Ghost of SOHO’s comet still lives!

That faint streak is all that's left of C/2015 D1 (SOHO). It was taken on Feb. 25, 2015. Details: Stack of 31 8-second-long exposures at ISO 1600, shot with a Nikon D5100 + 70-300mm telephoto at 135mm f/4.7. A tracking mount kept the stars from trailing. See below for a "blinking" version. Credit: Justin Cowart

That faint streak is all that’s left of C/2015 D1 (SOHO). It was taken on Feb. 25, 2015. Details: Stack of 31 8-second-long exposures at ISO 1600, shot with a Nikon D5100 + 70-300mm telephoto at 135mm f/4.7. A tracking mount kept the stars from trailing. See below for a “blinking” version. Credit: Justin Cowart

A comet that probably shouldn’t have survived its close encounter with the Sun last week appears made it out alive. If ailing a bit. C/2015 D1 SOHO, discovered in photos taken by the Solar and Heliospheric Observatory (SOHO), somehow stayed together in one piece after its near-death solar pass.

This photo taken on Feb. 25 in late evening twilight by geologist and amateur astronomer Justin Cowart of Alto Pass, Illinois, is the first of the comet’s ghostly remnant. It was taken on Feb. 25 during late evening twilight. Cowart didn’t have much hope after hearing speculation that the comet may have been “ISON-ized”. In late 2013, Comet ISON frittered away to little more than an expanding cloud of dust after a similar close pass by our star.

Animation showing the possible D1 SOHO comet and its position marked on an atlas based on its orbit. Credit: Justin Cowart / José Chambo

Animation showing the possible D1 SOHO comet and its position marked on an atlas based on its orbit. Credit: Justin Cowart / José Chambo

But rather than give up, he set up a camera and tracking mount and waited for the sky to clear in the west after sunset Wednesday evening. Comet SOHO was then located about 10° above the horizon near the star Theta Piscium at the time the photo was taken.

“I was able to see stars down to about 6th magnitude in the raw frames, but no comet,” wrote Cowart.  “I decided to stack my frames and see if I could do some heavy processing to bring out a faint fuzzy. To my surprise, when DeepSkyStacker spit out the final image I could see a faint cloud near Theta Picsium, right about where the comet expected to be!”

Stacking is a method of adding multiple pictures taken of the same object together to create a brighter, less grainy and more detailed image. Software programs make it easy.

Cowart sent the picture off to astronomer Karl Battams, who initially brought the comet into the limelight, for his opinion. Meanwhile, comet observer José Chambo got involved in the discussion and plotted D1’s position on a star atlas (in the blinking photo above) based on a recent orbit calculation. Bingo! Justin’s photo was dead on with the predicted position.

This photo was taken on Feb. 27 from Germany. Jost Jahn stacked 59 15-second exposures (ISO 1600, f/2.4) taken with an 85mm telescope. Credit: Jost Jahn

This photo, which confirms Cowart’s observation, was taken on Feb. 27 from Germany. Jost Jahn stacked 59 15-second exposures (ISO 1600, f/2.4) taken with an 85mm telescope. Credit: Jost Jahn

Two night later on the 27th, Jost Jahn of Amrum, Germany set up a small telescope and photographed the SOHO D1 which had by then moved a little higher in the western sky. No question about it – that’s the comet. But like the headless horseman in the Legend of Sleepy Hollow, it’s returned without its head! After a thorough toasting by the Sun, all that remains is an expanding, elongated dust cloud. ISON-ization indeed!

Watch Comet Lovejoy C/2011 W3 rise in this beautiful video by Stephane Guisard

Readers may remember that Comet Lovejoy (C/2011 W3) suffered a similar fate in late 2011, yet remained a remarkable sight in the dawn sky.

Photo taken last night (Feb. 26) with a 200mm lens at f/2.8 showing where the comet should have been found. I've marked a tenuous suspect. Details: 2-seconds at ISO 3200. Stars visible to about magnitude +10. Credit: Bob King

Photo taken last night (Feb. 26) with a 200mm lens at f/2.8 showing where the comet should have been found. I’ve marked a tenuous suspect. Details: 2-seconds at ISO 3200. Stars visible to about magnitude +10. Credit: Bob King

Inspired by Cowart’s possible capture, I set up my own camera two nights ago and photographed the comet’s position with a 200mm telephoto lens under a cold but very transparent twilight sky. Shot “raw” with no stacking, I’m not convinced the image shows a comet. It was still fun to give it a try, and I look forward to the moon leaving the sky next week for a go at seeing Comet SOHO D1 with a telescope.

Comet C/2015 D1's path now through March 3 as it tracks from Pisces into Andromeda in the western sky at dusk. Time is 7 p.m. CST and stars are shown to magnitude +8. Created with Chris Marriott's SkyMap software

Comet C/2015 D1’s path now through March 3 as it tracks from Pisces into Andromeda in the western sky at dusk. Time is 7 p.m. CST and stars are shown to magnitude +8. Created with Chris Marriott’s SkyMap software

Here’s a fresh map based on the most recent orbit published by the Minor Planet Center. Go out and give a try yourself at photographing it. Stacking images is preferred to enhance what’s obviously a faint and diffuse object. Cowart shot his photos between 60 and 70 minutes after sunset when the comet’s altitude ranged from 10° and 6° high. Mine were taken between 70 and 80 minutes after sundown.

A feather afloat. Comet D1 SOHO on the evening of Feb. 28 from Austria. Credit: Michael Jaeger

A feather of comet dust afloat. Comet D1 SOHO on the evening of Feb. 28 from Austria. Credit: Michael Jaeger

Cross your fingers and make appropriate sacrifices to the god of your choice. The comet may be visible in telescopes as it climbs higher into a dark sky after the moon departs the scene around March 6-7.

New Fast-Moving Comet May Become Visible from Earth

SOHO-2875 seen SOHO's LASCO C3, wide-field coronograph called LASCO C3 at 11:02 a.m. (CST) today Feb. 20. It's already moved a good distance to the east-southeast of the Sun and still displays a short tail. Credit: NASA/ESA

SOHO-2875 seen SOHO’s LASCO C3, wide-field coronograph called LASCO C3 at 11:02 a.m. (CST) today Feb. 20. It’s already moved a good distance to the east-southeast of the Sun and still displays a short tail. Credit: NASA/ESA

A newly-discovered comet may soon make an appearance in the evening sky. Dubbed SOHO-2875, it was spotted in photos taken by the Solar and Heliospheric Observatory (SOHO) earlier this week. Astronomer Karl Battams, who maintains the Sungrazer Project website, originally thought this little comet would dissipate after its close brush with the Sun. To his and our delight, it’s now outperforming expectations. Given the comet’s rapid movement away from the Sun, we won’t have to wait long to find out whether it might be visible in a telescope.

Composite of Comet SOHO-2875 crossing the C2 coronagraph field yesterday. Credit: NASA/ESA/Barbara Thompson

Composite of Comet SOHO-2875 crossing the C2 coronagraph field yesterday. Credit: NASA/ESA/Barbara Thompson

Most sungrazing comets discovered by SOHO are members of the Kreutz family, a group of icy fragments left over from the breakup of a single much larger comet centuries ago. We know they’re all family by their similar orbits. The newcomer, SOHO’s 2,875th comet discovery, is a “non-group” comet or one that’s unrelated to the Kreutz family or any other comet club for that matter. According to Battams these mavericks appear several times a year.

Photo taken at 20:00 UT (2 pm. CST) Feb. 19 with the SOHO C2 coronagraph, a device that blocks the Sun, allowing a view of the area close by. A faint tail can be seen just below the comet's bright head. Credit: NASA/ESA

Photo taken at 20:00 UT (2 pm. CST) Feb. 19 with the SOHO C2 coronagraph, a device that blocks the Sun, allowing a view of the area close by. A faint tail can be seen just below the comet’s bright head. Credit: NASA/ESA

What’s unusual about #2,875 is how bright it is. At least for now, it appears to have survived the Sun’s heat and gravitational tides and is turning around to the east headed for the evening sky. I’m no expert but having looked at many SOHO photos over the years, I’d estimate the comet is presently about magnitude +2.5 and some 5° from the Sun. No one can say for sure whether it has what it takes to hang on, so don’t get your hopes up just yet.

We’ll be watching and waiting. I’ll have an update on SOHO-2875’s progress soon.

What would the sky look like if Arcturus, Sirius or Alpha Centauri were our sun?

If Arcturus were put in place of the Sun it might look something like this at sunset, which would last an unusually long time given the vast dimensions of the star, some 25 times larger than our Sun. Credit: Roscosmos

I was out walking the other night around 11 o’clock when I noticed a new bright star poking through the trees low in the northeastern sky. For a moment I couldn’t figure it out, and then it came to me. Arcturus.

Arcturus, an orange giant star some 21 million miles in diameter, compared to the sun, Jupiter and other familiar stars.

Arcturus is a traditional spring-early summer star as that’s when it’s highest in the sky. But winter’s the time it first appears in the east as the midnight hour approaches. Arcturus is an orange-giant star 25 times larger than the Sun 36 light years from Earth.

If you’ve ever wondered how it might look in our sky, Russia’s Federal Space Agency or Roscosmos, has created a series of fun and instructive simulations of several familiar stars,including Arcturus, in place of the Sun.

While the Sun takes about two minutes to set once it touches the horizon, Arcturus’ massive disk would extend some13° across and require 52 minutes. Watching an Arcturian sunset would be a major time commitment reserved for weekends only.

Here are several other new stellar perspectives. In all, except perhaps Alpha Centauri, the Earth would roasted in the stars’ blazing heat and radiation. Keep that in mind as you take in the sights.

White-hot Sirius would blaze in our daytime sky. 1.75 times the size of the Sun and 26 times as luminous, we’d all be fried if Sirius stood where the Sun is. Credit: Roscosmos

How about a familiar triple star? This is Alpha Centauri, comprised of two stars slightly more massive and luminous than the Sun located 4.47 light years away. The third star (to the left) is Proxima Centauri, a dim red dwarf and third member of the system. Credit: Roscosmos

Vega in the constellation Lyra is our sit-in sun in this simulation. The star, 25 light years from Earth, rotates so rapidly it’s oval shaped instead of spherical. Vega measures 2.7 times the Sun’s diameter along its equator and is 36 times brighter than the Sun. The sight would make you go blind quickly. Earth would also be roasted in the heat. Credit: Roscosmos

Polaris or the North Star is a yellow supergiant 2,500 more luminous than the Sun and 45 times its size. What an eyeful we Earthlings would have if Polaris were our sun. Credit: Roscosmos

Here’s the whole works and more in a video in Russian. Enjoy! Tomorrow the fun continues when we’ll take a look at substituting planets and moons for the Sun.

Comet Lovejoy’s tail gets pinched / Let there be (refracted) light!

Lovejoy gets kinky. In this photo taken January 8th, the comet’s tail is caught in the act of separated from the head or coma. Magnetic fields embedded in the stream of particles from the Sun occasionally reconnect on the rear side of a comet and pinch off its tail. Credit: Rolando Ligustri

Looks like Comet Lovejoy got its locks trimmed again. A flutter of solar wind swung round the comet and pinched off its tail, an event captured in the dramatic photo above. You can already see a new tail growing in place.

The solar wind, a dilute stream of electrons and protons blown free of the Sun, wafts across the solar system and touches everything from the biggest planet to the smallest comet.

An ion or gas tail like the one in the photo forms when cometary gases, primarily carbon monoxide, are ionized by solar radiation and lose an electron to become positively charged. Once “electrified”, they can be twisted, kinked and even snapped off by magnetic fields embedded in the Sun’s particle wind.

Having passed closest to the Earth on January 7th, Comet Lovejoy is now high in the southeastern sky at nightfall and near its maximum brightness of 4th magnitude. It’s a little dim with the naked eye, but once you know where to look, I think you’ll be surprised how easy it stands out. At least from the less light-polluted outer suburban and rural areas.

If you can find Orion, you can find the comet. Use Betelgeuse and Rigel (above and below the constellation’s 3-star belt) to form a right triangle with Comet Lovejoy. Once you fix the spot with your eyes, you may see the comet directly. If not, just point your binoculars there and sweep around a bit. Source: Stellarium

I’ve been using bright stars in Orion and Taurus to first guide my binoculars – and then my eye – to the comet. It’s easy to use two bright stars, like Aldebaran and Betelgeuse, and extend a line from each to form a triangle with Lovejoy at one of the corners. If you then point binoculars at that spot in the sky, the comet should pop out. You can then lower the binoculars to see if you can spot it with your naked eye.

The map above is drawn just for tonight. Click HERE for a map showing the comet’s changing position through January 23rd.

A halo rings the bright moon and planet Jupiter (upper left of moon) Wednesday night. Ice crystals in high cirrostratus clouds bends or refracts moonlight into a circle of light. Credit: Bob King

Two nights ago, when I last looked at the comet, a bank of icy cirrostratus clouds moved in around moonrise and created a lovely halo around the moon and Jupiter. These familiar high, wispy clouds are composed of myriad six-sided ice crystals resembling the cells in a honeycomb. Light entering one side of the crystal is refracted or bent out another side. Add up billions of these tiny bits of bent light and they to form a circle around the Sun or moon called a 22-degree halo. The number indicates the radius of the halo or distance from the moon to the edge.

The Sun rises over a “steamy” Lake Superior in Duluth this morning as seen through the window of a local hospital. Credit: Bob King

At the moment, a large swath of the U.S. is steeped in bitter cold air. That often means clear skies at night. Allow yourself at least 5-10 minutes to get your eyes used to the darkness and then another 5 hunting for the comet. If you plan it right, you can be in and out in 20 minutes!

Patches of iridescent colors glow near the Sun an hour after sunrise this morning. Light scattered or diffracted by the extremely small ice crystals in the clouds creates a full range of vivid colors. A single sundog glows at left from light refracted by ice crystals in lower clouds or perhaps within a frozen wisp of vapor rising from the lake. Credit: Bob King

In Duluth, Minn. this morning the temperature dipped to around -10F°. Whenever we go below zero, water vapor above warmer Lake Superior condenses in the chill air into curly wisps of fog locally known as “steam fog”. This made for a very pretty sunrise. If that wasn’t enough, high altocumulus clouds passed near the Sun shortly after sunup, creating a palette of delicious greens, reds and purples. We even had a solitary sundog appear for a few minutes in a different set of lower clouds composed of ice crystals.

A closer view of the Sun and the strikingly beautiful iridescence. Click to learn more about diffraction and iridescence. Credit: Bob King

What a treat for the eyes! My wife and I saw all this unfold from the window of one of the local hospitals where we’d gone for a routine procedure. Whenever light puts on a show like it did this morning, I always tell myself I really need to get up earlier to catch more sunrises. And pack something a bit higher-end than a mobile phone!

Howl your heart out under tonight’s Full Wolf Moon

Tonight’s full moon is named for the wolves that call from the countryside on winter nights. Photo illustration: Bob King

Ahh-wooooooooo! January nights in the countryside can be bone-chillingly still. I’ve noticed only a few sounds during my winter forays into rural darkness – popping trees and howling wolves come to mind. Gun-shots seem to ring out from the trees as water-carrying vessels within them freeze. And there’s nothing like a wolf’s howl to tingle the spine.

When liquid water turns to ice it expands. Ice is also lighter than liquid water, the reason it floats in your cup and on the surface of a lake. Credit: Bob King

When water turns to ice, it expands. Like a pipe bursting in a poorly heated home on a bitter cold night, the little pipes in trees (xylem and phloem) burst and make a loud popping sound. If you’re already cold, the sound is unnerving as if you might be the next thing to shatter in the chill.

January’s full moon is named for the wolves that are active this time of year hunting and looking for mates. Wolves howl for many reasons including letting the pack know their location, as a rallying cry to gather the pack together and as a warning to other wolf packs to keep off their territory.

Howling gray wolf. Credit: Wikipedia

We’ve come to associate wolf howling with the full moon but studies have shown there’s no direct connection between the phase of the moon and howling.

Maybe it’s the way they point their muzzles to the moon and stars that makes us think they’re directing their calls to the sky. Wolves are just taking advantage of good acoustics. If you point your face upward and howl, your voice will carry much farther. Wolf howls can travel up to 6 miles in the forest and 10 miles across open terrain.

Tonight the moon will be fully full around 11 p.m. (CST) and spectacularly bright. While not any closer than normal, the January moon will appear brighter than a typical summer moon because it climbs much higher in the sky. With less atmosphere and fewer aerosols (dust, salt, water, smoke) in the way, the Wolf Moon will be silvery-white vs. the pale yellow of the warmer months.

Tonight’s full moon rises in Gemini the Twins. Its two brightest stars, Castor and Pollux, are the names of each of the twins. This view shows the sky facing east around 7 o’clock local time. Click image to find out when the moon rises for your location. Source: Stellarium

In early winter, the moon and Sun trade places in the sky with the moon occupying the place the Sun does around the summer solstice. Although it provides no warmth, the moon mimics the Sun by rising to nearly the top of the sky and remaining visible for hours and hours. If you go outside late tonight – between 11 and midnight – look around at the shadows cast by buildings and trees. You’ll see they’re summertime-short compared to the same shadows cast by the Sun the next day at noon.

If you’d like to explore the qualities of moonlight in more depth, I invite you to check out my recent article What Makes Moonlight Special on skyandtelescope.com or an earlier piece on 10 Ways to Enjoy a Full Moon. Happy howling!

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.

Winter solstice brings longest night, warm comforts

A wintry scene along the Superior Hiking Trail in northern Minnesota photographed earlier this week. Credit: Bob King

You can kiss the fall goodbye starting at 5:03 p.m. (CST) tonight. That’s when the Sun arrives at its southernmost point in the sky in the constellation Sagittarius. For those of us in the northern hemisphere it rises late, never climbs very high in the south and sets early, making today the shortest day and tonight the longest night of the year.

Earth’s tipped axis is responsible for the seasons. On one side of Earth’s orbit, the northern hemisphere is tilted away from the Sun and we experience winter; on the other side it’s tilted toward the Sun and we experience summer. Fall and spring are in-between times when the entire planet is broadside to the Sun and all places on the globe receive equal amounts of sunshine. From places like Australia, which is bisected by the Tropic of Capricorn, the Sun is high in the sky. For them and all other southern hemisphere locations, today marks the first day of summer. Credit: Wikipedia with additions by the author

Seen from the Tropic of Capricorn, that imaginary circle touching every location with a latitude of 23.5 degrees south, the Sun will be directly overhead at noon today. On the summer solstice, anyone living on the Tropic of Cancer at 23.5 degrees north latitude sees the Sun overhead at noon. The number 23.5 is special because it’s how many degrees the Earth’s axis is tilted from the vertical.

Because of the 23.5 tilt of Earth’s axis, the altitude of the sun varies with the seasons. In winter it’s 23.5 degrees below the celestial equator and shines over the Tropic of Capricorn, while in summer it’s 23.5 degrees above and shines over the Tropic of Cancer.  Source: Stellarium

At the winter solstice, the northern hemisphere is tilted away from the Sun, which makes it appear low in the sky. Not only are the Sun’s precious rays more spread out (less direct), but the days are short. Cold soon follows. In summer we experience exactly the opposite – the top of the globe is canted in the Sun’s direction. With our star high overhead, days are long and temperatures steamy.

Map of the continental U.S. showing the time of the average coldest day of the year. Click to enlarge. Credit: NOAA

While the start of winter can be cold, it’s rarely the coldest time of the season. Most places see their coldest days in mid to late January even as the days slowly grow longer and the Sun climbs higher. This seasonal delay occurs because the land is still losing more heat than what the feeble Sun can resupply, while the oceans, which effect climate worldwide, take more time than the land to cool down and warm up.

Likewise we don’t feel the hottest day of summer until the land and oceans heat up from day after day of a high-rolling Sun. That happens in July.

Because the Sun’s at its lowest point in the sky, your noontime shadow is longest this time of year. And if you’re paying close attention, you’ll notice that the earliest sunset occurred two weeks ago – not on the shortest day. However, the Sun will continue to rise later up to about January 4th.

The earliest sunsets happened two weeks ago. The sun sets about 3 minutes later today than it did in early December. Credit: Bob King

The reasons for the discrepancy have to do with both the tilt of the Earth’s axis and the planet’s varying speed due to its oblong, non-circular orbit. For a nice explanation of the phenomenon, head over to Prof. Kirk Korista’s Sunrise, Sunset and the Solstice page or HERE.

Christmas and other important holidays and celebrations happen at this darkest time of year to keep our spirits up and fan our hopes for the return of the light. They’re a time to revisit our deepest beliefs, spend time with family or just fall asleep in a soft chair next to a roaring fire.

A fire in the woodstove on the winter solstice. What could be better? Credit: Bob King

 

Solar flares and gobs of spots make for fiery fall finale

A freckle-faced Sun earlier this morning December 17 photographed by the Solar Dynamics Observatory. Regions 2242 and 2241 have produced several impressive M-class moderate flares in the past couple days. 2242 has a complex beta-gamma-delta magnetic field ripe for the production of strong flares. Credit: NASA

The Sun cares not for Earth’s seasons. It follows its own cycle of high and low activity. So while winter will soon be underway in the northern hemisphere, things have been heating up in recent days on our home star.

An M8 flare (almost an X-class!) in Region 2242 shines brilliantly in ultraviolet light in this photo taken by the Solar Dynamics Observatory at 10:57 p.m. (CST) last night. Credit: NASA

Nine sunspot groups speckle the Sun today with two of them – regions 2241 and 2242 – still growing and harboring the potential for M-class (moderate) or stronger flares in the coming days. Region 2242 let loose with an M1 flare around 7 p.m. (CST) yesterday evening and a stronger M8 flare at 11 p.m.

Along with so many other spot groups now pocking the solar disk, this week will be a good one for anyone with a small telescope and safe solar filter to get a great view of the Sun. This morning I could easily see Regions 2241 and 2242 with the naked eye through a #14 welder’s glass.

Tongue of fire! A coronal mass ejection (CME) of high speed electrons and protons departs the Sun around 2:30 a.m. (CST) today in the wake of last night’s M8 flare. This photo was taken with a coronagraph that blocks the brilliant solar disk so we can see what’s happening near the Sun. Arrow shows the direction of the blast. Credit: NASA/ESA

The more powerful of the two flares launched a large coronal mass ejection in a mostly southernly direction just below the Sun-Earth plane. However, there’s a chance for some spillover in our direction as particles traveling at over 400 miles per second (650 km/sec) arrive on or about Sunday the 21st, the first day of winter.

Quiet conditions in Earth’s ever-dynamic magnetic environment will be the rule the next couple days, but we’ll be keeping our eyes on those big sunspot groups and a possible glancing blow from that CME. A colorful red and green aurora would be so fitting for the season!

Ophiuchians, it’s time to fight for your sign

The Sun enters Ophiuchus today. A part of this large constellation lies between the traditional zodiac constellations Scorpius and Sagittarius. I’ve outlined its official border, set in 1930, in red. Stellarium

If you were born between November 29th and December 17th you’re being sold a zodiacal bill of goods. The astrology columns will tell you you’re a Sagittarius. Don’t believe it. You’re an Ophiuchian!

Ophiuchus (oh-fee-YOO-cuss) the Serpent Bearer represents a man with the snake Serpens coiled around his shoulders. To the ancient Greeks he was the god of medicine; the snake represented healing because of its seemingly magical ability to shed its skin as if being reborn.

Constellation boundaries before 1930 were often vague and varied from atlas to atlas. Now they’re precisely mapped with borders like those separating one country from another. Credit: Urania’s Mirror

Before 1930, the Sun passed seamlessly from Scorpius to Sagittarius during its yearly trip through the zodiac constellations. Now it spends 20 days in Ophiuchus between the two. In 1925, Eugene Delporte of the Royal Observatory of Brussels proposed the need for clear, universally-accepted constellation boundaries to the International Astronomical Union (IAU).

Boundaries were vague at the time and depended upon the star atlas you were using. Understandably, this created confusion for astronomers about what was where in the sky. If you discovered a new nova, you needed to let others know if it was in Sagittarius, Scorpius or wherever. Delporte drew up boundaries along existing vertical lines of right ascension (similar to longitude but applied to the sky) and horizontal lines of declination (latitude), extending the realm of Ophiuchus between Scorpius and Sagittarius.

Now the Sun can’t help but cross into Ophiuchus on November 29th. It doesn’t depart and enter Sagittarius until December 19th. A genuine zodiac constellation if I ever saw one, but will it ever get recognized as such? That’s up to Ophiuchians. Fight for your zodiacal rights!

Now let’s go a little further and examine the 12 traditional zodiacal signs.

The 12 traditional zodiac signs are the constellations the Sun appears to pass through during Earth’s yearly orbit around our star. Astrology allots an even one month per constellation. The actual time the Sun spends in each varies according to the size of the constellation.

Your astrological sign is determined by which of the 12 constellations the sun was in on the date of your birth 2,000 years ago. 2,000 years ago? Back when Rome was a world power, the Sun really did pass through Sagittarius from late November to late December. Not anymore. Because of something called precession, it occupies that constellation from December 17th to January 20th. All the other signs are likewise off about a month. So if you’re a Leo like I am, you’re really a Cancer in the 21st century.

Precession is the slow wobble of Earth’s axis over a period of 26,000 years caused by the combined gravitational tugging of the Sun and Moon. Spin a top and watch as it slow down. You’ll notice that the axis of the top describes a little circle (wobble) in the air before eventually tipping over. The Earth’s axis describes a similar circle in the sky. Since the pole star is determined by where our axis points, it follows that the pole star will shift position and change over that long cycle. Right now, Polaris in the Little Dipper sits in the hallowed spot at which our axis points, but in 14,000 A.D., brilliant Vega will occupy the position. Due to the cyclic nature of precession, Polaris will return as the North Star again in 28,000 A.D.

The slow, cyclic wobble of Earth’s axis called precession resembles the motion of a top slowing down. The wobble causes the pole star to change and the Sun to move westward along the zodiac. Credit: Earth and Planetary Magnetism Group ETH-Zurich

The Earth’s wobble also causes the sun to drift westward along the zodiac 1.4 degrees (about three sun diameters or an index finger held at arm’s length) per century. In 2,000 years, that adds up to 28 degrees or about one zodiac constellation width. Astrology practitioners stick with the Sun’s position two millennia ago, causing a disconnect between the Sun’s true position and one’s birth sign.

I’m no believer in astrology, but I think I understand why the practice hasn’t updated astrological signs to current times. Precession never stops. In another 500 years, the Sun’s position vs. the signs will have drifted even farther. It makes sense to adopt one time and stick with it. 2,000 years ago is as good as any.

If you’d like to know what your sign should be now in the 21st century, here’s an update:

Sagittarius: Dec. 17-Jan. 20. Capricornus: Jan. 20-Feb. 16. Aquarius: Feb. 16-March 11. Pisces: March 11-April 18. Aries: April 18-May 13. Taurus: May 13-June 21. Gemini: June 21-July 20. Cancer: July 20-Aug. 10. Leo: Aug. 10-Sept. 16. Virgo: Sept. 16-Oct. 30. Libra: Oct. 30-Nov. 23. Scorpius: Nov. 23-29. Ophiuchus: Nov. 29-Dec. 17

Sun keeps close company with the planets / New color maps of Saturn’s moons

Although not an official conjunction, three planets and the Moon are grouped within about 10 degrees of the Sun today. Except for the Moon, which will move on into the evening sky, the planets will be near the Sun the next few days. Stellarium

Hidden by sunlight today, the New Moon and three planets parade across the sky in the constellations Libra and Scorpius. It’s a big celestial gathering and one of the reasons few planets are visible in the evening sky this month — they’re all too close to the Sun.

Hanging like a dewdrop from a blade of grass, Saturn’s moon Tethys (TEE-thiss) is about 660 miles (1062 km) across and made of mostly ice. The narrow F-ring and wider A-ring cross in front of the moon in this image released last month and taken by the Cassini spacecraft. Credit: NASA/JPL-Caltech/Space Science Institute

Mars escapes the glare and so does Jupiter, which comes up in the east like a spark yellow fire around 11 o’clock. Saturn, east of the Sun, is now in the morning sky though still lost in the solar glare. Let’s stop by that planet and its largest moons today and look at some brand new maps made with NASA’s Cassini orbiter.

Color map of Enceladus. The yellow and magenta colors show differences in the depth of surface deposits. The blue “tiger stripes” in the southern hemisphere, where the moon vents water vapor and other material as geysers, show brightly in ultraviolet light. Researchers think it might be due to large-grained ice exposures. Credit: NASA/JPL-Caltech/Space Science Institute/Lunar and Planetary Institute

With its rings and butterscotch clouds, few planets rival Saturn for beauty, but its moons are equally fascinating for their strange colors, textures and alien features. NASA recently released a series of global, color mosaics of six of its largest moons based on 10 years of images taken by NASA’s Cassini spacecraft as it orbited the Saturn system. These are the first global color maps of these moons produced from the Cassini data. The colors are broader than what the human eye sees, extending into the ultraviolet and infrared (beyond red) part of the spectrum. They’re also VERY detailed – just click on any of them for a close-up. I’ve included four of the six. To see them all, click HERE.

Iapetus (eye-APP-eh-tuss) looks very strange with one hemisphere bright and icy and the other covered in about a foot of darker material. Iapetus rotates very slowly – once every 79 days. It’s thought that an impact of a darker object long ago coated part of  its surface, causing that area to absorb more sunlight over the long day. More heat meant more ice vaporized which then re-condensed as frost/ice on the moon’s bright side, further concentrating the darker material. This expanded in a positive feedback loop that eventually led to an ever-whitening hemisphere while the other grew blacker. Credit: NASA/JPL-Caltech/Space Science Institute/Lunar and Planetary Institute

On Tethys, scientists think the dark colors of the moon’s trailing hemisphere are due to changes in ice and minerals caused by bombardment from high-speed particles and radiation in Saturn’s powerful magnetic field. The lighter-colored leading hemisphere is coated with icy dust from Saturn’s E-ring, formed from tiny particles ejected from Enceladus’ south polar geysers. The purplish equatorial band gets its color from high-energy electrons in Saturn’s magnetic field slamming into the moon. Credit: NASA/JPL-Caltech/Space Science Institute/Lunar and Planetary Institute

Meet Dione, a 698-mile-wide moon. Its color variations are believed to be caused by the same factors affecting Tethys – radiation and high-speed particles weathering the trailing hemisphere ice and the effects of icy mist spewed by Enceladus on the leading hemisphere. Credit:  NASA/JPL-Caltech/Space Science Institute/Lunar and Planetary Institute