The planetary lineup at dawn from September 12th. Image credit and copyright: Alan Dyer (AmazingSky.com)
The planetary lineup at dawn (minus the Moon) from September 12th. Image credit and copyright: Alan Dyer (AmazingSky.com).
Following the Moon and wondering where are the fleeting inner solar system planets are this month?
While Jupiter and Saturn sink into the dusk on the far side of the Sun this month, the real action transpires in the dawn sky in mid-September, with a complex set of early morning conjunctions, groupings and occultations.
First, let’s set the stage for the planetary drama. Mercury just passed greatest elongation 18 degrees west of the Sun on September 12th.
The action warms up with a great pre-show on the morning of Saturday, September 16th, when the closest conjunction of two naked eye planets for 2017 occurs, as Mercury passes just 3′ north of Mars. The conjunction occurs at 16:00 UT, favoring the western Pacific region in the dawn hours. The pair is just 17 degrees from the Sun. As mentioned previously, this is the closest conjunction of two naked eye planets in 2017, so close the two will seem to merge to the naked eye and make a nice split with binoculars. This is also one of the first good chances to spy Mars for this apparition, fresh off of its solar conjunction on July 27th, 2017. Mars is now headed towards a favorable opposition next summer on July 27th, 2018, one that’s very nearly as favorable as the historic grand opposition of 2003.
Mars shines at magnitude +1.8 on Saturday morning with a disk 3.6” across, while Mercury shines at magnitude +0.05 with a 64% illuminated disk 6.4” across. Mars is actually 389 million km (2.6 AU) from the Earth this weekend, while Mercury is 158 million km (1.058 AU) distant.
The view looking east on the morning of September 17th. Stellarium
Follow that planet, as Mars also makes a close (12′) pass near Venus on October 5th. At the eyepiece, Venus will look like it has a large moon, just like the Earth!
Think this pass is close? Stick around until August 10th, 2079 and you can actually see Mercury occult (pass in front of) Mars… our cyborg body should be ready to download our consciousness into by then.
Mark your calendars: Mercury occults Mars in 2079. Stellarium
The waning crescent Moon joins the view on Monday, September 18th, making a spectacular series of passes worldwide as it threads its way through the stellar-planetary lineup. Occultations involving the waning Moon are never as spectacular as those involving the waxing Moon, as the bright limb of the Moon leads the way for ingress instead of the dark edge. The best sight to behold will be the sudden reappearance of the planet of star (egress) from behind the waning crescent Moon’s dark limb.
The sky looking east on the morning of September 18th. Stellarium
First up is an occultation of Venus on September 18th centered on 00:55 UT. Unfortunately, this favors the eastern Indian Ocean at dawn, though viewers in Australia and New Zealand can watch the occultation under post dawn daytime skies. The pair is 22 degrees west of the Sun, and the Moon is two days from New during the event. Shining at magnitude -4, it’s actually pretty easy to pick out Venus near the crescent Moon in the daytime. Observers worldwide should give this a try on the 18th as well… folks are always amazed when I show them Venus in the daytime. The last time the Moon occulted Venus was September 3rd, 2016 and the two won’t cross paths again until February 16th, 2018.
The footprint of the occultation of Venus by the Moon. Occult 4.2
Next up, the Moon occults the +1.4 magnitude star Regulus on the 18th at 4:56 UT. Observers across north-central Africa are best placed to observe this event. This is the 11th occultation of Regulus by the Moon in a series of 19, spanning December 2016 to April 2018.
The occultation of Regulus by the Moon. Occult 4.2
The brightest star in the constellation Leo, Regulus is actually 79 light years distant.
Next up, the dwindling waning crescent Moon meets the Red Planet Mars and occults it for the western Pacific at 19:42 UT. Shining at magnitude +1.8 low in the dawn sky, Mars is currently only 3.6” in size, a far cry from its magnificent apparition next summer when it will appear 24.3” in size… very nearly the largest it can appear from the Earth.
The occultation of Mars by the Moon. Occult 4.2
And finally, the slim 2% illuminated Moon will occult the planet Mercury on September 18th centered on 23:21 UT.
The occultation of Mercury by the Moon. Occult 4.2
Mercury occultations are tough, as the planet never strays very far from the Sun. The only known capture I’ve seen was out of Japan back in 2013:
This week’s occultation favors southeast Asia at dawn, and the pair is only 16 degrees west of the Sun. Mercury is gibbous 74% illuminated and 6” in size during the difficult occultation.
We just miss having a simultaneous “multiple occultation” this week. The Moon moves at the span of its half a degree size about once every hour with respect to the starry background, meaning an occultation must occur about 60 minutes apart for the Moon to cover two planets or a planet and a bright star at the same time, a rare once in a lifetime event indeed. The last time this transpired, the Moon covered Venus and Jupiter simultaneously for observers on Ascension Island on the morning of April 23rd 1998.
When is the next time this will occur? We’re crunching the numbers as we speak… watch this space!
Looking into next week, the Moon reaches New phase on Wednesday, September 20th at 5:31 UT/1:31 AM EDT, marking the start of lunation 1172. Can you spy the razor thin Moon Wednesday evening low to the west? Sighting opportunities improve on Thursday night.
Don’t miss this weekend’s dance of the planets in the early dawn sky, a great reason to rise early.
Read about conjunctions, occultations, tales of astronomy and more in our free guide to the Top 101 Astronomical Events for 2017 from Universe Today.
An artist's conception of an NEO asteroid orbiting the Sun. Credit: NASA/JPL.
An artist’s conception of an NEO asteroid similar to 3122 Florence orbiting the Sun. Credit: NASA/JPL.
Ready to hunt for low-flying space rocks? We’ve got an interesting pass of a Near Earth Asteroid (NEA) this upcoming U.S. Labor Day weekend, one that just slides over the +10th magnitude line into binocular range.
We’re talking about asteroid 3122 Florence, which passes 4.4 million miles from our fair planet (that’s 7 million kilometers, about 18 times the distance from Earth to the Moon) this Friday on September 1st at 12:06 Universal Time (UT)/ 8:06 AM Eastern Daylight Saving Time (EDT).
Universe Todayran an article on the close pass about a week ago. Now, we’d like to show you how to see this asteroid as it glides by.
Ordinarily, a four million mile pass (about 4.7% of an astronomical unit, just under the criterion to make 3122 Florence a Near Earth Object) isn’t enough to grab our attention. Lots of asteroids pass closer weekly, and 3122 Florence is certainly no danger to the Earth this or any week in the near future. What makes this asteroid an attractive target is its size: NASA’s NEOWISE and Spitzer infrared telescope missions estimate that 3122 Florence is about 2.7 miles (4.4 kilometers) in diameter, a pretty good-sized chunk of rock as near Earth asteroids go.
The inclined orbit of 3122 Florence. Credit: NASA/JPL.
The last large asteroid with a similar close approach was 4179 Toutatis, which passed just under four lunar distances (a little under a million miles) from the Earth on September 29th, 2004.
Asteroid 3122 Florence (1981 ET3) was discovered by prolific asteroid hunter Schelte J. Bus from Siding Spring observatory in Australia on the night of March 2nd, 1981. Named after social reformer and founder of modern nursing Florence Nightingale, this weekend’s pass is the closest 3122 Florence gets to Earth over a 600 year plus span, running from 1890 (well before its discovery) out past 2500 AD.
Plans are afoot to ping 3122 Florence using Goldstone and Arecibo radars as it passes by the weekend. we might just see if it has a any attending moonlets or a strange bifurcated shape like comets 67/P Churyumov-Gerasimenko or Comet 45/P Honda-Mrkos-Pajdušáková very soon.
Asteroid 2014 JO25 imaged by Arecibo earlier this year… are contact binary ‘rubber-duck’ shaped asteroids and comets a thing? Credit: NASA/Arecibo/NSF.
3122 Florence has an inclined orbit, tilted 22 degrees in respect to the ecliptic plane. Orbiting the Sun once every 859 days, 3122 Florence travels from around 1 to 2.5 AUs from the Sun, making it an Amor class asteroid which journeys beyond the orbit of Mars and approaches but doesn’t pass interior to the orbit of the Earth.
This week’s pass sees 3122 Florence rapidly vaulting up from the southern to northern hemisphere.
This apparition culminates on Friday, September 1st, at 12:06 UT as the asteroid crosses the along the border of the constellations Equuleus and Delphinus at closest approach, reaching +9th magnitude. 3122 Florence will be moving at 20′ per hour (that’s about 2/3rds the diameter of the Full Moon) at closest approach, fast enough that you’ll notice its motion against the background stars in a low power field of view after about 10 minutes or so.
The path of 3122 Florence through the sky this week, times for the tick marks are in EDT (UT-4 hours). Credit: Starry Night Education software.
3122 Florence crosses through the constellations Piscis Austrinus, Capricornus, Aquarius, Equuleus and Delphinus this week. Keep in mind, the Moon is headed towards Full next week on September 6th, making the next few evenings a good time to track this fleeting space rock down.
3122 Florence from August 28th, about 8 million kilometers from the Earth. The asteroid is the center dot, while the streak to the left is the geostationary satellite AMC-14. Credit: the Virtual Telescope Project.
Finding 3122 Florence
3122 Florence races across the ecliptic northward on the night of August 29th and also crosses the celestial equator on September 1st
Tonight is also a good time to track down 3122 Florence, as it passes just 16′ from +3.8 magnitude star Zeta Capricorni. It also threads its way through the tiny the diamond-shaped asterism of Delphinus the Dolphin just over week after its closest pass on the evening of Saturday, September 9th.
Currently, 3122 Florence is 45 degrees above the southern horizon around local midnight for observers based along 30 degrees north latitude. The best view during Friday’s pass is from the Pacific Rim, including Australia, New Zealand and surrounding regions at closest approach.
The orientation of the Earth as seen from asteroid 3122 Florence during Friday’s closest approach. Credit: Starry Night Education software.
North American viewers will get a good view at local midnight just about eight hours prior to closest approach on the night of August 31st/September 1st, about 60 degrees above the southern horizon. The next good views occur the following evening about 16 hours after closest approach, as the asteroid is receding but 10 degrees higher above the southern horizon.
The 24 hour celestial path of of 3122 Florence through the night sky, centered on the September 1st closest approach. Tick mark times are in EDT (UT-4 hours). Created using Starry Night Education software.
A series short wide field exposures over about an hour revealing stars down to +10 magnitude should reveal the motion of 3122 Florence against the starry background. A good visual alternative is to sketch the suspect star field about 10 minutes apart, carefully looking for a ‘star’ that has moved during the intervening time.
JPL Horizons is a good place to generate accurate right ascension and declination coordinates for 3122 Florence to aid you in your quest. This one is distant enough to simple geocentric coordinates should suffice, and observer parallax shouldn’t shift the position of the asteroid significantly.
Clouded out? The good folks over at the Virtual Telescope Project will be featuring 3122 Florence during a live webcast starting on Thursday, August 31st at 19:30 UT/3:30 PM EDT.
We can be thankful that 3122 Florence isn’t headed Earthward, as it’s perhaps about half the size of the 10-15 kilometer diameter Chicxulub impactor that hit the Yucatan 65 million years ago, causing a very bad day for the dinosaurs. Plus, it would just be weird if an asteroid named after humanitarian Florence Nightingale caused the extinction of humanity…
And this is a great pre-show for a smaller and closer anticipated asteroid pass coming up in a few short weeks, as 2012 TC4 buzzes the Earth on October 12th, 2017.
Good luck in your quest to find 3122 Florence… let us know what you see!
A brilliant diamond ring punctuates totality. Image credit and copyright: Shahrin Ahmad.
A brilliant diamond ring punctuates totality. Image credit and copyright: Shahrin Ahmad.
They came, they saw, they battled clouds, traffic and strange charger adapters in a strange land. Yesterday, millions stood in awe as the shadow of the Moon rolled over the contiguous United States for the first time in a century. If you’re like us, your social media feed is now brimming with amazing images of yesterday’s total solar eclipse.
Already, we’ve seen some amazing reader images at Universe Today, with more to come. As a special look at a unique event, we’ve collected reader testimonies from every state along the path of totality of just what the eclipse was like.
We drove from Dalles at 3 AM. Nearing the observation spot, we got a flat tire! It was 5:30 AM, and no phone line! I sent a text to the land owner and somehow it reached him and we managed to be there by 6:30 AM. We observed from a secluded spot about 30 miles from Madras, with a 2 minutes and 2 seconds of totality. The sky was really clear during sunrise, but as totality approached we got some thin clouds hovering in the east. Luckily, it was thin enough to not spoil anything. The corona was incredibly beautiful with longer (streamers) jutting out at the 4 and 8 o’clock position. The first and second diamond ring were spectacular with the eye, probably with the help with the thin clouds. We calculated about 7 degree drop in temperature. The shadow was enormous, engulfing Mt Hood from the west and flew past above us towards and towards the Sun. Mesmerizing! 2 minutes simply was not enough, since this is probably my best view of a total solar eclipse so far!
The bright star Regulus, tangled up in the solar corona. Image credit and copyright: Shahrin Ahmad.
(Note: to our knowledge, no one witnessed the brief moments of totality as the umbra of the Moon brushed tiny corners of Montana and Iowa… if you’re reading this and did so, let us know!)
How to describe such a magnificent spectacle in a “brief paragraph”? Our group from Edmonton observed totality under clear skies near Birch Creek, Idaho. After the Moon’s silhouette inexorably progressed & gradually swallowed up an impressive line of sunspots, the pace of dynamic events picked up dramatically in the minutes surrounding totality. The temperature dropped noticeably. Light faded & became “flat” while shadows became better defined & lost their fuzzy edges (penumbrae). The Moon’s onrushing shadow became visible on the mountains to our west, while rapidly-moving shadow bands squiggled on the ground around us. The sky took on an eerie indigo hue as the last vestiges of direct sunlight were obscured. A new & temporary centrepiece emerged in the sky: the black circle of the lunar night side highlighted by a spectacular corona, its far-flung pearly-white streamers contained within sharply defined edges. Around the black limb fiery coral pink prominences added intense colour highlights to the scene. Just beyond the corona gleamed Regulus, closer to the Sun than is possible for any other star of first magnitude or brighter, while off to one side Venus shone brilliantly, far higher in the sky than its customary window of dominance in normal twilight. All too soon the right edge of the lunar silhouette brightened, then blossomed in a brilliant diamond ring that continued to intensify for a couple of glorious seconds until filters again became a must. By now the mountains to our east were in darkness as the umbral shadow receded from our immediate location, leaving a number of our small party in tears from the intensity of the experience.
We woke up in the Tetons Monday morning to a sky streaked with clouds. But the hourly weather report showed clearing, so we headed to our spot before 7 AM. We were able to secure parking by our preferred observing location, the Mormon Barn with a view of the iconic Teton range in the background. Looking east, we saw the clouds slink away to the south until skies were blue and clear, despite lingering haze and smoke on the northern horizon from wildfires.
Crescent Suns along with the Tetons. image credit and copyright: Kelly Kizer Whitt.
Having been a science writer for two decades, I was well versed on total solar eclipses even though I’d never seen one first hand. But it didn’t unfold quite as I expected. The sky and air didn’t take on a twilight quality until the Sun was well over halfway obscured. Then when darkness fell, it came fast and the temperature dropped hard. We had on our eclipse glasses and were staring at the Sun, waiting to see bailey’s beads or the diamond ring. But first I glanced down and saw the slithering, wiggling lines of darkness and light known as the shadow bands. They have a truly creepy quality as they dance in the growing dark. Then we looked back up as the sliver of orange disappeared and the Sun winked out from our glasses. Pulling them off, my family let out cries of surprise when they saw the black hole where the Sun had been, surrounded by the long, wispy, intricate corona. The eclipsed Sun and corona took up a much larger space in the sky than I expected, but the photo I took (just like when photographing a full moon) does not give a true representation of what you can see with your eyes.
I only took three photos because I wanted to just enjoy the view. I almost forgot to look for the stars. We saw a plane, Venus, and Sirius. Our eyes never adjusted enough to spot Jupiter or the others and the rosy glow of a false twilight brightened all horizons in a 360-degree ring. So soon it was over. The bailey’s beads and diamond ring we missed as the total eclipse began, and appeared to us instead at the end. These phenomena were a bright and beautiful warning to get our eclipse glasses back on. The world returned to daylight fairly quickly, but the drop in temperature lingered a bit longer. Our memories will last a lifetime.
Having doubtful cloud forecasts for Scottsbluff & Carhenge, we met on a foggy morning in Sidney, Nebraska with thoughts of changing plans to Wyoming for clear skies. As the forecast improved, 15 of us set off for Carhenge. We arrived before 7 AM to plentiful parking & a few hundred people. Towards 9 AM the crowds started to swell, including aliens, welders and the governor of Nebraska. Joined by more people & dogs, I estimate around 3,000 people were at the site. Some clouds went by at mid-coverage, casting a spectacular crescent. Clouds cleared, and cheers rose as we went into totality, such a beautiful sight some were moved to tears as the diamond ring emerged. A thoroughly wonderful experience shared with friends and spellbound crowd, definitely worth the trip from Florida.
I saw it (the eclipse) from Weston, Missouri, just northwest of the Kansas-Missouri line. Clouds and rain obscured the sun for most of the eclipse, but the rain subsided during totality and allowed us to get outside for the quick move into darkness. Even though we couldn’t see the eclipse or corona, the atmosphere took on a different feel. There was a change in how things were colored — as if you were looking through darker and darker polarized glasses, and the silence took on a feeling, like a deep vibration.
Totality from Missouri. Image credit and copyright: Jeudy Blanco.
It was amazing. We changed plans last night, instead of going to St Joseph we drove to Columbia. I was really worried the first few minutes of the eclipse because it was cloudy, my PST couldn’t resolve the image of the Sun! But quickly the clouds dispersed. We were on a property from the family of my friend, around 25 people of all ages. When it was around 70% (partial) you could feel in the environment that something was going on. Everything got a lot more quiet and the temperature dropped. Everybody was trying to get pictures of the Sun with their phones on the PST. Then totality started, it was indescribable for me. I was seeing the Sun’s corona with my bare eyes. I was really nervous and anxious, actually. We could see Venus near the Sun. Everybody was super excited, I almost cried. The experience was amazing, a total success, the long trip was worth it.
Illinois- The Universe Today expedition to the Prairie State led by Publisher Fraser Cain also managed to catch a brief glimpse of totality through a gap in the clouds:
Earthshine (!) on the Moon, seen during totality. Image credit and copyright: Mike Weasner.
About 400 eclipse enthusiasts from around the world including me were part of a Sky and Telescope tour group. We were at Hopkinsville Community College located in Hopkinsville, Kentucky, where totality lasted 2 minutes and 40 seconds, which was too short. We arrived at the viewing site about 4.5 hours before First Contact. Traffic was surprisingly light. There were a few thin clouds but nothing significant. Anticipation was high. Many of us set up cameras and were ready well before First Contact. First Contact occurred with a clear sky, and the sky stayed mostly clear until about 30 minutes before Second Contact. Then a large cloud covered the Sun. Fortunately the cloud moved on within a couple of minutes and the sky was mostly clear through Fourth Contact. Totality was beautiful. Most people saw Venus, some saw Jupiter too, but no one seems to have seen any stars although it did get dark at the site. Many people in the group left soon after totality ended, but I and several others stayed to view and photograph the eclipse through Fourth Contact.
Tennessee- (Terry Horne @CapH_1)
My wife and I viewed the event from Sheep Barn Ridge, which is a few miles from Kingston, TN. We began the planning in late 2015 when we realized the shadow path was adjacent to our property near my folks in TN. Our location delivered 2 minutes and 29 seconds of totality, with clear skies, a valley pasture view among new friends, goats, llama, ducks, chickens and a few hounds.
An amazing expample of the “Diamond Ring” effect. Image credit and copyright: Phyllis Horne @sahgma
We experienced every awe & oddity we had studied during the ramp up to the event. My wife did an excellent job with her photo efforts. She balanced her personal viewing time and planned equipment duties well. This was a source of much worry and discussion during the months prior.
I’ll mention a few surprises. I was impressed by the amount of light cast on the landscape with barely a sliver of the Sun remaining. I suspect the ambient sunlight to the south east was the major source. The rapid transition to peak darkness was dramatic.
In contrast, I noticed a clear reduction of heat radiation on my skin with about 50% coverage. It was a hot day. I wished I’d had more time to observe the animals.
I found it somewhat humorous how many folks took all of the important PSA’s about retina damage to heart. Before totality they bowed their heads to the ground when they did not have their gasses on while walking, standing and sitting.
What I learned most was, to the inexperienced, East Tennessee Moonshine travels faster than the Moon’s shadow.
We found a lovely scenic overlook facing west in Sky Valley, just outside Dillard, Georgia. Skies were clear with only minimal cloud cover until about 13:30, when heavy cloud cover began to build in the south/southeast. The clouds obfuscated the remainder of our view of the eclipse directly. It did get much cooler, windy, and the crickets were singing just prior to and during totality.
A partially eclipsed Sun versus clouds. Image credit and copyright: Jeannette Iriye.
We didn’t make it to South Carolina, and had to turn the plane back because of weather. Watched instead from Saint Mary’s Georgia. Did feel the temperature drop and experienced darkening but not in totality.
And us? We watched from the Pisgah Astronomical Research Institute in North Carolina as the shadow of the Moon draped over the landscape. The rolling afternoon clouds afforded only brief glimpses of the partially eclipsed Sun. Then, just prior to totality, we caught the final moments as the Sun withered to a brief diamond ring flash… and was gone. Magic! Unfortunately, the corona remained hidden behind high clouds for the 107 seconds of darkness, though we were treated to an unworldly 360 degree sunset below the cloud deck. Nocturnal mosquitoes, fooled by the false dusk, began their rounds, as a light “eclipse wind” kicked up.
Author and wife (@MyschaTheriault) standing in the shadow of the Moon, plus our view from the Pisgah Astronomical Research Institute (PARI) just before totality. Thanks to @Dayveesutton for snapping the pic!
Then, it was over. Got the eclipse bug? Well, another total solar eclipse crosses the U.S. in 2024… but you don’t have to wait that long, as we’ve got one coming right up crossing Argentina and Chile on July 2nd, 2019…
The view of the corona during totality? This computational model was derived from NASA SDO data during the last solar rotation. Credit: Predictive Science Inc.
Totality! The view during the November 2012 total solar eclipse. Image credit and copyright: Sharin Ahmad (@Shahgazer)
It’s hard to believe: we’re now just one short weekend away from the big ticket astronomical event for 2017, as a total solar eclipse is set to cross over the contiguous United States on Monday, August 21st.
Celestial mechanics is a sure thing in this Universe, a certainty along with death and taxes that you can bet on. But there are still a few key question marks leading up to eclipse day, things that we can now finally make intelligent assumptions about a few days out.
Although totality slices through the U.S., partial phases of the eclipse touch on every continent except Antarctica and Australia. Credit: Michael Zeiler/The Great American Eclipse.
First up is solar activity. If you’re like us, you’ll be showing off the Sun in both visible and hydrogen alpha as the Moon begins making its slow hour long creep across the disk of Sol. First, the good news: sunspot active region AR 2671 made its Earthward debut on Tuesday August 15th, and will most likely stick around until eclipse day. The bad news is, it most likely won’t have lots of friends, as solar cycle #24 begins its long slow ebb towards the solar minimum in 2019-2020. Likewise, I wouldn’t expect to see any magnificent sprouting red prominences in the solar chromosphere in the seconds bracketing totality, though we could always be pleasantly surprised.
The Earthward face of Sol as of August 17, four days before totality. Sunspot AR 2671 is robust and growing in complexity. Credit: NASA/SDO/HMI
How will the white hot corona appear during totality? This is the signature climax of any total solar eclipse: veteran umbraphiles can actually glance at a photo of totality and tell you which eclipse it was from, just on the shape of the corona. The National Solar Observatory released a model of what that Sun’s magnetosphere was doing one Carrington rotation (27 days) prior to the eclipse on July 25th, a pretty good predictor of the corona might look like during those fleeting moments of totality:
The shape of the field lines of the solar corona, one rotation prior to the August 21st total solar eclipse. Credit: The National Solar Observatory.
NASA will be chasing the umbra of the Moon with two converted W-57 aircraft during the eclipse, hoping to unlock the “coronal heating paradox,” image Mercury in the infrared, and hunt for elusive Vulcanoid asteroids near the eclipsed Sun.
The view of the corona during totality? This computational model was derived from NASA SDO data during the last solar rotation. Credit: Predictive Science Inc.
The corona is about twice as bright as a Full Moon, and its interface with the solar wind extends out past the Earth. The very onset of totality is like the footstep of a giant passing over the landscape, as the door of reality is suddenly ripped open, revealing the span of the glittering solar system at midday. Keep your eyes peeled for Mercury, Venus, Mars, Jupiter and twinkling Regulus tangled up in the corona, just a degree from the Sun-Moon pair:
The line up of the planets, bright stars and the eclipsed Sun during totality at 2:37 PM EDT as seen from Franklin, North Carolina. Credit: Stellarium.
Also, be sure to scan the local horizon for a strange 360 degree sunset as you stand in the umbra of the Moon. An “eclipse wind” may kick up, as temperatures plummet and nature is fooled by the false dawn, causing chickens to come home to roost and nocturnal animals to awaken. I dare you to blink. Totality can affect the human heart as well, causing tears to cries of surprise.
Here’s an interesting, though remote, possibility. Could a sungrazing “eclipse comet” photo bomb the show? Karl Battams (@SungrazerComets) raises this question on a recent Planetary Society blog post. Battams works with the Solar Heliospheric Observatory (SOHO), which has discovered an amazing 3,358 comets crossing the field of view of its LASCO imagers since 1995. Comets have been discovered during eclipses before, most notably in 1882 and 1948. To be sure, it’s a remote possibility this late in the game, but Battams promises to give us one last quick look via SOHO the morning of the eclipse on his Twitter feed to see if any cometary interlopers are afoot.
The possible search area for Kreutz group sungrazers during the August 21st eclipse. Credit: Karl Battams.
Now, on to the biggest question mark going into this eclipse weekend: what’s the weather going to be like during the eclipse? This is the ever-dominating factor on everyone’s mind leading up to eclipse day. Keep in mind, the partial phases are long; even a partly cloudy sky will afford occasional glimpses of the Sun during the partial phases of an eclipse. Totality, however, is fleeting – 2 minutes and 40 seconds near Hopkinsville, Kentucky and less for most – meaning even a solitary cumulus cloud drifting across the Sun at the wrong moment can spoil the view. No weather model can predict the view of the sky to that refined a level. And while best bets are still out west, lingering forest fires in Oregon are a concern, along early morning fog on the western side of the Cascade Mountains. Michael Zeiler over at The Great American Eclipse has been providing ESRI models of the cloud cover over the eclipse path for Monday… here’s the outlook as of Thursday, August 17th:
A look at cloud cover prospects over the eclipse path as of August 17. Credit: Michael Zeiler/Great American Eclipse/ESRI.
Computer models should begin to come into agreement this weekend, a good sign that we know what the weather is going to do Monday. Needless to say, a deviation from the standard climate models could send lots of folks scrambling down the path at the last minute… I’ve heard of folks with up to 5 (!) separate reservations along the path of totality, no lie…
The NOAA also has a fine site dedicated to weather and cloud coverage across the path come eclipse day, and Skippy Sky is another great resource aimed at sky viewing and cloud cover.
Clouded out? The good folks at the Virtual Telescope have got you covered, with a webcast for the total solar eclipse starting at 17:00 UT/1:00 PM EDT:
Credit: The Virtual Telescope Project.
Of course, you’ll need to use proper solar viewing methods during all partial phases of the eclipse. This means either using a telescope with a filter specifically designed to look at the Sun, a pin hole projector, or certified ISO 12312-2 eclipse glasses. If you’ve got an extra pair, why not convert them into a safe filter for those binoculars or a small telescope as well:
Also be wary of heatstroke, standing out showing folks the partially eclipsed Sun for an hour or more. It is August, and heat exhaustion can come on in a hurry. Be sure you have access to shade and stay cool and hydrated in the summer Sun.
Finally, eyes from space will be watching the eclipse from the International Space Station as well. Looking out at Monday, the ISS will pass through the penumbra of the Moon and see partial phases of the eclipse three times centered on 16:32, 18:20, and 20:00 Universal Time. The center time is particularly intriguing, as astros have a chance to see the dark umbral shadow of the Moon crossing the central U.S. This also means that eclipse viewers on planet Earth around southern Illinois might want to glance northward briefly, to spy the ISS during totality. Also, viewers along a line along southern central Canada will have a chance to catch an ISS transit across the face of the partially eclipsed Sun around the same time. Check CALSky for details.
Three passes of the International Space Station versus the path of of totality. The inset shows the view of the partially eclipsed Sun as seen from the ISS. Credit: NASA/JSC.
We’ll be at the Pisgah Astronomical Research Institute in southwestern North Carolina, for a glorious 104 seconds of totality. We expect to be out of wifi range come eclipse day, but we’ll tweet out key eclipse milestones as @Astroguyz. We also plan on writing up the eclipse experience with state-by-state testimonials post eclipse.
Read more about the August 21st total solar eclipse and the true tale of Edison’s chickens and the 1878 eclipse in our free e-book: 101 Astronomical Events for 2017.
Stars and the limb of Earth seen in the background of the International Space Station on July 29, 2017. Credit: NASA/Jack Fischer.
I’ve often been asked the question, “Can the astronauts on the Space Station see the stars?” Astronaut Jack Fischer provides an unequivocal answer of “yes!” with a recent post on Twitter of a timelapse he took from the ISS. Fischer captured the arc of the Milky Way in all its glory, saying it “paints the heavens in a thick coat of awesome-sauce!”
Can you see stars from up here? Oh yeah baby! Check out the Milky Way as it spins & paints the heavens in a thick coat of awesome-sauce! pic.twitter.com/MsXeNHPxLF
But, you might be saying, “how can this be? I thought the astronauts on the Moon couldn’t see any stars, so how can anyone see stars in space?”
John W. Young on the Moon during Apollo 16 mission. Charles M. Duke Jr. took this picture. The LM Orion is on the left. April 21, 1972. Credit: NASA
It is a common misconception that the Apollo astronauts didn’t see any stars. While stars don’t show up in the pictures from the Apollo missions, that’s because the camera exposures were set to allow for good images of the bright sunlit lunar surface, which included astronauts in bright white space suits and shiny spacecraft. Apollo astronauts reported they could see the brighter stars if they stood in the shadow of the Lunar Module, and also they saw stars while orbiting the far side of the Moon. Al Worden from Apollo 15 has said the sky was “awash with stars” in the view from the far side of the Moon that was not in daylight.
Just like stargazers on Earth need dark skies to see stars, so too when you’re in space.
The cool thing about being in the ISS is that astronauts experience nighttime 16 times a day (in 45 minute intervals) as they orbit the Earth every 90 minutes, and can have extremely dark skies when they are on the “dark” side of Earth. Here’s another recent picture from Fischer where stars can be seen:
Twinkle, twinkle, little star… Up above the world so high Like a diamond in the sky… pic.twitter.com/8H7CshyP0p
For stars to show up in any image, its all about the exposure settings. For example, if you are outside (on Earth) on a dark night and can see thousands of stars, if you just take your camera or phone camera and snap a quick picture, you’ll just get a darkness. Earth-bound astrophotographers need long-exposure shots to capture the Milky Way. Same is true with ISS astronauts: if they take long-exposure shots, they can get stunning images like this one:
This long exposure image of the night sky over Earth was taken on August 9, 2015 by a member of the Expedition 44 crew on board the International Space Station. Credit: NASA.
This image, set to capture the bright solar arrays and the rather bright Earth (even though its in twilight) reveals no stars:
Sometimes you look out the window and it just takes your breath away from how beautiful Earth is. Today is one of those times… #EarthShapespic.twitter.com/53UqL9BFH1
The partial lunar eclipse of June 4th, 2012. Credit: Dave Dickinson
The partial lunar eclipse of June 4th, 2012. Credit: Dave Dickinson
Live on the wrong continent to witness the August 21st total solar eclipse? Well… celestial mechanics has a little consolation prize for Old World observers, with a partial lunar eclipse on the night of Monday into Tuesday, August 7/8th.
A partial lunar eclipse occurs when the Moon just nicks the inner dark core of the Earth’s shadow, known as the umbra. This eclipse is centered on the Indian Ocean region, with the event occurring at moonrise for the United Kingdom, Europe and western Africa and moonset/sunrise for New Zealand and Japan. Western Australia, southern Asia and eastern Africa will see the entire eclipse.
The path of the Moon through the Earth’s shadow Monday night. Credit: adapted from NASA/GSFC/Fred Espenak
The penumbral phase of the eclipse begins on August 7th at 15:50 Universal Time (UT), though you probably won’t notice a slight tea colored shading on the face of the Moon until about half an hour in. The partial phases begin at 17:23 UT, when the ragged edge of the umbra becomes apparent on the southeastern limb of the Moon. The deepest partial eclipse occurs at 18:22 UT with 25% of the Moon submerged in the umbra. Partial phase lasts 116 minutes in duration, and the entire eclipse is about five hours long.
The viewing prospects for the partial lunar eclipse. Credit: NASA/GSFC/Fred Espenak.
This also marks the start of the second and final eclipse season for 2017. Four eclipses occur this year: a penumbral lunar eclipse and annular solar eclipse this past February, and this month’s partial lunar and total solar eclipse.
Eclipses always occur in pairs, or very rarely triplets with an alternating lunar-solar pattern. This is because the tilt of the Moon’s orbit is inclined five degrees relative to the ecliptic, the plane of the Earth’s orbit around the Sun. The Moon therefore misses the 30′ wide disk of the Sun and the 80′ – 85′ wide inner shadow of the Earth on most passes.
The partial lunar eclipse of April 26th, 2013. Image credit and copyright: Henna Khan
Fun fact: at the Moon’s 240,000 mile distance from the Earth, the ratio of the apparent size of the Moon and the shadow is approximately equivalent to a basketball and a hoop.
When celestial bodies come into alignment, however, things can get interesting. For an eclipse to occur, the nodes – the point where the Moon’s orbit intersects the ecliptic – need to align with the position of the Moon and the Sun. There are two nodes, one descending with the Moon crossing the ecliptic from north to south, and one ascending. The time it takes for the Moon to return to the same node (27.2 days) is a draconitic month. Moreover, the nodes are moving around the Earth due to drag on the Moon’s orbit mainly by the Sun, and move all the way around the zodiac once every 18.6 years.
Got all that? Let’s put it into practice with this month’s eclipses. First, the Moon crosses its descending node at 10:56 UT on August 8th, just over 16 hours after Monday’s partial eclipse. Two weeks later, however, the Moon crosses ascending node just under eight hours from the central conjunction with the Sun, and a total solar eclipse occurs.
Tales of the Saros
The August 7th lunar eclipse is member number 62 of the 83 lunar eclipses in saros series 119, which started on October 14th, 935 AD and will end with a final shallow penumbral eclipse on March 25th, 2396 AD. If you witnessed the lunar eclipse of July 28th, 1999, then you saw the last lunar eclipse in the same saros. Saros 119 produced its last total lunar eclipse on June 15th, 1927.
The next lunar eclipse, a total occurs on January 31st, 2018, favoring the Pacific rim regions.
Partial lunar eclipses have occasionally work their way into history, usually as bad omens. One famous example is the partial lunar eclipse of May 22nd, 1453 which preceded the Fall of Constantinople to the Ottoman Turks by a week. Apparently, a long standing legend claimed that a lunar eclipse would be the harbinger of the fall of Byzantium, and the partially eclipsed Moon rising over the besieged city ramparts seemed to fulfill the prophecy.
In our more enlightened age, we can simply enjoy Monday’s partial lunar eclipse as a fine celestial spectacle. You don’t need any special equipment to enjoy a lunar eclipse, just a view from the correct Moonward facing hemisphere of the Earth, and reasonably clear skies.
See the curve of the Earth’s shadow? This is one of the very few times that you can see that the Earth is indeed round (sorry, Flat Earthers) with your own eyes. And this curve is true for observers watching the Moon on the horizon, or high overhead near the zenith.
This month’s lunar eclipse occurs in the astronomical constellation of Capricornus. The Moon will also occult the +5th magnitude star 29 Capricorni for southern India, Madagascar and South Africa shortly after the eclipse.
The viewing footprint for the 29 Capricorni occultation shortly after the eclipse. Credit: Occult 4.2.
Finally, anyone out there planning on carrying the partial lunar eclipse live, let us know… curiously, even Slooh seems to be sitting this one out.
Update: we have one possible broadcast, via Shahrin Ahmad (@shahgazer on Twitter). Updates to follow!
The final eclipse season for 2017 is now underway, starting Monday night. Nothing is more certain in this Universe than death, taxes and celestial mechanics, as the path of the Moon now sends it headlong to its August 21st destiny and the Great American Total Solar Eclipse.
-We’ll be posting on Universe Today once more pre-total solar eclipse one week prior, with weather predictions, solar and sunspot activity and prospects for viewing the eclipse from Earth and space and more!
A new comet discovery crept up on us this past weekend, one that should be visible for northern hemisphere observers soon.
We’re talking about Comet C/2017 O1 ASAS-SN, a long period comet currently visiting the inner solar system. When it was discovered on July 19th, 2017 by the All Sky Automated Survey for Supernovae (ASAS-SN) system, Comet O1 ASAS-SN was at a faint magnitude +15.3 in the constellation Cetus. In just a few short days, however, the comet jumped up a hundred-fold in brightness to magnitude +10, and should be in range of binoculars now. Hopes are up that the comet will top out around magnitude +8 or so in October, as it transitions from the southern to northern hemisphere.
Never heard of ASAS-SN? It’s an automated sky survey hunting for supernovae in both hemispheres, with instruments based at Haleakala in Hawaii and Cerro Tololo in Chile. Though the survey targets supernovae, it does on occasion pick up other interesting astronomical phenomena as well. This is the first comet discovery for the ASAS-SN team, as they join the ranks of PanSTARRS, LINEAR and other prolific robotic comet hunters.
Evoking the very name “ASAS-SN” seems to have sparked a minor controversy as well, as the International Astronomical Union (IAU) declined to name the comet after the survey, listing it simply as “C/2017 O1”. Word is, “ASAS-SN” was to close to the word “Assassin” (this is actually controversial?) For our money, we’ll simply keep referring to the comet as “O1 ASAS-SN” as a recognition of the team’s hard work and their terrific discovery.
The orbit of Comet C/2017 O1 ASAS-Sn through the inner solar system. Credit: NASA/JPL
But what’s in a name, and does an interplanetary iceball really care? On a long term parabolic orbit probably measured in the millions of years, O1 ASAS-SN has an orbit inclined 40 degrees to the ecliptic, and reaches perihelion 1.5 AU from the Sun just outside the orbit of Mars on October 14th. This is most likely Comet C/2017 O1 ASAS-SN’s first passage through the inner solar system.
Currently located in the constellation Eridanus, hopefully comet O1 ASAS-SN’s current outburst holds. Expect it to climb northward through Taurus and Perseus over the next few months as it begins the long climb towards the north celestial pole.
Anatomy of an outburst: Comet ASAS-SN shortly after discovery over the span of a week. Credit ASAS-SN1.
As seen from latitude 30 degrees north, the comet will move almost parallel to the eastern horizon, and clears about 20 degrees altitude around local midnight, very well placed for northern hemisphere observers.
The path of Comet C/2017 O1 ASAS-SN parallel to the eastern horizon through September as seen from latitude 30 degrees north. Credit: Stellarium
At its closest in mid-October, Comet O1 ASAS-SN will be moving a degree a day through the constellation Camelopardalis
Here’s a month-by-month blow by blow for Comet O1 ASAS-SN:
August
14- Crosses into Cetus.
16- Crosses the celestial equator northward.
20- Crosses into Taurus.
The celestial path of Comet C/2017 O1 ASAS-SN from late July through mid-October (click to enlarge). Credit: Starry Night.
September
11-The waning gibbous Moon passes two degrees to the south.
17- Crosses the ecliptic northward.
20- Photo op: passes 4 degrees from the Pleiades open star cluster (M45).
28-Crosses into Perseus.
The projected light curve for Comet C/2017 O1 ASAS-SN. Note the outburst from actual observations (black dots). Credit: Seiichi Yoshida’s Weekly Information About Bright Comets.
October
1-Reaches max brightness?
12-Crosses the galactic equator northward.
14-Reaches perihelion 1.5 AU from the Sun.
17-Crosses into Camelopardalis.
18- Passes closest to Earth at 0.722 AU distant.
29-Passes 10′ from the +4 mag star Alpha Camelopardalis.
November
17-Crosses into Cepheus
December
6-Passes 3 degrees from the north celestial pole.
12-Reaches opposition.
31-Drops back down below +10th magnitude
At the eyepiece, a small comet generally looks like a small fuzzy globular cluster that refuses to snap into focus. Seek out dark skies in your cometary quest, as the least bit of light pollution will dim it below visibility. And speaking of which, the Moon is also moving towards Full next week so the time to hunt for the comet is now.
Keep in mind, current magnitude estimates for Comet O1 ASAS-SN are still highly speculative, as we seem to have caught this one in outburst… hey, remember Comet Holmes back about a decade ago in 2007? One can only dream!
-Also check out this recent NEOWISE study suggesting that large long period comets may be more common that generally thought.
This orange blob shows the nearby star Betelgeuse, as seen by the Atacama Large Millimeter/submillimeter Array (ALMA). ALMA/ESO/NRAO
This orange blob is the nearby star Betelgeuse, as imaged recently by the Atacama Large Millimeter/submillimeter Array (ALMA). ALMA/ESO/NRAO
Just. Wow.
An angry monster lurks in the shoulder of the Hunter. We’re talking about the red giant star Betelgeuse, also known as Alpha Orionis in the constellation Orion. Recently, the Atacama Large Millimeter Array (ALMA) gave us an amazing view of Betelgeuse, one of the very few stars that is large enough to be resolved as anything more than a point of light.
Located 650 light years distant, Betelgeuse is destined to live fast, and die young. The star is only eight million years old – young as stars go. Consider, for instance, our own Sun, which has been shining as a Main Sequence star for more than 500 times longer at 4.6 billion years – and already, the star is destined to go supernova at anytime in the next few thousand years or so, again, in a cosmic blink of an eye.
An estimated 12 times as massive as Sol, Betelgeuse is perhaps a staggering 6 AU or half a billion miles in diameter; plop it down in the center of our solar system, and the star might extend out past the orbit of Jupiter.
As with many astronomical images, the wow factor comes from knowing just what you’re seeing. The orange blob in the image is the hot roiling chromosphere of Betelgeuse, as viewed via ALMA at sub-millimeter wavelengths. Though massive, the star only appears 50 milliarcseconds across as seen from the Earth. To give you some idea just how small a milliarcsecond is, there’s a thousand of them in an arc second, and 60 arc seconds in an arc minute. The average Full Moon is 30 arc minutes across, or 1.8 million milliarcseconds in apparent diameter. Betelgeuse has one of the largest apparent diameters of any star in our night sky, exceeded only by R Doradus at 57 milliarcseconds.
The apparent diameter of Betelgeuse was first measured by Albert Michelson using the Mount Wilson 100-inch in 1920, who obtained an initial value of 240 million miles in diameter, about half the present accepted value, not a bad first attempt.
You can see hints of an asymmetrical bubble roiling across the surface of Betelgeuse in the ALMA image. Betelgeuse rotates once every 8.4 years. What’s going on under that uneasy surface? Infrared surveys show that the star is enveloped in an enormous bow-shock, a powder-keg of a star that will one day provide the Earth with an amazing light show.
The bowshock created by Betelgeuse as it plows through the local interstellar medium. JAXA/Akari
Thankfully, Betelgeuse is well out of the supernova “kill zone” of 25 to 100 light years (depending on the study). Along with Spica at 250 light years distant in the constellation Virgo, both are prime nearby supernovae candidates that will on day give astronomers a chance to study the anatomy of a supernova explosion up close. Riding high to the south in the northern hemisphere nighttime sky in the wintertime, +0.5 magnitude Betelgeuse would most likely flare up to negative magnitudes and would easily be visible in the daytime if it popped off in the Spring or Fall. This time of year in June would be the worst, as Alpha Orionis only lies 15 degrees from the Sun!
An early springtime supernova in the future? Stellarium
Of course, this cosmic spectacle could kick off tomorrow… or thousands of years from now. Maybe, the light of Betelgeuse gone supernova is already on its way now, traversing the 650 light years of open space. Ironically, the last naked eye supernova in our galaxy – Kepler’s Star in the constellation Ophiuchus in 1604 – kicked off just before Galileo first turned his crude telescope towards the heavens in 1610.
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.
