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

The Sky This Week, 2017 March 21 – 28

Count stars in March’s Lion.
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Orion and Canis Major, imaged 2017 March 2,
from Flagstaff Mountain Road, Boulder, CO,
with a Canon EOS Rebel T2i DSLR

The Moon is inconspicuous for most of the week, best seen as a thin waning crescent in the pre-dawn southeastern sky. New Moon occurs on the 27th at 10:57 pm Eastern Daylight Time. You’ll find Luna among the faint stars of the rising autumnal constellations. She will re-appear inn the evening sky by the middle of next week.

Take advantage of the Moon’s absence this week to participate in the March campaign for the Globe at Night citizen-science program. This month we’re asking people to look for the constellation of Leo, the Lion, which is well-placed in the eastern sky by 10:00 pm. There are two asterisms that make up the constellation. The brighter part consists of the first-magnitude star Regulus, which can be seen as the period under a “backwards” question mark made up of second- and third-magnitude stars. Known popularly as “The Sickle”, it represents the Lion’s head, with Regulus marking his heart. The second asterism consists of a right triangle of two second- and one third-magnitude star. Most of these stars should be visible from a suburban yard away from direct lighting. There are many fainter stars as well, and your job is to see how faint a star you can see. You can record your findings on the Globe at Night website and help scientists measure the effects of outdoor lighting and air pollution.

You can still spend some quality time with the bright constellation Orion and his cohorts earlier in the evening. At the end of evening twilight the Hunter is well west of the meridian, closely followed by his faithful dog Canis Major. The bright blue star shimmering near the Dog’s “head” is Sirius, the brightest star in the nighttime sky.

Venus officially passes inferior conjunction, the moment when she passes between the Earth and the Sun, on the 25th at 6:17 am. The dazzling planet will quickly move into the morning sky, becoming visible in the twilight glow by the end of the month.

In the meantime, the fleet planet Mercury is undergoing his best evening apparition for the year. You should be able to locate him in binoculars, where you can find him about 10 degrees above the western horizon half an hour after sunset. The slim waxing crescent Moon should help you find him on the 29th, when the elusive planet lies about 10 degrees to the right of Luna.

Mars is also visited by the Moon on the evening of the 30th. The red planet will lie about seven degrees to the right of the Moon’s crescent. Mars continues his trek across the stars of Aries, drawing a bead on the brighter stars of nearby Taurus.

Jupiter is fast approaching opposition, and the giant planet now rises at around 8:30 pm. He’s well up in the southeast by 11:00 pm, and you may wish to take a look at him before retiring for the evening. On the evening of the 26th you can see the Great Red Spot rotate across the planet’s cloud-streaked disc. At the same time the shadow of the moon Io will also cross the planet’s face.

Saturn is still best seen in the pre-dawn sky. You’ll find the ringed planet near the meridian at 6:00 am EDT.

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

The Sky This Week, 2017 March 14 – 21

Spring is (really) here!
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Venus, 2017 March 9, 18:50 UT
imaged with USNO’s 30.5-cm (12-inch) f/15 Clark/Saegmüller refractor,
Antares 1.6X Barlow lens, and a Canon EOS Rebel T2i DSLR

The Moon moves into the morning sky this week, coursing her way through the stars of late spring and early summer. Last Quarter occurs on the 20th at 11:58 am Eastern Daylight Time. Luna forms an attractive triangle with Jupiter and the bright star Spica in the pre-dawn hours of the 15th. On the morning of the 20th you’ll find the Moon two degrees above the planet Saturn.

Although it doesn’t look like it from where I sit today, spring is just around the corner. The vernal equinox occurs on the 20th at 6:29 am EDT. At this moment in time the apparent center of the Sun’s disc reaches an ecliptic longitude of zero degrees. This also happens to be the point in the sky where the ecliptic plane intersects the celestial equator, so the Sun appears to move into the northern hemisphere of the sky. At the moment of the equinox Old Sol will stand directly over the equator above a point in central Africa. From an astronomical point of view the vernal equinox is an important marker in the sky. We measure the length of the year with respect to it, and the zero-point of the sky’s “right ascension” system is anchored to it. However, the equinox itself is not fixed to the stars. Thanks to the slow wobble of the Earth’s axis known as precession, the equinox slowly moves around the celestial sphere, completing one cycle in roughly 26,000 years. On an annual basis, the equinox moves westward against the distant stars by about 50 arcseconds, roughly the apparent diameter of the planet Jupiter. In ancient times the equinox was known as the “First Point of Aries” since it was located in that Zodiacal constellation some 4000 years ago, but today it is located on the constellation of Pisces. It will move into the constellation of Aquarius around the year 2600.

There’s quite a bit of action in the evening twilight sky this week. As Venus continues her precipitous plunge toward the Sun, the fleet planet Mercury vaults upward from the western horizon. This will be Mercury’s best evening apparition for the year, and you should have several evenings to photograph the two planets together during the course of the week. The best evenings for spotting the two worlds will be the 17th through the 20th, when Venus will be about 10 degrees to the right of Mercury relative to the horizon. Venus will show an extremely thin crescent in the telescope eyepiece, while Mercury will reveal a much smaller gibbous disc. Act quickly to catch Venus as she will rapidly disappear after the 21st.

Mars is now drifting eastward through the stars of the constellation Aries. He will continue to linger in the early evening sky for several more weeks as he wends his way toward the brighter stars of Taurus. Right now he’s fairly easy to spot as an isolated reddish “star” in the western sky as twilight transforms to darkness.

The switch to Daylight Time has temporarily delayed Jupiter’s entrance into the evening sky, but by the end of the week you’ll see Old Jove crest the eastern horizon at 9:00 pm. He should be high enough in the southeastern sky by 11:00 pm to train the telescope on his cloud-festooned surface. If you’re up before the Sun on the 15th you can see him in an attractive grouping with the Moon and the bright star Spica.

Saturn may be found lurking among the rising summer constellations in the southern sky as morning twilight gathers. You’ll find him located just two degrees south of the last quarter Moon on the morning of the 20th.

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

The Sky This Week, 2017 March 7 – 14

It’s time for Daylight Time!
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Looking west at the Moon, Lost Gulch Overlook, 2017 March 1
imaged near Boulder, CO, with a Canon EOS Rebel T2i DSLR and 24mm lens

The Moon brightens the overnight hours this week, moving from the stars of the Great Winter Circle into the rising stars of spring. Full Moon occurs on the 12th at 10:54 am Eastern Daylight Time more on this below). The March Full Moon has a number of popular names, several of which reflect the easing of winter’s icy grip. Among these are the Worm Moon and the Sap Moon. It is also known as the Lenten Moon if it occurs in the period of fasting before Easter. Look for the Moon near the bright star Regulus in Leo on the evening of the 10th. They will be separated by just under two degrees. On the evening of the 13th you’ll find the Moon just one degree east of the second-magnitude star Porrima in the constellation of Virgo. On the following night Luna rises in the company of the bright planet Jupiter.

This is the week when we perform an annual ritual to adjust our clocks to give us the illusion of more daylight in the late afternoon and evening hours. At 2:00 am on the morning of Sunday, March 12 we must set our clocks ahead by one hour to observe Daylight Time, which will be in effect until November 5th. The idea of Daylight Time originated in Great Britain in the early 20th Century with a man named William Willett. He began advocating for advancing clocks in 1907 when he noticed the number of people who were still sleeping when the Sun was up in the morning. Various attempts to push Parliament to adopt the scheme were attempted over the next several years, but it was the outbreak of World War I that cast the die. Germany adopted the new scheme to allow factories to remain open longer in the afternoon under natural light, and Britain soon followed suit. Here in the U.S. the idea was promoted so that factory workers could have more time in the afternoons and evenings to tend their “victory gardens” after work. Standard Time and Daylight Time were finally codified into law by Congress in 1918, but almost immediately Daylight Time became very unpopular. The Daylight Time portion of the law was repealed in 1919, and regulations regarding it were left up to local jurisdictions. Daylight Time was again mandated by Federal decree in World War II, but it wasn’t until 1966 that it was again incorporated into Federal statute. The start and end dates were modified several times over the next four decades with the current period of Daylight Time codified in the Energy Policy Act of 2005.

You have probably noticed that Venus, which has been a fixture in the evening sky for the past few months, is now becoming less prominent in the early evening sky. If you want to catch a glimpse of her thinning crescent you need to get the telescope on her as soon as you can see her in evening twilight. She sets five to six minutes earlier each night this week as she overtakes the Earth on her inner orbit around the Sun. Her plunge from the sky becomes even more dramatic by the end of the week, and by the 25th she will move from the evening into the morning sky. She will soon greet early morning commuters and remain visible before the Sun for the rest of the year.

Mars is now left alone in the early evening sky where he continues to move eastward against the stars of the constellation Aires. Fortunately there aren’t many objects of similar brightness in this part of the sky, so he should be relatively easy to pick out in the southwestern sky as darkness falls. He sets at about the same time each evening as he manages to keep pace with the advancing Sun.

Jupiter rises with the Moon on the evening of the 14th, and before the switch to Daylight Time is well-placed for viewing by 11:00 pm. The Giant Planet is one of the most rewarding targets for the small telescope. Any instrument will show the four moons first documented by Galileo in 1610, and a four-inch aperture scope will show the planet’s dark equatorial cloud belts. On the evening of the 9th look for the planet’s famous Great Red Spot crossing his central meridian. You might also spot the shadow if the planet’s largest moon, Ganymede.

Saturn is approaching the celestial meridian in the southern sky as morning twilight begins to brighten the sky. The ringed planet will spend the year located between the summer constellations of Scorpius and Sagittarius. Your best view right now will be about an hour before sunrise, but you’ll also have all summer to check him out.

The Sky This Week, February 28 – March 7, 2017 !

The Sky This Week, 2017 February 28 – March 7

Keeping watch on the Moon.
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The Moon, imaged 2017 February 3 with USNO’s 30.5-cm (12-inch) f/15
Clark/Saegmüller refractor

and a Canon EOS Rebel T2i DSLR

The Moon climbs into the evening sky this week, waxing through her crescent phases to First Quarter, which occurs on March 5th at 6:32 am Eastern Standard Time. You’ll find the young crescent about 10 degrees southeast of brilliant Venus during evening twilight on the 28th. On the following night she welcomes March from a perch just four degrees south of ruddy Mars. If you have binoculars of a small telescope you can spend the evening watching Luna drift through the Hyades star cluster. Along the way she will occult several of the cluster’s stars. At 11:04 pm she will hide the bright star Aldebaran for just over half an hour. Aldebaran will emerge from the Moon’s bright limb at 11:39 pm.

The Moon herself is the best telescopic target in the evening sky. The phases that flank First Quarter offer some of the most interesting sights for owners of telescopes of just about any size. As the terminator slowly crawls across the Moon’s face from night to night prominent craters, vast lava plains, and great chains of mountain peaks come into view, and gradually change their appearance as the local lighting from the Sun climbs higher in the lunar sky. This is also the time of year when the nights around First Quarter show the Moon at her highest declination in the northern sky, so you’re looking through the least amount of our atmospheric turbulence when you gaze at her stark airless surface. While the Moon’s surface often seems close enough to touch on nights of steady “seeing”, it’s still very hard to grasp the scale of her surface features. Even with our 12-inch refractor telescope here at the Naval Observatory the smallest features we can see under the best conditions are just under a kilometer across. To put that into perspective, if the famous Meteor Crater in Arizona were relocated to the Moon it would just be visible in that great telescope under the best conditions!

As Luna climbs to the apex of her path around the sky she casts more and more light, gradually swallowing the view of the fainter stars. Fortunately the Moon’s path takes her through the middle of the Great Winter Circle, so the bright outlines of Orion and his surrounding companions can still be seen despite the increasing glare of our only natural satellite. When you tire of looking at Luna’s battered surface, turn your telescope toward the bright stars of the Great Winter Circle and enjoy their subtle differences in brightness and color.

Dazzling Venus, which has dominated the view in the western early evening sky since last autumn, is poised to make a dramatic exit from the sky. Right now she is well-placed in the west as the Sun sets, popping into view just after the Sun goes down. She lingers until well after the end of evening twilight, but in less than a month she will pass between the Earth and the Sun, then vault into the morning sky. You’ll notice the beginning of this plunge from the sky this week; by the week’s end she will set five minutes earlier each successive night. However, there is a positive side to this if you won a telescope. Over the course of the next few weeks her apparent disc will grow in size as she becomes an ever-slimming crescent. You should be able to spot her phase in a pair of steadily-held binoculars.

Mars continues to keep pace ahead of the Sun, losing just a few minutes of visibility over the course of March. The red planet moves from the constellation of Pisces into Aires, the Ram. After Venus he is still the brightest object in the western sky at the end of evening twilight, and his characteristic pinkish glow should easily identify him.

Giant Jupiter now rises at around 9:00 pm, making steady progress toward better visibility in the evening sky. He will come to opposition in early April, but if you can’t wait until them to get him in your sights you can now get a good view of him by midnight. He is located just above the first-magnitude star Spica, and he will remain near the star during the majority of his 2017 apparition.

Saturn can be found low in the southeastern sky in the gathering morning twilight. The ringed planet is located just over 15 degrees east of the ruddy star Antares, which crosses the meridian at around 6:00 am EST.

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.

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.