The bright dot is Saturn and it shines on the back of the Galactic Dark Horse, a collection of dark nebulae in the constellation Ophiuchus that resembles a prancing horse. The head is to the right with a wisp of a tail to the left. The photo, taken on June 20, 2017, has been turned 90° to the right, so the horse stands upright. Credit: Bob King
I didn’t notice it with the naked eye, but as soon as the time exposure ended and I looked at the camera’s back display, there it was — Saturn riding barebacked on the Galactic Dark Horse! The horse, more of a prancing pony, is a collection of dark nebulae in the southern sky beautifully placed for viewing on late June evenings. The Dark Horse is part of the Great Rift, a dark gap that splits the band of the Milky Way in half, starting at the Northern Cross and extending all the way down to the “Teapot” of Sagittarius in the south.
The Great Rift appears to unzip the summer Milky Way right down the middle. Saturn and the Dark Horse are seen at lower right. Credit: Bob King
While appearing to be little more than empty, starless space, in reality the Rift consists of enormous clouds of cosmic dust and gas in the plane of the galaxy called dark nebulae that blot out the light of more distant stars. If you could suck it all up with a monster vacuum cleaner and expose the billions of stars otherwise hidden, the Milky Way would cast obvious shadows — even suburban skywatchers would routinely see it.
Saturn dominates the scene at left center in this photo taken on June 20. To its right you can see the prancing pony standing on its tail with legs sticking out to the right. Several bright Milky Way star clouds are also visible including the Small Sagittarius Star Cloud (left) and the Large Sagittarius Star Cloud below and left of Saturn. Antares in Scorpius is at upper right. Can you find the firefly that flashed during the exposure? Credit: Bob King
Tiny dust particles spewed by older, evolved stars and exploding supernovas have been settling in the plane of the galaxy since its birth 13.2 billion years ago. While the dust is sparse, it adds up over the light years to form a thick, dark band silhouetted against the more distant stars. Gravity has been at work on the dust since the earliest days, compressing the denser clumps into new stars and star clusters. But much raw material remains. Within the curdles of dark nebulae, astronomers use dust-penetrating infrared and radio telescopes to watch new stars in the process of incubation.
Dense cores of dust within the Pipe Nebula are collapsing to form new stars. We can’t see them yet because of obscuring dust. The left end of the Pipe forms the long back leg and rump of the Dark Horse. The much smaller Snake Nebula (shaped like the letter “S”) is visible at top center. Credit and copyright: Yuri Beletsky
There are more obvious parts of the Rift to the naked eye but few conjure up as striking an image as the Dark Horse, located about one outstretched fist to the left of the Scorpius’ brightest star, Antares. Saturn sits astride the horse’s back or eastern side. While it’s fun to see the horse as a single figure, astronomers catalog the various body parts as individual dark nebulae with separate numbers and even names. The largest part of the horse, the hind leg, is nicknamed the Pipe Nebula and lies 600-700 light years away. The Pipe is further subdivided into B59, B72, B77 and B78, from a survey of dark nebulae by early 20th century American astronomer E.E. Barnard.
You’ll need dark skies and averted vision to spot the Dark Horse. Let Saturn and Antares be your guides. The nebula is highest in the sky around 12:30 a.m. in late June as shown in the map above. Latitude shown is 40° North. Created with Stellarium
While the dark horse shows up well in time-exposure photos, you’ll need dark, rural skies to view it with the naked eye. It’s only a couple fists high for those of us living in the northern U.S. and southern Canada, but considerably higher up from the southern states and points south. The figure is large but faint, about 10° long by 7° wide, and stands due south and highest in the sky around 12:30 a.m. in late June. Allow your eyes time to fully dark adapt beforehand. Try for the dark rump and hind leg first then work from there to fill in the rest of the horse.
If we could see the Milky Way galaxy edge-on from afar, it would look similar to NGC 891 in Andromeda. Both have long bands of interstellar dust along their equators that appear dark against the bright, starry backdrop. Credit: Hunter Wilson
Once I knew what to look for, I could fleetingly see the entire horse with its various protrusions as a subtle darkness against the brighter Milky Way. Averted vision, the technique of playing your eye around the subject rather than staring directly at it, helped make it happen. Wide-field binoculars will show it easily and in greater detail against a fabulously rich star field.
The best time to horse around under the Milky Way happens from now till the end of the month, when the bright Moon sends the critter into hiding.
Comet V2 Johnson from February 21st, 2017. Image credit and copyright: John Purvis
Comet V2 Johnson from February 21st, 2017. Image credit and copyright: John Purvis
Had your fill of binocular comets? Turns out, 2017 may have saved the best for last. The past few months has seen a steady stream of dirty snowball visitations to the inner solar system, both short term periodic and long term hyperbolic. First, let’s run through the cometary roll call for the first part of the year: There’s 41P Tuttle-Giacobini-Kresák, 2P/Encke, 45P Honda-Markov-Padjudašáková, C/2015 ER61 PanSTARRS and finally, the latecomer to the party, C/2017 E4 Lovejoy.
Next up is a comet with a much easier to pronounce (and type) name, at least to the English-speaking tongue: C/2015 V2 Johnson.
It would seem that we’re getting a year’s worth of binocular comets right up front in the very first half.
Discovered by the Catalina Sky Survey by astronomer Jess Johnson on the night of November 3rd 2015 while it was still 6.17 astronomical units (AU) distant at +17th magnitude, Comet V2 Johnson is currently well-placed for mid-latitude northern hemisphere viewers after dusk. Currently shining at magnitude +8 as it glides through the umlaut-adorned constellation Boötes the Herdsman, Comet V2 Johnson is expected to top out at magnitude +6 in late June, post-perihelion.
The path of Comet C/2015 V2 Johnson through the inner solar system. Credit: NASA/JPL
Part of what’s making Comet V2 Johnson favorable is its orbit. With a high inclination of 50 degrees relative to the ecliptic, it’s headed down through high northern declinations for a perihelion just outside of Mars’ orbit on June 12th. Though Mars is on the opposite side of the Sun this summer, we’re luckily on the correct side of the Sun to enjoy the cometary view. Comet V2 Johnson passed opposition a few weeks ago on April 28th, and will become an exclusively southern hemisphere object in late July as it continues the plunge southward.
This is likely Comet V2 Johnson’s first and only journey through the inner solar system, as it’s on an open ended, hyperbolic orbit and is likely slated to be ejected from the solar system after its brief summer fling with the Sun.
This week sees Comet V2 Johnson 40 degrees above the eastern horizon in Boötes as seen from latitude 30 degrees north, one hour after sunset. The view reaches its climax on June 6th near the comet’s closest approach to the Earth, with a maximum elevation of 63 degrees from latitude 30 degrees north, one hour after sunset.
The path of Comet V2 Johnson as seen from latitude 30 degrees north, 45 minutes after sunset from mid-May to late June. The constellation positions are for the beginning date. Credit: Starry Night Edu. software.
The comet also sits just 5 degrees from the bright -0.05 magnitude star Arcturus on June 6th, providing a good guidepost to find the fuzzball comet. July sees the comet cross the ecliptic plane through Virgo, then head southward through Hydra and Centaurus. Another interesting pass occurs on the night of July 3rd, when the Moon just misses occulting the comet.
Comet V2 Johnson’s celestial path through August 1st. Credit: Starry Night Edu. Software.
Here are some key dates with destiny for Comet V2 Johnson through August 1st. Unless otherwise noted, all passes are less than one degree (two Full Moon diameters) away:
May 19th: passes near +3.4 magnitude Delta Bootis.
June 5th: Closest approach to the Earth at 0.812 AU distant.
June 12th: Perihelion 1.64 AU from the Sun.
June 15th: Crosses into the constellation Virgo.
June 21st: Crosses the celestial equator southward.
June 26th: Passes near the +4 magnitude star Syrma.
July 1st: Passes near (30″!) the +4.2 magnitude star Kappa Virginis
July 3rd: The waning gibbous Moon passes two degrees north of the comet.
Comet V2 Johnson vs Kappa Virginis and the Moon on July 3rd. Note: the graphic is a (very) idealized version of the comet! Credit: Starry Night Edu.
July 5th: Crosses the ecliptic southward.
July 17th: Crosses into the constellation Hydra.
July 22nd: Passes 2.5 degrees from the +3.3 magnitude star Pi Hydrae.
July 28th: Crosses into the constellation Centaurus.
The projected light curve for Comet C/2015 V2 Johnson. The purple vertical line marks perihelion, and the black dots are actual brightness observations to date. Image credit: adapted from Seiichi Yoshida’s Weekly information About Bright Comets.
Binoculars and a good finder chart are your friends hunting down a comet like V2 Johnson. We like to start our search from a nearby bright star, then slowly sweep the field with our trusty Canon 15×45 image-stabilized binoculars (hard to believe, we’ve had this amazing piece of astro-tech in our observing arsenal for nearly two decades now. They’re so handy, picking up a pair of “old-tech” none stabilized binocs feels weird now!). An +8th magnitude comet will look like a fuzzy globular cluster which stubbornly refuses to resolve when focused. A wide-field DSLR shot should also tease V2 Johnson out of the background.
Comet V2 Johnson from May 3rd. Image credit and copyright: Hisayoshi Kato.
The next week is also ideal for evening comet-hunting for another reason, as the New Moon (also marking the start of the Islamic month of Ramadan) occurs on May 25th, after which, the light-polluting Moon will begin to hamper evening observations.
It’s strange to think, there are no bright comets on tap for the remainder of 2017 after V2 Johnson, though that will likely change as the year wears on.
In the meantime, be sure to check out Comet V2 Johnson, as it makes its lonesome solitary passage through the inner solar system.
Discovered on March 15th, 2015 by the prolific PanSTARRS-1 NEO survey atop Haleakala in Maui, Hawaii, Comet ER61 PanSTARRS made our who’s-who list of bright comets to watch for in 2017. The odd “ER61” designation stems from the early identification of the object as an asteroid, before it presented observers with a cometary appearance.
The path of Comet C/2015 ER61 PanSTARRS through the sky from early May through mid-August. Credit: Starry Night Education software.
Late northern hemisphere Spring through Summer sees the comet maintaining a decent elevation above the eastern horizon at dawn, gliding north and parallel to the ecliptic plane through the constellations Pisces, Aries and Taurus from May through mid-August. The comet passed 1.08 AU from the Earth last month on April 4th, and is now racing away from us. The comet’s location near the March equinoctial point on the celestial hemisphere assures an equally good apparition for both the northern and southern hemisphere. As seen from latitude 30 degrees north, the comet sits 30 degrees above the eastern horizon, through the remainder of May. Venus also makes a brilliant beacon to track down Comet ER61 PanSTARRS, as the planet heads towards greatest elongation 46 degrees west of the Sun on June 3rd.
The orbit of Comet ER61 PanSTARRS through the inner solar system. Credit: NASA/JPL.
The comet is also on a 7,591 year long orbit inbound, which takes it out nearly 2,500 AU from the Sun. That’s 190 times the Pluto-Sun distance, and the fourth most distant aphelion of any solar system object known. The 2015-2017 passage of the comet through the inner solar system actually shortened the orbit of Comet ER61 PanSTARRS down to an aphelion of ‘only’ 854 AU due to a 0.9 AU pass near Jupiter last year on March 28th, 2016. A similar orbital shortening by Jove occurred for Comet Hale-Bopp in 1996, which came in on an 4,200 year orbit and departed the inner solar system on a shorter 2,500 year path around the Sun.
The projected light curve for Comet C/2015 ER51 PanSTARRS. The purple line denotes perihelion, and the black dots are actual observations. Adapted from Seiichii Yoshida’s Weekly Information for Bright Comets.
Prospects and Prognostications
Observers reported an outburst from the comet last month in the first week of April, causing it to jump about 2 magnitudes in brightness. Right now, it’s holding steady at +7th magnitude. Unfortunately, the Moon reaches Full phase this week on May 10th, though you’ve still got a slim window to hunt for the comet after Moonset and before sunrise. Once the Moon moves towards a slender crescent phase next late week, we’ll once again have dark predawn skies ideal for comet hunting.
Here are some key dates for Comet C/2015 ER61 PanSTARRS as it glides through the dawn sky:
(Stars highlighted are brighter than +5th magnitude, and passes are less than a degree unless otherwise noted.)
May 10th: Reaches perihelion at 1.04 astronomical units (AU) from the Sun.
May 12th: Passes near the +4.9 magnitude star 19X Piscium.
May 20-23rd: Passes less than 10 degrees from Venus.
May 21st: The waning crescent Moon passes less than 10 degrees to the south.
June 10th: Passes near the +3.6 magnitude star Eta Piscium.
June 11th: Passes near the galaxy M74.
June 16th: Passes into the constellation Aries.
June 19th: The waning crescent Moon passes 9 degrees to the south.
July 13th: Passes near (less than 5′) the +4.6 magnitude star Epsilon Arietis.
July 18th: The waning crescent Moon passes 9 degrees to the south.
July 23rd: Passes near the +4.8 star Zeta Arietis.
The comet versus Venus in the dawn sky – looking eastward on May 15th. Credit: Stellarium.
August 2nd: Crosses into the constellation Taurus.
August 15th: The waning crescent Moon passes 8 degrees to the south.
August 16th: Passes near M45 (The Pleiades)
After mid-August, Comet 2015 ER61 PanSTARRS will drop back down below +10th magnitude, not to return for several millennia to come.
Observing a comet like ER61 PanSTARRS is as simple as knowing where and when to look, then starting to slowly sweep the suspect area with binoculars for a little fuzzball looking like a globular cluster stubbornly refusing to snap into focus. In pre-telescopic times, ER61 PanSTARRS would’ve entered and exited the inner solar system unrecorded.
Comet C/2015 ER61 PanSTARRS from April 12th. Image credit and copyright: Joseph Brimacombe.
Next up: We’ve got one more predicted comet on tap for 2017, as C/2015 V2 Johnson brightens up to +7th magnitude in mid-June. Keep watching the skies, as the next great comet of the century could always appear unannounced at any time.
Watch for the Eta Aquarid shower this week, so called because meteors will appear to radiate from near the star Eta Aquarii. The meteors originate from fragments of Halley’s Comet strewn about its orbit. Every May, Earth crosses the stream and we get a meteor shower. At maximum on Saturday morning May 6, 25-30 meteors per hour might be seen from the right location under dark skies. Map: Bob King, Source: Stellarium
Halley’s Comet may be at the far end of its orbit 3.2 billion miles (5.1 billion km) from Earth, but this week fragments of it will burn up as meteors in the pre-dawn sky as the Eta Aquarid meteor shower. The comet last passed our way in 1986, pivoted about the Sun and began the long return journey to the chilly depths of deep space.
Comet Halley’s still hanging around in the evening sky a few degrees to the west of the head of Hydra the Water Snake not far from Procyon in Canis Minor. It’s currently 3.2 billion miles from Earth. Created with Stellarium
Today, Halley’s a magnitude +25 speck in the constellation Hydra. Although utterly invisible in most telescopes, you can imagine it below tonight’s half-moon near the outermost point in its orbit four Earth-sun distances beyond Neptune. Literally cooling its jets, the comet mulls its next Earth flyby slated for summer 2061.
Halley’s Comet follows an elongated orbit that takes 76 years to complete. Solar heating boils off debris that peppers the comet’s path coming and going. Earth intersects the stream twice: first in May on the outbound portion of Halley’s orbit, and again in October, on the inbound leg. Each time, the planet plows into the debris at high speed and it burns up in our atmosphere. Credit: Bob King
Some meteor showers have sharp peaks, others like the Eta Aquarids, a broad, plateau-like maximum. The shower’s been active since mid-April and will continue right up till the end of this month with the peak predicted Saturday morning May 6. Observers in tropical latitudes, where the constellation Aquarius rises higher than it does from my home in northern Minnesota, will spy 25-30 meteors an hour from a dark sky in the hour or two before dawn.
Skywatchers further north will see fewer meteors because the radiant will be lower in the sky; meteors that flash well below the radiant get cut off by the horizon, reducing the rate by about half ( about 10-15 meteors an hour). That’s still a decent show. I got up with the first robins a couple years back to see the shower and was pleasantly surprised with a handful of flaming Halley particles in under a half hour.
A long-trailed, earthgrazing Eta Aquarid meteor crosses a display of northern lights on May 6, 2013. Credit: Bob King
While a low radiant means fewer meteors, there’s an up side. You have a fair chance of seeing an earthgrazer, a meteor that skims tangent to the upper atmosphere, flaring for many seconds before either burning up or skipping back off into space.
The Eta Aquarids will be active all week. With the peak occurring Saturday morning, you should be able to see at least a few prior to dawn each morning. The quarter-to-waxing gibbous moon will set in plenty of time through Friday morning, leaving dark skies, but cuts it close Saturday when it sets about the same time the radiant rises in the east.
The annual Eta Aquarids meteor shower captured from Otago Harbour at Aramoana in New Zealand. Eta Aquarids are fast, striking the atmosphere at more than 147,000 mph (66 km/ sec). The photographer stacked multiple unguided 30-second exposures over 50 minutes taken with an 8mm fisheye lens @ f/3.5, Nikon D90, ISO 3200. Credit: Starman_nz
For best viewing, find as dark a place as possible with an open view to the east and south. I like to tote out a reclining lawn chair, face east and get comfy under a warm sleeping bag or wool blanket. Since twilight starts about an hour and three-quarters before your local sunrise, plan to be out watching an hour before that or around 3:30 a.m. I know, I know. That sounds harsh, but I’ve discovered that once you make the commitment, the act of watching a meteor shower becomes a relaxed pleasure punctuated by the occasional thrill of seeing a bright meteor.
You’ll be in magnificent company, too. The Milky Way rides high across the southeastern sky at that hour, and Saturn gleams due south in Sagittarius at the start of dawn. If you’d like to contribute observations of the shower to help meteor scientists better understand its behavior and evolution, check out the International Meteor Organization’s Eta Aquariids 2017 campaign for more information.
STEVE, as imaged by Dave Markel in the skies of northern Canada.. Copyright: https://instagram.com/davemarkelphoto
Nicknamed Steve, this unusual aurora feature is a 15.5-mile-wide (25 km) ribbon of hot gas flowing westward at about 13,300 mph, more than 600 times faster than the surrounding air. The photo was taken last fall. Copyright: Instagram.com/davemarkelphoto
This remarkable image was captured last fall by Dave Markel, a photographer based in Kamloops, British Columbia. Later, aurora researcher Eric Donovan of the University of Calgary, discovered Markel’s strange ribbon of light while looking through photos of the northern lights on social media. Knowing he’d found something unusual, Donovan worked sifted through data from the European Space Agency’s Swarm magnetic field mission to try and understand the nature of the phenomenon.
Swarm is ESA’s first constellation of Earth observation satellites designed to measure the magnetic signals from Earth’s core, mantle, crust, oceans, ionosphere and magnetosphere, providing data that will allow scientists to study the complexities of our protective magnetic field. Credit: ESA/AOES Medialab
Launched on 22 November 2013, three identical Swarm satellites orbit the Earth measuring the magnetic fields that stem from Earth’s core, mantle, crust and oceans, as well as from the ionosphere and magnetosphere. Speaking at the recent Swarm science meeting in Canada, Donovan explained how this new finding couldn’t have happened 20 years ago when he started to study the aurora.
A beautiful aurora featuring green arcs near the horizon and many parallel rays lights up the northern sky last October. A small meteor appears to the right of center. Credit: Bob King
While the shimmering, eerie, light display of auroras might be beautiful and captivating, they’re also a visual reminder that Earth is connected electrically and magnetically to the Sun. The more we know about the aurora, the greater our understanding of that connection and how it affects everything from satellites to power grids to electrically-induced corrosion of oil pipelines.
“In 1997 we had just one all-sky imager in North America to observe the aurora borealis from the ground,” said Prof. Donovan. “Back then we would be lucky if we got one photograph a night of the aurora taken from the ground that coincides with an observation from a satellite. Now we have many more all-sky imagers and satellite missions like Swarm so we get more than 100 a night.”
The Suomi NPP satellite photographed this view of the aurora on December 22, 2016, when the northern lights stretched across northern Canada. Credit: NASA Earth Observatory image by Jesse Allen / Suomi National Polar-orbiting Partnership. Colorized and labeled by the author
And that’s where sharing photos and observations on social media can play an important role. Sites like the Great Lakes Aurora Hunters and Aurorasaurus serve as clearinghouses for observers to report auroral displays. Aurorasaurus connects citizen scientists to scientists and searches Twitter feeds for instances of the word ‘aurora,’ so skywatchers and scientists alike know the real-time extent of the auroral oval.
At a recent talk, Prof. Donovan met members the popular Facebook group Alberta Aurora Chasers. Looking at their photos, he came across the purple streak Markel and others had photographed which they’d been referring to as a “proton arc.” But such a feature, caused by hydrogen emission in the upper atmosphere, is too faint to be seen with the naked eye. Donovan knew it was something else, but what?Someone suggested “Steve.” Hey, why not?
Aurora researchers now us a network of all-sky cameras and multiple satellites to keep track of the ever-shifting aurora. Click to see the video. Credit: University of Calgary
While the group kept watch for the Steve’s return, Donovan and colleagues looked through data from the Swarm mission and his network of all-sky cameras. Before long he was able to match a ground sighting of streak to an overpass of one of the three Swarm satellites.
“As the satellite flew straight though Steve, data from the electric field instrument showed very clear changes,” said Donovan.
“The temperature 186 miles (300 km) above Earth’s surface jumped by 3000°C and the data revealed a 15.5-mile-wide (25 km) ribbon of gas flowing westwards at about 6 km/second compared to a speed of about 10 meters/second either side of the ribbon. A friend of mine compared it to a fluorescent light without the glass.
Little did I know I’d met Steve back on May 18, 1990 in this remarkable, narrow arc that stretched from the northwestern horizon to the southeastern. To the eye, a “wind” of vague forms pulsed through the arc. The Big Dipper stands vertically at right. Credit: Bob King
It turns out that these high-speed “rivers” of glowing auroral gas are much more common than we’d thought, and that in no small measure because of the efforts of an army of skywatchers and aurora photographers who keep watch for that telltale green glow in the northern sky.
I spoke to Steve’s keeper, Dave Markel, via e-mail yesterday and he described what the arc looked like to his eyes:
“It’s similar to the image just not as intense. It looks like a massive contrail moving rapidly across the sky. This one lasted almost an hour and ran in an arc almost perfectly east to west. I was directly below it but often there are green pickets (parallel streaks of aurora) rising above the streak.”
This is the same May 18, 1990 streak as above but the eastern half. The bright star Arcturus is visible at upper right. Wish I’d had a fisheye! Credit: Bob King
I know whereof Dave speaks because thanks to his photo and Prof. Donovan’s research, I realize I’ve seen and photographed Steve, too! In decades of aurora watching I’ve only seen this rare streak a handful of times. On most of those occasions, there was either no other aurora visible or minor activity in the northern sky. The narrow arc, which lasted for an hour or so, pulsed and flowed with light and occasionally, Markel’s “pickets” were visible. Back in May 1990 I had a camera on hand to get a picture.
Goes to show, you never know what you might see when you poke your head out for a look. Keep a lookout when aurora’s expected and maybe you’ll get to meet Steve, too.
Jupiter from January 7th, 0217. Image credit and copyright: Fred Locklear.
Jupiter from January 7th, 0217. Image credit and copyright: Fred Locklear.
Been missing the evening planets? Currently, Saturn and Venus rule the dawn, and Mars is sinking into the dusk as it recedes towards the far side of the Sun. The situation has been changing for one planet however, as Jupiter reaches opposition this week.
Jupiter in 2017
Currently in the constellation Virgo near the September equinoctial point where the celestial equator meets the ecliptic in 2017, Jupiter rules the evening skies. Orbiting the Sun once every 11.9 years, Jupiter moves roughly one zodiacal constellation eastward per year, as oppositions for Jupiter occur about once every 399 days.
As the name implies, “opposition” is simply the point at which a planet seems to rise “opposite” to the setting Sun.
At opposition 2017 on Friday, April 7th, Jupiter shines at magnitude -2.5 and is 666.5 million kilometers distant. Jupiter just passed aphelion on February 16th, 2017 at 5.46 AU 846 million kilometers from the Sun, making this and recent oppositions slightly less favorable. An April opposition for Jupiter also means it’ll now start to occur in the southern hemisphere for this and the next several years. Jupiter crosses the celestial equator northward again in 2022.
The path of Jupiter through 2017. Image credit: Starry Night.
Can you see Ganymede with the naked eye? Shining at magnitude +4.6, the moon lies just on the edge of naked eye visibility from a dark sky site… the problem is, the moon never strays more than 5′ from the dazzling limb of Jupiter. Here’s a fun and easy experiment: attempt to spot Ganymede through this month’s opposition season, using nothing more than a pair of MK-1 eyeballs. Then at the end of the month, check an ephemeris for greatest elongations of the moon. Any matches?
With binoculars, the first thing you’ll notice is the four bright Galilean moons of Io, Europa, Ganymede and Callisto. At about 10x magnification or so, Jupiter will begin to resolve as a disk. With binoculars, you get a very similar view of Jupiter as Galileo had with his primitive spy glass.
At the telescope eyepiece at low power you can see the main cloud bands of Jove, the northern and southern equatorial belts. Shadow transits and eclipses of the Jovian moons are also fun to watch, and frequent for the innermost two moons Io and Europa. Orbiting Jupiter once every seven days, transits of Ganymede are less frequent, and outermost Callisto is the only moon that can “miss” Jupiter on occasion, as it does this year until transits resume in 2020.
Jupiter an the Great Red Spot from January 29th, 2017. Image credit and copyright: Efrain Morales.
Jupiter’s one of the best planets for imaging: unlike Venus or bashful Mars, things are actually happening on the cloudtops of Jove. You can see smaller storms come and go as the Great Red Spot make its circuit once every 10 hours. Follow Jupiter from sunset through sunrise, and it will rotate just about all the way around once. Strange to think, we’ve been using modified webcams to image Jupiter for over a decade and a half now.
Jupiter and Io from 2006. Photo by author.
The major moons of Jupiter cast shadows nearly straight back as seen from our vantage point near opposition. After opposition, the shadows of the moons and the planet itself begin to slide to one side and will continue to do so as the planet heads towards quadrature 90 degrees east of the Sun. In 2017, quadrature for Jupiter occurs on July 5th as the planet sits due south for northern hemisphere observers at sunset. Distances to Jupiter vary through opposition, quadrature and solar conjunction, and Danish astronomer Ole Rømer used discrepancies in predictions versus actual observed phenomena of Jupiter’s moons to make the first good estimation of the speed of light in 1676.
Double shadow transits are also interesting to watch, and a season of double events involving Io and Europa begins next month on May 12th.
Jupiter will rule the dusk skies until solar conjunction on October 26th, 2017.
It’s also interesting to note that while the Northern Equatorial Belt has been permanent over the last few centuries of telescopic observation, the Southern Equatorial Belt seems to pull a disappearing act roughly every decade or so. This last occurred in 2010, and we might just be due again over the next few years. The Great Red Spot has also looked a little more pale and salmon over the last few years, and may vanish altogether this century.
Finally, the Full Moon typically sits near a given planet near opposition, as occurs next week on the evening of April 10/11th.
Jupiter, the Moon and Spica on the evening of April 10th. Credit: Stellarium.
The next occultation of Jupiter by the Moon occurs on October 31st, 2019.
Don’t miss a chance to observe the king of the planets in 2017.
– Here’s a handy JoveMoons for Android and Iphone for planning your next Jovian observing session.
-Be sure to check out our complete guide to oppositions, elongations, occultations and more with our 101 Astronomical Events for 2017, a free e-book from Universe Today.
Credit and copyright: The Virtual Telescope Project
Comet C/2017 E4 Lovejoy from the morning of Monday, April 3rd, courtesy of Gianluca Masi. Credit and copyright: The Virtual Telescope Project
Had your fill of binocular comets yet? Thus far this year, we’ve had periodic comets 2P/Encke, 45P/Honda-Mrkos-Pajdušáková and 41P/Tuttle-Giacobini-Kresák all reach binocular visibility above +10th magnitude as forecasted. Now, we’d like to point out a surprise interloper in the dawn sky that you’re perhaps not watching, but should be: Comet C/2017 E4 Lovejoy.
If that name sounds familiar, that’s because E4 Lovejoy is the sixth discovery by prolific comet hunter Terry Lovejoy. Comets that have shared the Lovejoy moniker include the brilliant sungrazer C/2011 W3 Lovejoy, which amazed everyone by surviving its 140,000 kilometer (that’s about 1/3 the Earth-Moon distance!) pass near the blazing surface of the Sun on December 16th, 2011 and went on to be a great comet for southern hemisphere skies.
The path of Comet E4 Lovejoy through the end of April. Credit: Starry Night.
Unfortunately, E4 Lovejoy won’t get quite that bright, but it’s definitely an over achiever. Shining at a faint +15th magnitude when it was first discovered last month on March 9th, 2017, it has since jumped up to +7th magnitude (almost 160 times in brightness) in just a few short weeks. We easily picked it out near the +2.4 magnitude star Enif (Epsilon Pegasi) on Saturday morning April 1st in the pre-dawn sky. E4 Lovejoy was an easy catch with our Canon 15×45 image-stabilized binocs, and looked like a tiny +7 magnitude globular (similar to nearby Messier 15) that stubbornly refused to snap into focus. In fact, I’d say that E4 Lovejoy was a much easier comet to observe than faint Comet 41P/Tuttle-Giacobini-Kresák, which made its closest pass 0.142 Astronomical Units (21.2 million kilometers) from the Earth on the same day.
Comet E4 Lovejoy from the morning of April 4th. Image credit and copyright: Gerald Rhemann/Sky Vistas.
Prospects and Prognostications
E4 Lovejoy will remain an early pre-dawn object through April for northern hemisphere observers as it glides through the constellations Pegasus, Andromeda and Triangulum. If current predictions hold true, the comet should reach a maximum brightness of magnitude +6 around April 15th. On an estimated ~ 600,000 year orbit, Comet E4 Lovejoy may be a first time visitor to the inner solar system, and its current outburst may also be short-lived. In fact, there’s lots of speculation that Comet E4 Lovejoy may disintegrate altogether, very soon. Plus, the Moon is headed towards Full next week on April 11th, making this week the best time to catch a glimpse of this fleeting comet.
The projected light curve for Comet E4 Lovejoy. Credit: Seiichi Yoshida’sWeekly Information About Bright Comets.
And to think: we just missed having a bright naked eye comet! That’s because Comet E4 Lovejoy very nearly passed through the space that the Earth will occupy just next month. In fact, the comet passed just 0.11 AU (17 million kilometers) interior to the Earth’s orbit on March 22nd, 2017. Had it done the same on May 4th, it would have been 5 times closer and 25 (about 3 to 4 magnitudes) times brighter!
The orbit of Comet E4 Lovejoy through the inner solar system. NASA/JPL
A tantalizing miss, for sure. Comet C/2017 E4 Lovejoy reaches perihelion at 0.5 AU (77.5 million kilometers) from the Sun on April 23rd, and passed 0.6 AU (93 million kilometers) from the Earth on March 31st. This week, it will be moving through Pegasus at a rate of about four degrees (8 Full Moon diameters) a day. With an orbital inclination of 88 degrees, Comet E4 Lovejoy’s path is very nearly perpendicular to the ecliptic path traced out by the Earth. The comet swung up from the south during discovery, and is now headed northward towards perihelion.
Here are some key dates for Comet C/2017 E4 Lovejoy to watch out for in April:
April 7th: Passes less than one degree from the +3.5 magnitude star Sadal Bari (Lambda Pegasi).
April 9th: Passes less than 10′ from the +2.4 magnitude star Scheat (Beta Pegasi).
April 13th: Crosses into the constellation Andromeda.
April 19th: Photo-op, as the comet passes 4 degrees from the Andromeda Galaxy M31.
April 22nd: Passes between the +2nd magnitude star Mirach and the +4th magnitude star Mu Andromedae.
April 27th: Passes five degrees from the Pinwheel Galaxy M33.
April 28th: Crosses into the constellation Triangulum.
Looking to the northeast at 6 pm local on the morning of April 19th from latitude 30 degrees north. Credit: Stellarium.
Teaser for 2017 Comets
We’re barely a quarter of the way through 2017, with more cometary action to come. We’re expecting 2015 ER51 PanSTARRS (May), and 2015 V2 Johnson (June) to reach binocular visibility. You can read about comets, occultations, and more in our guide to 101 Astronomical Events for 2017, a free e-book from Universe Today.
We’re due for the next big one, for sure. It always seems like there’s a “Great Comet” per every generation or so, and its been 20 years now since comets Hale-Bopp and Hyakutake graced northern skies.
Binoculars are the best tool for observing comets like E4 Lovejoy, as they offer a generous true (i.e. not inverted) field of view. A good finder chart and dark skies also help. We like to find a good nearby ‘anchor’ object such as a bright star, then hop into the suspected comet area and start sweeping.
One thing’s for sure: we need more comets with names like Lovejoy… if nothing else, it’s much easier to pronounce, and us science writers don’t have to keep hunting through the ‘insert’ menu for those strange letter symbols that grace many of these icy denizens of the Oort Cloud as they pay a visit to the inner solar system.
Venus, just 10.5 hours before inferior conjunction on March 25th. Image credit and copyright: Shahrin Ahmad (@Shahgazer)
Venus just 10.5 hours before inferior conjunction on March 25th. Image credit and copyright: Shahrin Ahmad (@Shahgazer)
Have you seen it yet? An old friend greeted us on an early morning run yesterday as we could easily spy brilliant Venus in the dawn, just three days after inferior conjunction this past Saturday on March 25th.
This was an especially wide pass, as the planet crossed just over eight degrees (that’s 16 Full Moon diameters!) north of the Sun. We once managed to see Venus with the unaided eye on the very day of inferior conjunction back in 1998 from the high northern latitudes of the Chena Flood Channel just outside of Fairbanks, Alaska.
The planet was a slender 59.4” wide, 1% illuminated crescent during this past weekend’s passage, and the wide pass spurred many advanced imagers to hunt for the slim crescent in the daytime sky. Of course, such a feat is challenging near the dazzling daytime Sun. Safely blocking the Sun out of view and being able to precisely point your equipment is key in this endeavor. A deep blue, high contrast sky helps, as well. Still, many Universe Today readers rose to the challenge of chronicling the horns of the slender crescent Venus as they rotated ’round the limb and the nearby world moved once again from being a dusk to dawn object.
A daily sequence showing the ‘Horns of Venus’ rotate as it approaches inferior conjunction. Image credit and copyright: Shahrin Ahmad (@ShahGazer)
The orbit of Venus is tilted 3.4 degrees with respect to the Earth, otherwise, we’d get a transit of the planet like we did on June 5-6th, 2012 once about every 584 days, instead of having to wait again until next century on December 10th, 2117.
The joint NASA/European Space Agency’s SOlar Heliospheric Observatory (SOHO) mission also spied the planet this past weekend as it just grazed the 15 degree wide field of view of its Sun-observing LASCO C3 camera:
The glow of Venus (arrowed) just barely bleeding over into the field of view of SOHO’s LASCO C3 camera. Credit: SOHO/NASA/LASCO
Venus kicks off April as a 58” wide, 3% illuminated crescent and ends the month at 37” wide, fattening up to 28% illumination. On closest approach, the planet presents the largest apparent planetary disk possible as seen from the Earth. Can you see the horns? They’re readily readily apparent even in a low power pair of hunting binoculars. The coming week is a great time to try and see a crescent Venus… with the naked eye. Such an observation is notoriously difficult, and right on the edge of possibility for those with keen eyesight.
One problem for seasoned observers is that we know beforehand that (spoiler alert) that the Horns of Venus, like the Moon, always point away from the direction of the Sun.
True Story: a five year old girl at a public star party once asked me “why does that ‘star’ look like a tiny Moon” (!) This was prior to looking at the planet through a telescope. Children generally have sharper eyes than adults, as the lenses of our corneas wear down and yellow from ultraviolet light exposure over the years.
Still, there are tantalizing historical records that suggest that ancient cultures such as the Babylonians knew something of the true crescent nature of Venus in pre-telescopic times as well.
The Babylonian frieze of Kudurru Melishipak on display at the Louvre, depicting the Sun Moon and Venus. According to some interpretations, the goddess Ishtar (Venus) is also associated with a crescent symbol… possibly lending credence to the assertion that ancient Babylonian astronomers knew something of the phases of the planet from direct observation. Credit: Wikimedia Commons/Image in the Public Domain.
Another fun challenge in the coming months is attempting to see Venus in the daytime. This is surprisingly easy, once you know exactly where to look for it. A nearby crescent Moon is handy, as occurs on April 23rd, May 22nd, and June 20th.
Venus (arrowed) near the daytime Moon. Photo by author.
Strangely enough, the Moon is actually darker than dazzling Venus in terms of surface albedo. The ghostly daytime Moon is just larger and easier to spot. Many historical ‘UFO’ sightings such as a ‘dazzling light seen near the daytime Moon’ by the startled residents of Saint-Denis, France on the morning on January 13th, 1589 were, in fact, said brilliant planet.
The Moon near Venus on May 22nd. Credit: Stellarium.
Venus can appear startlingly bright to even a seasoned observer. We’ve seen the planet rise as a shimmering ember against a deep dark twilight sky from high northern latitudes. Air traffic controllers have tried in vain to ‘hail’ Venus on more than one occasion, and India once nearly traded shots with China along its northern border in 2012, mistaking a bright conjunction of Jupiter and Venus for spy drones.
The third brightest object in the sky behind the Sun and the Moon, Venus is even bright enough to cast a shadow as seen from a dark sky site, something that can be more readily recorded photographically.
Watch our nearest planetary neighbor long enough, and it will nearly repeat the same pattern for a given apparition. This is known as the eight year cycle of Venus, and stems from the fact that 13 Venusian orbits (8x 224.8 days) very nearly equals eight Earth years.
Follow Venus through the dawn in 2017, and it will eventually form a right triangle with the Earth and the Sun on June 3rd, reaching what is known as greatest elongation. This can vary from 47.2 to 45.4 degrees from the Sun, and this year reaches 45.9 degrees elongation in June. The planet then reaches half phase known as dichotomy around this date, though observed versus theoretical dichotomy can vary by three days. The cause of this phenomenon is thought to be the refraction of light in Venus’ dense atmosphere, coupled with observer bias due to the brilliance of Venus itself. When do you see it?
Also, keep an eye out for the ghostly glow on the night-side of Venus, known as Ashen Light. Long thought to be another trick of the eye, there’s good evidence to suggest that this long reported effect actually has a physical basis, though Venus has no large reflecting moon nearby… how could this be? The leading candidate is now thought to be air-glow radiating from the cooling nighttime side of the planet.
Cloud enshrouded Venus held on to its secrets, right up until the Space Age less than a century ago… some observers theorized that the nighttime glow on Venus was due to aurorae, volcanoes or even light pollution from Venusian cities (!). This also fueled spurious sightings of the alleged Venusian moon Neith right up through the 19th century.
Venus should also put in a showing 34 degrees west of the Sun shining at magnitude -4 during the August 21st, 2017 total solar eclipse. Follow that planet, as it makes a complex meet up with Mars, Mercury, and the Moon in late September of this year.
More to come!
-Read about planets, occultations, comets and more for the year in our 101 Astronomical Events for 2017, out as a free e-book from Universe Today.
Mercury requests the company of your gaze now through the beginning of April, when it shines near Mars low in the west after sunset. Created with Stellarium
March has been a busy month for planet and comet watchers. Lots of action. Venus, the planet that’s captured our attention at dusk in the west for months, is in inferior conjunction with the Sun today. Watch for it to rise before the Sun in the eastern sky at dawn in about a week.
Mercury like Venus and the Moon shows phases when viewed through a telescope. Right now, the planet is in waning gibbous phase. Stellarium
As Venus flees the evening scene, steadfast Mars and a new planet, Mercury keep things lively. For northern hemisphere skywatchers, this is Mercury’s best dusk apparition of the year. If you’d like to make its acquaintance, this week and next are best. And it’s so easy! Just find a spot with a wide open view of the western horizon, bring a pair of binoculars for backup and wait for a clear evening.
Plan to watch starting about 40 minutes after sundown. From most locations, Mercury will appear about 10° or one fist held at arm’s length above the horizon a little bit north of due west. Shining around magnitude +0, it will be the only “star” in that part of the sky. Mars is nearby but much fainter at magnitude +1.5. You’ll have to wait at least an hour after sunset to spot it.
Have a telescope? Check out the planet using a magnification around 50x or higher. You’ll see that it looks like a Mini-Me version of the Moon. Mercury is brightest when closest to full. Over the next few weeks, it will wane to a crescent while increasing in apparent size.
If you have any difficulty finding brilliant Jupiter and its current pal, Spica, just start with the Big Dipper, now high in the northeastern sky at nightfall. Use the Dipper’s handle to “arc to Arcturus” and then “jump to Jupiter.” Credit: Bob King
If you like planets, don’t forget the combo of Jupiter and Spica at the opposite end of the sky. Jupiter climbs out of bed and over the southeastern horizon about 9 p.m. local time in late March, but to see it and Spica, Virgo’s brightest star, give it an hour and look again at 10 p.m. or later. Quite the duo!
You’re not afraid of getting up with the first robins are you? If you set your alarm to a half hour or so before the first hint of dawn’s light and find a location with an open view of the southeastern horizon, you might be first in your neighborhood to spot Terry Lovejoy’s brand new comet. His sixth, the Australian amateur discovered C/2017 E4 Lovejoyon the morning of March 10th in the constellation Sagittarius at about 12th magnitude.
C/2017 E4 Lovejoy glows blue-green this morning March 26. Structure around the nucleus including a small jet is visible. The comet is currently in Aquarius and quickly moving north and will reach perihelion on April 23. Credit: Terry Lovejoy
The comet has rapidly brightened since then and is now a small, moderately condensed fuzzball of magnitude +9, bright enough to spot in a 6-inch or larger telescope. Some observers have even picked it up in large binoculars. Lovejoy’s comet should brighten by at least another magnitude in the coming weeks, putting it within 10 x 50 binocular range.
This map shows the sky tomorrow morning before dawn from the central U.S. (latitude about 41° north). Created with Stellarium
Good news. E4 Lovejoy is moving north rapidly and is now visible about a dozen degrees high in Aquarius just before the start of dawn. I’ll be out the next clear morning, eyepiece to eye, to welcome this new fuzzball from beyond Neptune to my front yard. The map above shows the eastern sky near dawn and a general location of the comet. Use the more detailed map below to pinpoint it in your binoculars and telescope.
This chart shows the comet’s position nightly (5:30 a.m. CDT) through April 9. On the morning of April 1 it passes just a few degrees below the bright globular cluster M15. Click to enlarge, save and then print out for use at the telescope. Map: Bob King, Source: Chris Marriott’s SkyMap
Spring brings with it a new spirit and the opportunity to get out at night free of the bite of mosquitos or cold. Clear skies!
Comet 41P glows green (left) and shows its true coma and just the hint of a stubby tail in the negative (red) image (right) from March 19th. Image credit and copyright: Hisayoshi Kato
Comet 41P Tuttle-Giacobini-Kresák glows green (left) and shows its true coma and just the hint of a stubby tail in the negative (red) image (right) from March 19th. Image credit and copyright: Hisayoshi Kato
Miss out on comet 45P Honda-Mrkos-Pajdušáková? Is Comet 2P Encke too low in the dawn sky for your current latitude? Well, the Universe is providing us northerners with another shot at a fine binocular comet, as 41P Tuttle-Giacobini-Kresák glides through Ursa Major this week.
As seen from 30 degrees north, Comet 41P Tuttle-Giacobini-Kresák (sometimes called “Comet 41P” or “Comet TGK”) starts the last week of March about 40 degrees above the NE horizon at 9PM local. It then makes the plunge below 30 degrees elevation on April 1st for the same latitude at the same time. At its closest on April 5th, the comet will be moving at two degrees a day (the width of four Full Moons!) as seen from the Earth as it slides down through the snaky constellation of Draco.
The path of Comet 41P from March 20th through April 20th. Credit: Starry Night.
The comet reaches an elevation of 10 degrees for evening viewers around April 15th, and passes 10 degrees north of another up and coming binocular comet C/2015 V2 Johnson right around the same date. After early April, your odds get better to see Comet 41P Tuttle-Giacobini-Kresák high in the sky at its upper culmination past local midnight towards dawn.
There’s another reason to try and recover this comet this week, as the Moon is now a waning crescent headed towards New on March 28th. From there, the waxing Moon begins to interfere with cometary observations as it heads towards the Easter Full Moon on April 11th, pushing efforts to recover and follow the comet towards pre-dawn hours.
First discovered by astronomer Horace Tuttle 1858, the comet was independently recovered by Michel Giacobini in 1907 and L’ubor Kresák in 1951 and its periodic nature was uncovered.
Note: We believe that the “May 3rd, 1858” date given for the discovery of this comet around ye ole Web is in fact, erroneous, as both Stellarium and Starry Night put the comet just a few degrees from the Sun on this date! Perhaps both programs are wrong looking that far back in time… but they’re both exactly wrong. Perhaps a bit of astronomical detective work is in order? More to come!
Due for a revision? Here’s the position of Comet 41P Tuttle-Giacobini-Kresák on the oft quoted discovery date of May 3rd, 1858… just 8 degrees from the Sun! Credit: Stellarium.
Orbiting the Sun once every 5.4 years, this is the 29th perihelion return of the comet since its discovery in 1858. The comet’s orbit takes it from 5.1 AU, out to near the orbit of Jupiter, to a perihelion just 0.13 AU outside the orbit of the Earth. This year’s passage is nearly as close as the comet can approach the Earth, with solar opposition also occurring on April 5th. The comet’s orbit is inclined about nine degrees to the ecliptic plane. Think of the comet zipping down over the northern hemisphere of the Earth, reaching perihelion as it heads from north to south, then headed back out over the southern hemisphere.
Currently at +9th magnitude, the comet should flirt with naked eye visibility of magnitude +6 in early April. This comet is also worth watching, as it’s known for periodic outbursts. Flashback to 1973, and Comet 41P Tuttle-Giacobini-Kresák made an easy naked eye apparition of +4. This is also the closest approach of Comet 41P Tuttle-Giacobini-Kresák near the Earth in our lifetimes, and the closest in the two century span from 1900 to 2100.
The projected light curve for Comet 41P Tuttle-Giacobini-Kresák. The pink line denotes perihelion, at the black dots mark recorded magnitude estimates. Adapted from Seiichi Yoshida’s Weekly Information About Bright Comets.
Arecibo did ping 41P Tuttle-Giacobini-Kresák in early March, but probably won’t image the comet near perihelion due to its northerly declination (Arecibo is only partially steerable). They did, however nab a great animation of the twin lobbed Comet 45P Honda-Mrkos-Pajdušáková on February 12th:
An amazing view: Comet 45P Honda-Mrkos-Pajušáková pinged by Arecibo radar last month. Credit: Arecibo/USRA
That makes two, bi-bulbous comets, if you include Comet 67P Churyumov-Gerasimenko. Are twin-lobbed comets in fact as common as comet-hunters with umlauts in their name?
Here are some key highlight events for Comet 41P Tuttle-Giacobini-Kresák to watch out for. Close passes are less than one degree unless otherwise noted:
March 21st: Photo-op: passes between M108 and M97 the Owl Nebula March 29th: passes into Draco April 2nd: Passes near the 3.6 magnitude star Thuban (Alpha Draconis) April 5th: Passes just 0.15 AU (23.2 million kilometers) from the Earth at 13:30 UT. April 7th: passes just 22 degrees from the north celestial pole at declination 68 degrees north. April 11th: reaches perihelion at 1.05 AU (162.7 million kilometers) from the Sun. April 18th: passes the 2.7 magnitude star Rastaban (Beta Draconis) April 20th: passes into the constellation Hercules
The comet vs two Messier objects: the view on March 22nd at 12:00 UT. Credit: Starry Night
Observing comets is an exercise in patience, as that quoted magnitude is often smeared out over an extended area. Dark skies and a good star chart are key. I like to use binoculars when hunting for comets brighter than +10th magnitude, as it gives you a true (un-inverted both up/down and left to right) view, coupled with a generous field of view.
Comet 41P Tuttle-Giacobini-Kresák from March 15th. Image credit and copyright: Wendy Clark.
If Comet 41P Tuttle-Giacobini-Kresák outperforms into the +6th magnitude range or brighter, it could become a fine target to image with foreground objects. We’re already seeing some amazing images streaming in, with more to come as perihelion approaches.
Other binocular comets to watch for in 2017 include C/2015 ER61 PanSTARRS (May) and C/2015 V2 Johnson (June).
If Comet 41P Tuttle-Giacobini-Kresák performs at or above expectations (and if no great “comet(s) of the century show up!) it could be the best binocular comet of 2017. Don’t miss it!
-Send those images to Universe Today’s Flickr page.
-Be sure to read about the brightest comets of the year and more in our 2017 Astronomical Guide, free from Universe Today.
