Archive for February, 2017

The Sky This Week, February 21 – 28, 2017 !

The Sky This Week, 2017 February 21 – 28

Count some stars, then cozy up to Venus.
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Venus, imaged 2017 February 6 with USNO’s 30.5-cm (12-inch) f/15
Clark/Saegmüller refractor,

a 1.6X Antares Barlow lens and a Canon EOS Rebel T2i DSLR

The Moon is notable for her near-absence from the sky this week. New Moon occurs on the 26th ay 9:58 am Eastern Standard Time. You might catch a glimpse of her waning crescent phases in the pre-dawn sky early in the week. She should re-appear in evening twilight on the evening of the 27th. On the following evening she sees February out the door in an attractive grouping with dazzling Venus and ruddy Mars.

You have another opportunity to participate in the Globe at Night citizen-science program this week by counting the number of stars you can see in the vicinity of the familiar outline of Orion, the Hunter. He crosses the meridian just before 8:00 pm, so you should have a good view of him under darkness at that time. To participate in the program, go to the website and compare your view of Orion with the various charts that show his appearance under different sky conditions, then enter your report. There are free apps you can get for your smart phone that you can use to report directly from the field. Submit as many reports as you desire, preferably from different locations. You’ll help scientists determine the spread of urban light pollution and map out dark-sky sites for skywatchers to use.

Despite what the groundhog indicated a few weeks ago, the signs of spring are definitely in the air in the Washington, DC area. One sure way to see this is the rapidly lengthening change in the length of day. By the end of the week sunset occurs at 6:00 pm EST and the length of day increases by about three minutes per day. By the end of February we’ll have just under two hours’ more daylight than we did at the winter solstice. In just three more weeks we’ll have the official vernal equinox, so enjoy the last few weeks of early evening darkness.

Once Orion slips west of the meridian, followed by the eastern stars of the Great Winter Circle, the stars of spring begin to take over the sky. By midnight the signature constellations of spring are approaching their apexes. To the north you’ll find the seven stars of the Big Dipper asterism, and just south of the zenith look for the bright star Regulus, the heart of Leo, the Lion. The deep-sky objects shift from galactic star clusters and nebulae to external galaxies as our gaze is directed above and out of the plane of the Milky Way galaxy. Several of these remote star cities are visible in small telescopes, and binoculars at a dark sky site will show Messier 81 and 82, one of the closer galaxy groups to our vast spiral home.

Venus continues to dazzle in the western sky during twilight and for over an hour in full darkness. She is now turning northward away from ruddy Mars, and over the course of the week the gap between them widens by nearly four degrees. A small telescope will easily show her crescent phase, which narrows a bit each day as she begins her plunge toward the Sun.

Mars manages to continue to keep pace with the Sun, setting each night at around 9:30 pm. His telescopic disc has now shrunk to miniscule proportions, just under five arcseconds across. You’ll need a large telescope and steady air to see any detail on his distant surface.

Jupiter now rises four minutes earlier with each passing night, and by the end of the month comes up at around 9:20 pm. He’s well up in the southeast by midnight. Look just a few degrees below Old Jove for the bright blue star Spica.

Saturn is now best seen in morning twilight, far to the south among the rising stars of Sagittarius. The ringed planet will be at his best during the summer months this year, but if you’re up before the sun he offers a pleasant view of his wide-open rings right now.

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

The Sky This Week, 2017 February 14 – 21

Rosettes are red…
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The Rosette Nebula, NGC 2237 in Monoceros, imaged 2015 February 14
with an 80mm (3.1-inch) f/6 Antares Sentinel refractor
and a Canon EOS Rebel T2i DSLR

The Moon swings into the morning sky this week, drifting from the rising springtime stars and ending the week with the pre-dawn summer constellations. Last Quarter occurs on the 18th at 2:33 pm Eastern Standard Time. Early risers can see a nice grouping of the Moon, Jupiter, and the bright star Spica before sunrise on the morning of the 15th. On the mornings of the 20th and 21st look for Luna in the southeastern sky near the yellow-tinted planet Saturn.

The bright stars of the Great Winter Circle are prominently featured in the early evening sky. The familiar figure of Orion the Hunter crosses the meridian at 8:00 pm EST, surrounded by many other prominent star patterns. By using the Hunter’s three “belt” stars, you can find your way around five other constellations. If you follow a line through the belt stars to the northwest you’ll encounter the bright amber-hued star Aldebaran, the lead star of Taurus, the Bull. Surrounding Aldebaran is a V-shaped aggregation of third-magnitude and fainter stars that make up the Hyades star cluster. This group of stars is one of the closest galactic clusters to the solar system, about 150 light-years away. Aldebaran itself is not a cluster member, being about half as far away. They Hyades and the nearby Pleiades are wonderful targets for binoculars from dark-sky sites. Moving back to Orion’s belt, extending a line to the southeast will bring you to Sirius, the brightest star in the sky. Sirius is a dazzling sight in binoculars with an icy blue-white glimmer that contrasts nicely with Aldebaran and ruddy Betelgeuse in Orion. It leads Canis Major, one of Orion’s hunting dogs, across the sky behind its master. From a dark sky you’ll see the faint glow of the winter Milky Way rising from above Sirius, passing just east of Orion. Buried in these star clouds id the faint constellation of Monoceros, the Unicorn, whose brightest star is just above fourth magnitude. What it lacks in stars is more than made up for by the star clusters and gaseous nebulae that can be seen in binoculars of small telescopes. You can follow the Milky Way up past the bright star Procyon, then through the “feet” of the Gemini twins, ultimately winding up in the pentagon-shaped constellation of Auriga, the Charioteer. For the naked eye, nine of the 25 brightest stars in the sky can be found in these constellations in addition to the dozens of deep-sky objects brought to light with modest optical aid. It remains one of my favorite parts of the sky to haunt.

Brilliant Venus is now beginning to lose ground on both the nearby planet Mars and the ever-persistent Sun. She now sets a little bit earlier each night as she begins to move toward inferior conjunction, when she passes between Earth and the Sun. She will remain prominent for the next few weeks, but a month from now she will seem to fall from the sky like a stone.

Mars continues to move eastward along the ecliptic, drifting through the faint starfields of Pisces. The red planet is also gradually losing ground to the encroaching Sun, but unlike Venus he’ll remain visible in the post twilight sky until mid-May.

You’ll now find Jupiter rising in the late evening. By the 18th he crests the eastern horizon at around 10:00 pm EST. Look for him near the rising Moon before midnight on the evenings of the 14th and 15th. In the pre-dawn hours of the 15th he entertains the Moon and the bright star Spica. Your best telescopic view of him will still be between 3:00 am and dawn.

Saturn wallows in the far southerly declination of the ecliptic. As morning twilight gathers you’ll find him low in the southeast some 15 degrees east of the ruddy star Antares in the constellation of Scorpius. The telescope will reveal the planet’s unmistakable rings, but sharp detail will be thwarted by his low altitude above the horizon.

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

The Sky This Week, 2017 February 7 – 14

Stalking The Hunter by moonlight.
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The Moon, imaged 2017 February 3 with the USNO’s 12-inch refractor
and a Canon EOS Rebel T2i DSLR

The Moon brightens the overnight hours this week, with the Full Moon occurring on the 10th at 7:33 pm Eastern Standard Time. February’s Full Moon is popularly known as the Snow Moon or Hunger Moon, although we’d have a hard time living up to the first name judging by the winter we’ve had so far. There will be a penumbral lunar eclipse coinciding with the Full Moon. Luna enters the penumbral shadow as she rises over the DC metro area, and at maximum eclipse at 7:43 pm you will probably notice a dark grey shading to the Moon’s northern limb. Luna leaves the penumbra at 9:55 pm.

The bright stars of the Great Winter Circle share the limelight with the Moon. The circle is dominated by the familiar figure of Orion, the Hunter, which crosses the meridian at around 8:30 pm EST. Orion is one of the most recognized star patterns in the sky, being visible from every inhabited part of the planet. We can trace the origins of Orion back to the ancient Egyptians, who early in their civilized history linked the constellation to Osiris, their great god of the underworld. The Pharaoh himself was transformed into Osiris upon his death, and texts pertaining to this transformation can be found in the texts inscribed on the walls of pyramids from the Fifth Dynasty. References to Orion can be found in such diverse religions as Hinduism and Christianity, where the Hunter is mentioned in the Bible’s Book of Job. Even the inhabitants of J.R.R. Tolkien’s Middle Earth had a name for the constellation, calling him “Menelvagor”, the Swordsman of the Sky. The constellation’s most notable feature is the “belt” of three stars that run diagonally between the bright reddish star Betelgeuse and icy-blue Rigel. These three stars would be ranked among the brightest in other constellations, but here they play second fiddle to the first-magnitude luminaries. Each of the Belt Stars is a very hot “blue supergiant” star located at vast distances from the Earth. The middle star, Alnilam, beams at us from over 2000 light-years away. If it were located at the same distance as nearby Sirius (a mere 8.6 light years distant) it would shine in our sky with the equivalent brightness of the first-quarter Moon! Most of Orion’s stars are similar in nature, having formed in the heart of a vast cloud of hydrogen gas and dust that pervades long-exposure images of the constellation.

The dazzling planet Venus is now at her best showing for the evening sky this year. Glowing with a staggering -4.8 magnitude, she is at her highest and brightest now and for the next couple of weeks. From a dark location her glow is bright enough to cast shadows on a moonless evening stroll. Her sparkle is readily seen in broad daylight if you know just where to look for her, looking like a sun-glint from a high-flying airplane. On nights with moderate overcast her glow and that of the Moon are the only objects that cut through the murk.

Mars appears just east of Venus and continues to slide eastward against the faint stars of Pisces. His steady pace begins to leave Venus behind as the latter begins to slow her motion before falling back toward the Sun.

Late-night skywatchers will begin to notice the bright glow of Jupiter in the east if they are out at midnight. The giant planet rises at around 10:30 pm EST, but he doesn’t cross the meridian until 4:00 am. Your best view of him will still be during the hours before sunrise.

Saturn rises at around 3:30 am and is visible low in the southeast as morning twilight begins to gather. The ringed planet will spend most of this year’s apparition at his lowest declination during his 29.5 year circuit of the sky. This doesn’t bode well for Northern Hemisphere observers, and we’ll have to be content to view him through the turbulence of our atmosphere as he heads toward opposition shortly before the summer solstice.

The Sky This Week, January 31 – February 7, 2017 !

The Sky This Week, 2017 January 31 – February 7

Will he or won’t he?
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The Moon, Venus, and Mars by the USNO flagpole,
imaged 2017 January 30

with a Canon EOS Rebel T2i DSLR

The Moon greets evening skywatchers, waxing as she climbs the ecliptic towards the bright winter constellations. First Quarter occurs on the 3rd at 11:19 pm Eastern Standard Time. Luna starts the week in the vicinity of bright Venus and ruddy Mars. When twilight fades on the evening of the 5th you’ll find Luna just one degree from the bright star Aldebaran in Taurus, the Bull. As the evening progresses watch the Moon drift eastward from the red-hued star.

Forget the Super Bowl; the truly significant event of early February is Groundhog Day, one of our more popular “semi-holidays”. It is similar in character to Halloween in that most everybody is aware of it and “observes” it in some fashion, but they’re not really sure why they do. We’re all familiar with the annual ritual of a group of nattily-dressed gentlemen in top hats and tails gathered on a small hilltop in rural Pennsylvania to await the outcome of a certain large indigenous rodent’s ability to “see his shadow” and therefore predict the coming of spring. Once a year atop Gobbler’s Knob in Punxsutawney, PA the eyes of the world settle on Phil the Groundhog as dawn breaks. If Phil casts a shadow, then there will be six more weeks of winter, and if he doesn’t, well, there will still be six more weeks of winter! Groundhog day falls mid-way between the winter solstice and the Vernal equinox, and since the average season is 12 weeks long the answer either way is a sure bet. Despite the modern exploitation, the roots of Groundhog Day date back well over a thousand years to a Celtic feast called Imbolc, which celebrated the coming of spring and the beginning of the “lambing season”. The spread of Christianity then linked it to the feast known as Candlemas which celebrated the presentation of the infant Jesus at the temple 40 days after his birth. This was one of the so-called “cross-quarter” days of ancient timekeeping tradition, which, along with the quarterly seasonal markers, were the dates when serfs paid rent to their feudal lords. Halloween is the other cross-quarter day that’s still widely observed here in America, and Europeans still observe May Day. Lammas, the final cross-quarter day, falls on August 1st, which is the traditional start of summer vacation days in many parts of the world.

This is a great week to observe the Moon, especially if you have a new telescope to try out. Luna’s motion along the ecliptic takes her on a high arc through the winter constellations, and she presents ideal phases to gradually reveal new detail with each passing night. The stark lighting on the Moon’s battered landscapes offers mute testament to violence that formed the solar system. It’s hard to believe that the surface of the Earth once looked like this, but billions of years of erosion by wind, rain, and plate tectonics have all but wiped out these features on our fair home planet.

Venus dominates the early evening sky, beaming down in the southwestern sky shortly after sunset. If you know where to look you can even pick her out during the daytime, especially in the hour or so before sunset. She is now glowing at her brightest for this year’s evening apparition. Through the telescope she now has a distinct crescent shape.

Mars keeps pace just east of Venus, separated from the dazzling planet by about five degrees. Despite the fact that Venus is over 100 times brighter than the red planet, his ruddy hue still makes him a distinctive sight.

Jupiter now rises at around 11:00 pm and should be easily seen in the southeastern sky by midnight. Your best view of him is still just before dawn, where you’ll find him high in the south in the company of the bright star Spica. Jupiter reaches the first stationary point of this year’s apparition on the 6th.

Saturn is also best seen in the pre-dawn sky. If you’re up an hour before sunrise look for the ringed planet about 15 degrees above the southeast horizon.