David Dickinson, Author at Universe Today

June 7, 2017June 7, 2017 by David Dickinson

Summer Astronomy, Minimoon & Saturn Opposition 2017

Saturn from June 1st. Image credit and copyright: Peter on the Universe Today Flickr forum.

Saturn on June 1st, nearing opposition. Image credit and copyright: Peter on the *Universe Today* Flickr forum

Summertime astronomy leaves observers with the perennial question: when to observe? Here in Florida, for example, true astronomical darkness does not occur until 10 PM; folks further north face an even more dire situation. In Alaska, the game in late July became “on what date can you first spot a bright planet/star? around midnight.

And evening summer thunder showers don’t help. Our solution is to get up early (4 AM or so) when the roiling atmosphere has settled down a bit.

But there’s one reason to stay up late, as the planet Saturn reaches opposition next week on June 15^th and crosses into the evening sky.

Southern hemisphere observers have it best this year, as the ringed planet loiters in southern declinations for the next few years. In fact, Saturn won’t pop up over the celestial equator again until April, 2026. You’ll still be able to see Saturn from mid-northern latitudes, looking low to the south.

First, a brief rundown of the planets this summer. Mars is currently on the far side of the Sun and headed towards solar conjunction of July 26^th. Meanwhile, Mercury is headed towards greatest eastern (dusk) elongation on June 21^st. Early AM viewers, can follow Venus, which has just passed greatest elongation west of the Sun on June 3^rd, just last week. Finally, Jupiter joins Saturn in the dusk sky, high to the south at sunset and headed towards quadrature 90 degrees east of the Sun on July 6th.

Looking eastward on the evening of June 9th. Credit: Stellarium.

There’s another astronomical curiosity afoot this coming weekend: the MiniMoon for 2017. This is the Full Moon nearest to lunar apogee, a sort of antithesis of the over-hyped “SuperMoon.” Lunar apogee occurs on Thursday, June 8^th and the Full Moon occurs just 14 hours after.

2017 sees Saturn traveling from the dreaded “13^th constellation” of zodiac Ophiuchus the Serpent Bearer into Sagittarius. This also means that Saturn is headed towards bottoming out near 23 degrees southern declination next year in late 2018. Saturn truly lives up to its “father time” namesake, marking up its slow 29 year passage once around the zodiac. This struck home to us a few years back when Saturn passed Spica in the constellation Virgo, right back where I first started observing the planet as a teenager three decades before.

The path of Saturn through the last half of 2017. Credit: Starry Night Education Software.

The rings are also at their widest tilt in 2017, making for an extra photogenic view. 27 degrees wide as seen from our Earthly vantage point is as wide as Saturn’s ring system ever gets. Saturn isn’t really “tipping” back and forth as much as it’s orbiting the Sun and dipping one hemisphere towards us, and then another. In 2017, it’s the planet’s northern hemisphere time to shine.

Saturn: the changing view. Image credit and copyright: Andrew Symes (@failedprotostar)

Here’s the last/next cycle rundown:

-Rings wide open: (southern pole of Saturn tipped earthward): 2003

–Rings edge on: 2009

–Rings wide open: (northern pole of Saturn tipped earthward): 2017

-Rings edge on: 2025

-Rings wide open: (southern pole of Saturn tipped earthward): 2032

Even a small 60 mm refractor and a low power eyepiece will reveal the most glorious facet of Saturn: its glorious rings. Galileo first saw this confounding view in 1610, and sketched Saturn as a curious double-handled world. In 1655 Christaan Huygens first correctly deduced that Saturn’s rings are a flat plane, fully disconnected from the planet itself.

Crank up the magnification a bit, and the large Cassini Gap in the rings and the shadow play of the rings and the planet becomes apparent. This gives the view an amazing 3-D effect unparalleled in observational astronomy. The shadow cast by the bulk of the planet disappears behind it during opposition, then slowly starts to reemerge to one side after. Other things to watch for include the retro-reflector Seeliger Effect ( also known as opposition surge) as the planet brightens near opposition. And can you spy the bulk of the planet through the Cassini gap?

The moons of Saturn. Image credit and copyright: John Chumack

Hunting for Saturn’s moons is also a fun challenge. Saturn has more moons visible to a backyard telescope than any other planet. Titan is easiest, as the +8 magnitude moon orbits Saturn once every 16 days. In a small to medium-sized (8-inch) telescope, six moons are readily visible: Enceladus, Mimas, Rhea, Dione, Iapetus and Tethys. Large light bucket scopes 10” and larger might just also tease out the two faint +15th magnitude moons Hyperion and Phoebe.

There’s also something else special about Saturn in 2017 in the world of space flight: the venerable Cassini mission comes to an end this September. Hard to believe, this mission soon won’t be with us. Launched in 1997, Cassini arrived at Saturn in in July 2004, and has since provided us with an amazing decade plus of science. The internet and science writing online has grown up with Cassini, and it’ll be a sad moment to see it go.

All thoughts to ponder, as you check out Saturn at the eyepiece this summer.

May 18, 2017May 18, 2017 by David Dickinson

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 3^rd 2015 while it was still 6.17 astronomical units (AU) distant at +17^th 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 12^th. 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 28^th, 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 6^th 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 3^rd, 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 1^st. Unless otherwise noted, all passes are less than one degree (two Full Moon diameters) away:

May 19^th: passes near +3.4 magnitude Delta Bootis.

June 5^th: Closest approach to the Earth at 0.812 AU distant.

June 12^th: Perihelion 1.64 AU from the Sun.

June 15^th: Crosses into the constellation Virgo.

June 21^st: Crosses the celestial equator southward.

June 26^th: Passes near the +4 magnitude star Syrma.

July 1^st: Passes near (30″!) the +4.2 magnitude star Kappa Virginis

July 3^rd: 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 5^th: Crosses the ecliptic southward.

July 17^th: Crosses into the constellation Hydra.

July 22^nd: Passes 2.5 degrees from the +3.3 magnitude star Pi Hydrae.

July 28^th: 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 +8^th 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.

May 11, 2017May 11, 2017 by David Dickinson

Movie Review – Alien: Covenant

Promotional poster for Alien: Covenant. Credit: 20th Century Fox

Warning: mild plot spoilers ahead for the upcoming summer film Alien: Covenant, though we plan to focus more on the overall Alien sci-fi franchise and some of the science depicted in the movie.

So, are you excited for the 2017 movie season? U.S. Memorial Day weekend is almost upon us, and that means big ticket, explosion-laden sci-fi flicks and reboots/sequels. Lots of sequels. We recently got a chance to check out Alien: Covenant opening Thursday, May 18^th as the second prequel and the seventh film (if you count 2004’s Alien vs. Predator offshoot) in the Alien franchise.

We’ll say right up front that we were both excited and skeptical to see the film… excited, because the early Alien films still stand as some of the best horror sci-fi ever made. But we were skeptical, as 2012’s Prometheus was lackluster at best. Plus, Prometheus hits you with an astronomical doozy in the form of the “alien star chart” right off the bat, not a great first step. Probably the best scene is Noomi Rapace’s terrifying self-surgery to remove the alien parasite. Mark Watney had to do something similar to remove the antenna impaled in his side in The Martian. Apparently, Ridley Scott likes to use this sort of scene to really gross audiences out. The second Aliens film probably stands as the benchmark for the series, and the third film lost fans almost immediately with the death of Newt at the very beginning, the girl Sigourney Weaver and crew fought so hard to save in Aliens.

How well does Alien: Covenant hold up? Well, while it was a better attempt at a prequel than Prometheus, it approaches though doesn’t surpass the iconic first two. Alien: Covenant is very similar to Aliens, right down to the same action beats.

The story opens as the crew of the first Earth interstellar colony ship Covenant heads towards a promised paradise planet Origae-6. En route, the crew receives a distress signal from the world where the ill-fated Prometheus disappeared, and detours to investigate. If you’ve never seen an Alien film before, we can tell you that investigating a mysterious transmission is always a very bad idea, as blood and gore via face-hugging parasites is bound to ensue. As with every Alien film, the crew of the Covenant is an entirely new cast, with Katherine Waterston as the new chief protagonist similar to Sigourney Weaver in the original films. And like any sci-fi horror film, expect few survivors.

Alien: Covenant is a worthy addition to the Alien franchise for fans who know what to expect, hearkening back to the original films. As a summer blockbuster, it has a bit of an uphill battle, with a slower opening before the real drama begins.

So how does the science of Alien: Covenant hold up?

The Good: Well, as with the earlier films, we always liked how the aliens in the franchise were truly, well, alien, not just human actors with cosmetic flourishes such as antennae or pointed ears. Humans are the result of evolutionary fortuity, assuring that an alien life form will trend more towards the heptapods in Arrival than Star Trek’s Mr. Spock. Still more is revealed about the parasitic aliens in Alien: Covenant, though the whole idea of a inter-genetic human alien hybrid advanced in the later films seems like a tall order… what if their DNA helix curled the wrong way? Or was triple or single, instead of double stranded?

Spaceships spin for gravity in the Alien universe, and I always liked Scott’s industrial-looking, gray steel and rough edges world in the Alien films, very 2001: A Space Odyssey.

Now, for a very few pedantic nit picks. You knew they were coming, right? In the opening scenes, the Covenant gets hit with a “neutrino burst” dramatically disabling the deployed solar array and killing a portion of the hibernating crew. Through neutrinos are real, they, for the most part, pass right through solid matter, with nary a hit. Millions are passing through you and me, right now. The burst is later described as due to a “stellar ignition event” (a flare? Maybe a nova?) Though the crew states there’s no way to predict these beforehand… but even today there is, as missions such as the Solar Dynamics Observatory and SOHO monitor Sol around the clock. And we do know which nearby stars such as Betelgeuse and Spica are likely to go supernova, and that red dwarfs are tempestuous flare stars. An interstellar colonization mission would (or at least should) know to monitor nearby stars (if any) for activity. True, a similar sort of maguffin in the form of the overblown Mars sandstorm was used in The Martian to get things rolling plot-wise, but we think maybe something like equally unpredictable bursts high-energy cosmic rays would be a bigger threat to an interstellar mission.

The crew also decides to detour while moving at presumably relativistic speeds to investigate the strange signal. This actually happens lots in sci-fi, as it seems as easy as running errands around town to simply hop from one world to the next. In reality, mass and change of momentum are costly affairs in terms of energy. In space, you want to get there quickly, but any interstellar mission would involve long stretches of slow acceleration followed by deceleration to enter orbit at your destination… changing this flight plan would be out of the question, even for the futuristic crew of the Covenant.

Expect a high body count: the crew of the Covenant. Credit: 20th Century Fox

Another tiny quibble: the Covenant’s computer pinpoints the source of the mysterious signal, and gives its coordinates in right ascension and declination. OK, this is good: RA and declination are part of a real coordinate system astronomers use to find things in the sky… here on Earth. It’s an equatorial system, though, hardly handy when you get out into space. Maybe a reference system using the plane of the Milky Way galaxy would be more useful.

But of course, had the crew of the Covenant uneventfully made it to Origae-6 and lived happily ever after stomach-exploding parasite free, there would be no film. Alien: Covenant is a worthy addition to the franchise and a better prequel attempt than Prometheus… though it doesn’t quite live up to the thrill ride of the first two, a tough act to follow in the realm of horror sci-fi.

May 9, 2017May 9, 2017 by David Dickinson

See Comet C/2015 ER61 PanSTARRS at its Best

Have you been following the springtime parade of bright comets? Thus far, the Oort cloud has offered up several fine binocular comets, including Comet 2/P Encke, 41/P Tuttle-Giacobini-Kresak, 45/P Honda-Mrkos-Pajdusakova, C/2016 U1 NEOWISE and C/2017 E4 Lovejoy. Now, another comet joins the dawn ranks, as it brightens up ahead of expectations: 2015 ER61 PanSTARRS.

Discovered on March 15^th, 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.

ER61 PanSTARRS Skychart — 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 4^th, 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 28^th, 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 +5^th magnitude, and passes are less than a degree unless otherwise noted.)

May 10^th: Reaches perihelion at 1.04 astronomical units (AU) from the Sun.

May 12^th: Passes near the +4.9 magnitude star 19X Piscium.

May 20-23^rd: Passes less than 10 degrees from Venus.

May 21^st: The waning crescent Moon passes less than 10 degrees to the south.

June 10^th: Passes near the +3.6 magnitude star Eta Piscium.

June 11^th: Passes near the galaxy M74.

June 16^th: Passes into the constellation Aries.

June 19^th: The waning crescent Moon passes 9 degrees to the south.

July 13^th: Passes near (less than 5′) the +4.6 magnitude star Epsilon Arietis.

July 18^th: The waning crescent Moon passes 9 degrees to the south.

July 23^rd: Passes near the +4.8 star Zeta Arietis.

The comet versus Venus in the dawn sky – looking eastward on May 15th. Credit: Stellarium.

August 2^nd: Crosses into the constellation Taurus.

August 15^th: The waning crescent Moon passes 8 degrees to the south.

August 16^th: Passes near M45 (The Pleiades)

After mid-August, Comet 2015 ER61 PanSTARRS will drop back down below +10^th 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.

April ER61 PanSTARRS — 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.

April 13, 2017 by David Dickinson

NEO Asteroid 2014 JO25 Set to Buzz Earth on April 19th

Artist's concept of a large asteroid passing by the Earth-Moon system. Credit: A combination of ESO/NASA images courtesy of Jason Major/Lights in the Dark.

Missed us… a concept image of a large asteroid passing by the Earth-Moon system. Credit: A combination of ESO/NASA images courtesy of Jason Major/Lights in the Dark.

It’s a shooting gallery out there. The spattered face of Earth’s Moon and large impact sites such as Meteor Crater outside of Flagstaff, Arizona remind us that we still inhabit a dangerous neck of the solar neighborhood. But despite the inevitable cries proclaiming the “End of the World of the Week” this coming weekend, humanity can breathe a collective sigh of relief next Wednesday on April 19^th, when asteroid 2014 JO25 passes safely by the Earth.

To be sure, lots of smaller space rocks pass by the Earth closer than the Moon (that’s an average of 240,000 miles distant) on a monthly basis. Take for example 4-meter asteroid 2017 GM, which passed just 16,000 kilometers distant on April 4th. What makes 2014 JO25 special is its size: measurements from NASA’s NEOWISE mission suggest that 2014 JO25 is about 2,000 feet (650 meters) along its longest axis, about twice the length of a Nimitz-class aircraft carrier. 2014 JO25 is passing 1.1 million miles (1.8 million kilometers) or 4.6 times the Earth-Moon distance on Wednesday, the closest large asteroid pass since 5-km Toutatis in September, 2004. The next predicted large asteroid pass near Earth is 1999 AN10, set to pass 1 LD (lunar distance) from the Earth in 2027.

4179 Toutatis as seen from China’s Chang’e 2 spacecraft. Credit: CNSA

This is also the closest passage of 2014 JO25 near the Earth for a 900 year span.

Discovered on May 5th, 2014 by the Catalina Sky survey, asteroid 2014 JO25 orbits the Sun once every three years, taking it from a perihelion of 0.237 AU (interior to Mercury’s orbit) out to an aphelion of 3.9 distant in the asteroid belt, interior to Jupiter’s orbit.

The orbit of NEO asteroid 2014 JO25. Credit: NASA/JPL.

Finding 2014 JO25 at its Closest Approach

With an estimated albedo (surface brightness) about twice that the lunar surface, 2014 JO25 will reach magnitude +10 to +11 on closest approach on Wednesday. Currently low in the dawn sky in the Square of Pegasus asterism, asteroid 2014 JO25 passed perihelion sunward as seen from the Earth at 1.015 Astronomical Units (AU) distant on March 11th. At its closest to the Earth on April 19^th at 12:24 Universal Time (UT)/6:24 AM EDT, asteroid 2014 JO25 will skim the jagged Draco-Ursa Minor border below the bowl of the Little Dipper, moving at a whopping three degrees per hour. Sitting just 25 degrees from the north celestial pole on closest approach, catching sight of 2014 JO25 at favors western North America and northeastern Asia, though the eastern half of North America and Europe have a shot at the asteroid a few hours prior to closest approach in the early morning hours of April 19^th. North American viewers get another shot at catching the fleeting asteroid later the same evening 13 hours after closest approach as the asteroid sails through the galaxy-rich constellation Coma Berenices.

The 24 hour path of asteroid 2014 JO25 from midnight UT April 18th through April 19th. (note: hourly time hacks are in Eastern Daylight Saving Time EDT UT-4). Credit: Starry Night Education software.

At +11^th magnitude, you’ll need a telescope of at least 6” aperture or larger and a good star chart to nab 2014 JO25 as it glides against the starry background. Fellow Universe Today contributor Bob King has some great star charts of the pass over at Sky & Telescope. The Moon will be at Last Quarter phase on the morning of the 19^th, providing moderate light pollution.

Plans are also afoot for NASA to ping asteroid 2014 JO25 using Arecibo and Goldstone radar… expect stunning animations to follow next week.

Clouded out? The good folks at the Virtual Telescope Project have you covered, with a live webcast featuring the passage of NEO 2014 JO25 starting at 21:30 UT/5:30 PM EDT on April 19^th.

And if you’re out hunting for asteroids on the coming mornings, there are currently two bright binocular comets in the dawn sky to keep you company: Comet C/2017 E4 Lovejoy in the constellation Andromeda and Comet C/2015 ER61 PanSTARRS in Aquarius. Both are currently performing above expectations at about magnitude +7.

A busy neighborhood: Known asteroids as of April 1st, 2016. Credit: NASA/JPL.

“What if” an asteroid the size of 2014 JO25 hit the Earth? Well, the Chelyabinsk meteor was an estimated 20 meters in size; the impactor that formed Meteor Crater in Arizona was about 50 meters in diameter. The Chicxulub event off the Yucatan peninsula 66 million years ago was an estimated 10 kilometer-sized impactor well over ten orders of magnitude bigger than 2014 JO25. While the impact of a 600 meter asteroid would be a noteworthy event and a bad day locally, it would pale in comparison to an extinction level event.

All something to consider, as you watch the faint dot of asteroid 2014 JO25 pass harmlessly by the Earth and through the news cycle for the coming week.

April 6, 2017 by David Dickinson

By Jove: Jupiter at Opposition 2017

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 16^th, 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 5^th 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 12^th.

Jupiter will rule the dusk skies until solar conjunction on October 26^th, 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 31^st, 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.

-Send those images of Jupiter in to Universe Today’s Flickr forum.

April 3, 2017April 4, 2017 by David Dickinson

Surprise: Comet E4 Lovejoy Brightens

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 +10^th 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 16^th, 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 +15^th magnitude when it was first discovered last month on March 9^th, 2017, it has since jumped up to +7^th 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 1^st 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 15^th. 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 11^th, 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’s *Weekly 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 22^nd, 2017. Had it done the same on May 4^th, 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 23^rd, and passed 0.6 AU (93 million kilometers) from the Earth on March 31^st. 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 7^th: Passes less than one degree from the +3.5 magnitude star Sadal Bari (Lambda Pegasi).

April 9^th: Passes less than 10′ from the +2.4 magnitude star Scheat (Beta Pegasi).

April 13^th: Crosses into the constellation Andromeda.

April 19^th: Photo-op, as the comet passes 4 degrees from the Andromeda Galaxy M31.

April 22^nd: Passes between the +2^nd magnitude star Mirach and the +4^th magnitude star Mu Andromedae.

April 27^th: Passes five degrees from the Pinwheel Galaxy M33.

April 28^th: 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.

March 29, 2017March 29, 2017 by David Dickinson

Watch Rotating Horns of Venus at Dawn

Venus inferior conjunction — 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 25^th.

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.

Venus rotating horns — 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 5-6^th, 2012 once about every 584 days, instead of having to wait again until next century on December 10^th, 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:

Venus SOHO — 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 23^rd, May 22^nd, and June 20^th.

Daytime Venus — 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 13^th, 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 3^rd, 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 19^th century.

Venus should also put in a showing 34 degrees west of the Sun shining at magnitude -4 during the August 21^st, 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.

March 20, 2017 by David Dickinson

Catch Comet 41P Tuttle-Giacobini-Kresák At Its Best

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

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 15^th, 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 11^th, 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 3^rd, 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 5^th. 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 +9^th 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 12^th:

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 21^st: Photo-op: passes between M108 and M97 the Owl Nebula
March 29^th: passes into Draco
April 2^nd: Passes near the 3.6 magnitude star Thuban (Alpha Draconis)
April 5^th: Passes just 0.15 AU (23.2 million kilometers) from the Earth at 13:30 UT.
April 7^th: passes just 22 degrees from the north celestial pole at declination 68 degrees north.
April 11^th: reaches perihelion at 1.05 AU (162.7 million kilometers) from the Sun.
April 18^th: passes the 2.7 magnitude star Rastaban (Beta Draconis)
April 20^th: 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 +10^th 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 +6^th 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.

March 10, 2017March 12, 2017 by David Dickinson

Comet Encke Reemerges in the Dawn Sky

Comet 2P Encke glides through Pisces on February 16th. Image credit and copyright: Hisayoshi Kato.

Miss out on Comet 45/P Honda-Mrkos-Padadušáková last month? We’ll admit, it was fairly underwhelming in binoculars… but fear not, there are several other binocular comets in the pipeline for 2017.

Maybe you managed to catch sight of periodic Comet 2P Encke in late February after sunset before it disappeared into the Sun’s glare. Pronounced (En-Key), the comet actually passes through the field of view of the joint NASA/ESA Solar Heliospheric Observatory’s (SOHO) LASCO C3 camera from March 8^th to March 14^th before reemerging in the dawn sky.

I see you… Comet 2P Encke is now in SOHO’s LASCO C3 field of view, above Mercury (the bright object) moving in the opposite direction: pic.twitter.com/gcYwv0Sdkp

— Dave Dickinson (@Astroguyz) March 10, 2017

Northern hemisphere observers have already got a sneak peek at Encke’s performance low in the dusk in February as it heads towards perihelion. Now the comet heads southward, as it vaults up into the dawn sky for folks south of latitude 30 degrees north in mid-March. From latitude 30 degrees north, Encke will clear 15 degrees elevation above the southeastern horizon around March 31^st. Viewers south of the equator will have a much better viewing prospect, as Encke glides southward through Aquarius. When will you first spot it?

The dawn path of 2P Encke through the first week of April as seen from latitude 30 degrees north. Credit: Starry Night.

Also: don’t forget to ‘spring forward’ to Daylight Saving Time this weekend for a majority of North America prior to beginning your dawn comet vigil… Europe and the United Kingdom gets a brief reprieve ’til March 26th.

Her are some upcoming key events for Comet 2P Encke:

Closest to Sun: March 10^th, with a perihelion of 0.33 AU.

Closest to Earth: March 12^th, at 0.65 AU distant.

Brightest: Around March 15. Encke is currently at magnitude +7, and should top out at magnitude +6, though it’ll only be 14 degrees from the Sun on this date.

The projected light curve for comet 2P Encke. Image credit: Seiichi Yoshida’s *Weekly Information About Bright Comets*.

Next good apparition: 0.4 AU from Earth in 2036.

This is Encke’s 63rd passage through the solar system since Pierre Méchain linked successive passages of the comet to the same in 1819. Like Edmond Halley, Encke didn’t discover the most famous of comets that now bears his name, but instead merely deduced its periodic nature. Halley was 1^st, and Encke was second (hence the “2” in 2P…) The shortest short period comet, Encke was captured sometime thousands of years ago into its short period orbit, and is destined to burn out one day as it ventures from 4.1 to 0.33 AU from the Sun. Encke is also the source of the annual Taurid meteor shower in November, notable for producing a high rate of fireballs.

Comet 2P Encke on February 19th. Image credit and copyright: Cajun Astro.

Comets can be elusive beasties, as all of that precious quoted magnitude is smeared out over an extended surface area. Add on top this the fact that comets are also notorious for often under- and occasionally over-performing expectations. Just look at the ‘none more black’ albedo of comet 67P Churumov-Gerasimenko chronicled by ESA’s Rosetta spacecraft: it’s a miracle we can see ’em at all. And finally, that low contrast dawn sky can easily hide a faint binocular comet, fading it to invisibility. Start your comet vigil early, sweeping the horizon with binocs. An early start and a clear view are key. The slim waning crescent Moon sits 12 degrees north of Comet Encke on the morning of March 26^th, and the comet also passes less than 3 degrees from the Helix Nebula (NGC 7293) on (no joke) April Fool’s Day April 1^st.

The view on the morning of March 26th, 30 minutes before sunrise. Credit: Stellarium.

Flashback to one Encke orbit ago to 2013 and the comet provided a good dawn preshow to that biggest of cosmic let downs, Comet ISON. And although Encke makes its rounds every 3.3 years, orbital geometry assures that we won’t get another favorable viewing from Earth until 2036.

Speaking of great comets that never were, we juuuust missed having a spectacular comet this past month, when recently discovered long-period Comet 2017 E1 Borisov passes just 0.045 AU (!) interior to our orbit. Unfortunately, this occurs five months too early, with the Earth almost exactly at the wrong place in its orbit. Now, if it was only August…

Comet Teaser for 2017

Yeah, the gambler’s fallacy would tell us that we’re due for the next great comet of the century, for sure. In the meantime, we’ve still got Comets 41P/Tuttle-Giacobini-Kresák (late March/April), C/2015 ER61 PanSTARRS (May), and C/2015 V2 Johnson (June) on tap as good binocular comets in 2017.

Be sure to enjoy elusive comet Encke as it flits once more though the dawn skies.

-Read about comets, occultations, eclipses and more for the year, in our new free e-book 101 Astronomical Events for 2017 out from Universe Today.