David Dickinson, Author at Universe Today

October 28, 2015December 23, 2015 by David Dickinson

Hunting Prospero

A relic of the early Space Age turns 44 years old this week.

The United Kingdom’s first and only successful space launch using a UK-built rocket is still visible in low Earth orbit today, if you know exact where and how to look for it.

Launched atop a 3-stage Black Arrow R3 rocket on October 28^th, 1971 from the Woomera launch station in the Australian outback, Prospero (sometimes also referred to simply as the X-3) was designed to test key communications satellite technologies.

Prospero wasn’t the first satellite fielded by the United Kingdom–that credit goes to the Ariel 1 satellite launched atop a Thor DM-19 Delta rocket by the United States from Cape Canaveral on April 26^th, 1962—but Prospero was notable as part of a program cut short in its early stages.

The Black Arrow project from which Prospero was born was cancelled shortly after the launch, making the X-3 the only successful mission fielded by the program (X-2 failed to achieve orbit due to an early shut-down of the stage 2 rocket). Prospero almost didn’t make it as well, as the final Waxwing stage hit the satellite upon deployment, taking one of Prospero’s four radio antennae clean off!

How to spot fainter satellites

Unlike watching for bright passes of naked eye objects in low Earth orbit such as the International Space Station, hunting for binocular satellites such as Prospero takes careful planning. Our tried and true technique is not unlike the method recently described on Universe Today to hunt for near Earth grazers such as the Halloween asteroid 2015 TB 145. In stakeout mode, you’ll need to know exactly when Prospero passes near a bright object, such as a star or planet.

Heavens-Above is a great resource, and catalogs every satellite back through the early Space Age. And what’s really nifty is that Heavens-Above will plot the passage of the satellite showing the timing of the pass against the sky against the background of constellations and stars for your specific location.

If you have Space-Track access, you can also download the TLEs (Two Line Elements) for a particular satellite for manual entry into a program such as Starry Night or Orbitron to forecast passes. You’ll be aiming your binoculars at the target star Project Moonwatch-style at the appointed time, and simply waiting for the satellite to drift by. For precise timing, we like to listen to WWV radio broadcasting the time (in Universal or Greenwich Mean/Zulu Time) out of Fort Collins Colorado on AM shortwave 5000, 10000, 15000 and 20000 Hz. WWV radio calls out the time at the top of each minute, with time ticks for each second, allowing the observer to keep eyes on the sky continuously. Just which WWV station comes in clearest can vary after sunset, as the ionosphere changes in terms of radio reflectivity at dusk.

We tracked down a good pass on the errant ‘space tool bag’ lost by International Space Station astros back in 2008 using this method once it was assigned an individual NORAD ID number… there it was, a lost tool satchel with a date with a fiery reentry destiny, drifting right by the bright star Spica at the appointed time.

Prospects for Prospero

Radio operators tracked Prospero for decades on transmission frequency 137.560 MHz until 2004, eight years past its official deactivation in 1996. As of this writing, there aren’t any official future attempts to contact Prospero in the works, though it’s certainly possible for a motivated party to do in theory… Prospero isn’t expected to reenter until 2070, and perhaps it’ll last until its centenary in space.

For latitudes 30-40 degrees north, good viewing prospects for Prospero start up again around December 20^th of this year at dusk. At its brightest on a pass straight overhead through the observer’s zenith, expect Prospero to reach about +8 magnitude in brightness, well within range of binoculars. Prospero orbits Earth once every 103 minutes in a 527 by 1,304 kilometre orbit, inclined 82 degrees relative to the Earth’s equator. Prospero’s NORAD ID COSPAR designator is 1971-093A catalog number (05580).

Other relics of the Space Age are also visible in backyard near you, including:

The Vanguards: launched in starting in 1958 by the United States, The three Vanguard satellites represent the oldest bits of human artifacts in Earth orbit, and they aren’t due for reentry for another two centuries.

Allouette-1: The first Canadian satellite, launched from Vandenberg AFB in 1962 and still in orbit.

Tracking relics of the Space Age brings home the personal relevance of early space history. Looking further out towards satellites in geostationary orbit, we are seeing artifacts that may long withstand the tests of time and become the solitary testaments of our current civilization to a far off future era.

-Got a favorite relic of the Space Age you’d like us to track down? Let us know!

October 23, 2015December 23, 2015 by David Dickinson

Seeing Starspots: The Curious Case of XX Trianguli

Ever wonder what happens on the surface of other stars?

An amazing animation was released this week by astronomers at the Leibniz Institute for Astrophysics (AIP) in Potsam Germany, showing massive sunspot activity on the variable star XX Trianguli (HD 12545). And while ‘starspot’ activity has been seen on this and other stars before, this represents the first movie depicting the evolution of stellar surface activity beyond our solar system.

“We can see our first application as a prototype for upcoming stellar cycle studies, as it enables the prediction of a magnetic-activity cycle on a dramatically shorter timescale than usual,” says Leibniz Institute for Astrophysics Potsdam astronomer Andreas Kunstler in a recent press release.

The images were the result of a long term analysis of the star carried out using the twin STELLA (STELLar Activity) robotic telescopes based on Tenerife in the Canary Islands. The spectroscopic data was gathered over a period of six years, and this video demonstrates that, while other stars do indeed have sunspot cycles similar to our Sun, those of massive stars such as XX Tri are much more intense than any we could imagine here in our own solar system.

Image credit: Leibniz Institute for Astrophysics Potsdam (AIP) — STELLA on the hunt. Image credit:

Even the largest and closest of stars have a minuscule angular diameter –measured in milliarcseconds (mas, our 1/1,000ths of an arc second)—in size. For example, we know from lunar occultation timing experiments that the bright star Antares at 550 light years distant and 5 times the radius of our Sun is about 41 mas in size. At an estimated 910 to 1,500 light years distant and 10 times the radius of our Sun, XX Tri is probably comparable, at about 20 mas in size.

That’s tiny from our perspective, though the massive starspot depicted must be truly gigantic to see up close.

To image something on that scale, astronomers use a technique known as Doppler tomography gathered from high-resolution spectra. Over said six year span covering a period from July 2006 to April 2012, 667 viable spectra were gathered, covering 86 total rotational periods for the star. Incidentally, that’s not much longer than the average equatorial rotational period of our Sun—remember, as a ball of gas, the rotational period of our Sun varies with solar latitude—at about 22 days.

Our relatively sedate host star. image credit: Dave Dickinson — Our relatively sedate host star. Image credit: Dave Dickinson

The views compiled by the team show a pole facing, Mercator projection, and a spherical ‘real view’ of the star. Of course, to see XX Tri up close would be amazing, if a not a little intimidating with those massive, angry spots dappling its surface.

Watch the animation, and you can see the changing morphology of the spots, as they decay, merge and defuse again. Just how permanent is that massive pole spot? Why are we seeing spots across the pole of a star like XX Tri at all, something we never see on the Sun? Do other stars follow something analogous to Spörer’s Law and their own version of the 11-year sunspot cycle that we see on Sol?

Capabilities such as those demonstrated by STELLA may soon crack these questions wide open. Composed of two 1.2 meter robotic telescopes jointly operated by the Institute for Astrophysics at Potsdam and the Instituto de Astrofísica de Canarias (IAC), STELLA combines the capability of a wide-field photometric imager with that of a high-resolution spectrograph, ideal for this sort of analysis of remote stellar surfaces.

Hey, here’s a crazy idea: turn STELLA loose on KIC 8462852 and see if the hypothesized ‘exo-comets’ or ‘alien mega-structures’ turn up… though it weighs in much smaller than XX Tri at 1.4x solar masses, KIC 8462852 is also about 1,400 light years distant, perhaps just doable using high resolution spectroscopy…

Want to see XX Tri for yourself? An RS Canum Venaticorum variable orange giant star (spectral type K0 III) located in the constellation of Triangulum the Triangle, XX Tri shines at magnitude +8.5 and varies over about half a magnitude in brightness. Its coordinates are:

Right Ascension: 2 hours 3 minutes 47 seconds

Declination: 35 North 35 minutes 29 seconds

The more we learn about other stars, the more we understand about how to live with our very own sometimes placid, sometimes tempestuous host star.

Read more about the curious case of XX Trianguli:

–On the Starspot Temperature of HD 12545

–HD 124545: A Study in Spottedness

–Spot evolution on the Star XX Triangulum (sic)

Does XX Trianguli look familiar? That might be because it was featured as the Astronomy Picture of the Day as ‘imaged’ by the Coude Feed Telescope on Kitt Peak way back when on November 2nd, 2003.

October 22, 2015December 23, 2015 by David Dickinson

Can Lunar Earthshine Reveal Ashen Light on Venus?

A recent celestial event provided a fascinating look at a long-standing astronomical mystery.

Is the ‘ashen light of Venus’ a real phenomena or an illusion?

On October 8^th, the waning crescent Moon occulted (passed in front of) the bright planet Venus for observers in the southern hemisphere. And while such occurrences aren’t at all rare—the Moon occults Venus 3 times in 2015, and 25 times in this decade alone worldwide—the particulars were exceptional for observers in Australia, with a -4.5 magnitude, 40% illuminated Venus 30” in size emerging under dark skies 45 degrees west of the Sun from behind the dark limb of the Moon.

David and Joan Dunham rose to the challenge, and caught an amazing sequence featuring a brilliant Venus reappearing from behind the Moon as seen from the Australian Outback. When I first watched the video posted on You Tube by International Occultation Timing Association (IOTA) North American coordinator Brad Timerson, I was a bit perplexed, until I realized we were actually seeing the dark nighttime side of a waning Moon, with the bright crescent just out of view. Venus fully emerges in just under a minute after first appearing, and its -4^th magnitude visage shines like a spotlight when revealed in its full glory.

“Joan and I observed the reappearance of Venus from behind the dark side of the 15% sunlit waning crescent Moon, from a dark and wide parking area on the east side of the Stuart Highway that afforded a low (1-2 degree) horizon to the east,” Dunham said. “Since the past observations of ashen light were visual, I decided that it would be best to use the 25mm eyepiece with the 8-inch visually rather than just make a redundant video. Neither the real-time visual observation, nor close visual inspection of the video recording, showed any sign of the dark side of Venus.”

We’ve written about the strange puzzle of ashen light on the nighttime side of Venus previously.

Reports by visual observers of ashen light on the dark limb of Venus over the centuries remain a mystery. On the crescent Moon, it’s easy to explain, as the Earth illuminates the nighttime side of our natural satellite; no such nearby illumination source exists in the case of Venus. Ashen light on Venus is either an illusion—a trick of the dazzling brilliance of a crescent Venus fooling the eye of the observer—or a real, and not as yet fully described phenomenon. Over the years, suggestions have included: lightning, airglow, volcanism, and aurora. A good prime candidate in the form of an ‘auroral nightglow” was proposed by New Mexico State University researchers in 2014. 19^th century astronomers even proposed we might be seeing the lights of Venusian cities, or perhaps forest fires!

Could we ever separate the bright crescent of Venus from its nighttime side? A lunar occultation, such as the October 8^th event provides just such a fleeting opportunity. Though it’s hard to discern in the video, Dunham also watched the event visually through the telescope, and noted that, in his words, “the dark side of Venus remains dark,” with no brief appearance prior to sighting the crescent shining through the lunar valleys.

A tentative light curve made by Mr. Timerson seems to support this assertion, as the appearance of Venus quickly over-saturates the view:

Of course, this is far from conclusive, but seems to support the idea that the ashen light of Venus noted by ground observers is largely an optical illusion. Not all occultations of Venus by the Moon are created equal, and the best ones to test this method occur when Venus is less than half illuminated and greater than 40 degrees from the Sun against a relatively dark sky. Compounding problems, the ‘dark’ limb of the Moon has a brightness of its own, thanks to Earthshine. Dunham notes that observers in southern Alaska may have another shot at seeing this same phenomenon on December 7^th, when the 13% illuminated crescent Moon occults a -4.2 magnitude 69% illuminated Venus, 42 degrees west of the Sun… the rest of North and South America will see this occultation in the daytime, still an interesting catch.

Looking at future occultations, there’s an intriguing possibility to hunt for the ashen light on the evening of October 10^th, 2029, when then Moon occults a 57% illuminated Venus against dark skies for observers along the U.S. West Coast. Incidentally, a dawn occultation provides a better circumstance than a dusk one, as Venus always reemerges from the Moon’s dark limb when it’s waning. It enters the same when waxing, perhaps allowing for observer bias.

Can’t wait for December? The Moon also occults the bright star Aldebaran on October 29^th for Europe and North America on November 26^th near Full phase… the good folks at the Virtual Telescope will carry the October event live.

For now, the ashen light of Venus remains an intriguing mystery. Perhaps, an airborne observation could extend the appearance of Venus during an occultation, or maybe the recently announced Discovery-class mission to Venus could observe the night side of the planet for an Earthly glow… if nothing else, it’s simply amazing to watch the two brightest objects in the nighttime sky come together.

October 19, 2015December 23, 2015 by David Dickinson

The 2015 Orionids: Watch the Meteors Fly from the Club of Orion

(Note: we’ll be posting this article as a running blog with updates over the next few mornings, as the Orionids are already moderately active for this week. Watch this space for info as it is added after our first meteor vigil tomorrow morning and Wednesday, weather and clear skies willing…)

The month of October is about midway through meteor shower season for the northern hemisphere, and one of the annual sure-fire best bets is the Orionid meteor shower. One of two meteor showers emanating from debris shed by that most famous of all periodic comets –1/P Halley—the Orionids generate a typical zenithal hourly rate of around 20 per hour, though surges heading towards a ZHR of in the range 70 are not unknown on some years.

Orionid radiant — The radiant for the Orionid meteors, looking eastward around 2 AM local. Image credit: Stellarium

2015 sees the shower peaking right around the morning of Wednesday, October 21^st. This will place the Moon at a 59% illuminated waxing gibbous phase and setting around local midnight, setting the stage for dark AM skies, perfect for meteor hunting.

Like the springtime Eta Aquarids also generated by Halley’s Comet, the Orionids are swift movers, striking the atmosphere at about 66 kilometers per second. The shower’s radiant drifts across the club of Orion the Hunter toward the astronomical constellation Gemini near its peak, and the radiant rides highest around 4 AM local time. This is also typically the best time to carry out a meteor vigil, as early morning hours places an Earth-bound observer facing forward into the oncoming meteor stream.

The twin Spring and Fall showers hailing from Halley’s are a product of the geometry of its elliptical orbit: Halley’s Comet spends most of its 75.3 year orbit south of the ecliptic, and only briefly ‘pops up’ northward above the Earth’s orbit for northern hemisphere viewers for a few months around perihelion, which next occurs on July 28th, 2061.

Let’s see, I’ll be 90-something next time Halley’s Comet comes ‘round next…

Like many meteor showers, researchers (with the tongue-twisting title of meteoriticists) are still working to precisely model the debris streams of showers such as the Orionids. There’s evidence to suggest an 11 year periodicity for the Orionid meteor stream undergoing modification by the gravitational influence of the giant planet Jupiter, a period which we’re approximately passing the mid-point low for in 2015.

Rates for the Orionids from previous years seem to support this trend: over the last few years, observers saw the Orionids top out at a ZHR of 21(2014), 45(2012), 33(2011) and 38(2010) as per the International Meteor Organization (IMO).

The next few mornings are key for a successful Orionid vigil. The Orionids also display a broad swath of activity, typically running from early October, to the first week of November before falling back down to levels below the background sporadic rate.

And while 2015 may be an off year for the Orionids, another shower may prompt a once a decade fireball swarm to rival the Full Moon this Halloween right into early November…

Will the Northern Taurids of 2015 perform? Stay tuned!

Update: Well, skies were indeed clear over the Central Florida peninsula this AM, allowing for a brief one hour vigil before dawn ensued. We counted three swift Orionids for about 40 minutes of total effective observing time, suggesting the the current rate is already well above the background sporadic rate, not bad. A late season Draconid meteor, and a curious unidentified tumbling satellite on a retrograde (read ‘Earth observing’ or spy satellite) orbit also joined the fray, along with the current cavalcade of dawn planets. A nice pass of the Hubble Space Telescope capped off the session as dawn broke, not bad.

The Orionids are noticeably speedy, flitting briefly in and out of view. Another great plus with this shower: The radiant is almost directly at the zenith for Florida residents at around 5 AM or so. This means that the Orionids can be enjoyed fairly far southward as well… has anyone ever studied just why a majority of major meteor shower radiants reside in the northern hemisphere?

The IMO hasn’t yet put up their live tracker yet, but hey, you can still report those Orionid rates worldwide…. We’ll see what Wednesday and Thursday morning brings as the Orionid meteor peak arrives. Unlike many showers, the Orionids have a very broad peak, and should be active all week into late October.

And don’t forget the tweet those sightings to #Meteorwatch!

October 16, 2015December 23, 2015 by David Dickinson

ExoMars Heads to the Red Planet in 2016

An artist's concept of the S EDM Lander separating from the ExoMars Trace Gas Orbiter. Image Credit: ESA

The 2016 launch window for Mars missions is fast approaching along with opposition, and ESA is refining its target window for ExoMars. Mars launch season offers the optimal time to make the trip from Earth to Mars, as missions prepare to break the surly bonds and head towards the Red Planet next spring. NASA’s InSight lander will also make the trip.

ExoMars is the first joint European Space Agency (ESA) Roscosmos mission to the Red Planet. The ExoMars Trace Gas Orbiter is under contract to Thales Alenia Space, and the EDM stationary lander dubbed Schiaparelli after the 19th century Italian astronomer is being constructed by Airbus Defense and Space. This would be Russia’s first successful Mars lander mission for over a dozen tries if successful.

The ExoMars Trace gas Orbiter in the lab. Image credit: ESA — The ExoMars Trace Gas Orbiter in the lab. Image credit: ESA

The ExoMars project is a two-part mission, and will culminate in an ExoMars rover in 2018. The key objective for the Trace Gas Orbiter, lander and rover to follow in 2018 is to seek out the controversial source of methane on Mars. A product of biology—think bovine flatulence—on Earth, researchers have proposed various sources—inorganic and otherwise—as a source of the anomalous methane seen in the Martian atmosphere. The Trace Gas Orbiter will remain on-station in orbit through 2018 to relay communications from the ExoMars rover. The Entry, Descent and Landing Demonstrator Module Schiaparelli will demonstrate key technologies for landing, including a hybrid Buck Rodgers fins-first style retro-rocket landing reminiscent of Viking, along with a deformable underside meant to absorb impact.

The landing sequence for the EDL Lander. Image credit: ESA

The landing with be a dramatic one on Meridiani Planum at the expected height of dust storm season, and we may get some interesting footage from the onboard descent camera. Along with weather and atmospheric measurements, the EDM Lander will also make the first electrical field measurements from the surface of Mars.

Image credit: MOLA Science Team and NASA/JPL/Arizona State Unversity — The landing ellipse for EDL. Note that its very close to the NASA rover Opportunity. Image credit: MOLA Science Team and NASA/JPL/Arizona State University

Unfortunately, EDM’s life will be short; Roscosmos originally intended to supply a 100-watt plutonium-powered RTG for the lander, but later opted due to export control to use an on-board battery. The EDM’s lifespan will be measured in a few days, at best.

Heading to Mars in 2016

An issue related to two propulsion system sensors aboard the EDM Lander recently prompted mission planners to opt for a launch for ExoMars at the end of the window next year, with liftoff set for March 14^th atop a Proton rocket from the Baikonur Cosmodrome in Kazakhstan instead of January, as originally intended. NASA’s Mars InSight will depart Earth for the Red Planet just ten days earlier on March 4^th from Vandenberg AFB in a rare dramatic night shot of an Atlas 5 rocket deploying an interplanetary mission from the US West Coast. InSight’s primary objective is to study seismic activity and the Martian interior, and will land in one of four selected sites (1 primary and 3 backup) in Elysium Planitia on September 28^th, 2016.

Naturally, ESA and Roscomos are taking every precaution to assure the success of ExoMars and EDM. The 2011 failure of Phobos-Grunt highlighted the perils of tempting the ‘Great Martian Ghoul’ with more tasty spacecraft. Space is hard, and landing on Mars even more so.

Opposition 2016 for Mars occurs on May 22^nd, 2016. Mars is always high in the early morning sky a few months prior to opposition, presenting an optimal window to send spacecraft to the Red Planet on the most efficient in trajectory in terms of fuel and time. This 3-month wide window comes around every 26 months leading up to opposition season. Oppositions of Mars are now getting more favorable, and the next opposition after 2016 in 2018 will be nearly as favorable as the historic 2003 event.

Typical Earth to Mars launch trajectories, in this case, for NASA’s twin Mars Exploration Rovers. Image credit: NASA/JPL

Our robots are swiftly colonizing Mars on our behalf. Here’s a Who’s Who scorecard of functioning spacecraft. On the surface: NASA’s Opportunity and Mars Curiosity rovers. In orbit: Mars Odyssey, (Since 2001!) Mars Express, HiRISE, India’s Mars Orbiter, and MAVEN. Add the ExoMars 2016 and 2018 missions, InSight and the Mars 2020 rover for NASA, and we’ve truly established a redundant sort of ‘telepresence’ on and around Mars.

An artist's conception of the ExoMars 2018 rover on the Red Planet. Image credit: ESA — An artist’s conception of the ExoMars 2018 rover on the Red Planet. Image credit: ESA

Will the EDM Lander become the first successful non-NASA lander to approach the Red Planet? Keep an eye on the Insight and the first of two ExoMars missions, as Earth invades Mars in 2016!

October 14, 2015December 23, 2015 by David Dickinson

Is This Month’s Jupiter-Venus Pair Really a Star of Bethlehem Stand In?

Image credit and copyright: Clapiotte Astro

Eclipse tetrads of doom. Mars, now bigger than the Full Moon each August. The killer asteroid of the month that isn’t. Amazing Moons of all stripes, Super, Blood, Black and Blue…

Image credit and copyright: @TaviGrainer(ck) — Venus, Mars, Jupiter and the Moon from October 9th. Image credit and copyright: @TaviGreiner

The internet never lets reality get in the way of a good meme, that’s for sure. Here’s another one we’ve caught in the wild this past summer, one that now appears to be looking for a tenuous referent to grab onto again next week.

You can’t miss Jupiter homing in on Venus this month, for a close 61.5’ pass on the morning on Oct 25^th. -1.4 magnitude Jupiter shows a 33” disk on Sunday’s pass, versus -4 magnitude Venus’ 24” disk.

Oct 26 Stellarium — Looking east on the morning of October 26th. Credit: Stellarium

We also had a close pass on July 1^st, which prompted calls of ‘the closest passage of Venus and Jupiter for the century/millennia/ever!’ (spoiler alert: it wasn’t) Many also extended this to ‘A Star of Bethlehem convergence’ which, again, set the web a-twittering.

Will the two brightest planets in the sky soon converge every October, in the minds of Internet hopefuls?

This idea seems to come around every close pass of Jupiter and Venus as of late, and may culminate next year, when an extra close 4’ pass occurs on August 27^th, 2016. But the truth is, close passes of Venus and Jupiter are fairly common, occurring 1-2 times a year. Venus never strays more than 47 degrees from the Sun, and Jupiter moves roughly one astronomical constellation eastward every Earth year.

Much of the discussion in astrological circles stems from the grouping of Jupiter, Venus and the bright star Regulus this month. Yes, this bears a resemblance to a grouping of the same seen in dawn skies on August 12^th, 2 BCE. This was part of a series of Jupiter-Venus conjunctions that also occurred on May 24^th, 3 BCE and June 17^th, 1 BCE. The 2 BCE event was located in the constellation Leo the Lion, and Regulus rules the sign of kings in the minds of many…

Stall — Looking eastward on the morning of August 12th, 2 BCE. Credit: Stellarium

But even triple groupings are far from uncommon over long time scales. Pairings of Jupiter, Venus in any given zodiac constellation come back around every 11-12 years. Many great astronomical minds over the centuries have gone broke trying to link ‘The Star’ seen by the Magi to the latest astronomical object in vogue, from conjunctions, to comets, to supernovae and more. If there’s any astronomical basis to the allegorical tale, we’ll probably never truly know.

The October 25th pass of Venus vs Jupiter. Created using Starry Night Education software.

Aaron Adair, the author of The Star of Bethlehem: A Skeptical View has this to say to Universe Today:

“The 3/2 BCE conjunctions don’t fit the time of Jesus’ birth. There is also no evidence that these sorts of conjunctions were considered all that good; I even found evidence that they were bad news for a king, especially if Jupiter was circling around Regulus. And of course, none of this even comes close to doing the things the Star of Bethlehem was claimed to have done.

So, we have a not terribly rare situation in the sky that conforms to something that doesn’t really fit the Gospel story in a time frame that doesn’t fit the Jesus chronology which doesn’t really have anything all that auspicious about that to ancient observers.”

The dance of the planets also gives us a brief opening teaser on Saturday morning, as Mars passes just 0.38 degrees NNE of Jupiter on Oct 17^thlooking like a fifth pseudo-moon.

Finally, the crescent Moon joins the scene once again on November 7^th, passing 1.9 degrees SSW of Jupiter and 1.2 SSW of Venus, a great time to attempt to spy both in the daytime using the crescent Moon as a guide. And keep an eye on Venus, as the next passage of the crescent Moon on December 7^th features a close grouping with binocular Comet C/2013 US10 Catalina as well.

How close can the two planets get?

Stick around ‘til November 22^nd 2065, and you can watch Venus actually transit the face of Jupiter:

Though rare, such an occlusion involving the two brightest planets happens every other century or so… we ran a brief simulation, and uncovered 11 such events over the next three millennia:

Bruce McCurdy of the Royal Canadian Astronomical Society posed a further challenge: how often does Venus fully occult Jupiter? We ran a simulation covering 9000 BC to 9000 AD, and found no such occurrence, though the July 14^th, 4517 AD meeting of Jupiter and Venus is close.

Let’s see, I’ll be on my 3^rd cyborg body, in the post- Robot Apocalypse by then…

This sort of total occlusion of Jupiter by Venus turns out to be rarer than any biblical conjunction. Why?

Well, for one thing, Venus is generally smaller in apparent size than Jupiter. When Jupiter is near Venus, it’s also near the Sun and in the 30-35” size range. Venus only breaks 30” in size for about 20% of its 584 synodic period. But we suspect a larger cycle may be in play, keeping the occurrence of a large Venus meeting and covering a shrunken Jove in our current epoch.

A Moon, a star, three planets and... a space station? A close pass of Tiangong-1 (arrowed) near this month's grouping. Image credit: Dave Dickinson — A Moon, a star, three planets and… a space station? A close pass of Tiangong-1 (arrowed) near this month’s grouping. Image credit: Dave Dickinson

Astronomy makes us ponder the weirdness of our skies gracing our backyard over stupendously long time scales. Whatever your take on the tale and the modern hype, be sure to get out and enjoy the real show on Sunday morning October 25th, as the brightest of planets make for a brilliant pairing.

October 6, 2015December 23, 2015 by David Dickinson

Comet US10 Catalina: Our Guide to Act II

Itching for some cometary action? After a fine winter’s performance from Comet C/2014 Q2 Lovejoy, 2015 has seen a dearth of good northern hemisphere comets. That’s about to change, however, as Comet C/2013 US10 Catalina joins the planetary lineup currently gracing the dawn sky in early November. Currently located in the constellation Centaurus and shining at magnitude +6, Comet US10 Catalina has already put on a fine show for southern hemisphere observers over the last few months during Act I.

Currently buried in the dusk sky, Comet US10 Catalina is bashful right now, as it shares nearly the same right ascension with the Sun over the next few weeks, passing just eight degrees from our nearest star as seen from our Earthly vantage point on November 7^th — and perhaps passing juuusst inside of the field of view for SOHO’s LASCO C3 camera — and into the dawn sky.

The hunt is on come early November, as Comet US 10 Catalina vaults into the dawn sky. From 30 degrees north latitude here in Central Florida, the comet breaks 10 degrees elevation an hour prior to local sunrise right around November 20^th. This should see the comet peaking in brightness right around magnitude +5 near perihelion the same week on November 16^th.

The angle of the comet’s orbit is favorable for northern hemisphere viewers in mid-November, as viewers start getting good looks in the early morning from latitude 30 degrees northward and the comet gains about a degree of elevation per day. This will bring it up out of the murk of twilight and into binocular view.

Mark your calendar for the morning of December 7^th, as the crescent Moon, Venus and a (hopefully!) +5 magnitude comet US10 Catalina will all fit within a five degree circle.

Here are some key dates with celestial destiny for Comet US10 Catalina for the remainder of 2015:

October

20-Crosses into the constellation Hydra.

November

2-Crosses into the constellation Libra.

16-Crosses into the constellation Virgo.

16-Reaches perihelion at 0.823 AU (127.6 million kilometers) from Sun.

26-Crosses the ecliptic plane northward.

27-Passes less than one degree from the +4.5 magnitude star Lambda Virginis.

December

7-Fits inside a five degree circle with Venus and the waning crescent Moon.

8-Passes less than one degree from the +4 magnitude star Syrma (Iota Virginis).

17-Crosses the celestial equator northward.

24-Crosses into the constellation Boötes.

In January, Comet US10 Catalina starts the New Year passing less than a degree from the -0.05 magnitude star Arcturus. From there, the comet may drop below +6 magnitude and naked eye visibility by mid-month, just prior to its closest approach to the Earth at 0.725 AU (112.3 million kilometers) on January 17^th. By February 1^st, the comet may drop below +10^th magnitude and binocular visibility, into the sole visual domain of large light bucket telescopes under dark skies.

Or not. Comets and predictions of comet brightness are always notoriously fickle, and rely mainly on just how the comet performs near perihelion. Then there’s twilight extinction to contend with, and the fact that the precious magnitude of the comet is diffused over its extended surface area, often causing the comet to appear fainter visually than the quoted magnitude.

But do not despair. Comets frequently under-perform pre-perihelion passage, only to put on brilliant shows after. Astronomers discovered Comet US10 Catalina on Halloween 2013 from the Catalina Sky Survey based just outside of Tucson, Arizona. On a several million year orbit, all indications are that Comet US10 Catalina is a dynamically new Oort Cloud visitor and will probably get ejected from the solar system after this all-too brief fling with the Sun. Its max velocity at perihelion will be 46.4 kilometers per second, three times faster than the New Horizons spacecraft currently on an escape trajectory out of the solar system.

The odd ‘US10’ designation comes from the comet’s initial identification as an asteroidal object, later upgraded to cometary status. The comet’s high orbital inclination of 149 degrees assured two separate showings, as the comet approached the Sun as seen from the Earth’s southern hemisphere, only to then vault up over the northern hemisphere post-perihelion. As is often the case, the comet was closest to the Sun at exactly the wrong time: had perihelion occurred around May, the comet would’ve passed the Earth just 0.17 AU (15.8 million miles or 26.3 million kilometers) distant! That might’ve placed the comet in the negative magnitudes and perhaps earned it the title of ‘the Great Comet of 2015…’

But such was not to be.

Ah, but the next ‘big one’ could come at any time. In 2016, we’re tracking comet C/2013 X1 PanSTARRS, which will ‘perhaps’ become a fine binocular comet next summer…

More to come. Perhaps we’ll draft up an Act III for US10 Catalina in early January if it’s a top performer.

September 29, 2015April 26, 2016 by David Dickinson

Challenge-Watch the Daytime Moon Occult Aldebaran for North America This Friday

How about that total lunar eclipse this past Sunday? Keep an eye of the waning gibbous Moon this week, as it begins a dramatic dive across the ecliptic towards a series of photogenic conjunctions throughout October.

The Main Event: This week’s highlight is an occultation of the bright +0.9 magnitude star Aldebaran (Alpha Tauri) by the waning gibbous Moon on Friday morning October 2^nd.

The occultation footprint for Friday’s occultation of Aldebaran by the Moon, with pre-dawn, dawn and post-dawn zones annotated. Image credit: Occult 4.0 software

This occurs in the pre-dawn hours for Alaskan residents, and under favorable dawn twilight skies along the U.S. and Canadian Pacific west coast; the remainder of the contiguous United States and Canada will see the occultation transpire after sunrise. This is the 10th of 49 occultations of Aldebaran by the Moon worldwide running from January 29th, 2015 through September 3rd, 2018. The Moon will be at 74% waning gibbous phase, and Aldebaran will disappear behind its illuminated limb to reappear from behind its trailing dark limb.

Check out this amazing Vine of the last occultation of Aldebaran by the Moon courtesy of Andrew Symes @FailedProtostar:

It’s interesting to note that the southern graze-line for the occultation roughly follows the U.S./Mexican border. Seeing a bright star wink in and out from behind the lunar valleys can be an unforgettable sight, adding an eerie 3D perspective to the view. A detailed analysis of the event can even help model the rugged limb of the Moon.

Hunting stars and planets in the daytime can be an interesting feat of visual athletics. We’ve managed to spy Aldebaran near the lunar limb with binoculars during an occultation witnessed from Alaska on September 4^th, 1996, and can attest that it’s quite possible to see a +1^st magnitude star near the Moon with optical aid. A clear blue sky is key. The Greek philosopher Thales noted that stars could be seen from the bottom of a well (though perhaps he’d fallen down a well or two too many in his time)… Friday’s event should push your local seeing to its limits. Start tracking Aldebaran before local sunrise, and you should be able to follow it all the way to the lunar limb, clear skies willing.

The occultation path for various locales across the United States Friday morning. Image credit: Dave Dickinson/Stellarium

Here’s a listing of times for key events for Friday from around the U.S. Check out The International Occultation Timing Association’s page for the event for an extensive listing:

Key times for the occultation for the same locales depicted in the graphic above, along with the lunar elevation (altitude) above the local horizon at the time noted. Image credit: Dave Dickinson

And whenever the Moon meets Aldebaran, it has to cross the open star cluster of the Hyades to get there, meaning there’ll be many other worthy occultations of moderately bright stars around October 2^nd as well. Gamma Tauri, 75 Tauri, Theta^1 Tauri, and SAO93975 are all occulted by the Moon on the morning of October 2^nd leading up to the Aldebaran occultation; particularly intriguing is the grazing occultation of +5 magnitude 75 Tauri across the Florida peninsula.

The path of the moon through the Hyades this weekend. Image credit: Starry Night Education software — The path of the Moon through the Hyades this weekend. Image credit: Starry Night Education software

Fun fact: the Moon can, on occasion, occult members of the M45 Pleiades star cluster as well, as last occurred in 2010, and will next occur on 2023.

Chasing the Moon through October

Follow that Moon for the following dates with astronomical destiny worldwide:

The Moon reaches Last Quarter phase on Sunday, October 4th at 21:06 UT/5:06 PM EDT.
A close pass with Venus on October 8^th, with a brilliant occultation visible in the pre-dawn hours from Australia.
A tight photogenic grouping of the Moon, Mars and Jupiter in a four degree circle on the morning on October 9^th;
A close pass of the Moon just 36 hours from New near Mercury on the morning of Sunday, October 11^th, with another occultation of the planet visible from Chile at dawn;
And finally, New Moon (sans eclipse, this time) occurring at 00:06 UT on October 13^th, marking the start of lunation 1148.

Why occultations? Consider the wow factor; light from Aldebaran left about 65 years ago, before the start of the Space Age, only to get ‘photobombed’ by the occulting Moon at the last moment. Four bright stars (Regulus, Spica, Antares and Aldebaran) lie along the Moon’s path in our current epoch. Dial the celestial scene back about two millennia ago, and the Moon was also capable of occulting the bright star Pollux in the astronomical constellation of Gemini as well.

We’ll be running video for the event clear skies willing Friday morning here from Hudson, Florida in the Tampa Bay area. And as always, let us know of your tales of astronomical tribulation and triumph!

September 24, 2015December 23, 2015 by David Dickinson

Sunday Night: Getting Ready For a ‘Super-Harvest-Blood-Moon Total Lunar Eclipse’

So, heard the one about this weekend’s impending ‘Super-Harvest-Blood-Moon eclipse?’ Yeah, us too. Have no fear; fortunately for humanity, the total lunar eclipse transpiring on Sunday night/Monday morning is a harbinger of nothing more than a fine celestial spectacle, clear skies willing.

This final eclipse of the ongoing lunar tetrad has some noteworthy events worth exploring in terms of science and lore.

The Supermoon Total Lunar Eclipse of September 27-28 2015 from Michael Zeiler on Vimeo.

The Specifics: First, you almost couldn’t ask for better timing. This weekend’s total lunar eclipse occurs during prime time Sunday night for North and South America, and early Monday morning for Europe, Africa and most of the Middle East. This means the Atlantic Region and surrounding areas will see totality in its entirety. This eclipse occurs very near the northward equinoctial point occupied by the Sun during the Northern Hemisphere Spring equinox in March. The date says it all: this eclipse coincides with the Harvest Moon for 2015, falling just under five days after the September equinox.

Early cloud cover prospects for Sunday night over the contiguous United States. Image credit: The National Weather Service

For saros buffs, Sunday’s eclipse is part of lunar saros series 137, member 28 of 81. This saros started back in 1564 and produced its first total lunar eclipse just two cycles ago on September 6^th 1979. Saros 137 runs all the way out to its final eclipse on April 20^th, 2953 AD.

And yes, this upcoming total lunar eclipse occurs very near the closest lunar perigee for 2015. How rare are ‘Supermoon’ lunar eclipses? Well, we took a look at the phenomenon, and found 15 total lunar eclipses occurring near lunar perigee for the current century:

You’ll note that four saroses (the plural of saros) are producing perigee or ‘Proxigean’ total lunar eclipses during this century, including saros 137.

Does the perigee Moon effect the length of totality? It’s an interesting question. Several factors come into play that are worth considering for Sunday night’s eclipse. First, the Moon moves a bit faster near perigee as per Kepler’s second law of motion. Second, the Moon is a shade larger in apparent size, 34’ versus 29’ near apogee. Lastly, the conic section of the Earth’s shadow or umbra is a bit larger closer in; you can fit three Moons side-by-side across the umbra around 400,000 kilometers out from the Earth. Sunday night’s perigee occurs 65 minutes after Full Moon at 2:52 UT/10:52 PM EDT. Perigee Sunday night is 356,876 kilometers distant, the closest for 2015 by just 115 kilometers, and just under 500 kilometers short of the closest perigee that can occur. This is, however, the closest perigee time-wise to lunar totality for the 21^st century; you have to go all the way back to 1897 to find one closer, at just four minutes apart.

Now, THAT was and eclipse!

This all culminates in a period for totality on Sunday night of just under 72 minutes in duration, 35 minutes shy of the maximum possible for a central total lunar eclipse. An eclipse won’t top this weekend’s in terms of duration until January 31^st 2018.

Here are the key times to watch for on Sunday night:

Penumbral phase begins: 00:12 UT/8:12 PM EDT (on the 27^th)

Partial phase begins: 1:07 UT/9:07 PM EDT

Totality begins: 2:11 UT/10:11 PM EDT

Totality ends: 3:23 UT/11:23 PM EDT

Partial phase ends: 4:27 UT/00:27 AM EDT

Penumbral phase ends: 5:22 UT/1:22 AM EDT

Note that one 18 year 11 day and 8 hour saros period later, saros 137 will again produce a perigee eclipse nearly as close as this weekend’s on October 8^th, 2033.

The classic hallmark of any total lunar eclipse is the reddening of the Moon. You’re seeing the combination of all the world’s sunsets, refracted into the inky umbra of the Earth and cast upon the surface of the Moon. To date, no human has stood upon the surface of the Moon and gazed upon the spectacle of a solar eclipse caused by the Earth.

Not all eclipses are created equal when it comes to hue and color. The amount of dust and aerosols suspended in the atmosphere can conspire to produce anything from a bright, yellowish-orange tint, to a brick dark eclipse where the Moon almost disappears from view entirely. The recent rapid fire tetrad of four eclipses in 18 months has provided a good study in eclipse color intensity. The deeper the Moon dips into the Earth’s shadow, the darker it will appear… last April’s lunar eclipse was just barely inside the umbra, making many observers question if the eclipse was in fact total at all.

We the describe color of the eclipsed Moon in terms of its number on the Danjon scale, and recent volcanic activity worldwide suggests that we may be in for a darker than normal eclipse… but we could always be in for a surprise!

Old time mariners including James Cook and Christopher Columbus used positional measurements of the eclipsed Moon at sea versus predictions published in almanac tables for land-based observatories to get a one-time fix on their longitude, a fun experiment to try to replicate today. Kris Columbus also wasn’t above using beforehand knowledge of an impending lunar eclipse to help get his crew out of a tight jam.

And speaking of the next perigee Moon total lunar eclipse for saros 137 on October 8th, 2033… if you catch that one, this weekend’s, and saw the September 16^th, 1997 lunar eclipse which spanned the Indian Ocean region, you’ll have completed an exeligmos, or a triple saros of eclipses in the same series 54 years and 33 days in length, an exclusive club among eclipse watchers and a great word to land on a triple letter word score in Scrabble…

Exeligmos is also the title of one of our original scifi tales involving eclipses, along with Shadowfall.

Here’s another neat challenge: the International Space Station makes two shadow passes during the lunar eclipse over the contiguous United States. The first one occurs during totality, and spans from eastern Louisiana to central Maine from 2:14 to 2:20 UT; the second pass occurs during the final partial phases of the eclipse spanning from southern Arizona to Lake Superior from 3:47 to 3:54 UT. These are un-illuminated shadow passes of the ISS. Observers have captured transits of the ISS during a partial solar eclipse, but to our knowledge, no one has ever caught a transit of the ISS during a total lunar eclipse; ISS astros should also briefly be able to spy the eclipsed Moon from their orbital vantage point. CALSky will have refined passage times about 48 hours prior to Sunday.

Clouded out? Live on the wrong side of the planet? The good folks at the Virtual Telescope Project have got you covered, with a live webcast of the total lunar eclipse starting at 1:00 UT/9:00 PM EDT.

And as the eclipse draws to an end, the question of the hour always is: when’s the next one? Well, the next lunar eclipse is a dim penumbral on March 23^rd, 2016, which follows a total solar eclipse for southeastern Asia on March 9^th, 2016… but the next total lunar won’t occur until January 31^st, 2018, which also happens to be the second Full Moon of the month… a ‘Blue Blood Moon Eclipse?’

Sorry, we had to go there. Hey, we could make the case for Sunday’s eclipse also occurring on World Rabies Day, but perhaps a ‘Rabies Eclipse’ just doesn’t have the SEO traction. Don’t fear the Blood Moon, but do get out and watch the final lunar eclipse of 2015 on Sunday night!

September 22, 2015April 8, 2018 by David Dickinson

Watch This Amazing Video of an Exoplanet in Motion

An amazing .gif animation of Beta Pictoris in orbit. Image credit: M. Millar-Blanchaer, University of Toronto/R. Marchis (SETI Institute)

Exoplanet Beta Pic b orbiting Beta Pictoris from Dunlap Institute on Vimeo.

Just. Wow. The motion of an alien world, reduced to a looping .gif. We truly live in an amazing age. A joint press release out of the Gemini Observatory and the University of Toronto demonstrates a stunning first: a sequence of direct images showing an exoplanet… in motion.

The world imaged is Beta Pictoris b, about 19 parsecs (63 light years) distant in the southern hemisphere constellation Pictor the Painter’s Easel. The Gemini Planet Imager (GPI), working in concert with the Gemini South telescope based in Chile captured the sequence.

The images span an amazing period of a year and a half, starting in November 2013 and running through April of earlier this year. Beta Pictoris b has an estimated 22 year orbital period… hey, in the year 2035 or so, we’ll have a complete animation of its orbit!

Current estimates place Beta Pictoris b in the 7x Jupiter mass range, about plus or minus 4 Jupiter masses… and yes, the high end of that range is flirting with the lower boundary for a sub-stellar brown dwarf. Several exoplanet candidates blur this line, and we suspect that the ‘what is a planet debate?’ that has plagued low mass worlds will one day soon extend into the high end of the mass spectrum as well.

An annotated diagram of the Beta Pictoris system. Image credit: ESO/A.-M Lagrange et al.

Beta Pictoris has long been a target for exoplanetary research, as it is known to host a large and dynamic debris disk spanning 4,000 astronomical units across. The host star Beta Pictoris is 1.8 times as massive as our Sun, and 9 times as luminous. Beta Pic is also a very young star, at an estimated age of only 8-20 million years old. Clearly, we’re seeing a very young solar system in the act of formation.

Orbiting its host star 9 astronomical units distant, Beta Pictoris b has an orbit similar to Saturn’s. Place Beta Pictoris b in our own solar system, and it would easily be the brightest planet in the sky.

The Heavyweight world B Pictoris b vs planets in our solar system... note the rapid rotation rate! Image credit: ESO/I. Snellen (Leiden University) — The Heavyweight world B Pictoris b vs planets in our solar system… note the rapid rotation rate! Image credit: ESO/I. Snellen (Leiden University)

“The images in the series represent the most accurate measurements of a planet’s position ever made,” says astronomer Maxwell Millar-Blanchaer of the Department of Astronomy and Astrophysics at the University of Toronto in a recent press release. ‘With the GPI, we’re able to see both the disk and the planet at the exact same time. With our combined knowledge of the disk and the planet we’re really able to get a sense of the planetary system’s architecture and how everything interacts.”

A recent paper released in the Astrophysical Journal described observations of Beta Pictoris b made with the Gemini Planet Imager. As with bodies in our own solar system, refinements in the orbit of Beta Pictoris b will enable astronomers to understand the dynamic relationship it has with its local environment. Already, the orbit of Beta Pictoris b appears inclined out of our line of sight in such a way that a transit of the stellar disk is unlikely to occur. This is the case with most exoplanets, which elude the detection hunters such as the Kepler space telescope. As a matter of fact, watching the animation, it looks like Beta Pictoris b will pass behind the occluding disk and out of view of the Gemini Planet Imager in the next few years.

The location of Beta Pictoris in the southern hemisphere sky. Image credit: Stellarium

“It’s remarkable that Gemini is not only able to directly image exoplanets but is also capable of effectively making movies of them orbiting their parent star,” Says National Science Foundation astronomy division program director Chris Davis in Monday’s press release. The NSF is one of five international partners that funds the Gemini telescope program. “Beta Pic is a special target. The disk of gas and dust from which planets are currently forming was one of the first observed and is a famous laboratory for the study of young solar systems.”

The Gemini Planet Imager is part of the GPI Exoplanet Survey (GPIES), which discovered its first exoplanet 51 Eridani b just last month. The survey will target 600 stars over the next three years. The current tally of known exoplanets currently sits at 1,958 and counting, with thousands more in the queue courtesy of Kepler awaiting confirmation.

And as new spacecraft such as the Transiting Exoplanet Survey Satellite (TESS) take to orbit in 2018, we wouldn’t be surprised if the tally of exoplanets hits five digits by the end of this decade.

An amazing view of a brave new world in motion. It’s truly a golden age of exoplanetary science, with more exciting discoveries to come!