Snake-tongued Comet Lovejoy slithers north, slowly fades

Right now Comet Lovejoy’s faint, double-rayed gas tail extends many degrees to the east of the bright coma. Observers using 10×50 and similar binoculars have traced it out to 10° or more. This photo was taken on Jan. 18th. Credit: Chris Schur

Forked tongues allow snakes to smell in stereo – each fork senses slightly different chemicals in the snake’s vicinity and feeds a separate signal to its brain. When combined, they create a complete “picture” of the reptile’s odiferous world. In much the same way, the two ears on opposite sides of our heard allow us to hear the world in rich stereo sound.

Comet Lovejoy’s nucleus is jetting gas and dust just like Comet 67P/Churyumov-Gerasimenko in this photo taken by the Rosetta spacecraft on November 22, 2014 from a distance of 18.6 miles (30 km). The nucleus is deliberately overexposed in order to reveal the faint jets of activity. Credits: A/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

Lovejoy’s forked tail is hardly an operative organ, but it’s sure amazing sight for stereo eyes. Composed principally of carbon monoxide gas, each of the two primary rays is incredibly well-defined. Gases like water vapor, carbon monoxide and carbon dioxide boil off the nucleus as the Sun warms the comet and help create its big blue-green head or coma. As described here before, the solar wind ionizes or electrifies the gases which allows the magnetic fields embedded in the wind to peel back the gases to form a the glowing gas or ion tail.

Comet Lovejoy arcs up into Triangulum the Triangle later this week and continues into Andromeda into Cassiopeia. Northern hemisphere observers are favored, while those in the southern hemisphere will soon see the comet drop below their horizon. This chart shows Lovejoy’s position every 5 days around 7 p.m. (CST). Stars to magnitude +6. Click to enlarge. Created with Chris Marriott’s SkyMap software

I hope you’ve had the chance to see Comet Lovejoy. While the naked eye view isn’t impressive (though always a pleasure to behold any comet without optical aid), binoculars clearly show the faint, smoky tail extending east of the fuzzy head. In a telescope, even a fairly large one like the 15-inch (37-cm) reflector I use, the fainter rays are indistinct, though the forked tongue shows a little more clearly.

With the moon now returning to the evening sky (see below) and the comet starting to fade, it will gradually become more difficult to see with the naked eye. By mid-February, Lovejoy will probably have dimmed to the naked eye limit of around magnitude +6. But if you use binoculars, you’ll be able to follow our feathery friend through full moon and beyond.

The returning thin crescent moon gathers with brilliant Venus and fading Mercury low in the west-southwest sky during twilight this evening January 21st. This map shows the sky about 40-50 minutes after sunset. Stellarium

Northern skywatchers are fortunate that the comet continues to move north and ever higher in the sky. By late February it will be circumpolar from many locations and remain visible all night.

You can use the map to help you find Lovejoy as it climbs into Triangulum the Triangle this weekend and from there to Andromeda and Cassiopeia.

Venus and Mercury dance cheek-to-cheek as new year begins

Venus and Mercury shine over the Duluth, Minn. city skyline this evening December 31st about 40 minutes after sunset. Venus was very easy to spot but Mercury quite tricky with the naked eye. Binoculars showed it easily. In the coming nights, Mercury rises higher and will get easier to see. Credit: Bob King

Hey, hey, what’s this? Another planet creeping up on Venus? Just in time for the new year, speedy Mercury is quickly catching up to the goddess world.

Surreptitious Mercury climbs toward Venus in the next week. Tonight you’ll find the innermost planet 3.5° below and right of Venus. Look for the pair starting 20 minutes to a half-hour after sunset. Venus is about 6° high. Source: Stellarium

Starting tonight you can see both inner planets low in the southwest at dusk starting about 20 minutes after sunset. All you need is an open horizon in that direction. Just to make sure you spot Mercury, carry along a pair of binoculars. Focus first on Venus, then place it at the top of the field of view and look along the bottom for Mercury. The photo above will serve as a guide.

Facing southwest on January 10th, we’ll see Venus and Mercury at their closest, under a degree apart. This map shows the sky about 25 minutes after sunset when the two planets will be about 10° high or about one balled fist held at arm’s length. Source: Stellarium

As 2015 begins, Mercury is heading into a splendid evening apparition, reaching its greatest distance from the Sun on January 14th. With Venus as helper planet, this will be one of the best times in the new year to find furtive Mercury.

For six nights starting on the 8th, the two planets will dance cheek-to-cheek only 1° or less apart. Their tightest separation, when they’ll be just 2/3° apart, occurs on January 10th. Great sights lie ahead!


Aqua comet and Venus surprise

A sketch made with Photoshop showing Comet Lovejoy’s pretty aqua-colored coma as it passed very close to the globular cluster M79 in Lepus last night December 28th. The tiny nuclear region was bright and intense. Inside this dusty “cocoon” lies the icy comet itself. Credit: Bob King

If you’ve ever been to the Caribbean you know how enticing the water is. Aqua hues delight the eye, inviting you to jump in for a snorkel or swim. These warm thoughts sailed into my head last night when Comet Lovejoy swam into my telescope. Its huge coma, a little more than half the size of the full moon, glowed a subtle blue-green from carbon molecules boiled off the nucleus fluorescing in sunlight.

Wow! Check this out. Photo taken through a 12.5-inch telescope last night from Arizona shows the comet during its close passage of M79. Credit: Chris Schur

Had the half-moon not been out, I’m sure the comet would have been visible with the naked eye. Come on – it’s already 5th magnitude and still brightening! As it was, Lovejoy showed easily enough in 8×40 binoculars as a fuzzy blob in Lepus the Hare. Through the scope the coma was huge compared to the meek-looking globular cluster M79, a mere 410,000 light years in the far distance despite its apparent proximity to the comet.

Comet Lovejoy was bright enough to nab in a 15-second time exposure with a 200mm telephoto lens last night. Details: f/2.8 at 13 seconds. Credit: Bob King

You can follow Lovejoy for a few more nights until the full moon makes it a challenge. Patience, patience. Come January 6-7, the moon will begin to exit the sky and leave us with welcome darkness, perfect for more Lovejoy looking.

Venus from Peggys Cove, Nova Scotia on December 27th. Look low above the horizon a little more than halfway from the lighthouse to the left edge of the photo. Credit: Carol Behan-Sokolow

Funny story. After more than 3 weeks of clouds, I went out Sunday evening to find Venus after sunset. I drove to an open place and carefully scanned the southwestern horizon about 25 minutes past sundown. After a minute or two without success I wondered whether Venus might be hidden by the distant treeline. Then it hit me. Actually, Venus hit me. Suddenly the planet was there – but MUCH higher than I had thought. My brain was still stuck in the past when the sky had last been clear. In those 3 weeks the planet had climbed high enough to knock me over the head.

Unmistakable Venus, goddess of beauty, seen 30 minutes after sunset yesterday December 28th. Credit: Bob King

So now I can say with confidence that Venus is easily visible from 20-40 minutes after sunset shining brightly in the southwestern sky well to the left of the sunset point. Take a look the next clear night and you might be surprised.

Venus returns, joins exceptionally young moon tonight

Look low in the southwestern sky starting about 20 minutes after sunset this evening for a little spark of light – Venus. About 5° (one binocular field of view) to its upper right you might glimpse the moon, just 20 hours old from the East Coast (21 hours from the Midwest, 22 hours from the mountain states and 23 hours from the West Coast.) Source: Stellarium

Have you noticed something missing lately? Venus has been absent from view since late last summer. We last saw it struggling against the solar glare at dawn.

Now, just in time for the holidays, Venus is returning to the evening sky, low in the southwest after sundown. Tonight there’s even a chance to see it next to an exceptionally thin crescent moon.

Look for the goddess of beauty and love to meet up with the moon some 20 minutes after sundown low in the southwestern sky. Most of us consider seeing a day-old crescent moon quite a feat, but from the Midwest this evening, Luna will be just 21 hours old, a fragile crust if ever there was and a chance to break your personal young moon record.

I’d bring binoculars just to be sure you see the two. Venus will be only 6° above the horizon this evening. Make slow horizontal sweeps with your binoculars to the left of the brightest part of the lingering glow of sunset. As long as the sky is haze-free, Venus should pop into view. Once you’ve nailed it, move to the upper right in the field of view and locate the moon. Now, lower the binoculars and try sighting both with your naked eye alone.

Venus revolves around the Sun interior to Earth’s orbit. Right now it’s still near its greatest distance from Earth on the opposite side of the Sun from us. Over the coming weeks and month, it will draw closer to Earth and grow in apparent size as its phase changes from full to crescent. Source: Wikipedia with additions by the author

Venus underwent superior conjunction on October 25th, when it lined up with the Sun on the opposite side of its orbit from Earth. It was most distant from us then and appeared like a tiny full moon. The planet’s still pretty far away and will remain near the Sun in evening twilight for the next month or so. Although Venus’ orbital speed varies little over its nearly circular orbit, it appears to travel very slowly this winter because it’s very far from us.

Fear not! Its appearance this month is a harbinger for this spring and early summer’s exceptional apparition when the brightest of the planets will catch your eye in the west all evening long.

Looking at the diagram, notice that Venus, moving faster than Earth because it’s closer to the Sun, is slowly catching up with our planet. As it does, the angle it makes to Sun and Earth continuously changes which changes the appearance of Venus. Through a small telescope we can easily see its phase shrink from full to half to crescent exactly like the phases of the moon.

Panels illustrating several of the closest and best conjunctions of Venus and the planets in the coming year. Source: Stellarium

Venus is famous creating spectacular scenes with other bright planets and the moon. We call these events conjunctions. I’ve illustrated a few of them above. The best will occur on July 1st when the sky’s two brightest planets will be just 0.4° apart.

I love it when Venus returns to view. It always puts a bright face on every clear night.

Mars meets Kaus Borealis tonight

Mars passes very close to Kaus Borealis (a.k.a. Lambda Sagittarii) tonight. If your skies are clear, take a look during evening twilight about an hour after sunset low in the southwestern sky. Source: Stellarium

Just a quick heads up. I always like to report when a planet and star pair up in the night sky. That happens to happen tonight (Nov. 3) when Mars passes just 1/2° north of Kaus Borealis, the star at the top of the Teapot of Sagittarius.

To spy this temporary “double star”, go out about an hour after sunset and look low in the southwestern sky. That bright red-orange object is Mars. Immediately to its lower left, you’ll see Kaus Borealis deliciously close.

The sky facing southwest on Nov. 18, 1984 shortly before Venus occulted Kaus Borealis. The map shows the sky from Duluth, Minn. during evening twilight. Source: Stellarium

Kaus Borealis, a name combining the Arabic word for ‘bow’ and the Latin word for ‘northern’, refers to the bow of Sagittarius the Archer, the constellation’s formal name. At magnitude +2.8, the star is easy to spot with the naked eye. Since it lies near the ecliptic, the path followed by the Sun, Moon and planets, it’s occasionally occulted by one of these bodies. Back on the evening of November 18, 1984, Venus passed directly over the star and blanked from view for a time. What a scene! Not only did the star blank out, but Jupiter, the sky’s second brightest planet, shone nearby in the same constellation.

Mars won’t occult Kaus, but for a fun activity tonight and over the next few nights, compare the colors of Mars and the star. Kaus Borealis is an orange subgiant star (not quite as big as Arcturus, an orange giant) 2.3 times as massive as the Sun and 52 times brighter. Is Mars more red or are they nearly the same? Have fun getting acquainted with a star we might otherwise ignore were it not for Mars’ proximity.

Goodmorning moon / Tomorrow’s Titan flyby

Look east Monday morning around 6 a.m. to spot the goodmorning moon. Only 2.5% of the moon will be illuminated by the sun; the remainder by ghostly earthshine. Venus will be about a fist held at arm’s length to the moon’s lower left. Stellarium

Like a lot of parents, we read Goodnight Moon by Margaret Wise Brown to our kids to get them ready for bed at night. The calming words and repetition soothed child and adult alike at the end of the day.

Maybe a sequel titled “Goodmorning Moon” will be written someday about waking up to the smiling crescent in the east and getting ready for the day. Tomorrow morning we’ll see exactly that, a very thin moon, low in the eastern sky at dawn. Its delicate arc will surely make you stop and realize how much beauty nature puts on the plate for enjoyment and study every day.

Venus seekers can use the moon to make one last attempt to find the planet, now nestled very low in the east just a degree or two above the horizon 40 minutes before sunrise.

Animation showing clouds of methane moving over Ligeia Mare, a large sea of liquid methane near Titan’s north pole, between July 20 and 22, 2014 as Cassini departed the moon during the last flyby. Credit: NASA/JPL-Caltech/SSI

While we’re on the topic of planets, NASA’s Cassini spacecraft will make a close flyby of Saturn’s moon Titan tomorrow September 22nd. At 3,201 miles (5,150 km) across, Titan is the solar system’s second largest moon, only 79 miles smaller than Jupiter’s Ganymede. It’s also unique in having a very thick atmosphere – 1.5 times thicker than Earth’s – a feature usually found only on planets.

It’s still not known how Titan managed to hold onto all its air, which consists of primarily nitrogen mingled with methane and various other hydrocarbons that react in sunlight to create an orange smog that gives the moon its distinctive color. Several other moons such as Ganymede, Rhea and even our own moon have atmospheres, but they’re exceedingly thin compared to Titan’s.

In this photo taken by Cassini, Saturn’s airless, cratered moon Dione is juxtaposed with Titan. Titan appears smaller because it’s 600,000 miles farther away from the spacecraft’s perspective. To see beneath the clouds and map the surface, Cassini observes the moon in infrared light and with radar. Credit: NASA/JPL-Caltech

It’s thought that Titan maintains and replenishes its atmosphere through outgassing from its interior. The bitter cold temperatures at Saturn’s nearly billion mile distance from the sun along with Titan’s considerable gravitational pull undoubtedly help preserve and hang on to its air. Comet impacts may also contribute to the moon’s stockpile of ices and organic compounds.

Along with an atmosphere come clouds, though of methane rather than the water vapor variety found on Earth. Temperatures at the surface hover just 90 degrees above absolute zero (-290º F, -179º C), chill enough for methane clouds to form and supply at least some of the precipitation to lakes of liquid ethane, methane and propane below.

This will be Cassini’s 9th flyby of Titan this year. During a flyby, the craft zips by the moon at high speed while keeping its instruments precisely pointed at the target using either its reaction wheels or thrusters, which spin the spacecraft to track the moon as it passes by. Thrusters are also used to keep Cassini from tumbling when it experiences drag while passing through Titan’s upper atmosphere during close flybys.

Descent through Titan’s atmosphere made by the Huygens probe on January 14, 2005

On Monday, Cassini will be traveling at 13,000 mph (21,000 km/hr) and come within 870 miles of Titan’s surface as it photographs seas and lakes – including Ligeia Mars shown above – around the north pole. Another instrument will observe Titan’s southern hemisphere atmosphere in ultraviolet light by observing the dimming of Alkaid, the star at the end of the Big Dipper’s handle as its light passes through the moon’s varied atmospheric layers.

To twinkle or not to twinkle, that is the question

Venus passes Regulus on the morning of September 5. Look low in the eastern sky 30-45 minutes before sunrise to see the pair. Bring binoculars in case twilight overwhelms Regulus. Stellarium

Early Friday morning September 5, skywatchers will see Venus and Leo’s brightest star Regulus in a close conjunction. The two will be separated by just 1° and look very nice in binoculars. Find a place with a view down to the eastern horizon and start looking about 40 minutes before sunrise. Jupiter, higher up in a darker sky, can help guide you to Venus.

This will be Venus’ last encounter with a bright star at dawn before it’s lost in the glare of the sun. It’s often said that one way you can tell a planet from a star is that a planet’s light appears steady, while stars twinkle. Not always. Stars only appear as points of light even through the largest telescopes and are easily shoved this way and that by air turbulence. These tiny shifts in position are what cause twinkling.

When we look at stars low in the sky we look across hundreds of miles of air in the lower, densest part of the atmosphere. Air currents across that great distance push a star’s light around causing it to twinkle. It can have the same effect on bright, naked eye planets when they’re far away and show a smaller than usual disk. Credit: Bob King

Planets have measurable disks and are less affected by the flutter of air, so we rarely catch them shimmering. But when the planet is far from Earth and very low in the sky, the rules change. Both Venus and Mars range in size from tiny blips to substantial disks (or in the case of Venus, a substantial half-moon or crescent). When viewed at low altitude, I’ve seen both twinkle lively.

Illustration showing how a planet, with a measurable disk, defeats air turbulence compared to a star which appears as a tiny point of light through a telescope. Credit: Bob King with Jupiter pic by Damian Peach

I witnessed it last Thursday morning with Venus. Jupiter, larger and higher in the sky, was a steady beacon. Venus, now nearly on the opposite side of the sun from Earth and about as small as it ever gets, trembled like a flame in the wind. What will you see Friday morning?

Venus remains visible for another two weeks before it’s lost in the solar glare. We won’t see the planet at all for more than a month until it returns to the evening sky around Thanksgiving in November. Watch for it to shake and shimmy its way up the western sky until fattening up around Christmas.

Miss the conjunction? Here’s your consolation prize

Clear skies prevailed over Königswinter, Germany for a great view of Venus and Jupiter just 0.2° apart at dawn this morning August 18. Credit: Daniel Fischer

Those killers of all things astronomical – clouds – were back again this morning, so no Venus-Jupiter conjunction here. Looks like I’ll pin my hopes on the one scheduled for next June 30 in Leo at dusk. I’m grateful for the flatness of the solar system, which guarantees that every few years we get repeat planet pairings.

Look east this coming Saturday morning for a sweet pairing of the bright planets and wiry crescent moon. This view shows the sky about 45 minutes before sunrise. Stellarium

I hope some of you got to see the conjunction from your home or on the way to work this morning. While Venus and Jupiter will now part ways, they’ll be one more blast of celestial awesomeness involving the duo and the crescent moon this weekend. Consider it a consolation prize. Who knows, this event might be even prettier than what passed this morning.

On Saturday morning, August 23rd about 30-45 minutes before sunrise, the thin, waning lunar crescent joins Jupiter and Venus in a stunning triangle of loveliness in the eastern sky.The threesome will all fit inside an 8° circle.

Now that I know this is coming I don’t feel so bad about missing the conjunction.

Moon nestles in Hyades then departs for Venus

The crescent moon slips in front of the Hyades star cluster only a degree from Aldebaran tomorrow morning. Don’t miss the other bright star cluster, the Pleiades, just above. Look low in the northeastern sky about an hour before sunrise to catch the scene. Stellarium

That old devil moon’s up to its old tricks again. Tomorrow morning, early risers will see it tucked inside the V-shaped face of Taurus the Bull. Better known as the Hyades star cluster, look for the crescent to pass just 1° north of the bright star Aldebaran. A pair of binoculars will enhance the view by pulling in more stars and revealing details in the spooky, earth-lit moon. Sunlight illuminates the lunar crescent, but the remainder is light reflecting off Earth out to the moon and back again.

The crescent is lit by the sun while the remainder glows dimly from twice-reflected light called earthshine. Credit: Bob King

To the eye, ‘earthlight’ looks smoky gray and nearly featureless though binoculars will show the lunar seas and larger craters. The quality of the light mimics a lunar eclipse but instead of red we see the pale blue glow of sunlight reflecting back from our planet’s oceans.

At 153 light years, the Hyades is the nearest star cluster to our solar system, one of the reasons you can see it without a telescope. Aldebaran appears to be a full-fledged cluster member, but it’s a ruse. The bright, ruddy star lies much closer to us along the same line of sight.

Venus and a very thin crescent moon on July 24 about 45 minutes before sunrise low in the northeast. Stellarium

The Hyades were born in a dense cloud of interstellar dust and gas 625 million years ago around the time underwater life flourished in the late Precambrian era. When you gaze at the cluster tomorrow, the light that touches your retinas left the Hyades the same time Abraham Lincoln took office.

The moon moves on toward Venus after vacationing in the Hyades, passing south of the planet on Thursday morning. It will be extremely thin that morning and should make a pretty sight for anyone looking low in the northeastern sky 45 minutes before sunrise.

Catch Comet Jacques near Venus at dawn

Venus will help us find Comet Jacques in Taurus an hour and a half before sunrise tomorrow morning July 16, 2014. The comet will be near the naked eye star Beta Tauri during the next week. Source: Stellarium

I don’t take getting up at dawn in summer lightly. After all, it means you’ve got to set the alarm for the ungodly hour of 4 a.m. (even earlier if you live in the northern U.S. or southern Canada.) But I wanted to alert you to the return of Comet C/2014 E2 Jacques.

Comet Jacques was taken on July 7, 2014 displays a small, condensed head or coma and two tails – a dust tail to the left and ion or gas tail to the right. Credit: Gerald Rhemann

Jacques disappeared in evening twilight a month ago, passed closest to the sun on July 2 and has recently returned to view low in the northeastern sky at dawn. Still stoked from its solar encounter, the comet shines at magnitude +6, the naked eye limit.

Don’t expect to see it yet without optical aid however. Jacques flirts with morning twilight and only climbs to around 10° (one fist held at arm’s length) the next couple mornings. Low haze and dust will make it look fainter, but not so much that a pair of 50mm binoculars might catch it.

Detailed map with stars shown to magnitude 7. Comet Jacques will be near a great ‘skymark’ this coming week, the star Beta Tauri. Use it and Venus to guide you there. Comet positions are marked every five days; Venus shown for July 16.  Click to enlarge and then print out a copy for outdoor use. Source: Chris Marriott’s SkyMap

We’re fortunate to have Venus and the star Beta Tauri to help guide us to the comet. The critical requirement for seeing Jacques, whether it be in binoculars or more likely in a small telescope, is an open view of the northeastern sky.

Timing is also important. In the northern U.S., the comet will be a little higher in the sky but observers will have to compete with earlier and longer twilights. The southern U.S. has the edge for the moment with the comet a little better placed in a darker sky.

Views will improve for everyone over the next few weeks as Jacques pulls away from the sun, buoyed along by the seasonal drift of the stars and its own westward motion.

Indications are that the comet will remain near the naked eye limit through early August, so we may really get a chance to see it without optical aid from rural skies. In any case, binoculars should reveal it as a small fuzzball rolling across Auriga and Perseus.

The thin crescent moon drops by the neighborhood on July 23, a great morning to seek out the comet. Source: Stellarium

By mid-August, Jacques will fade but remain visible in the evening sky through the remainder of the year. I hope you become fast friends with this blurry blob soon!

* UPDATE July 16, 2014 – Checked the comet this morning and although there were a few clouds, I wasn’t able to see it in 10×50 binoculars. Too much twilight here in the northern U.S. ! But the view in the telescope was excellent. Jacques was an obvious fuzzy glow with a bright center a couple degrees below Beta Tauri even in dawn light. I estimated magnitude 6.