viewing of the Sun through specially equipped telescopes, and hours of nighttime observing through telescopes provided by club members. If you’re considering buying a telescope, here’s a golden chance to see what different types can do to satisfy your cosmic curiosity. The event is free and takes place “rain or shine” and best of all it’s free. Further details can be found on the club’s website at

Saturn will be a popular target during the early evening at the Star Gaze. The ringed planet still graces the southwestern sky during the twilight hours and will remain visible for an hour or so after twilight ends. Star Gaze telescopes may also be pointed at the more distant planets Neptune and Uranus as the night passes on.

The real highlights for Star Gaze participants will be views of some of the finest star clusters, nebulae, and external galaxies through the many different telescopes that will grace the observing field.

Venus remains very bright in the pre-dawn sky. You’ll have no trouble spotting her about 10 degrees above the eastern horizon at 6:30 am. On the morning of the 18th see if you can spot the slender waning crescent Moon about halfway between Venus and the horizon. Ruddy Mars appears about eight degrees above Venus on the morning of the 18th. By the week’s end Venus will pad that distance by another five degrees.

The Sky This Week, October 10 – 17, 2017 !

The Sky This Week, 2017 October 10 – 17

Rambling through the Milky Way.
The “Double Cluster”, NGCs 869 & 884
imaged 2013 August 15 from Fishers Island, NY
by Geoff Chester with an Antares Sentinel 3-inch f/6 refractor
and Canon EOS Rebel T2i DSLR.

The Moon wanes in the early morning sky this week, passing through the Last Quarter phase on the 12th at 8:25 am Eastern Daylight Time. Luna begins the week among the stars of winter, which are on the meridian at 6:00 am as morning twilight begins to brighten the sky. She moves steadily eastward toward the rising stars of spring, and occults the bright star Regulus in Leo before dawn on the 15th. The star will disappear behind the Moon’s bright limb at 5:38 am EDT and re-appear from her dark limb at 6:41 am. This event should be easy to view in binoculars.

As Luna swings into the morning sky the evenings benefit by her absence. You still have time to enjoy the last of the summertime constellations and the sweeping glow of the Milky Way, which bisects the sky from southwest to northeast at 8:00 pm, the time of the end of evening twilight. You’ll find the Summer Triangle of the bright stars Vega, Deneb, and Altair crossing the zenith at this time, and skywatchers in rural locations can marvel at the structure of our Galaxy passing through this bright asterism. Note the dark rift that begins to split the Milky Way in the middle of the Triangle. Use binoculars to sweep the bright star clouds that trend to the southwest; you’ll pass by several bright knots of amorphous light that betray the locations of star clusters and gaseous nebulae. These are also great targets for small low-magnification telescopes. Moving toward the northeast, the Milky Way runs through the faint constellation of Cepheus, which resembles a child’s drawing of a house, and the more familiar “W”- shaped grouping of Cassiopeia. The area around these star patterns is chock-full of star clusters, many of which resolve nicely in the small telescope. My favorite small-telescope target in this part of the sky is the so-called “Double Cluster”, which can be seen as a bright hazy spot in the Milky Way between Cassiopeia and the bright star Mirfak in Perseus. Binoculars will show two fuzzy spots, but my 3-inch refractor with a wide-field eyepiece will show two distinct clusters of stars set in the background of a Milky Way star cloud. Formally known as NGC 869 and NGC 884, these clusters contain some of the most luminous stars in the galaxy, many of which shine with over 100,000 times the brightness of our Sun.

The early evening is also the time to catch a glimpse of Saturn, which may be found low in the southwest as evening twilight darkens the sky. The ringed planet is the brightest object in the southwestern sky at this hour, and you’ll have to act fast to catch a good view of him in the small telescope as he now sets by 10:00 pm.

Venus and Mars continue to dance in the pre-dawn sky. At 6:30 am you’ll easily spot bright Venus about 10 degrees above the eastern horizon, while Mars will probably require binoculars to spot a few degrees above the brighter Venus. Venus will continue to put more distance between herself and the red planet. By the week’s end they will be almost 8 degrees apart. Look for the slender waning crescent Moon as she passes just over a degree north of Mars on the morning of the 17th.

The Sky This Week, October 3 – 10, 2017 !

The Sky This Week, 2017 October 3 – 10

Solace in the light of the Moon
Gibbous Moon, imaged 2017 October 3, 01:17-01:27 UT
from Alexandria, Virginia by Geoff Chester
Composite of 6 images made with an Explore Scientific AR102
4-inch f/6.5 refractor and Canon EOS Rebel T2i DSLR.

The Moon brightens the overnight hours for much of the week. The Full Harvest Moon occurs on the 5th at 2:40 pm Eastern Daylight Time, and Luna’s nearly-full face graces the evening sky for a couple of nights surrounding that date. During the later evenings in the week she wanes through her gibbous phases, reaching Last Quarter on the morning of the 12th. During the course of the week Luna moves from the barren starfields of the autumn sky to a position among the rising stars of winter. Look for her stationed above the bright stars of Orion, the Hunter during the gathering morning twilight of the 10th and 11th.

The Full Moon is often thought of as a bane to the serious stargazer since her bright light renders even the most rural sky almost as bright and devoid of stars as those above urban centers. Normally I don’t spend as much time with the telescope during these bright nights, but the events of the past couple of weeks have led me to spend more time in the yard being transported to distant places through my personal portal to the sky. I found myself spending most of last night quietly looking at the Moon, noting not only the steadfastness of her features but also the slow change of light along the terminator causing shadows to reveal subtle details in formations that I have known for many years. For a brief time I was lost in another place, disconnected from the tribulations of the Earth, absorbed in moonlight.

The bright skies are not totally devoid of sights to enjoy. The early evening offers the bright stars of the Summer Triangle asterism floating serenely overhead. The three stars, Vega, Deneb, and Altair, are the brightest members of their respective constellations of Lyra, Cygnus, and Aquila, but the star patterns themselves become hard to see due to moonlight. Smack in the middle of the triangle is a third-magnitude star called Albireo that to the naked eye is otherwise quite nondescript, but time and again I find myself slewing the telescope in its direction. Albireo is a double star as seen through the eyepiece, and it is known doe the fine color contrast between its two components. These colors are much more apparent in small telescopes, and my best views are through my 3- and 4-inch refractors. Last night I was particularly aware of the colors, which are decidedly blue and yellow-gold. Enjoy a view of them in your telescope the next time you’re out under the early autumn sky.

Jupiter has slipped into invisibility in the early evening twilight leaving Saturn as the sole bright evening planet. You’ll find him low in the southwestern sky as twilight deepens, and he sets about two hours after the end of evening twilight. We are now at the time in Saturn’s orbit when the planet’s rings are tipped at their maximum toward the Earth. For the next several years the rings will slowly tilt away from our line of sight, becoming edge-on in March of 2025.

Venus and Mars start the week in a close conjunction, with minimum separation occurring on the morning of the 5th. Use binoculars to locate Mars just a quarter of a degree from Venus in the gathering twilight on the morning of the 5th. Venus won’t linger near the red planet for long; by the end of the week Mars will trail his more dazzling rival by 3.5 degrees.