Skywatching Archives

January 14, 2015December 23, 2015 by David Dickinson

Challenge Yourself! See an Astronomical Event that Only Happens Once Every 26 Years

This artist’s impression shows an eclipsing binary star system. Credit: ESO/L. Calçada.

Update: It’s off. This past weekend, the AAVSO issued Special Notice #395 calling off the campaign to observe Alpha Comae Berenices this month due to “position measurements published a century ago (which) contained errors that affected the predictions for the time of eclipse…”

And the mystery of Alpha Comae Berenices continues. Oh well. Such is the wiles and whims of the universe, and the exciting field of variable star observing!

A truly fascinating event may be in the offing this month.

Picture two distant burning embers (candles, light bulbs, LEDs, what have you) circling each other in the distance. From our far-flung vantage point, the two points of light are too faint to resolve individually, but as they pass in front of each other, a telltale dip in combined brightness occurs as one blocks out the other.

Welcome to the fascinating world of eclipsing binary stars. This week, we’d like to turn our attention towards a special star in the constellation of Coma Berenices which may — or may not — put on such a dimming act later this month.

An Alpha Comae Berenices (Diadem) finder chart, with comparison stars and magnitudes, decimals omitted. Credit: Starry Night Education Software.

The brightest star in the constellation Coma Berenices, Alpha (sometimes referred to as Diadem, or the ‘crown’ of Queen Berenice) shines at an apparent magnitude of +4.3. Located 63 light years distant, the system consists of two +5^th magnitude F-type stars each about 3 times more luminous than our Sun locked in a 26 year orbital embrace. The physical separation of the pair is about 10 astronomical units: place Alpha Comae Berenices in our solar system, and the pair would fit nicely between the Sun and Saturn.

The orbital plane of the pair is inclined nearly along our line of sight as seen from the Earth, and it’s long been thought that catching a grazing or central eclipse of the pair might just be possible. No eclipse was recorded last time ‘round back in February 1989, but times have changed lots in observational astronomy. Today, there are enough backyard observers armed with dedicated observatories and rigs that’d be the envy of a small university that documenting such an eclipse might just be possible. In fact, a central eclipse might just dim the star by 0.8 magnitudes, and should be noticeable to the naked eye.

The binary nature of Alpha Comae Berenices was first noted by F. G. W. Struve in 1827, and the split is a challenging one during the best of years with a maximum angular separation of just 0.7 arc seconds. The pair also has a third faint +10th magnitude companion located about 89 arc seconds away.

Simplified — A simplified diagram depicting an eclipsing binary event along our line of sight. Created by the author.

The American Association of Variable Star Observers (AAVSO) has an Alert Notice calling for sky watchers worldwide to monitor the star. We also understand the orbit of Alpha Comae Berenices much better in 2015 than back in 1989, and the suspected eclipse should occur somewhere between January 22^nd and January 28^th and may last anywhere from 28 to 45 hours. This lingering ambiguity means that having a dedicated team of observers worldwide may well be key to nabbing this eclipse.

Bootes-Labeled — Alpha Comae Berenices rising. Photo by the author.

The Navy Precision Optical Interferometer (NPOI) has already begun refining measurements of the brightness of the star last month, and professional facilities, to include the Fairborn Observatory atop Mt Hopkins in Arizona and the CHARA (the Center for High Angular Resolution Astronomy) Array at Mount Wilson Observatory in southern California will also be monitoring the event.

Sky and Telescope magazine also has an excellent article in their January 2015 issue on the prospects for catching this eclipse.

Looking eastward past local midnight. Credit: Stellarium.

In late January, the constellation of Coma Berenices rises high to the northeast just after local midnight. It’s worth noting that, if the eclipsing binary nature of Alpha Comae Berenices is confirmed, it would be the longest period known, beating out 14.6 year Gamma Persei discovered in 1990 by more than a decade. A system with as wide a separation as Alpha Comae Berenices would have about a 1 in 1,200 chance in eclipsing along our line of sight due to random chance.

Note: Epsilon Aurigae does have a comparable 27 year period involving a debris disk surrounding its host star. Thanks to sharp-eyed reader Dr. John Barentine for pointing this out!

Of course, the universe does provide us with lots of near misses, allowing for an ‘occasional Diadem’ to indeed occur. Most famous eclipsing variables, such as Algol or Beta Lyrae have periods measured over the span of days or hours. Incidentally, these also make great ‘practice stars’ to test your skills as a visual athlete leading up to the big event next week. A skilled visual observer can note a change as slight as a 0.1 of a magnitude, and it’s a good idea to begin familiarizing yourself with the environs of the star now. The Coma Cluster of galaxies, the globular cluster M53, and the galactic plane crossing intruder Arcturus all lie nearby.

The Coma Cluster as seen by Spitzer Space Telescope and the Sloan Digital Sky Survey. Credit: NASA/Spitzer.

Why study eclipsing binaries? Well, said fleeting mutual events when coupled with spectroscopic measurements and determinations of parallax can tell us a good deal about the astrophysical nature of the stars involved. Eclipsing binary stars have even been used to back up standard candle measurements over extragalactic distances. And of course, orbiting observatories such as Kepler and TESS (to be launched in 2017) look for transiting exoplanets using virtually the same method.

Credit: Brad Timerson. — Have a scope+DSLR? Then you can make refined measurements of eclipsing variable stars. Credit: Brad Timerson/IOTA.

But beyond its practical application, we just think that it’s plain cool that you can actually see something out beyond our solar system changing in the span of just a few days or hours.

Observers also still carry out visual observations of variable stars, just like those pipe-smoking, pocket watch carrying astronomers of yore. This involves merely comparing the target star to nearby stars of the same brightness. If you have a DSLR or a CCD rig plus a telescope, the AAVSO also has instructions for how to monitor a star’s brightness as well. No pocket watch required.

A homemade interferometer used to measure the separation of close double stars. — A homemade ‘card interferometer’ used to measure the separation of close double stars. Photo by author.

Unless, of course, you want to carry a pocket watch just for good luck. Don’t let the cold January winters keep you from joining the hunt. Let’s make some astrophysical history!

January 10, 2015December 23, 2015 by Bob King

How to Find and Make the Most of Comet Lovejoy

This photo map shows Comet Lovejoy's nightly position among the winter stars through January 19th as it travels across the constellation Taurus not far from Aldebaran and the Pleiades star cluster. Click to enlarge. Credit: Bob King

Comet Q2 Lovejoy passed closest to Earth on January 7th and has been putting on a great show this past week. Glowing at magnitude +4 with a bluish coma nearly as big as the Full Moon, the comet’s easy to see with the naked eye from the right location if you know exactly where to look. I wish I could say just tilt your head back and look up and bam! there it would be, but it’ll take a little more effort than that. But just a little, I promise.

Comet Lovejoy and its spectacular "lively" ion tail photographed on January 8th by Nick Howes at Tzec Muan Network at Siding Spring Australia — Comet Lovejoy and its spectacular “lively” ion tail photographed on January 8th by Nick Howes at Tzec Muan Network at Siding Spring Australia

Last night, under a dark rural sky, once I spotted the comet and noticed its position in relation to nearby bright stars, I could look up and see it anytime. Finding anything other than the Moon or a bright planet in the night sky often requires a good map. I normally create a star-chart style map but thought, why not make a photographic version? So last night I snapped a few guided images of Lovejoy as it glimmered in the wilds of southern Taurus and then cloned the comet’s nightly position through onto the image. Maybe you’ll find this useful, maybe not. If not, the regular map is also included.

Comet Lovejoy position is shown for each night tonight through January 23rd. The comet should remain in the 4-5 magnitude range throughout. Click for a larger map you can print out and use outdoors. Click to enlarge and print for use outdoors. Source: Chris Marriott’s SkyMap software — Comet Lovejoy’s position is shown for each night tonight through January 23rd. The comet should remain in the 4-5 magnitude range throughout. Lovejoy is currently high in the southeastern sky at nightfall and crosses the meridian due south around 9 o’clock local time. Click for a larger map you can print out and use outdoors. Source: Chris Marriott’s SkyMap software

To see Comet Lovejoy with the naked eye you’ll need reasonably dark skies. It should be faintly visible from outer ring suburbs, but country skies will guarantee a sighting. I’ve been using bright stars in Orion and Taurus to guide binoculars – and then my eye – to the comet. Pick a couple 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. If you don’t find it immediately, sweep around the position a bit. After you find it, lower the binoculars and try to spot it with the naked eye.

Comet Lovejoy last night January 9th around 8 p.m. (CST) shows a bright coma and faint ~1.5-degree-long tail. This photo, made with a 200mm lens, gives a good idea of what the comet looks like in 50mm binoculars. Details: f/2.8, ISO 800, 2-minute exposure. Credit: Bob King

This week, as Lovejoy continues trekking north, you can use bright orangey Aldebaran in Taurus and the Pleiades, also called the Seven Sisters star cluster, to “triangulate” your way to the comet. Look for a glowing fuzzball. In 10×50 and 8×40 binoculars, it’s obviously different from a star — all puffed up with a brighter center. The 50mm glass even shows a hint of the coma’s blue color caused by carbon molecules fluorescing in ultraviolet sunlight and a faint, streak-like tail extending to the northeast. With the naked eye, at first you might think it’s just a dim star; closer scrutiny reveals the star has a hazy appearance, pegging it as a comet.

Comet Lovejoy sketches from last night made using a 15-inch telescope. The coma is big - almost a half-degree across. The drawing shows the bright nuclear region and tiny "false nucleus". At right, a suspected plume extends to the southwest of the false nucleus. Color is how the comet really looks in the telescope. Credit: Bob King — Comet Lovejoy sketches from last night made using a 15-inch telescope. The coma is big – almost a half-degree across. The drawing shows the bright nuclear region and tiny “false nucleus”. At right, a suspected plume extends to the southwest of the false nucleus. Color is how the comet really looks in the telescope. South is up. Credit: Bob King

Through a telescope the coma is a HUGE pale blue tiki lamp of a thing with a small, much brighter nuclear region. The rays of the ion tail, so beautifully shown in photographs, are indistinct but visible with patience and a moderate-sized telescope under dark skies. At low magnification, the nucleus – the false nucleus actually, since the real comet nucleus is hidden by a shroud of dust and gas – looks like a misty star of about magnitude +9. On close inspection at high magnification (250x and up), you penetrate more deeply into the nuclear zone and the star-like center shrinks and dims to around magnitude +13.

Fascinating plumes of dust recorded by Gianluca Masi on January 6th. South is up, west to the left. Credit: Gianluca Masi

If the seeing is good and comet active, high magnification will often reveal jets or fans of dust in the sunward direction, in this case west of nucleus. I’ve been studying the comet the past couple nights and am almost convinced I can see a short, very low contrast plume poking to the south of center. Generally, plumes and jets are subtle, low-contrast features. Challenging? Yes, but with Lovejoy as close as it’s going to get, now’s the time to seek them.

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 — 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. A new one quickly grows to replace the old. Credit: Rolando Ligustri

Just before Christmas, fluctuations in the solar wind snapped off Comet Lovejoy’s tail. Guess what? It happened again on January 8th as recorded in dramatic fashion by astrophotographer Rolando Ligustri. 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.

Of course, the comet didn’t miss a breath but grew another tail immediately. Look closely at the photo and you see another faint streak of light pointing beyond the coma below and left of the bright nuclear region. This may be Lovejoy’s dust tail. Most comets sport both types of tails – gas and dust – since they release both materials as the Sun heats and vaporizes their ices.

Lovejoy’s been a thrill to watch because it’s doing all the cool stuff that makes them so fun to follow. Gianluca Masi, an Italian astrophysicist and lover of all things cometary, will offer a live feed of the comet on Monday January 12th starting at 1 p.m. CST (7 p.m. UT). May your skies be clear tonight!

January 10, 2015December 23, 2015 by Bob King

Mercury and Venus an Awesome Duo at Dusk

You couldn't miss Mercury and Venus together last night January 9th 45 minutes after sunset in the southwestern sky. Very easy to see! They'll be even closer tonight. Credit: Bob King

As Universe Today’s Dave Dickinson described earlier this week not only has Venus returned to the evening sky, but Mercury has climbed up from the horizon to join it. Last night (Jan. 9th) the two planets were separated by just a hair more than one Moon diameter. The photo only hints at amazingly easy the pair was to see. Consider the duo a tasty hors d’oeuvres before the onset of night and the Comet Lovejoy show.

Tonight the duo will be at their closest and remain near one another for the next week or so. This is one of Mercury’s best apparitions of the year for northern hemisphere skywatchers and well worth donning your winter uniform of coat, boots, hat and thick gloves for a look. Just find a location with a decent view of the southwestern horizon and start looking about a half hour after sunset. Mercury and Venus will be about 10° or one fist held at arm’s length high above the horizon.

Through a telescope both Venus and Mercury are in gibbous phase with Venus more fully filled out. Both are also very small with Venus about 10 arc seconds and Mercury 6 seconds across. Source: Stellarium — Through a telescope both Venus and Mercury are in gibbous phase with Venus more fully filled out. Both are very small with Venus about 10 arc seconds in diameter and Mercury 6 seconds. Source: Stellarium

Venus will jump right out. Mercury’s a couple magnitudes fainter and lies to the right of the goddess planet. By 45 minutes after sunset, Mercury gets even easier to see. Find your sunset time HERE so you can best plan your outing.

Mark your calendars for a cool conjunction of the 1-day-old lunar crescent, Mercury and Venus on January 21st. Source: Stellarium

Because both planets are still fairly low in the sky and far away, they present only tiny, blurry gibbous disks in the telescope. Later this spring, Venus will climb higher and show its changing phases more clearly. Keep watch the coming week to catch the ever-shifting positions of Venus and Mercury in the evening sky as each follows the binding arc of its own orbit. The grand finale occurs on January 21st when a skinny crescent Moon joins the duo (Mercury now fading) for a triumphant trio. Has this been an exciting month or what?

January 5, 2015December 23, 2015 by David Dickinson

Catch Mercury Brushing Past Venus in a Spectacular Dusk ‘Quasi-Conjunction’ This Week

Missing Venus? The third brightest natural object in the heavens returns to prime time dusk skies in 2015 after being absent and lingering in the dawn for most of 2014. But there’s another reason to hunt down the Cytherean world this week, as elusive Mercury chases after it low in the dusk. If you’ve never seen Mercury for yourself, now is a great time to try, using brilliant Venus as a guide.

The circumstances surrounding this pairing are intriguing. We have to admit, we missed this close conjunction whilst filtering through research for the Top 101 Astronomical Events for 2015 due to those very same unique attributes until an astute reader of Universe Today pointed it out.

December 31st Bob King — Venus and Mercury setting over the Duluth, Minnesota skyline on December 31st. Credit and copyright: Bob King.

On the evening of January 5^th, Venus shines at magnitude -3.3 and sits about 18 degrees east of the Sun in dusk skies. You’ll have a narrow window of opportunity to nab Venus, as it’ll sit only 10 degrees above the southwestern horizon as seen from latitude 40 degrees north about an hour after sunset. Make sure you have a clear, uncluttered horizon, and start sweeping the field with binoculars about half an hour after sunset.

Do you see a tiny point of light about a degree and a half to Venus’s lower right? That’s Mercury, just beginning its first dusk apparition of seven for 2015, the most possible in a calendar year. Shining at -0.7 magnitude, Mercury is currently about 8 times fainter than Venus, and drops to +1.4 magnitude by late January.

If you watch the pair on successive evenings, you’ll see Mercury — aptly named after the fleet-footed Roman god — racing to rapidly close the gap. Mercury crosses the one degree separation threshold from January 8^th through January 12^th, and sits just 39’ — slightly larger than the apparent size of the Full Moon — right around 7:00 PM EST/Midnight Universal Time on January 10^th, favoring dusk along eastern North America just a few hours prior.

Credit Jose — Venus and Mercury as seen from Venezuela on January 2nd. Credit and copyright: Jose Rozada.

This also means that you’ll be able to squeeze both Mercury and Venus into the same low power telescopic field of view. They’ll both even show the same approximate gibbous phase, with Venus presenting a 10.5” sized 95% illuminated disk, and Mercury subtending 6” in apparent diameter with a 74% illuminated visage. Venus will seem to be doing its very own mocking impersonation of the Earth, appearing to have a single large moon… Neith, the spurious pseudo-moon of Venus lives!

One curious facet of this week’s conjunction is the fact that Venus and Mercury approach, but never quite meet each other in right ascension. We call such a near miss a “quasi-conjunction.” This is the closest pairing of Venus and Mercury since 2012, though you have to go all the way back to 2005 for one that was easily observable, and the last true quasi-conjunction was in October 2001. Miss this week’s event, and you’ll have to wait until May 13^th 2016 to catch Mercury — fresh off of transiting the Sun a week earlier — passing just 26’ from Venus only 6.5 degrees west of the Sun. This is unobservable from your backyard, but SOHO’s LASCO C3 camera’s 15 degree wide field of view will have a front row cyber-seat.

Venus 2015 — The dusk path of Venus through early 2015. Credit: Starry Night Education software.

In 2015, Venus will become ever more prominent in the dusk sky before reaching greatest elongation 45.4 degrees east of the Sun on June 6^th, 2015. The angle of the January ecliptic at dusk is currently shoving Mercury and Venus southward for northern hemisphere observers, though that’ll change dramatically as we head towards the March equinox. Venus reaches solar conjunction sans transit (which last occurred in 2012 and won’t happen again til 2117 A.D.) on August 15^th before heading towards its second elongation of 2015 on October 26^th in the dawn sky. And don’t forget, it’s possible to see Venus in the daytime as it approaches greatest elongation. Venus is also occulted by the Moon 4 times in 2015, including a fine daytime occultation on December 7^th for North America.

The path of Mercury through January 2015. Credit: Starry Night Education software.

This month, Mercury reaches greatest eastern elongation on January 14th at 18.9 degrees east of the Sun. Mercury begins retrograde movement later this month — one of the prime reasons this week’s conjunction is quasi — before resuming direct (eastward) motion as seen from our terrestrial vantage point. Though it may seem convenient to blame your earthly woes on Mercury in retrograde as astrologers will have you believe, this is just an illusion of planetary orbital motion. And speaking of motion, Mercury transits the Sun next year on May 9th.

John Barantine — Venus and Mercury as seen from Tucson, Arizona on January 3rd. Credit and copyright: John Barentine (@JohnBarentine)

Mercury and Venus factor in to space exploration in 2015 as well. NASA’s MESSENGER spacecraft wraps up its successful mission in orbit around Mercury in a few months, and the Japanese Space Agency takes another crack at putting its Akatsuki spacecraft in orbit around Venus this coming November.

So don’t fear the bone-chilling January temps (or Mercury in retrograde) but do get out there these coming evenings and check out the fine celestial waltz being performed by the solar system’s two innermost worlds.

January 2, 2015December 23, 2015 by David Dickinson

Finding Lovejoy: How to Follow the Path of Comet 2014 Q2 Through January

A splendid capture of comet Q2 Lovejoy as it passes near M79 at the end of 2014. Credit and copyright: Andre van der Hoeven.

Have you seen the amazing pics? A bright comet graces evening skies this month, assuring that 2015 is already on track to be a great year for astronomy.

We’re talking about Comet C/2014 Q2 Lovejoy. Discovered by comet hunter extraordinaire Terry Lovejoy on August 17^th, 2014, this denizen of the Oort Cloud has already wowed observers as it approaches its passage perihelion through the inner solar system in the coming week.

First, our story thus far. We’ve been following all Comet Q2 Lovejoy action pretty closely here at Universe Today, from its surreptitious brightening ahead of schedule, to its recent tail disconnection event, to its photogenic passage past the +8.6 magnitude globular cluster Messier 79 (M79) in the constellation Lepus. We also continue to be routinely blown away by reader photos of the comet. And, like the Hare for which Lepus is named, Q2 Lovejoy is now racing rapidly northward, passing into the rambling constellation of Eridanus the River before entering the realm of Taurus the Bull on January 9^th and later crossing the ecliptic plane in Aries.

Credit: Starry Night — The path of Comet Q2 Lovejoy from January 2nd to the 31st. Ticks mark the position of the comet at 7PM EST/midnight Universal Time. Credit: Created using Starry Night Education software.

And the best window of opportunity for spying the comet is coming right up. We recently caught our first sight of Q2 Lovejoy a few evenings ago with our trusty Canon 15x 45 image-stabilized binocs from Mapleton, Maine. Even as seen from latitude 47 degrees north and a frosty -23 Celsius (-10 Fahrenheit) — a far cry from our usual Florida based perspective — the comet was an easy catch as a bright fuzz ball. Q2 Lovejoy was just outside of naked eye visibility for us this week, though I suspect that this will change as the Moon moves out of the evening picture this weekend.

Currently shining at magnitude +5.5, Comet Q2 Lovejoy has already been spied by eagle-eyed observers unaided from dark sky sites to the south. Astrophotographers have revealed its long majestic dust and ion tails, as well as the greenish hue characteristic of bright comets. That green color isn’t kryptonite, but the fluorescing of diatomic carbon and cyanogen gas shed by the comet as it’s struck by ultraviolet sunlight. This greenish color is far more apparent in photographs, though it might just be glimpsed visually if the intrinsic brightness of the coma exceeds expectations. Q2 Lovejoy just passed opposition at 0.48 AU from the Earth today on January 2^nd, and will make its closest passage from our fair world on January 7th at 0.47 AU (43.6 million kilometres) distant.

Comet Q2 Lovejoy via Iphone (!) and a NexStra 8SE telescope. Credit and copyright: Andrew Symes.

What’s so special about the coming week? Well, we also cross a key milestone for evening observing, as the light-polluting Moon reaches Full phase on Sunday January 5^th at 4:54 UT (11:54 PM EDT on the 4^th) and begins sliding out of the evening sky on successive evenings. That’s good news, as Comet Q2 Lovejoy enters the “prime time” evening sky and culminates over the southern horizon at around 10:30 PM local this weekend, then 8:00 PM on January the 15^th, and just before 6:00 PM by January 31^st.

While many comets put on difficult to observe dusk or dawn appearances — the 2013 apparition of another comet, C/2011 L4 PanSTARRS comes to mind — Q2 Lovejoy is well placed this month in the early evening hours.

The current projected peak brightness for Comet Q2 Lovejoy is +4th magnitude right around mid-January. Already, the comet is bright enough and well-placed to the south for northern hemisphere observers that it’s possible to catch astrophotos of the comet along with foreground objects. If you’ve got a tripod mounted DSLR give it a try… it’s as simple as aiming, focusing manually with a wide field of view, and taking 10 to 30 second exposures to see what turns up. Longer shots will call for sky tracking via a barn-door or motorized mount. Binoculars are you friend in your comet-hunting quest, as they can be readily deployed in sub-zero January temps and provide a generous field of view.

Q2 Lovejoy will also pass near the open clusters of the Hyades and the Pleiades through mid-January, and cross into the constellations of Aries and Triangulum by late January before heading northward to pass between the famous Double Cluster in Perseus and the Andromeda Galaxy M31 in February, proving further photo ops.

A comet hung up among the winter trees... Credit and Copyright: Per/Kam75 — A comet hung up among the winter trees… Credit and Copyright: Per/Kam75

From there, Q2 Lovejoy is expected to drop below naked eye visibility in late February before passing very near the North Star Polaris and the northern celestial pole at the end of May on its way out of the inner solar system on its 8,000 year journey.

So, although 2014 didn’t produce the touted “comet of the century,” 2015 is already getting off to a pretty good start in terms of comets. We’re out looking nearly every clear night, and the next “big one” could always drop by at anytime… but hopefully, the first discovery baring the name “Comet Dickinson” will merely put on a spectacular show, and not prove to be an extinction level event…

A green New Year's Eve comet. Credit and Copyright: Roger Hutchinson. — A green New Year’s Eve comet. Credit and Copyright: Roger Hutchinson.

– Got images of Comet Q2 Lovejoy? Send ‘em in to Universe Today.

– Up late looking for comets? Be sure to also check out the Quadrantid meteors this weekend.

-What other comets offer good prospects in 2015? Check out our Top 101 Events for the Year.

December 30, 2014December 23, 2015 by Bob King

End the Year with a Bang! See a Bright Supernova in Virgo

The bright supernova (at tick marks) in the galaxy NGC 4666 photographed on December 24, 2014. Credit: Gregor Krannich

A 14th magnitude supernova discovered in the spiral galaxy NGC 4666 earlier this month has recently brightened to 11th magnitude, making it not only the second brightest supernova of the year, but an easy find in an 8-inch or larger telescope. I made a special trip into the cold this morning for a look and saw it with ease in my 10-inch (25-cm) scope at low power at magnitude 11.9.

Before the Moon taints the dawn sky, you may want to bundle up and have a look, too. The charts below will help you get there.

NGC 4666 is also known as the Superwind Galaxy. Home to vigorous star formation, a combination of supernova explosions and strong winds from massive stars in the starburst region drives a vast outflow of gas from the galaxy into space, a so-called “superwind”. Credit: ESO/J. Dietrich — NGC 4666 is also known as the Superwind Galaxy. Home to vigorous star formation, a combination of supernova explosions and strong winds from massive stars in the starburst region drives a vast outflow of gas from the galaxy into space, called a “superwind”. Credit: ESO/J. Dietrich

With the temporary name ASASSN-14lp, this Type Ia supernova was snatched up by the catchy-titled “Assassin Project”, short for Automated Sky Survey for SuperNovae (ASAS-SN) on December 9th. Only 80 million light years from Earth, NGC 4666 is a relatively nearby spiral galaxy famous enough to earn a nickname.

Extra-planar soft X-ray emitting hot gas is observed above the most actively star-forming regions in the galactic disk of NGC 4666 and coexists together with filaments of the warm ionized medium, cosmic rays and vertical magnetic field structures channelling (or following) the outflow. Credit: M. Ehle and ESO — Hot, X-ray emitting gas in NGC 4666 billows around the main galaxy as a superwind seen here as outflows on either side of the optical image. Photo taken with the XMM-Newton telescope. Credit: M. Ehle and ESO

Called the Superwind Galaxy, it’s home to waves of intense star formation thought to be caused by gravitational interactions between it and its neighboring galaxies, including NGC 4668, visible in the lower left corner of the photo above.

Supernovae also play a part in powering the wind which emerges from the galaxy’s central regions like pseudopods on an amoeba. X-ray and radio light show the outflows best. How fitting that a bright supernova should happen to appear at this time. Seeing one of the key players behind the superwind with our own eyes gives us a visceral feel for the nature of its home galaxy.

Wide view map showing the location of the galaxy NGC 4666 in Virgo not far from Porrima or Gamma Virginis. This map shows the sky facing south shortly before the start of dawn in early January. Source: Stellarium — “Big picture” map showing the location of the galaxy NGC 4666 in Virgo not far from Porrima. The view faces south shortly before the start of dawn in early January. Source: Stellarium

Spectra taken of ASASSN-14lp show it to be a Type Ia object involving the explosive burning of a white dwarf star in a binary system. The Earth-size dwarf packs the gravitational might of a sun-size star and pulls hydrogen gas from the nearby companion down to its surface. Slowly, the dwarf gets heavier and more massive.

When it attains a mass 1.4 times that of the sun, it can no longer support itself. The star suddenly collapses, heats to incredible temperatures and burns up explosively in a runaway fusion reaction. Bang! A supernova.

Detailed map with stars to about magnitude 10. The galaxy is just a little more than a degree northeast of Porrima (Gamma Virginis). Source: Stellarium

Here are a couple maps to help you find the new object. Fortunately, it’s high in the sky just before the start of dawn in the “Y” of Virgo only a degree or so from the 3rd magnitude double star Porrima, also known as Gamma Virginis. Have at it and let us know if you spot the latest superwind-maker.

For more photos and magnitude updates, check out Dave Bishop’s page on the supernova. You can also print a chart with comparison magnitudes by clicking over to the AAVSO and typing in ASASSN-14lp in the “name” box.

December 30, 2014December 23, 2015 by David Dickinson

Work Those Quads: Our Guide to the 2015 Quadrantid Meteors

Don't fear the moonlight... Credit and copyright: John Chumack.

Quick… what’s the only major meteor shower named after a defunct constellation? If you said the January Quadrantids, you’d be correct, as this often elusive but abrupt meteor shower is set to peak this coming weekend early in 2015.

And we do mean early, as in the night of January 3^rd going into the morning of January 4^th. This is a bonus, as early January means long dark nights for northern hemisphere observers. But the 2015 Quadrantids also has two strikes going against them however: first, the Moon reaches Full just a day later on January 5^th, and second, January also means higher than average prospects for cloud cover (and of course, frigid temps!) for North American observers.

Jan 4th 3AM local. Starry Night Education Software. — The rising radiant of the Quads on the morning of January 4th at 3AM local. Note that the Moon and Jupiter are on the scene as well. Created using Starry Night Education software.

Don’t despair, however. In meteor shower observing as in hockey, you miss 100% of the shots that you don’t take.

Sorry for the sports analogy. The radiant for the Quadrantids is located in the modern day constellation of Draco near the Hercules-Boötes border at a right ascension 15 hours, 18 minutes and declination +49.5 degrees north. This puts it very near the +3.3 magnitude star Iota Draconis (Edasich).

Quads 2UT. Credit: Orbitron — The orientation of the Earth’s shadow at the predicted peak of the Quads on January 4th, 2:00 UT. Credit: Orbitron.

In 2015, bets are on for the Quadrantids to peak centered on 2:00 UT January 4^th (9:00 PM EST on the 3rd), favoring northern Europe pre-dawn. The duration for the Quadrantids is short lived, with an elevated rate approaching 100 per hour lasting only six hours in duration. Keep in mind, of course, that it’ll be worth starting your vigil on Saturday morning January 3^rd in the event that the “Quads” kick off early! I definitely wouldn’t pass up on an early clear morning on the 3^rd, just in case skies are overcast on the morning of the 4^th…

Due to their high northern radiant, the Quadrantids are best from high northern latitudes and virtually invisible down south of the equator. Keep in mind that several other meteor showers are active in early January, and you may just spy a lingering late season Geminid or Ursid ‘photobomber’ as well among the background sporadics.

Avast: ye ole Mural Quadrant spied at the Columbia River Maritime Museum in Astoria, Oregon. Photo by author.

Moonset on the morning of the 4^th occurs around 6 AM local, giving observers a slim one hour moonless window as dawn approaches. Blocking the Moon out behind a building or hill when selecting your observing site will aid you in your Quadrantid quest.

Antonio Brucalassi made the first historical reference to the Quadrantids, noting that “the atmosphere was traversed by… falling stars” on the morning of January 2^nd, 1825. It’s interesting to note that the modern day peak for the Quads has now drifted a few days to the fourth, due mostly to the leap year-induced vagaries of our Gregorian calendar. The early January meteor shower was noted throughout the 19^th century, and managed to grab its name from the trendy 19^th century constellation of Quadrans Muralis, or the Mural Quadrant. Hey, we’re lucky that other also-rans, such as Lumbricus the ‘Earthworm’ and Officina Typograhica the ‘Printing Office’ fell to the wayside when the International Astronomical Union formalized the modern 88 constellations in 1922. Today, we know that the Quadrantids come from 2003 EH₁, which is thought to be an extinct comet now trapped in the inner solar system on a high inclination, 5.5 year orbit. Could 2003 EH₁ be related to the Great Comet of 1490, as some suggest? The enigmatic object reached perihelion in March of 2014, another plus in the positive column for the 2015 Quads.

What the heck is a Mural Quadrant? Like everything he did, Tycho Brahe super-sized his quadrant, depicted here. Credit: Wikimedia Commons.

Previous years for the Quadrantids have yielded the following Zenithal Hourly Rate (ZHR) maximums as per the International Meteor Organization:

2011= 90

2012= 83

2013= 137

2014= +200

The Quadrantid meteor stream has certainly undergone alterations over the years as a result of encounters with the planet Jupiter, and researchers have suggested that the shower may go the way of the 19^th century Andromedids and become extinct entirely in the centuries to come.

Don’t let cold weather deter you, though be sure to bundle up, pour a hot toddy (or tea or coffee, as alcohol impacts the night vision) and keep a spare set of batteries in a warm pocket for that DSLR camera, as cold temps can kill battery packs quicker than you can say Custos Messium, the Harvest Keeper.

And though it may be teeth-chatteringly cold where you live this weekend, we actually reach our closest point to the Sun this Sunday, as Earth reaches perihelion on January 4th at around 8:00 UT, just 5 hours after the Quads are expected to peak. We’re just over 147 million kilometres from the Sun at perihelion, a 5 million kilometre difference from aphelion in July. Be thankful we live on a planet with a relatively circular orbit. Only Venus and Neptune beat us out in the true roundness department!

…and no, you CAN’T defy gravity around perihelion, despite the current ill conceived rumor going ‘round ye ole net…

And as a consolation prize to southern hemisphere observers, the International Space Station reaches a period of full illumination and makes multiple visible passes starting December 30^th until January 3^rd. This happens near every solstice, with the December season favoring the southern hemisphere, and June favoring the northern.

2003 Credit and Copyright: Frankie Lucena. — A 2003 south bound Quad nabbed from Cabo Rojo, Puerto Rico (Yes, that’s the Southern Cross!) Credit and Copyright: Frankie Lucena.

So don’t let the relatively bad prospects for the 2015 Quadrantids deter you: be vigilant, report those meteor counts to the IMO, send those meteor pics in to Universe Today and tweet those Quads to #Meteorwatch. Let’s “party like it’s 1899,” and get the namesake of an archaic and antiquated constellation trending!

December 29, 2014December 23, 2015 by Bob King

Put Yourself in the Way of Beauty

Comet C/2014 Q2 Lovejoy photographed overnight December 28-29, 2014 remotely from Siding Spring, Australia as passed within 1/6 degree of the globular cluster M79. The coma glows green from fluorescing carbon molecules while the narrow ion tail is carbon monoxide gas fluorescing in UV sunlight. Credit: Rolando Ligustri

Oh my, oh my. Rolando Ligustri captured this scene last night as Comet Q2 Lovejoy swished past the globular cluster M79 in Lepus. If you’ve seen the movie Wild or read the book, you’ll be familiar with the phrase “put yourself in the way of beauty”, a maxim for living life adopted by one of its characters. When I opened up my e-mail today and saw Rolando’s photo, I felt like the beauty truck ran right over me.

Another striking image of the comet's juxtaposition with the globular cluster M79. Lovejoy is presently 48 million miles from Earth; the cluster shines from the immense distance of 410,000 light years. Credit: Chris Schur — Another striking image of the comet’s juxtaposition with the globular cluster M79. Lovejoy is presently 48 million miles from Earth; the cluster lies at the immense distance of 41,000 light years. Credit: Chris Schur

More beautiful images arrived later including this one by Chris Schur of Arizona.

Even with the Moon at first quarter phase, the comet was plainly visible in binoculars last night shining at magnitude +5. I used 8x40s and had no problem seeing Lovejoy’s blobby glow. With a coma about 15-20 arc minutes in diameter or more than half the size of a the Full Moon, it really fills up the field of view when seen through a telescope at low to medium magnification.

A tighter view of the top image shows not only the star cluster but also shows 13th magnitude NGC 1886, an edge-on spiral galaxy. Credit: Rolando Ligustri

If you love the aqua blue hues of the Caribbean, Lovejoy will remind you it’s time to book another tropical vacation. In both my 15-inch (37-cm) and 10-inch (25-cm) reflectors, the coma glowed a delicious pale blue-green in contrast to the pearly white cluster. I encourage you to look for the comet in the next few nights before the Moon is full. Starting on January 6-7, the Moon begins its move out of the evening sky, giving observers with dark skies a chance to view Lovejoy with the naked eye. I’m looking forward to seeing its long, faint tail twist among the stars of Eridanus as the comet rapidly moves northward over the next week.

Using Photoshop I made this drawing of the comet and cluster that captures its visual appearance through the telescope. Credit: Bob King — Using Photoshop I made this drawing of the comet and cluster that captures its visual appearance through the telescope last night December 28th. The nuclear region is very intense and bright and about 10 arc seconds across. Credit: Bob King

For a map on how to find the comet, check my recent article on Lovejoy’s many tails. Cheers to finding beauty the next clear night!

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

December 28, 2014December 23, 2015 by Bob King

Half-Moon Makes Dramatic Pass at Uranus Tonight

The half-moon creeps up on the planet Uranus this evening. The two will be near each other all night in the constellation Pisces, but closest - less than one-third of a moon diameter apart - just before midnight (CST). The views are what you'll see in a pair of binoculars. The 4th magnitude star Delta Piscium is at top in the field. Source: Stellarium

Sunlight. Moonlight. Starlight. I saw all three for the first time in weeks yesterday. Filled with photons, I feel lighter today, less burdened. Have you been under the clouds too? Let’s hope it’s clear tonight because there’s a nice event you’ll want to see if only because it’s so effortless.

The half-moon will pass very close to the planet Uranus for skywatchers across North America this evening Sunday, Dec. 28th. Pop the rubber lens caps off those binoculars and point them at the Moon. If you look a short distance to the left you’ll notice a star-like object. That’s the planet!

Seattle, two time zones west of the Midwest, will see the two closest around 9:30 p.m. local time. Source: Stellarium

You can do this anytime it’s dark, but the later you look the better because the Moon moves eastward and closer to the planet as the hours tick by. Early in the evening, the two will be separated by a couple degrees, but around 11:30 p.m. CST (9:30 p.m. PST) when the Moon reclines in the western sky, the planet will dangle like an solitary diamond less than a third of a lunar diameter away. When closest to the Moon, Uranus may prove tricky to see in its glare. If you hide the Moon behind a chimney, roofline or power pole, you’ll find it easier to see the planet.

The farther north you live, the closer the twain will be. Skywatchers in Japan, the northeastern portion of Russia, northern Canada and Alaska will see the Moon completely hide Uranus for a time. The farther west you are, the higher the Moon will be when they conjoin. West Coast states see the pair highest when they’re closest, but everyone will get a good view.

Binocular view from the desert city of Tucson around 10:45 p.m. local time tonight. Source: Stellarium — Binocular view from the desert city of Tucson around 10:45 p.m. local time tonight. You can see that the Moon is a little farther north of the planet compared to the view from Seattle. The 1,500 miles between the two cities is enough to cause our satellite, which is relatively close to the Earth, to shift position against the background stars. Source: Stellarium

When closest, the radically different character of each world can best be appreciated in a telescope. Pump the magnification up to 150x and slide both planet and Moon into the same field of view. Uranus, a pale blue dot, wears a permanent cover of methane-laced clouds where temperatures hover around -350°F (-212°C).

Though the moon will be lower in the sky, observers in the eastern U.S. and Canada will still see planet and moon only about 1/2 degree apart before moonset. Source: Stellarium — Though the Moon will be lower in the sky in the eastern U.S. and Canada when it’s closest to Uranus, observers there will still see planet and Moon only 1/2 degree apart shortly before moonset. Source: Stellarium

The fantastically large-appearing Moon in contrast has precious little atmosphere and its sunny terrain bakes at 250°F (121°C). And just look at those craters! First-quarter phase is one of the best times for Moon viewing. The terminator or shadow-line that divides lunar day from night slices right across the middle of the lunar landscape.

Shadows cast by mountain peaks and crater rims are longest and most dramatic around this time because we look squarely down upon them. At crescent and gibbous phases, the terminator is off to one side and craters and their shadows appear scrunched and foreshortened.

The day-night line or terminator cuts across a magnificent landscape rich with craters and mountain ranges emerging from the lunar night. Several prominent lunar "seas" or maria and prominent craters are shown. Credit: Christian Legrand and Patrick Chevalley / Virtual Moon Atlas — The day-night line or terminator cuts across a magnificent landscape rich with craters and mountain ranges emerging from the lunar night. Several prominent lunar “seas” or maria and prominent craters are shown. Credit: Christian Legrand and Patrick Chevalley / Virtual Moon Atlas

Enjoy the tonight’s conjunction and consider the depth of space your view encompasses. Uranus is 1.85 billion miles (2.9 billion km) from Earth today, some 7,700 times farther away than the half-moon.

December 27, 2014December 23, 2015 by Bob King

Comet Q2 Lovejoy Loses Tail, Grows Another, Loses That One Too!

Panel of negative images showing the tail of Comet Lovejoy disconnecting. Credit: Hisayoshi Kato

Maybe you’ve seen Comet Q2 Lovejoy. It’s a big fuzzy ball in binoculars low in the southern sky in the little constellation Lepus the Hare. That’s the comet’s coma or temporary atmosphere of dust and gas that forms when ice vaporizes in sunlight from the nucleus. Until recently a faint 3° ion or gas tail trailed in the coma’s wake, but on and around December 23rd it snapped off and was ferried away by the solar wind. Just as quickly, Lovejoy re-grew a new ion tail but can’t seem to hold onto that one either. Like a feather in the wind, it’s in the process of being whisked away today.

Magnetic field lines bound up in the sun’s wind pile up and drape around a comet’s nucleus to shape the blue ion tail. Notice the oppositely-directed fields on the comet’s backside. The top set points away from the comet; the bottom set toward. In strong wind gusts, the two can be squeezed together and reconnect, releasing energy that snaps off a comet’s tail. Credit: Tufts University.

Easy come, easy go. Comets usually have two tails, one of dust particles that reflect sunlight and another of ionized gases that fluoresce in Sun’s ultraviolet radiation. Ion tails form when cometary gases, primarily carbon monoxide, are ionized by solar radiation and lose an electron to become positively charged. Once “electrified”, they’re susceptible to magnetic fields embedded in the high-speed stream of charged particles flowing from the Sun called the solar wind. Magnetic field lines embedded in the wind drape around the comet and draw the ions into a long, skinny tail directly opposite the Sun.

Part of Comet Lovejoy Q2's ion tail (left) cuts the cord and floats away from the comet as photographed on December 23, 2014. Credit: Chris Schur — Part of Comet Lovejoy Q2’s ion tail (left) cuts the cord and floats away from the comet as photographed on December 23, 2014. Carbon monoxide in the tail fluoresces blue in ultraviolet sunlight. Credit: Chris Schur

Disconnection events happen when fluctuations in the solar wind cause oppositely directed magnetic fields to reconnect in explosive fashion and release energy that severs the tail. Set free, it drifts away from the comet and dissipates. In active comets, the nucleus continues to produce gases, which in turn are ionized by the Sun and drawn out into a replacement appendage. In one of those delightful coincidences, comets and geckos both share the ability to re-grow a lost tail.

Comet Encke tail disconnection April 20, 2007 as seen by STEREO

Comet Halley experienced two ion tail disconnection events in 1986, but one of the most dramatic was recorded by NASA’s STEREO spacecraft on April 20, 2007. A powerful coronal mass ejection (CME) blew by comet 2P/Encke that spring day wreaking havoc with its tail. Magnetic field lines from the plasma blast reconnected with opposite polarity magnetic fields draped around the comet much like when the north and south poles of two magnets snap together. The result? A burst of energy that sent the tail flying.

Diagram showing how a CME slams into a comet (B) to create a tail disconnection event, known in the biz as a DE. Soon enough the comet grows a new one (D). Credit: NASA — Diagram showing how a CME slammed into Comet Encke (B) and snapped off its tail. Soon enough, the comet grew a new one (D). Credit: NASA

Comet Lovejoy may have also crossed a sector boundary where the magnetic field carried across the Solar System by Sun’s constant breeze changed direction from south to north or north to south, opposite the magnetic domain the comet was immersed in before the crossing. Whether solar wind flutters, coronal mass ejections or sector boundary crossings, more tail budding likely lies in Lovejoy’s future. Like the chard in your garden that continues to sprout after repeated snipping, the comet seems poised to spring new tails on demand.

Because Comet Lovejoy rapidly moves into the evening sky by mid-late December, its position on this detailed map is shown at 10 p.m. (CST) nightly. Credit: — Comet Lovejoy picks up speed in late December as it travels from southern Lepus into Eridanus. Its position shown nightly at 10 p.m. (CST). On Sunday night December 28th it passes very close to the bright globular cluster M79. Stars shown to magnitude +8.0. Source: Chris Marriott’s SkyMap software

If you haven’t seen the comet, it’s now glowing at magnitude +5.5 and faintly visible to the naked eye from a dark sky site. Without an obvious dust tail and sporting a faint ion tail(s), the comet’s basically a giant coma, a fuzzy glowing ball easily visible in a pair of binoculars or small telescope.

A second tail disconnection event recorded on December 26, 2014 by John Nassr from his observatory in Baguio, Philippines. The fram is 3 wide. Credit: John Nassr — A second tail disconnection event recorded on December 26, 2014 by John Nassr from his observatory in Baguio, Philippines. The frame is 3° wide. Credit: John Nassr

In a very real sense, Comet Lovejoy experienced a space weather event much like what happens when a CME compresses Earth’s magnetic field causing field lines of opposite polarity to reconnect on the back or nightside of the planet. The energy released sends millions of electrons and protons cascading down into our upper atmosphere where they stimulate molecules of oxygen and nitrogen to glow and produce the aurora. One wonders whether comets might even experience their own brief auroral displays.

Excellent visualization showing how magnetic fields line on Earth’s nightside reconnect to create the rain of electrons that cause the aurora borealis. Notice the similarity to comet tail loss.