Comet V2 Johnson Takes Center Stage

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.

V2 Johnson light curve
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.

Weekly Space Hangout – February 10, 2017: Weekend Eclipse, Occultation and Comet 45P!

Host: Fraser Cain (@fcain)

Guests:

Paul M. Sutter (pmsutter.com / @PaulMattSutter)
Morgan Rehnberg (MorganRehnberg.com / @MorganRehnberg)
Dave Dickinson (www.astroguyz.com / @astroguyz)

Their stories this week:

Comet 45P Flies Past Earth

A new “kind” of black hole

A Penumbral Lunar Eclipse

The Moon Occults Regulus

Mars didn’t have enough CO2 to sustain liquid water

ISS is getting a commercial airlock

We use a tool called Trello to submit and vote on stories we would like to see covered each week, and then Fraser will be selecting the stories from there. Here is the link to the Trello WSH page (http://bit.ly/WSHVote), which you can see without logging in. If you’d like to vote, just create a login and help us decide what to cover!

If you would like to join the Weekly Space Hangout Crew, visit their site here and sign up. They’re a great team who can help you join our online discussions!

If you would like to sign up for the AstronomyCast Solar Eclipse Escape, where you can meet Fraser and Pamela, plus WSH Crew and other fans, visit our site linked above and sign up!

We record the Weekly Space Hangout every Friday at 12:00 pm Pacific / 3:00 pm Eastern. You can watch us live on Universe Today, or the Universe Today YouTube page<

Watch Comet 45P Honda-Mrkos-Pajdušáková Fly Past Earth This Week

A recent image of Comet 45P from February 4th. Image credit and copyright: Hisayoshi Kato.

Hankering for some cometary action? An interplanetary interloper pays us a visit this weekend, sliding swiftly through the pre-dawn northern hemisphere sky.

If you’ve never caught sight of periodic comet 45/P Honda-Mrkos-Pajdušáková, this week is a good time to try. Currently shining at magnitude +6.5, the comet makes a close 0.08 AU (7.4 million miles or 12.3 million kilometers) pass near the Earth on Saturday, February 11, at 14:44 Universal Time (UT) or 9:44 AM Eastern Standard Time. This is the closest passage of the comet for the remainder of this century, and with the Moon also reaching Full this weekend, the time to track down this comet is now.

The path of Comet 45/P through Monday, February 13th. Credit: Starry Night Edu.

We wrote about the first act for this comet last December, and Bob King also wrote up a preview last month. The comet passed perihelion 0.53 AU (49.3 million miles/ 82.1 million kilometers) from the Sun on New Year’s Eve 2016, reemerging into the dawn sky. It’s now on a swift sprint through the constellation Ophiuchus, and will cross Hercules at closest approach and into Corona Borealis and Boötes in just one week. At its closest, it’ll be moving at a whooping 23 arc minutes per hour, about three-quarters the diameter of a Full Moon!

The position of Comet 45/P as seen from latitude 30 degrees north at 4 AM. Credit: Stellarium.

At closest approach, the comet may just top naked eye brightness under dark skies at +6 magnitude.

Independently discovered by three observers worldwide in late 1948, Comet 45/P Honda-Mrkos-Pajdušáková orbits the Sun once every 5.25 years. The cumbersome name is often abbreviated as “Comet 45P HMP” or sometimes simply “Comet 45P.” The comet actually passed close enough back in 2011 for Arecibo radar to ping it, one of the very few comets to do so.

Not all apparitions of a given comet are equal, and most passages of Comet 45P were and will be uneventful. Dr. P. Clay Sharrod of the Arkansas Sky Observatory recently wrote a great account of the 1974 passage of Comet 45P, hearkening back to the same year when we were all awaiting Comet Kohoutek and Comet West was yet to come. This account might also hint at what could be in store for comet hunters this weekend.

A sketch of Comet 45P from December 10th, 1974. Image credit and copyright: Dr P. Clay Sherrod.

We managed to nab Comet 45P for the first time this AM from central Florida, though its still a tough catch. Shining at magnitude +7.5, we wouldn’t have otherwise noticed it as we swept along with our trusty Canon 15×45 image-stabilized binocs. Star-hopping finally brought us to the comet, a little fuzzy ‘star’ that stubbornly refused to snap into focus.

Comet 45P from early January, post-perihelion. Image credit and copyright: Sharin Ahmad (@shahgazer).

Unfortunately, the Moon reaches Full on Friday night, entering into the dawn sky this weekend. I’d advise hunting for the comet on every clear morning leading up to this weekend as the comet vaults northward into the pre-dawn sky. Friday night’s subtle penumbral eclipse won’t help much by way of dimming the Moon, though you can always place a house or hill between yourself and the Moon in a bid to block it out and aid in your cometary quest. There’s also a great photo op on February 16, when Comet 45P passes less than three degrees from the globular cluster M3.

As close shaves go, this passage of Comet 45P ranks as the 21st closest recorded passage of a comet near the Earth. The record goes to Comet Lexell, which passed just 0.0151 AU (1.4 million miles, or just under six times the distance to the Moon) past the Earth on July 1st, 1770. At its closest, Lexell had a visible coma spanning more than two degrees, more than four times the diameter of a Full Moon. In recent times, the last close passage of a comet other than 45P was Comet IRAS-Araki-Alcock, which zipped 0.063 AU past the Earth on June 12, 1983.

Ah, those were the days… a depiction of the Great Comet of 1769 as seen from Amsterdam, just one year (!) prior to the passage of Lexell’s Comet. Image in the Public Domain.

The gambler’s fallacy would say we’re due for the next big bright comet, though the universe seems to stubbornly refuse to roll the dice. In addition to 45P, 2017 does host a string of binocular comets, including Comet 2P Encke (March), Comet 41P/Tuttle-Giacobini-Kresák (April), Comet C/2015 ER61 PanSTARRS (May), and Comet C/2015 V2 Johnson (June). These are all explored in detail in our free e-book guide to the year, 101 Astronomical Events for 2017 out from Universe Today.

Stay warm on your comet vigil, and let us know of those observational tales of tribulation and triumph.