David Dickinson, Author at Universe Today

November 10, 2015December 23, 2015 by David Dickinson

From a Roar to a Purr: Prospects for the 2015 November Leonid Meteors

A November rain hails from the Sickle of the Lion.

Hot on the heels of the October Orionids and the Halloween fireballs of the Taurid meteors comes the Leonid meteor shower. On most years, the Leonids are a moderate shower, with hourly local rates reaching around 20. Once every 33 years, however, the Leonids are responsible for putting on one of the greatest astronomical shows ever witnessed, producing a grand storm with a zenithal hourly rate topping thousands per hour.

The orientation of the Earth and the relative positions of the Sun, Moon and the Leonid meteor radiant on November 17th at 4:00 UT. Image credit: Stellarium

Prospects for 2015

First, the bad news. 2015 isn’t forecast to be a ‘storm year’ for the Leonids, though that shouldn’t stop a vigilant observer from watching. The good news is, we’re just about midway betwixt the storm years of 1998-99 and 2031-32. The Leonids intensify once every 33 years, and if the increased activity seen in the late 1990s was any indication, we’d bet we’ll start seeing a pickup in rates from the Leonids in the late 2020’s or so. The good news for 2015, however, is that the peak for the Leonids occur on November 18^th at around 4:00 Universal Time (UT)/ (11:00 PM EST on November 17^th). This places the waxing crescent Moon out of the picture, just a day before reaching First Quarter phase. New Moon for November 2015 occurs on November 11^th at 17:47 UT/12:47 PM EST.

Fun fact: the August Perseids, November Leonids and the December Geminid meteor showers are spaced out on the calendar in such a way that, when the Moon phase is favorable for one shower on a particular year, it is nearly always favorable across all of them.

The Leonids are mildly active from November 6^th through November 30^th, and though the above prediction for activity in 2015 favors European longitudes at dawn, some predictions have the peak arriving up to seven hours early this year.

The Leonids are the dusty remnants laid down by periodic comet 55P Tempel-Tuttle on its 33-year path through the inner solar system. The Leonids are fast-movers, hitting the Earth nearly head-on in the dawn. You can see this in the relative position of the radiant, which rises in mid-November around 11PM local, and reaches the zenith around 6AM local time.

A late season Leonid meteor from 2014. Image credit: The UK Monitoring network (UKMON)

Often bluish in color, the Leonids hit the Earth’s atmosphere at over 70 km/sec… almost the fastest theoretical speed possible. For best results, watch for Leonids to spike in activity close to local dawn.

A 1799 woodcut depicting the Leonids at sea. Image credit: Public Domain

The Leonids have a storied history, going back 902 AD report from Arabic annals of the ‘Year of Stars.’ The Great Meteor Storm of 1833 dazzled (and terrified) residents of the eastern seaboard of the United States, and the spectacle not only inspired astronomer Denison Olmsted to pioneer studies into the fledgling field of meteor shower science, but has been attributed to adding fervor to many of the religious revivalist movements that sprang up in the 1830s in the United States as well.

The last outburst from the Leonids that reached such an apocalyptic scale was in 1966, when observers across the southwestern United States reported hourly rates approaching an amazing ZHR=144,000. Witnesses that remember this spectacle say it produced an illusion reminiscent of the Star Trek ‘warp speed’ effect, as Earth rammed headlong into the dense Leonid meteor stream.

Our own personal encounter with a Leonid meteor storm in 1998 from the dark desert skies of Kuwait wasn’t quite that intense, but thrilling to see nonetheless. Rates neared one every few seconds towards sunrise, with several fireballs punctuating the action, lighting up the desert floor. Here, as US coalition forces were on the verge of unleashing what would become Operation: Desert Fox over Iraq, the Universe was putting on a fireworks show of its own.

The Leonid meteor storms are the stuff of astronomical legend, a once in a lifetime event. Ever since we witnessed just what the Leonids are capable of, we never miss this annual shower, as we remember one night back in 1998, and look forward to the storms of 2032.

Here’s what the Leonids have been doing on previous recent years:

ZHR=15 +/-4 (2014)

Mostly washed out by the near-Full Moon (2013)

ZHR=47 +/-11 (2012)

ZHR=22 +/-3 (2011)

ZHR=32+/-4 (2010)

Report those Leonid sightings to the International Meteor Organization, and also be sure to Tweet em to #Meteorwatch
Got an image of a Leonid meteor? Send ‘em in to Universe Today at our Flickr Forum… we just might feature it in an after-action round up!

November 3, 2015December 30, 2015 by David Dickinson

The Moon Greets the Planets in the November Dawn

A tri-planetary grouping from the morning of October 31st. Image credit and copyright: Joseph Brimacombe

So, did this past weekend’s shift back to Standard Time for most of North America throw you for a loop? Coming the day after Halloween, 2015 was the earliest we can now shift back off Daylight Saving Time. Sunday won’t fall on November 1^st again until 2020. Expect evenings get darker sooner for northern hemisphere residents, while the planetary action remains in the dawn sky.

Though Mercury has exited the morning twilight stage, the planets Jupiter, Venus and Mars continue to put on a fine show, joined by the waning crescent Moon later this week. The action starts today on November 3^rd, which finds +1.9 magnitude Mars passing just 0.68 degrees (40’, just over the apparent diameter of a Full Moon) from brilliant -3.9 magnitude Venus. Though the two nearest planets to the Earth appear to meet up in the dawn sky, Mars is actually 2.5 times more distant than Venus, which sits 74.4 million miles (124 million kilometres) from the Earth. Venus exhibits a 57% illuminated gibbous phase 21” across this week, versus Mars’ paltry 4.5” disc.

November 6th. Image credit: Starry Night Education Software — The lunar planetary lineup on the morning of November 6th… Image credit: Starry Night Education Software

Watch the scene shift, as the Moon joins the dance this weekend. The mornings of Friday, November 6^th and Saturday, November 7^th are key, as the Moon passes just two degrees from the Jupiter and Mars pair and just over one degree from Venus worldwide. Similar close pairings of the Moon and Venus adorn many national flags, possibly inspired by a close grouping of Venus and the Moon witnessed by skywatchers of yore.

Saturday November 7^th is also a fine time to try your hand at seeing Venus in the daytime, using the nearby crescent Moon as a guide. The Moon will be only four days from New, and the pair will be 46 degrees west of the Sun, an optimal situation as Venus just passed greatest western elongation 46.4 degrees west of the Sun on October 26th.

Nov 3 — Mars meets Venus on November 3rd-4th… the center circle = 1 degree FoV. Image credit: Stellarium

Though Venus may seem like a difficult daytime object, it’s actually intrinsically brighter than the Moon per square arc second. Difficulty finding it stems from seeing it against a low contrast blue daytime sky, its small size, and lack of context and depth. The larger but dimmer Moon actually serves as a good anchor to complete this feat of visual athletics.

Venus from the morning of November 3rd. Image credit and copyright: Shahrin Ahmad

Looking for more? Comet C/2013 US10 Catalina will join the planetary lineup next lunation ‘round, hopefully shining at magnitude +5 as it glides past Venus and the Moon on December 7^th. Karl Battams at the U.S. Naval Research Labs has confirmed that Comet US10 Catalina—which reaches perihelion this month on November 15^th –should also briefly graze the field of view for SOHO’s LASCO C3 camera on November 7th.

There’s also a few notable lunar occultations this week. The Moon also occults the +5 magnitude star Chi Leonis for viewers around the Gulf of Mexico on November 4^th, including a dramatic grazing event for Northern Florida. The Moon also occults the +3.5 magnitude star Omicron Leonis on Nov 4^th for Alaska as well.

See a bright star near the Venus this week? It’s none other than +3.6 magnitude Beta Virginis (Zavijava). The star passes 15’ from Venus on the morning of November 6th. Stick around ‘til 2069, and you can actually witness Venus occult Beta Virginis. Between Beta Virginis and Mars, Venus has the appearance this week of having the large pseudo-moon it never possessed. From Venus, our Moon would appear near magnitude +0.4 with a disk 6.4” this week, and range 12’ from the Earth.

Nov 7 — The closeup view on the morning of November 7th along with a 5 degree Telrad FoV. image credit: Stellarium

Now for the wow factor. All of these disparate objects merely lie along our Earthbound line of sight this week. Traveling at the speed of light (186,282 miles or 299,792 kilometers a second), the Moon lies just over a second away. Venus, Mars and Jupiter are next, at 6, 18, and 49 light minutes out, respectively… and Beta Virginis? It lies 36 light years distant.

This pass of the Moon also sets us up for an occultation of Mars and a dramatic daytime occultation of Venus for North America during the next lunation…

More to come!

-Got pictures of the planetary grouping this week with the Moon? Be sure to send ’em in to Universe Today and our Flickr forum.

October 30, 2015December 23, 2015 by David Dickinson

Images from Enceladus ‘Plume Dive’ Courtesy of Cassini

Oh, to hitch a ride aboard NASA’s Cassini spacecraft this week. The Saturn orbiting sentinel recently completed an amazing series of passes near the enigmatic ice-covered moon Enceladus, including a daredevil dive only 49 km (31 miles) above the southern pole of the moon and through an ice geyser. Images of the dramatic flyby were released by the Cassini team earlier this morning, revealing the moon in stunning detail.

“Cassini’s stunning images are providing us a quick look at Enceladus from this ultra-close flyby, but some of the most exciting science is yet to come,” says NASA mission project scientist Linda Spilker in today’s NASA/JPL press release.

Launched in 1997 from Cape Canaveral Florida in a dramatic night shot, Cassini arrived at the Saturnian system in 2004, and has delivered on some amazing planetary science ever since.

Discovered in 1789 by William Herschel, we got our very first views of Enceladus via the Voyager 1 spacecraft at 202,000 kilometers distant in 1980. Cassini has flown by the moon 21 times over the past decade, and ice geysers were seen sprouting from the surface of the moon by Cassini on subsequent flybys. one final flyby of Enceladus is planned for this coming December.

Mission planners are getting more daring with the spacecraft as its mission nears completion in 2017. The idea of reaching out and ‘tasting’ an icy plume emanating from Enceladus has been an enticing one, though a fast-moving good-sized ice pellet could spell disaster for the spacecraft.

NASA successfully established contact with the spacecraft on Wednesday night October 28^th after the closest approach for the flyby at 11:22 AM EDT/ 15:22 UT (Universal Time) earlier in the day. Cassini is reported to be in good health, and we should see further images along with science data returns in the weeks to come.

A second, more distant flyby of Enceladus was completed by Cassini earlier this month as it passed 1,142 miles (1,839 kilometers) from the northern pole of Enceladus on October 14^th, 2015 on its E-20 flyby.

But beyond just pretty post-cards from the outer solar system, Cassini’s successive passes by the mysterious moon will characterize just what might be occurring far down below.

Why Enceladus? Well, ever since ice geysers were spotted gushing from the fractured surface of the moon, it’s been on NASA’s short list of possible abodes for life in the solar system. Other contenders include Mars, Jupiter’s moon Europa, and Saturn’s giant moon, Titan. If the story of life on Earth is any indication, you need a place where an abundant level of chemical processes are occurring, and a subsurface ocean under the crust of Enceladus heated by tidal flexing may just fit the bill.

We’ll be adding further images and info to this post as more data comes in over the weekend, plus Cassini mission highlights, a look at the mission and final objectives and the last days of Cassini and more…

Stay tuned!

The end of Cassini in 2017 as it burns up in the atmosphere of Saturn will be a bittersweet affair, as our outer solar system eyes around the ringed planet fall silent. Cassini represents the most distant spacecraft inserted into orbit around a planet, and ESA’s Huygens lander on Titan marked the most remote landing on another world as well. Will we one day see a Titan Blimp or Ocean Explorer, or perhaps a dedicated life-finding mission to Enceladus? Final mission objectives for NASA’s Cassini spacecraft include a final flyby of Saturn’s large moon Titan, which will set the course for its final death plunge into the atmosphere of Saturn on September 15^th, 2017.

A high-resolution capture of Enceladus released this weekend by the Cassini team. The spacecraft was about 60,000 miles (96,000 kilometers) out when this image was taken. You can see the stark contract of the moon's fractured cantlope terrain, versus craters in the opposite hemisphere imaged criedt: NASA/JPL-CalTech/Space Science Institute — A high-resolution capture of Enceladus released this weekend by the Cassini team. The spacecraft was about 60,000 miles (96,000 kilometers) out when this image was taken. You can see the stark contract of the moon’s fractured cantaloupe terrain, versus craters in the opposite hemisphere imaged. Credit: NASA/JPL-CalTech/Space Science Institute

Want to see Enceladus for yourself? The moon orbits Saturn once every 1.4 days, reaching a maximum elongation of 13″ from the ring tips of Saturn and a maximum brightness of magnitude +11.7. Enceladus is one of six major moons of Saturn visible in a backyard telescope, and one of 62 moons of the ring planet known overall. The other five moons within reach of an amateur telescope are: Titan, Mimas, Dione, Rhea, and Tethys, and the fainter moon Hyperion shining at magnitude +15 might just be within reach of skill observers with large light bucket instruments.

Enjoy the amazing views of Enceladus, courtesy of Cassini!

October 29, 2015December 23, 2015 by David Dickinson

A Halloween Season ‘Taurid Meteor Swarm’ on Tap for 2015?

Asteroid 2015 TB145 isn’t the only cosmic visitor paying our planet a trick-or-treat visit over the coming week. With any luck, the Northern Taurid meteor shower may put on a fine once a decade show heading into early November.

About once a decade, the Northern Taurid meteor stream puts on a good showing. Along with its related shower the Southern Taurids, both are active though late October into early November.

The motion of the radiant of the Northern Taurid meteors from mid-October through mid-November. Image credit: Stellarium — The motion of the radiant of the Northern Taurid meteors from mid-October through mid-November. The shower typically peaks around November 12th annually. Image credit: Stellarium

Specifics for 2015

This year sees the Moon reaching Full on Tuesday October 27^th, just a few days before Halloween. The Taurid fireballs, however, have a few things going for them that most other showers don’t. First is implied in the name: the Northern Taurids, though typically exhibiting a low zenithal hourly rate of around 5 to 10, are, well, fireballs, and thus the light-polluting Moon won’t pose much of a problem. Secondly, the Taurid meteor stream is approaching the Earth almost directly from behind, meaning that unlike a majority of meteor showers, the Taurids are just as strong in the early evening as the post midnight early morning hours. As a matter of fact, we saw a brilliant Taurid just last night from light-polluted West Palm Beach in Florida, just opposite to the Full Moon and a partially cloudy sky.

A 2014 Taurid. Image credit and copyright: Brian who is called Brian

In stark contrast to the swift-moving Orionids from earlier this month, expect the Taurid fireballs to trace a brilliant and leisurely slow path across the night sky, moving at a stately 28 kilometre per second (we say stately, as the October Orionids smash into our atmosphere at over twice that speed!)

Ever since the 2005 event, the Northern Taurids seemed to have earned the name as “The Halloween Fireballs” in the meme factory that is the internet. It’s certainly fitting that Halloween should have its very own pseudo-apocalyptic shower. The last good return for the Northern Taurids was 2005-2008, and 2015 may see an upswing in activity as well.

Obviously, something interesting has to be occurring on Comet 2P Encke—the source of the two Taurid meteor streams—to shed the pea-sized versus dust-sized material seen in the Southern and Northern Taurids. With the shortest orbital period 3.3 years of all periodic comets known, the Taurid meteor stream—like Encke itself—follows a shallow path nearly parallel to the ecliptic plane.

Discovered in 1822 by astronomer Johann Encke, Comet 2P Encke has been observed through many perihelion passages over the last few centuries, and passes close to Earth once 33 years, as it last did in 2013.

What constitutes a ‘meteor swarm?’ As with many terms in meteoritics, no hard-and-fast definition of a true ‘meteor swarm’ exists. A meteor storm is generally quoted as having a zenithal hourly rate greater than 1000. Expect activity to be broad over the next few weeks, and the Taurid fireballs always have the capacity to produce the kind of brilliant events captured by security cams and dashboard video cameras that go viral across ye ole Internet.

Watching for fireballs is a thrilling pursuit. These may often leave persistent glowing meteor trails in their wake. We caught the 1998 Leonids from the dark sky deserts of Kuwait, and can attest to the persistence of glowing fireball trails from this intense storm, sometimes for minutes. Again, the 2015 Taurids aren’t expected to reach that level of intensity, though the ratio of fireballs to faint meteors will be enhanced.

The path of the stream isn’t fully understood, and that is where volunteer observations can come in handy. The International Meteor Organization is always looking for reports from skilled observers, as is the American Meteor Society (AMS).

There’s even been evidence for a recorded meteorite strike related to the northern Taurid fireballs back in 2015 on the dark limb of the Moon as well, a rare event indeed.

After a slow summer, Fall meteor shower activity is definitely heating up. And though 2015 is an off year for the November Leonids, we’re now almost midway between the 1998-99 outbursts, and the possibility of another grand meteor storm in the early 2030s. And another obscure wildcard shower known as the Alpha Monocerotids may put on a surprise showing in November 2015 as well…

Bright Meteor 4th November 2013 from Richard Fleet on Vimeo.

More to come on that. Keep watching the skies, and don’t forget to tweet those Northern Taurid fireball sightings and images to #Meteorwatch!

-Got an image of a Northern Taurid fireball? Send ‘em in to Universe Today for our Flickr forum… we may just feature your pic in an after action round up!

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.