Archive for November, 2016

The Sky This Week, November 29 – December 6, 2016 !

The Sky This Week, 2016 November 29 – December 6

Signs of winter.
Orion rising, viewed from Blue Ridge Regional Park,
near Bluemont, Virginia, November 2004

The Moon returns to the evening sky this week, waxing through the crescent phases as she climbs through the southwestern sky. First Quarter occurs on the 7th at 4:03 am Eastern Standard Time. Look for Luna near the bright planet Venus on the evenings of the 2nd and 3rd. She passes ruddy Mars on the evenings of the 4th and 5th.

As November rolls into December we find ourselves experiencing the longest nights of the year here in the Northern Hemisphere. Even though the winter solstice doesn’t occur until the 21st, this week marks the beginning of a month-long period of solstice–related phenomena. From December 1st to the 11th we will see our earliest sunsets for the year. Here in Washington that time is 4:46 pm EST. However, the solstice itself doesn’t occur until the 21st, while the latest sunrise won’t occur until early January. Why the discrepancy? If we actually kept apparent solar time (like the time recorded by sundials), latest sunrise and earliest sunrises would indeed coincide with the solstice. However, the length of day as measured by the successive noon transits of the Sun is actually a bit longer than 24 hours at this time of the year. This is a result of Earth’s faster orbital motion as it nears perihelion, which occurs shortly after the start of the new year. The civil time that we observe is based on a “mean Sun” time that gives us a day that’s exactly 24 hours long. The difference between “apparent Sun” and “mean Sun” means that the extremes of sunrise and sunset don’t coincide with the solstice, but the length of day on the winter solstice is still the shortest for the year. The solstice “season” lasts about a month in December, and similar effects take place in June but only over a two-week interval. You can measure this for yourself. Old Sol will set about five minutes later than he does this week by the time the solstice rolls around. By the end of the month he sets 10 minutes earlier.

Another sure sign of the coming of winter is the rising of the bright stars that surround the constellation of Orion, the Hunter. By 10:00 pm the eastern sky is full of bright stars that surround the distinctive outline of Orion. The Hunter’s most prominent feature is the three bright stars that form his distinctive “belt”. Follow an imaginary line toward the zenith ad the stars will point you toward the orange-tinted star Aldebaran in the constellation of Taurus, the Bull. Follow a similar line toward the horizon and you’ll spy the brightest star in the sky, Sirius, cresting the horizon. This star is usually and icy-blue beacon, but when it is close to the horizon it can seem to flicker through all the colors of the rainbow. Orion himself sports mostly blue stars, the exception being the ruddy-hued Betelgeuse. The star’s unusual name is a Latinized version of the ancient Arabic name “Ibt al Jauzah”, which loosely translates as “The armpit of the mighty one”.

In the early evening sky you’ll find Venus dominating the southwestern sky, popping out of the twilight shortly after sunset. She will be well-placed for photo opportunities on the 2nd and the 3rd when he hosts the waxing crescent Moon. She moves from Sagittarius into Capricornus by the end of the week.

Mars also receives a visit from the Moon on the evenings of the 4th and 5th. He is also trekking across the stars of Capricornus, keeping a nearly constant distance ahead of the Sun. When the Moon isn’t in the area you’ll find him as a solitary reddish beacon in a very barren stretch of the sky.

You’ll find Jupiter high in the east as morning twilight begins to gather. He is slowly drifting through the rising stars of Virgo, not far from the bright star Spica. He’s well-placed for an early-morning peek through the telescope.


The Sky This Week, November 22 – 29, 2016 !

The Sky This Week, 2016 November 22 – 29

A cornucopia of celestial morsels
NGC 869 & NGC 884, the Perseus Double Cluster
Imaged from Fishers Island, NY on 2013 April 15
with an Antares Sentinel 80mm (3.1-inch) f/6 refractor
and a Canon EOS Rebel T2i DSLR

The Moon greets early risers as a waning crescent in the pre-dawn sky this week. New Moon occurs on the 29th at 7:18 am Eastern Standard Time. Look for the Moon near bright Jupiter on the mornings of the 24th and 25th.

The absence of the Moon finds us in the middle of the November observing campaign for the international “Globe at Night” campaign. This global “citizen science” effort is dedicated to determining the effects of light pollution around the world, and it is very simple for anyone to participate. This month the effort focuses on the constellation of Perseus, the Hero, which may be found high in the northeastern sky at around 9:00 pm. If you face north at his time you’ll see the “W”-shaped constellation of Cassiopeia on the meridian; she’ll actually look a bit more like an “M”. Perseus occupies the space just to the right of Cassiopeia and is centered on the second-magnitude star Mirfak. I think of Perseus as resembling the “winner’s” portion of a wishbone, which seems quite appropriate for this time of year. The top of the wishbone points back toward Cassiopeia while the longer tine follows a gentle arc that will lead you to the Pleiades star cluster. The shorter, upper tine ends in a most unusual star, Algol. Its name derives from ancient Persian and means “the head of the demon”, and it represents an eye on the severed head of the Gorgon Medusa that Perseus dispatched in one of his many adventures. The star is unusual in that its apparent brightness dims by over one magnitude every 2.87 days, as if it was slowly winking at us. This was noticed by the classical Arab astronomers in the first millennium, who thus gave it a very descriptive name. The reason for this unusual behavior is that Algol is an “eclipsing binary” star, in which a dim companion star periodically blocks the light from the brighter component. The next minima of Algol occur on the 26th at 10:44 pm and on the 29th at 7:33 pm EST. You should have little trouble in finding Mirfak and Algol from suburban skies, although Algol may be difficult when it is at a minimum. To make a measurement for Globe at Night, compare your view to the online charts on the project’s website and add your data to the growing knowledge base.

Just below Perseus you’ll find a bright star that has a very distinctive golden tint. This is Capella, the brightest star in the constellation of Auriga the Charioteer. Capella’s name is derived from the Latin word for “goat”, and it represents Amalthea, the she-goat who nursed the infant Zeus as he was hidden from his father Cronus. In one legend the young Zeus accidentally broke off one of the goat’s horns which then became the source of boundless nourishment, the Cornucopia. Fittingly in our modern traditions Capella is close to the meridian at midnight when we take the time to celebrate the bounty and nourishment in our lives with the Thanksgiving feast.

Venus is trekking through the stars of Sagittarius, starting the week near the constellation’s brightest star Nunki. She is now beginning to move northward along the ecliptic, and sets well over an hour after the end of evening twilight.

Mars spends the week crossing through the heart of the dim autumn constellation of Capricornus. You’ll find him in the early evening sky in the southwestern sky, a solitary ruddy beacon in an otherwise bland star field. He keeps a steady pace against the advancing Sun and sets at the same time, 9:48 pm, each night this week.

Jupiter is very well placed for early rising skywatchers, high in the east as morning twilight begins to lighten the horizon. He gets a visit from the Moon on the 24th and 25th, and on the latter morning there will be a fine grouping of Luna, Old Jove, and the first-magnitude star Spica.

The Sky This Week, November 15 – 22, 2016 !

The Sky This Week, 2016 November 15 – 22

Celestial jewel boxes
NGC 869 & NGC 884, the Perseus Double Cluster
Imaged from Fishers Island, NY on 2013 April 15
with an Antares Sentinel 80mm (3.1-inch) f/6 refractor
and a Canon EOS Rebel T2i DSLR

The Moon wanes in the late night and early morning sky this week, taking a respite from the “Super Moon” hype that peaked on the 14th. Last Quarter occurs on the 21st at 3:33 am Eastern Standard Time. Luna opens the week among the stars of Taurus, the Bull. She then moves eastward through the bright stars of the Great Winter Circle. By the end of the week you’ll find her in the morning sky, where she will pass just over a degree to the south of the bright star Regulus before dawn on the 21st.

As the Moon moves into the morning sky you now have time in the early evening to explore some of the interesting constellations of the late autumn sky. A few weeks ago we introduced you to Pegasus, or more generally the “Great Square” asterism that makes up the bulk of the constellation. You’ll find it on the meridian just south of the zenith at around 8:30 pm EST this week. If you turn and face northward, you should see the “W” asterism that marks the constellation of Cassiopeia, the Queen. From a dark location you’ll see the Milky Way running through Cassiopeia, and this is one of the most fertile hunting grounds for owners of binoculars and small telescopes. There are dozens of star clusters embedded in the star clouds of the Galaxy here. They will look like knotty globs of light in binoculars, but a good three-inch telescope will reveal their stellar nature. To the east of Cassiopeia you’ll see a bright star embedded in the Milky Way that’s surrounded by a group of fainter stars. This is Mirfak, the lead star in the constellation of Perseus, the Hero. From a dark location the stars scattered around Mirfak are just visible to the naked eye, and they offer the suburban skywatcher a wonderful view in binoculars. This is an actual star cluster, one of the closer ones to us at a distance of a bit over 500 light-years. Between Mirfak and Cassiopeia you’ll find one of the best treasures of the nighttime sky. Visible as a hazy enhancement of the Milky Way from dark skies, it is one of the most rewarding sights for telescopes of any aperture. “It” is actually “them”, since what you’re looking at is popularly known as the Perseus Double Cluster. The telescope will reveal a pair of fine galactic clusters that each contain hundreds of stars. Among these stars are some of the brightest known in the Galaxy, with luminosities some 60,000 times that of our Sun. These are thought to be some of the youngest star clusters in the heavens, with an estimated age of a mere 12.5 million years. They are located some 7,500 light years away.

Venus continues to put more distance between herself and the Sun. She is now beginning to creep northward along the ecliptic as she moves into the constellation of Sagittarius. You’ll find her dazzling glow in the southwest in the hours after sunset.

We now bid a fond farewell to Saturn for 2016. The ringed planet is now draped in bright twilight and will pass behind the Sun in early December. He’ll become prominent in the evening sky next year, when his opposition occurs on June 15.

Mars is now embarking on his long transit through the faint autumnal constellations. This week he transits the constellation of Capricornus, the Sea-goat. This constellation has a sway-backed triangular shape, but with its brightest stars coming in at third magnitude it is only clearly visible from dark skies. Mars far outshines its brightest rivals in this part of the sky.

Jupiter rises at around 3:30 am and is well-placed for viewing as morning twilight begins to glimmer on the horizon. He will be the brightest object in the eastern sky at this time. He’s now high enough to grab a quick view in the telescope before sunrise, when the air is generally nice and still for viewing detail.

The Sky This Week, November 8 – 15, 2016 !

The Sky This Week, 2016 November 8 – 15

First Quarter Moon, 2016 November 7, 22:42 UT
Imaged at the U.S. Naval Observatory with the
vintage 1895 30.5-cm (12-inch) f/15 Clark/Saegmüller refractor
and a Canon EOS Rebel T2i DSLR

The Moon waxes in the evening sky this week, brightening from First Quarter to Full Moon, which occurs on the 14th at 8:52 am Eastern Standard Time. November’s Full Moon is popularly known as the Beaver Moon, named by Native Americans and early fur trappers who noticed increased activity by these industrious rodents to finish their dams and winter dens before their ponds froze over.

This is a great week to enjoy the changing aspect of the Moon’s face. Each successive evening reveals a new set of features along the lunar terminator, and the variety of craters, plains, mountains, rilles, domes, and ridges should keep viewers entertained for hours. Small- to medium-aperture telescopes work best for viewing the Moon’s stark features. Larger instruments tend to be affected more by turbulence in the Earth’s atmosphere, and as the phase approaches full the glare can become overwhelming. No doubt by now you have heard much ado about the so-called “super Moon” which has been bandied about on social media for the past few lunations. This term has been liberally applied to Full Moons that occur close in time to the year’s closest lunar perigees, and the one that occurs this month fits the bill. In fact, this is the closest lunar perigee we’ve seen so far in the 21st Century. At 6:21 am EST on the 14th the centers of Earth and Moon will be 365,508 kilometers (221,524 miles) apart. We’ll have to wait until November 25, 2034 for a closer perigee. So what does this all mean to the average skywatcher? The Moon will appear about 14% larger than an “average” Full Moon, and it will be about 30% brighter. This is actually pretty difficult for most of us to judge, since the small disc of the Moon in a star-poor area of the sky is very difficult to measure quantitatively with the naked eye in terms of both apparent size and brightness. However, a crisp autumn landscape illuminated by the Full Moon is still a thing of beauty. Try taking some time exposures with your digital camera under Luna’s pale light. You’ll get some interesting results with the ground illuminated as if it were daylight with stars hanging in the sky at the same time. Point your tripod-mounted camera to the west to get the stars of the Summer Triangle in the view and try exposures of 10 or more seconds.

With sunset now occurring at around 5:00 pm the late afternoon and early evening hours are dominated by the bright glow of Venus, who currently holds court in the southwest. The dazzling planet continues to pull farther eastward from the Sun, and after the 14th begins to slowly climb northward along the ecliptic. She now sets well after the end of evening twilight.

Saturn now sets before the end of evening twilight, making him a difficult object to locate in the early evening. In just over a month he’ll disappear behind the Sun and emerge into the morning sky by the year’s end.

Mars is still quite bright and easy to identify in the south as twilight fades. His distinctive reddish hue gives him away. Through the telescope he presents a small gibbous disc with a bright pink color, but any detail requires lots of magnification and very steady air.

Jupiter continues to climb higher in the pre-dawn sky. He now clears my roof top when I go out to get the paper, so it won’t be long before I’ll be out with the telescope to greet him.

The Sky This Week, November 1 – 8, 2016 !

The Sky This Week, 2016 November 1 – 8

Remember to “fall back”!
Moon, Jupiter, and the second-magnitude star Porrima
Imaged from Alexandria, Virginia on 2016 October 28

The Moon returns to the evening sky this week, waxing to the First Quarter phase on the 7th at 2:51 pm Eastern Standard Time. Luna’s thin crescent can be seen in the company of the bright planet Venus and the somewhat subdued planet Saturn in the early evening of the 2nd. Luna will be close to ruddy Mars on the evenings of the 5th and 6th. She then enters the dim starfields of the autumnal constellations.

You may have noticed that I used “standard time” in the above paragraph. Once again it’s that time of the year when we adjust our clocks back by one hour. This will result in more daylight in the morning hours at the expense of earlier sunsets in the afternoons. The idea of adjusting our clocks to manipulate available daylight has been around for nearly 100 years, having first been implemented by Germany and Great Britain during World War I. The United States adopted Daylight Time in 1918. In Europe the move was seen as a way to keep factories in production for a longer time, while in the U.S. the incentive was to allow people more daylight to tend their “victory gardens”. The idea was immensely unpopular from the start, and after the war daylight time regulations fell to state and local jurisdictions. Federal regulation returned in 1966 with the passage of the Uniform Standard Time Act, which placed enforcement authority under the Department of Transportation. The dates of effect for Daylight Time were changed in 1986 and modified in 2005 to the current system when we advance an hour on the third Sunday in March and “fall back” on the first Sunday in November. An ironic twist of this system is that we now spend more of the year on “Daylight Time” than we do on “Standard Time”. Whether we like it or not, remember to set your clocks back one hour before you go to bed on the night of the 4th unless you live in Arizona or Hawai’i.

The return to Standard Time means that sunset will occur at around 5:00 pm EST, giving us ample time to watch the changing constellation patters as the night passes. Early in the evening we can still enjoy the bright stars of the Summer Triangle, which will be just west of the meridian at the end of evening twilight. Vega, Deneb, and Altair will gradually give way to the Great Square of Pegasus, which crosses the meridian at around 9:00 pm. Look to the east at this time and you will see one of the age-old harbingers of approaching winter in the form of the Pleiades star cluster. This small group of stars is a true star cluster located about 410 light-years from the Earth. It figures very prominently in the sky lore of almost every culture that has existed throughout history, and the evening appearance of the cluster has been associated with stormy weather for thousands of years. In mythology they are associated with another group of stars, the Hyades, which form a “V”-shaped grouping of stars around the bright star Aldebaran in the constellation of Taurus, the Bull. Taurus is one of the first of winter’s constellations to appear, and it is followed by Orion and the rest of the star patterns that create the asterism known as the Great Winter Circle. You’ll see all of the bright winter stars by local midnight on Standard Time.

Venus steadily moves eastward against the stars sky and passed by Saturn just before Halloween. She is joined by the slim waxing crescent Moon on the evening of the 2nd. Go out about an hour after sunset and look to the southwest to see the duo. If it’s clear you should see Saturn between them in the darkening twilight sky.

Saturn watches as Venus leaves him in her wake, then sets just after the end of evening twilight. The ringed planet will soon be lost in the glare of the encroaching Sun, but he’ll return to the early morning sky in the late winter months next year.

Mars moves into the stars of the dim constellation of Capricornus this week. The red planet will remain visible in the early evening sky for the rest of the year as he traverses autumn’s other faint constellations, Aquarius and Pisces.

Jupiter is becoming well-placed for telescopic viewing in the pre-dawn hours. He rises an hour before the beginning of morning twilight and offers a fine sight in the gathering light of dawn.