Archive for January, 2015

The Sky This Week, January 27 thru February 3, 2015 !

The Sky This Week, 2015 January 27 – February 3

Tired of winter? Relief is on the way.
The Moon, imaged with USNO’s 12-inch (30.5-cm) f/15 Clark/Saegmüller refractor

The Moon brightens the night as she traverses the stars of the Great Winter Circle.  She begins the week near the First Quarter phase well west of the bright star Arcturus, then ends the week in the company of Jupiter.  Full Moon occurs on February 3rd at 6:09 pm Eastern Standard Time.  February’s Full Moon is popularly known as the Snow Moon or Hunger Moon, appropriate names for the winter’s harshest month.  Look for Luna about four degrees east of the bright star Aldebaran on the evening of the 29th.  On the 31st she passes just one degree above the second-magnitude star Alhena, which marks one of the “feet” of Pollux, one of the Gemini twins.

The bright light of the Moon will wash out most of the fainter objects in the sky this week, but you should still be able to find Comet C/2014 Q2 (Lovejoy) as it drifts northward into the stars of Andromeda.  The most recent reports I’ve seen still show it performing better than predictions would have it, glowing at a solid fourth magnitude.  It should be fairly easy to follow with binoculars from suburban locations, visible as a condensed ball of light as it edges toward the second-magnitude star Gamma Andromedae, the easternmost bright star in that constellation.  The comet will be located within one degree of the star on the evenings of the 3rd, 4th, and 5th.  The best time to hunt it down is during the early evening at around 7:00 pm, when the comet will be just west of the zenith.  Here is a finder chart showing the comet’s position at 7:00 pm EST for the next two weeks.

Venus is becoming more prominent in the hour after sunset.  The dazzling planet continues to forge her way into darker skies and by the end of the week sets a half an hour after the end of evening twilight.  As the sky darkens, look about 10 degrees above her for the fainter but pink-hued glow of Mars.  Venus continues to keep the red planet in her sights, and by the end of the week she trails her target by just seven degrees.

Jupiter reaches opposition at the end of next week, and you’ll find that he is in prime viewing position shortly after sunset, casting his cream-colored glow in the eastern sky in the early evening.  By the late evening he’s high in the southeast and beckoning for a view through the telescope.  Last week’s rare “triple shadow transit” of the moons Io, Europa, and Callisto was unfortunately obscured by clouds here in the DC area, so it looks as if I’ll have to wait until the year 2032 to see another one, but transits of the shadows of single Galilean moons are fortunately quite common.  If you have a modest telescope you can watch the shadow of Io cross the face of the planet on the evening of February 1st between 9:00 and 11:00 pm EST.  At the same time see if you can catch a glimpse of Jupiter’s most famous atmospheric feature, the Great Red Spot.

Saturn continues to be best seen by early risers in the southeastern sky just before the onset of morning twilight.  The ringed planet spends the week slowly drifting eastward above the second-magnitude star Graffias in the “head” of Scorpius.  His yellow tint should contrast nicely with the blue-white hue of the star.

We can’t let the week go by without mentioning one of our favorite little-known astronomical celebrations.  Groundhog Day falls on the 2nd, marking one of the “cross-quarter” days in traditional agricultural calendars.  Transplanted to the U.S. from European traditions by German immigrant farmers, the date marks the mid-point of the season of winter.  It is believed that if the groundhog sees his shadow on that date there will be six more weeks of winter, and if he doesn’t there will be an early spring.  The groundhog (or woodchuck, take your pick) was an easy substitute for the European badger in the legend for the transplanted farmers, so their tradition now lives on in something of a minor media circus that we all look forward to.  The six-week prediction is actually fairly accurate; the vernal equinox falls six weeks and four days after the groundhog’s prognosticative appearance!


The Sky This Week, January 20 – 27, 2015 !

The Sky This Week, 2015 January 20 – 27

Comet Lovejoy remains well-placed, and a bonanza of events on Jupiter…
Comet C/2014 Q2 (Lovejoy), 2015 JAN 11, centered on 03:20 UT
Imaged from near Mount Vernon, VA
80mm (3.1-inch) f/6 Antares Sentinel refractor on iOptron Cube Pro mount,
Canon EOS Rebel T2i DSLR

The Moon waxes through her crescent phases this week, climbing up from the western horizon as she wends her way toward the bright stars of the winter sky.  First Quarter occurs on the 26th at 11:48 pm Eastern Standard Time.  Look for the day-old Moon near bright Venus in the fading evening twilight of the 21st.  On the following night she is just over three degrees to the northwest of Mars.  For the rest of the week she sails through the dim “water signs” of autumn.

As the Moon waxes she gradually brightens up the sky, but early in the week you should still be able to see the fuzzy glow of Comet C/2014 Q2 (Lovejoy) as it moves through the stars of Aries and closes in on the eastern stars of Andromeda.  This comet has been quite photogenic lately, glowing with a nearly third-magnitude greenish coma and sporting a tail nearly 10 degrees long for viewers at dark-sky locations.  I have seen it with the unaided eye from just south of DC near Mount Vernon, and it has been very easy to pick up in binoculars from the light-polluted suburb of Alexandria.  This week it passes nearly overhead at the end of evening twilight, so you might want to consider lying on a lawn chair to sweep it up in your binoculars.  The comet is now pulling away from the Earth, but it won’t reach perihelion, its closest point to the Sun, until January 30th.  It is now gradually beginning to fade but should remain bright enough to see in binoculars for the next few weeks.  Here is a finder chart showing the comet’s position at 7:30 pm EST for the rest of January.

Venus continues to climb higher in the early evening sky.  Over the past couple of weeks the dazzling planet has played host to Mercury, but the latter world is now rapidly moving back toward the Sun and is lost in the twilight glare.  Venus is bright enough to be seen almost as soon as the Sun has set, and starting this week she sets after the end of evening twilight.  She continues to gain about a minute or two on the advancing Sun and will climb higher into the sky until late spring.  This week she is visited by a very slender crescent Moon on the evening of the 21st.  On the 22nd she passes just a degree north of the third-magnitude star Deneb Algeidi in Capricornus.  You’ll probably need binoculars and deep twilight to see this close conjunction.

Mars continues to linger in the evening sky, setting each night at around 8:14 pm EST.  He is losing about a minute of visibility to the approaching Sun, and he is also the next bright object in Venus’ sights.  You’ll notice him in deep twilight about 15 degrees above Venus.  On the 22nd the Moon keeps him company before sidling off toward the winter stars.  Mars will pass half a degree from the fourth-magnitude star Lambda Aquarii on the evenings of the 26th and 27th.

Jupiter is casting his cheery glow in the eastern sky, rising shortly after sunset.  He’s pretty hard to miss as he ascends between the dim stars of the constellation of Cancer, the Crab and Regulus, the brightest star in Leo, the Lion.  Old Jove will reach opposition in another two weeks, when he rises at sunset and sets at dawn.  Jupiter’s bright Galilean moons are always entertaining to watch, and this year they will be particularly interesting.  Every six years Jupiter, like the Earth, experiences an equinox when the Sun appears directly over the planet’s equator.  This is one of those years for Jupiter, which means that its bright moons, which orbit in the planet’s equatorial plane, experience mutual eclipses and occultations of each other.  One of the year’s most interesting of these events will occur late Friday evening into early Saturday morning.  If you look at Jupiter at around 10:30 pm EST on the 23rd you’ll see the moon Io just north of Callisto and the shadow of Callisto entering a transit across Jupiter’s disc.  Just over an hour later at around 11:36 pm Io’s shadow will begin to cross the planet’s face.  Io itself begins to transit Jupiter at 11:55 pm; after a few minutes its tiny disc will be lost over Jupiter’s cloud tops.  But by 12:44 am Io’s shadow will catch up to that of Callisto, and Io will enter the cone of Callisto’s shadow.  Over the course of the next 12 minutes the two shadows will appear to merge, and the eclipsed disc of Io will appear as a darkish spot to the east of the combined shadows.  At 1:21 am Callisto will begin its own transit over Jupiter’s face, its much darker surface resembling another moon shadow.  At the same time Io’s now fully-illuminated disc will cover Callisto’s shadow.  But wait!  We’re not done yet.  At 1:30 Europa’s shadow begins crossing Jupiter’s disc, which means that three moon shadows and the dark disc of Callisto will dot the usually cream-white surface of the giant planet.  If you’re still up at 2:10 am, you’ll see Io exiting the disc as Europa begins its own transit.  I know where I’ll be that evening!

Saturn is now well up in the southeastern sky as morning twilight begins to gather.  The ringed planet is keeping the company of the bright stars of Scorpius, which means he’ll be around to grace the evening skies in late spring and summer.  If you can’t wait until then, this is a good time to catch a quick preview of the planet’s offerings.  His rings are now generously tipped in our direction and easy to see in even a small telescope.

The Sky This Week, January 13 – 20, 2015 !

The Sky This Week, 2015 January 13 – 20

All of the planets and a comet to boot!
Comet C/2014 Q2 (Lovejoy), 2015 JAN 11, centered on 03:20 UT
Imaged from near Mount Vernon, VA
80mm (3.1-inch) f/6 Antares Sentinel refractor on iOptron Cube Pro mount,
Canon EOS Rebel T2i DSLR

The Moon wanes through her crescent phases this week, and is best seen in the morning sky as twilight begins to brighten the eastern horizon.  New Moon occurs on the 20th at 8:14 am Eastern Standard Time.  Luna has a close encounter with Saturn on the morning of the 18th when she passes just a degree north of the ringed planet.  This should be a treat for viewing in binoculars since the conjunction takes place near the bright stars that form the “head” of Scorpius, the Scorpion.

As we mentioned last week, Venus and Mercury are closely paired in the southwestern sky during early evening twilight.  If you haven’t had a chance to see them you should make the effort to do so on the next clear evening.  As the week opens they are still around one degree apart, with Mercury just to the right of and slightly below Venus.  Both planets should be easy to spy with the naked eye by around 5:45 pm.  Mercury reaches his greatest elongation from the Sun on the afternoon of the 14th; after that date his motion against the stars will slow dramatically and he’ll begin to fade.  You can still use Venus to find him, but the dazzling planet’s steady eastward pace will put some five degrees of sky between them by the end of the week.  In addition, Mercury will begin a rapid fade as he begins to fall back toward the Sun, dimming by a full magnitude by the 19th.

While I was outside admiring the Venus and Mercury show last Saturday I noticed Mars pop out of the fading twilight glow some twenty degrees above the brighter planet duo.  Mars pales in comparison to dazzling Venus, but he is now moving through a very sparse starfield and is the only relatively bright object in the area.  Once the sky has turned a deep blue his ruddy color becomes apparent.  Mars continues to keep apace of the Earth as the two objects whirl in their respective orbits, and he will set at the same time, 8:13 pm, for the next several weeks.  However, he is gradually losing the footrace between Venus and the Sun to overtake him.  This week Venus trims some three degrees in their separation, and by week’s end that gap between them closes to about 15 degrees.  Venus will pass the red planet in another month.

The big story this week is the continuing fine showing by Comet C/2014 Q2 (Lovejoy), which is now marching northward through the stars of Taurus, the Bull.  It is currently about 4th magnitude, so it won’t dazzle us urban stargazers in the same way that Comet Hale-Bopp did back in 1997, but it is still an easy target to track down.  As the week opens the comet lies about 15 degrees west of the bright star Aldebaran in Taurus, and by the weekend it will drift about 10 degrees to the west of the Pleiades star cluster.  The finder chart that we posted last week may still be found here.  I’ve been able to see it consistently in binoculars from my light-polluted yard in the DC suburbs, and last Saturday I ventured just south of the urban sprawl to look for it from near George Washington’s Mount Vernon estate.  From there the sky was sufficiently dark to show the comet as a “hazy star” to my unaided eye, and through my binoculars it was a round fuzzy patch of light about the same apparent diameter as the full Moon.  Through my three-inch telescope I could see a bright, star-like nucleus surrounded by a faintly greenish cloud of haze.  Colleagues who live under darker skies have reported seeing a tail spanning several degrees in their binoculars.  While I couldn’t see the tail by eye, it was easy to pick out in photographs.  Comet Lovejoy is probably at its peak brightness by now, but it should remain a nice binocular target for several more weeks as it drifts toward the easternmost stars in Andromeda.

Jupiter is fast approaching opposition in early February and he is now well-placed in the late evening and overnight hours for telescopic viewing.  Some 405 years ago Galileo turned his primitive telescope toward the planet’s jolly glow and found four star-like objects that accompanied the planet as it moved against the background stars.  Although he was not the first person to see them, he was the first to publish his observations of them, so the four brightest moons in Jupiter’s stable of 67 known satellites are known as The Galileans.  Watching the nightly changes in these four worlds was an endless source of fascination to me as a youngster.  Today modest amateur telescopes can follow their comings and goings in detail, and this year is a particularly good one to do so.  During their orbits the moons sometimes pass between the Sun and their master, casting their shadows on his cloud-tops below.  On the night of the 16th at around 11:30 pm EST you’ll have a chance to see two moons casting their shadows on the planet at once.

Saturn graces the southeastern sky as morning twilight gathers.  He is slowly drifting eastward near the second-magnitude star Graffias, northernmost of the three stars that delineate the “head” of the Scorpion.  He gets a visit from the waning Moon on the morning of the 16th, which would be a great time for a quick peek at both objects through the telescope.  As majestic as Saturn is, when viewed in the same context as our Moon it suddenly becomes very apparent how far away this giant world really is.

The Sky This Week, January 6 – 13, 2015 !

The Sky This Week, 2015 January 6 – 13

A busy celestial start to the new year!
Comet C/2014 Q2 (Lovejoy), 2015 JAN 1, 03:51-04:27 UT
Imaged from near Morattico, Virginia, USA
80mm (3.1-inch) f/6 Antares Sentinel refractor,
Canon EOS Rebel T2i DSLR

Happy New Year from the U.S. Naval Observatory!

2015 gets underway with a bang as the evening sky plays host to four bright planets, bright stars, and a “prime-time” comet.  Keep those binoculars and telescopes handy, since they will be getting quite a workout over the next couple of weeks.

The Moon wends her way into the morning sky this week, waxing from near Full to Last Quarter, which occurs on the 13th at 4:46 am Eastern Standard Time.  Look for bright Jupiter five degrees north of the Moon in the late evening on the 7th.  She passes just under two degrees north of the bright star Spica before dawn on the 13th.

We are currently experiencing the latest sunrises for the year as we wind up the phenomena associated with the winter solstice.  Here in Washington the Sun will continue to rise at around 7:27 am EST until the 11th, when the time of sunrise begins to slip to a bit earlier.  Some of you may already have noticed that sunset now occurs after 5:00 pm, some 15 minutes later than it was on December 7th.  It’s a sure sign that spring can’t be too far behind.

Take the time this week to look just after sunset for a pair of planets in the glow of evening twilight.  One of them, Venus, should be almost instantly obvious within 20 minutes of sunset.  The other is Mercury, and you may have to work a bit harder to find him.  However, both planets are separated by about one degree or less for most of the week, and this should make Mercury an easy target for binoculars and the naked eye.  I glimpsed both of them on my trip home on Monday night at about 5:30 pm thanks to the transparency offered by the crisp, clear skies over Arlington.  The two objects will be closest together on the evenings of the 10th and 11th with just over half a degree of the sky between them.  They will remain fairly close to each other through much of next week.  If you’ve never seen Mercury before, this is one of the best opportunities you’ll have for the next few years.

The next planet in Venus’ sights is ruddy Mars, which glimmers a dull pinkish hue among the faint stars of Capricornus, the Sea Goat.  The red planet is keeping pace with the Earth, setting at 8:14 pm each night for the rest of the month, but he’s losing ground to the rapidly approaching Venus and the slightly less speedy Sun.  He should be easily visible in the southwest about 45 minutes after sunset about 20 degrees above and to the left of Venus as the week begins.

By mid-evening the familiar outline of Orion and his attendant Great Winter Circle of bright stars dominates the eastern sky.  While there are many interesting things to explore among the stars of the Hunter and his friends, for the next couple of weeks a celestial interloper will be getting most of my attention.  Comet C/2014 Q2 (Lovejoy) was discovered by Australian amateur astronomer Terry Lovejoy on August 17 of last year.  At the time it was a faint 15th magnitude smudge of light among the stars of the constellation Puppis deep in the southern Milky Way.  Since that time it has surprised most of us by brightening to between fourth and fifth magnitude and is now drifting northwestward toward the constellations of Taurus and Aries.  It should be quite easy to spot with binoculars as it wends its way through the sparse area of stars to the west (right) of Orion.  I first glimpsed it around Christmastime with binoculars and had very nice views of it from Virginia’s Northern Neck around New Years, despite the close proximity of the nearly Full Moon.  As the week progresses and the Moon moves into the morning sky it should be easy to spot from the suburbs as a glowing greenish-grey fuzzy  ball of light, and if you can get out to a dark-sky site you should be able to easily spot it with the naked eye.  Binoculars under these conditions should also show a nice, ropy tail.

Jupiter is now becoming very prominent in the late evening eastern sky as he marches inexorably toward opposition in another month.  The giant planet now rises at around 7:30 pm, and by 10:00 pm he should be well above the trees and rooftops for telescopic viewing.  Jupiter’s constantly changing cloud belts are now under near-constant scrutiny by a small army of amateur astronomers around the world who track the day-to-day changes in the planet’s extraordinary weather.  I’ll soon be adding my telescope to their ranks for the current apparition.

Fans of Saturn will still have to wait until the pre-dawn hours to glimpse the distant ringed planet, but those who do will get a taste of what’s to come when he reaches opposition in mid-May.  He’s slowly drifting eastward toward the stars that form the “head” of Scorpius, and he’ll spend the next year in this general vicinity.  If you spot him, just think of the warm late spring nights to come when he’ll be best-placed for viewing.