Astronomers Spot a Intriguing ‘5-Star’ Multiple System

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An interesting multiple star discovery turned up in the ongoing hunt for exoplanetary systems.

The discovery was announced by Marcus Lohr of Open University early this month at the National Astronomy Meeting that was held at Venue Cymru in Llandudno, Wales.

The discovery involves as many as five stars in a single stellar system, orbiting in a complex configuration.

The name of the system, 1SWASP J093010.78+533859.5, is a phone number-style designation related to the SuperWASP exoplanet hunting transit survey involved with the discovery. The lengthy numerical designation denotes the system’s position in the sky in right ascension and declination in the constellation Ursa Major.

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The SuperWASP-North array of cameras at La Palma in the Canary Islands. Image credit: The SuperWASP consortium

And what a bizarre system it is. The physical parameters of the group are simply amazing, though not as unique as some media outlets have led readers to believe. What is amazing is the fact that both pairs of binaries in the quadruple group are also eclipsing along our line of sight. Only five other quadruple eclipsing binary systems of this nature are known, to include BV/BW Draconis and V994 Herculis.

The very fact that the orbits of both pairs of stars are in similar inclinations will provide key insights for researchers as to just how this system formed.

The first pair in the system are contact binaries of 0.9 and 0.3 solar masses respectively in a tight embrace revolving about each other in just under six hours. Contact binaries consist of distorted stars whose photospheres are actually touching. A famous example is the eclipsing contact binary Beta Lyrae.

 

 

 

 

 

 

 

An animation of the orbits of the contact binary pair Beta Lyrae captured using the CHARA interferometer. Image credit: Ming Zhao et al. ApJ 684, L95 

A closer analysis of the discovery revealed another pair of detached stars of 0.8 and 0.7 solar masses orbiting each other about 21 billion kilometres (140 AUs distant) from the first pair. You could plop the orbit of Pluto down between the two binary pairs, with room to spare.

But wait, there’s more. Astronomers use a technique known as spectroscopy to tease out the individual light spectra signatures of close binaries too distant to resolve individually. This method revealed the presence of a fifth star in orbit 2 billion kilometers (13.4 AUs, about 65% the average distance from Uranus to the Sun) around the detached pair.

“This is a truly exotic star system,” Lohr said in a Royal Society press release. “In principle, there’s no reason it couldn’t have planets in orbit around each of the pairs of stars.”

Indeed, ‘night’ would be a rare concept on any planet in a tight orbit around either binary pair. In order for darkness to occur, all five stellar components would have to appear near mutual conjunction, something that would only happen once every orbit for the hypothetical world.

Such a planet is a staple of science fiction, including Tatooine of Star Wars fame (which orbits a relatively boring binary pair), and the multiple star system of the Firefly series. Perhaps the best contender for a fictional quadruple star system is the 12 colonies of the re-imagined Battlestar Galactica series, which exist in a similar double-pair configuration.

How rare is this discovery, really? Multiple systems are more common than solitary stars such as our Sun by a ratio of about 2:1. In fact, it’s been suggested by rare Earth proponents that life arose here on Earth in part because we have a stable orbit around a relatively placid lone star. The solar system’s nearest stellar neighbor Alpha Centauri is a triple star system. The bright star Castor in the constellation of Gemini the Twins is a famous multiple heavyweight with six components in a similar configuration as this month’s discovery. Another familiar quadruple system to backyard observers is the ‘double-double’ Epsilon Lyrae, in which all four components can be split. Mizar and Alcor in the handle of the Big Dipper asterism is another triple-pair, six-star system. Another multiple, Gamma Velorum, may also possess as many as six stars. Nu Scorpii and AR Cassiopeiae are suspected septuple systems, each perhaps containing up to seven stars.

Fun fact: Gamma Velorum is also informally known as ‘Regor,’ a backwards anagram play on Apollo 1 astronaut ‘Roger’ Chaffee’s name. The crew secretly inserted their names into the Apollo star maps during training!

What is the record number of stars in one system? Hierarchy 3 systems such as Castor are contenders. A.A. Tokivinin’s Multiple Star Catalogue lists five components in a hierarchy 4 system in Ophiuchus named Gliese 644AB, with the potential for more.

How many stars are possible in one star system? Certainly, a hierarchy 4 type system could support up the eight stars, though to our knowledge, no example of such a multiple star system has yet been confirmed. Still, it’s a big universe out there, and the cosmos has lots of stars to play with.

A wide-field view of the constellation Ursa Major, with Theta Ursae Majoris selected (inset). image credit; Stellarium
A wide-field view of the constellation Ursa Major, with Theta Ursae Majoris selected (inset). Image credit; Stellarium

And you can see 1SWASP J093010.78+533859.5 for yourself. At 250 light years distant, the +9th magnitude binary is about 1.5 degrees north-northwest of the star Theta Ursa Majoris, and is an tough but not impossible split with a separation of 1.88” between the two primary pairs.

Image credit: Stellarium
Finder chart for 1SWAP J093010.78+533859.5 with a five degree Telrad foV. Image credit: Stellarium

Congrats to the team on this amazing discovery… to paraphrase Haldane, the Universe is proving to be stranger than we can imagine!

Moonspotting-A Guide to Observing the Moons of the Solar System

Triple crescents. Image credit:

Like splitting double stars, hunting for the faint lesser known moons of the solar system offers a supreme challenge for the visual observer.

Sure, you’ve seen the Jovian moons do their dance, and Titan is old friend for many a star party patron as they check out the rings of Saturn… but have you ever spotted Triton or Amalthea?

Welcome to the challenging world of moon-spotting. Discovering these moons for yourself can be an unforgettable thrill.

One of the key challenges in spotting many of the fainter moons is the fact that they lie so close inside the glare of their respective host planet. For example, +11th magnitude Phobos wouldn’t be all that tough on its own, were it not for the fact that it always lies close to dazzling Mars. 10 magnitudes equals a 10,000-fold change in brightness, and the fact that most of these moons are swapped out is what makes them so tough to see. This is also why many of them weren’t discovered until later on.

But don’t despair. One thing you can use that’s relatively easy to construct is an occulting bar eyepiece.   This will allow you to hide the dazzle of the planet behind the bar while scanning the suspect area to the side for the faint moon. Large aperture, steady skies, and well collimated optics are a must as well, and don’t be afraid to crank up the magnification in your quest. We mentioned using such a technique previously as a method to tease out the white dwarf star Sirius b in the years to come.

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A homemade occulting bar eyepiece with the barrel removed. One bar is a strip of foil, and the other is a E-string from a guitar. Image credit: Dave Dickinson

What follows is a comprehensive list of the well known ‘easy ones,’ along with some challenges.

We included a handy drill down of magnitudes, orbital periods and maximum separations for the moons of each planet right around opposition. For the more difficult moons, we also noted the circumstances of their discovery, just to give the reader some idea what it takes to see these fleeting worlds.  Remember though, many of those old scopes used speculum metal mirrors which were vastly inferior to commercial optics available today. You may have a large Dobsonian scope available that rivals these scopes of yore!

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The orbits of the Martian moons. Image credit: Starry Night Education Software

Mars- The two tiny moons of Mars are a challenge, as it’s only possible to nab them visually near opposition, which occurs about once every 26 months.   Mars next reaches opposition on May 22nd, 2016.

Phobos:

Magnitude:  +11.3

Orbital period:  7 hours 39 minutes

Maximum separation: 16”

Deimos:

Magnitude:  +12.3

Orbital period: 1 day 6 hours and 20 minutes

Maximum separation: 54”

The moons of Mars were discovered by American astronomer Asaph Hall during the favorable 1877 opposition of Mars using the 26-inch refracting telescope at the U.S. Naval Observatory.

Jupiter- Though the largest planet in our solar system also has the largest number of moons at 67, only the four bright Galilean moons are easily observable, although owners of large light buckets might just be able to tease out another two.  Jupiter next reaches opposition March 8th, 2016.

Ganymede:

Magnitude: +4.6

Orbital period: 7.2 days

Maximum separation: 5’

Callisto

Magnitude: +5.7

Orbital period: 16.7 days

Maximum separation: 9’

Io

Magnitude: +5.0

Orbital period: 1.8 days

Maximum separation: 1’ 50”

Europa

Magnitude: +5.3

Orbital period: 3.6 days

Maximum separation: 3’

Amalthea

Magnitude:  +14.3

Orbital period: 11 hours 57 minutes

Maximum separation: 33”

Himalia

Magnitude: +15

Orbital period: 250.2 days

Maximum separation: 52’

Note that Amalthea was the first of Jupiter’s moons discovered after the four Galilean moons. Amalthea was first spotted in 1892 by E. E. Barnard using the 36” refractor at the Lick Observatory. Himalia was also discovered at Lick by Charles Dillon Perrine in 1904.

Titan and Rhea imaged via Iphone and a Celestron NexStar 8SE telescope. Image credit: Andrew Symes (@failedprotostar)
Titan and Rhea imaged via Iphone and a Celestron NexStar 8SE telescope. Image credit: Andrew Symes (@failedprotostar)

Saturn- With a total number of moons at 62, six moons of Saturn are easily observable with a backyard telescope, though keen-eyed observers might just be able to tease out another two:

(Note: the listed separation from the moons of Saturn is from the limb of the disk, not the rings).

Titan

Magnitude: +8.5

Orbital period: 16 days

Maximum separation: 3’

Rhea

Magnitude: +10.0

Orbital period: 4.5 days

Maximum separation: 1’ 12”

Iapetus

Magnitude: (variable) +10.2 to +11.9

Orbital period: 79 days

Maximum separation: 9’

Enceladus

Magnitude: +12

Orbital period: 1.4 days

Maximum separation: 27″

Dione

Magnitude: +10.4

Orbital period: 2.7 days

Maximum separation: 46”

Tethys

Magnitude: +10.2

Orbital period: 1.9 days

Maximum separation: 35”

Mimas

Magnitude: +12.9

Orbital period: 0.9 days

Maximum separation: 18”

Hyperion

Magnitude: +14.1

Orbital period: 21.3 days

Maximum separation: 3’ 30”

Phoebe

Magnitude: +16.6

Orbital period: 541 days

Maximum separation: 27’

Hyperion was discovered by William Bond using the Harvard observatory’s 15” refractor in 1848, and Phoebe was the first moon discovered photographically by William Pickering in 1899.

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The orbits of the moons of Uranus. Image credit: Starry Night Education software

Uranus- All of the moons of the ice giants are tough. Though Uranus has a total of 27 moons, only five of them might be spied using a backyard scope. Uranus next reaches opposition on October 12th, 2015.

Titania

Magnitude: +13.9

Orbital period:

Maximum separation: 28”

Oberon

Magnitude: +14.1

Orbital period: 8.7 days

Maximum separation: 40”

Umbriel

Magnitude: +15

Orbital period: 4.1 days

Maximum separation: 15”

Ariel

Magnitude: +14.3

Orbital period: 2.5 days

Maximum separation: 13”

Miranda

Magnitude: +16.5

Orbital period: 1.4 days

Maximum separation: 9”

The first two moons of Uranus, Titania and Oberon, were discovered by William Herschel in 1787 using his 49.5” telescope, the largest of its day.

Triton in orbit around Neptune near opposition in 2011. Image credit: Efrain Morales
Triton in orbit around Neptune near opposition in 2011. Image credit: Efrain Morales

Neptune- With a total number of moons numbering 14, two are within reach of the skilled amateur observer. Opposition for Neptune is coming right up on September 1st, 2015.

Triton

Magnitude: +13.5

Orbital period: 5.9 days

Maximum separation: 15”

Nereid

Magnitude: +18.7

Orbital period: 0.3 days

Maximum separation: 6’40”

Triton was discovered by William Lassell using a 24” reflector in 1846, just 17 days after the discovery of Neptune itself. Nereid wasn’t found until 1949 by Gerard Kuiper.

Pluto-Yes… it is possible to spy Charon from Earth… as amateur astronomers proved in 2008.

Charon

Magnitude: +16

Orbital period: 6.4 days

Maximum separation: 0.8”

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Pluto! Click here for a (possible) capture of Charon as well. Image credit: Wendy Clark

In order to cross off some of the more difficult targets on the list, you’ll need to know exactly when these moons are at their greatest elongation. Sky and Telescope has some great apps in the case of Jupiter and Saturn… the PDS Rings node can also generate corkscrew charts of lesser known moons, and Starry Night has ‘em as well. In addition, we tend to publish cork screw charts for moons right around respective oppositions, and our ephemeris for Charon elongations though July 2015 is still active.

Good luck in crossing off some of these faint moons from your astronomical life list!

Catch a Fine Lunar Planetary Grouping This Weekend

Image Credit: Andrew Symes (@FailedProtostar).

Phew! Our eyes and thoughts have been cast so far out into the outer reaches of the solar system following New Horizons and Pluto this week, that we’re just now getting to the astronomical action going on in our own backyard.

You’ll recall that Venus and Jupiter have made a fine pairing in the evening sky since their close approach on July 1st. Despite some of the incredulous ‘Star of Bethlehem’ claims that this was a conjunction that happens ‘once every two thousand years,’ this sort of pairing is actually quite common. In fact, Venus and Jupiter are set to meet up again in the dawn sky later this year on October 25th. Continue reading “Catch a Fine Lunar Planetary Grouping This Weekend”

Naming Pluto: Christening Features on Brave New Worlds

Artist's impression of Charon (left) and Pluto (right), showing their relative sizes. Credit:

‘Here be Dragons…’ read the inscriptions of old maps used by early seafaring explorers. Such maps were crude, and often wildly inaccurate.

The same could be said for our very understanding of distant planetary surfaces today. But this week, we’ll be filling in one of those ‘terra incognita’ labels, as New Horizons conducts humanity’s very first reconnaissance of Pluto and its moons.

The closest approach for New Horizons is set for Tuesday, July 14th at 11:49 UT/7:49 AM EDT, as the intrepid spacecraft passes 12,600 kilometres (7,800 miles) from Pluto’s surface. At over 4 light hours or nearly 32 astronomical units (AUs) away, New Horizons is on its own, and must perform its complex pirouette through the Pluto system as it cruises by at over 14 kilometres (8 miles) a second.

This also means that we’ll be hearing relatively little from the spacecraft on flyby day, as it can’t waste precious time pointing its main dish back at the Earth. With a downlink rate of 2 kilobits a second—think ye ole 1990’s dial-up, plus frozen molasses—it’ll take months to finish off data retrieval post flyby. A great place to watch a simulation of the flyby ‘live’ is JPL’s Eyes on the Solar System, along with who is talking to New Horizons currently on the Deep Space Network with DSN Now.

A snapshot of the current July 13th view of New Horizons as it nears Pluto. (Image credit: NASA's Eyes on the Solar System).
A snapshot of the current July 13th view of New Horizons as it nears Pluto. (Image credit: NASA’s Eyes on the Solar System).

Launched in 2006, New Horizons is about to join the ranks of nuclear-fueled explorers that have conducted first time reconnaissance of solar system objects.

Bob King also wrote up an excellent timeline of New Horizons events for Universe Today yesterday. Also be sure to check out the Planetary Society’s in-depth look at what to expect by Emily Lakdawalla.

Seems strange that after more than a decade of recycling the same blurry images and artist’s conceptions in articles, we’re now getting a new and improved shot of Pluto and Charon daily!

To follow the tale of Pluto is to know the story of modern planetary astronomy. Discovered in 1930 by American astronomer Clyde Tombaugh from the Lowell Observatory, Pluto was named by 11-year old Venetia Burney. Venetia just passed away in 2009, and there’s a great short documentary interview with her entitled Naming Pluto.

Blink comparitor
The blink comparitor Clyde Tombaugh used to discover Pluto, on display at the Lowell Observatory. Image Credit: David Dickinson

Fun fact: Historians at the Carnegie Institute recently found images of Pluto on glass plates… dated 1925, from five years before its discovery.

Despite the pop culture reference, Pluto was not named after the Disney dog, but after the Roman god of the underworld. Pluto the dog was not named in Disney features until late 1930, and if anything, the character was more than likely named after the buzz surrounding the newest planet on the block.

We’re already seeing features on Pluto and Charon in the latest images, such as the ‘heart,’ ‘donut,’ and the ‘whale’ of Pluto, along with chasms, craters and a dark patch on Charon. The conspicuous lack of large craters on Pluto suggests an active world.

The International Astronomical Union (IAU) convention for naming any new moons discovered in the Plutonian system specifies characters related to the Roman god Pluto and tales of the underworld.

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Brake for New Horizons on July 14th… Image credit: David Dickinson

With features, however, cartographers of Pluto should get a bit more flexibility. Earlier this year, the Our Pluto campaign invited the public to cast votes to name features on Pluto and Charon related to famous scientists, explorers and more. The themes of ‘fictional explorers and vessels’ has, of course, garnered much public interest, and Star Trek’s Mr. Spock and the Firefly vessel Serenity may yet be memorialized on Charon. Certainly, it would be a fitting tribute to the late Leonard Nimoy. We’d like to see Clyde Tombaugh and Venetia Burney paid homage to on Pluto as well.

We’ve even proposed the discovery of a new moon be named after the mythological underworld character Alecto, complete with a Greek ‘ct’ spelling to honor Clyde Tombaugh.

The discovery and naming of Charon in 1978 by astronomer Robert Christy set a similar precedent. Christy choose the name of the mythological boatman who plied the river Styx (which also later became a Plutonian moon) as it included his wife Charlene’s nickname ‘Char.’ This shibboleth  also set up a minor modern controversy as to the exact pronunciation of Charon, as the mythological character is pronounced with a hard ‘k’ sound, but most folks (including NASA) say the moon as ‘Sharon’ in keeping with Christy’s in-joke that slipped past the IAU.

And speaking of Pluto’s large moon, someone did rise to the occasion and take our ‘Charon challenge,’ we posed during the ongoing Pluto opposition season recently. Check out this amazing capture of the +17th magnitude moon winking in and out of view next to Pluto courtesy of Wendy Clark:

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Click here to see the animation of the possible capture of Charon near Pluto. Image credit and copyright: Wendy Clark

Clark used the 17” iTelescope astrograph located at Siding Spring Observatory in Australia to tease out the possible capture of the itinerant moon.

Great job!

What’s in a name? What strange and wonderful discoveries await New Horizons this week? We should get our very first signal back tomorrow night, as New Horizons ‘phones home’ with its message that it survived the journey around 9:10 PM EDT/1:10 UT. Expect this following Wednesday—in the words of New Horizons principal Investigator Alan Stern—to begin “raining data,” as the phase of interpreting and evaluating information begins.

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The women who power the New Horizons mission to Pluto. Image credit: SwRI/JHUAPL

And there’s more in store, as the New Horizons team will make the decision to maneuver the spacecraft for a rendezvous with a Kuiper Belt Object (KBO) next month. Said KBO flyby will occur in the 2019-2020 timeframe, and perhaps, we’ll one day see a Pluto orbiter mission or lander in the decades to come…

Maybe one way journeys to ‘the other Red Planet’ are the wave of the future.’ Pluto One anyone?

Is Kapteyn B Not to Be?

The hypothetical super-Earth Kapteyn-b compared to Earth. Image credit:

Are the ancient planets discovered around Kapteyn’s Star for real?

As the saying goes, all that glitters isn’t gold, and the same could be said in the fast-paced hunt for exoplanets. In 2014, we reported on an exciting new discovery of two new exoplanets orbiting Kapteyn’s Star. The news came out of the American Astronomical Society’s 224th Meeting held in Boston Massachusetts, and immediately grabbed our attention. The current number of exoplanet discoveries as of July 2015 sits at 1,932 and counting.

An M-class red dwarf, Kapteyn’s Star is relatively nearby at only 13 light years distant. The planetary discovery consisted of a  world five times the mass of the Earth  in a 48 day orbit (Kapteyn b), and a world seven times the mass of the Earth  in a 122 day orbit (Kapteyn c). The discovery was hailed as an example of an ancient—possibly over 11 billion years old—system with its innermost world cast as a ‘super-Earth’ in the habitable zone…

But is Kapteyn-b not to be?

An interesting paper came up in the Astrophysical Journal Letters recently that suggests the exoplanets discovered orbiting Kapteyn’s Star in 2014 may in fact be spurious detections.

Image credit: Jcpag2012 under a Wikimedia Commons 4.0 International license
Kapteyn’s Star versus the Sun, Jupiter and the Earth. Image credit: Jcpag2012 under a Wikimedia Commons 4.0 International license

The idea of a planetary system around Kapteyn’s Star, real or not, is an interesting tale of exoplanet science.  The original discovery was made using the High Accuracy Radial velocity Planetary research (HARP) instrument at the European Southern Observatory, with supporting observations from the Las Campanas and Keck Observatory. You’d think that would make the discoveries pretty air-tight. The planets discovered orbiting Kapteyn’s Star were discerned using the radial velocity method, looking at the spectra of the star for the characteristic tugging of an unseen companion.

Recent research led by Paul Robertson of Pennsylvania State University suggests that the signal for the discovery of Kapteyn B may in fact be the result of stellar activity. Starspots—think sunspots on our own host star—can mimic the spectral signal of an unseen planet. Analyzing the HARPS data, we know that Kapteyn’s Star rotates once every 143 days. Kapteyn-b’s orbit of 48 days is very close to an integer fraction (143/48= 2.979) making it extremely suspicious.

Universe Today recently caught up with Paul Robertson, who had this to say about exoplanets around Kapteyn’s Star:

Q-How does this put the existence of a planet around Kapteyn’s Star in jeopardy?

“Based on our analysis of the star’s magnetic activity, we determined the star has a rotation period that is three times that of the orbital period for ‘planet b.’  Theoretical simulations have predicted—and subsequent observations have proven—that a star can create Doppler signals at integer fractions of its rotation period (that is, one half, one third, etc).  Furthermore, the measurements of the star’s magnetic activity are correlated with the predicted Doppler shifts caused by planet b.  In such cases, the simplest explanation for the observations is that the Doppler periodicity is caused by the star’s activity, rather than a planet whose signal coincidentally matches the star’s activity.”

Q-Is it possible to discern the starspot cycle that we’re seeing on Kapteyn’s Star?

“We infer the presence of active magnetic regions—possibly starspots—on the stellar surface through the variability of certain magnetically-sensitive absorption lines in the star’s spectrum. Previous observations suggest that the star’s brightness is relatively constant, so any starspots must be fairly small or not especially dark. It is possible that a space-based photometer such as K2 or TESS might see starspots.”

Q-Are future observations planned?

“Honestly, I don’t know.  My paper used data from previous observing programs that are now available in public archives.  I certainly think additional data would be quite valuable for Kapteyn’s Star.  Given that Kapteyn’s Star is somewhat special, being the closest halo star and one of the oldest nearby stars, I suspect someone will take more observations.”

This discovery is significant either way. An ancient super-Earth orbiting in the habitable zone of a nearby star has had lots of time to get the engine of evolution underway, more than twice the span of the history of life on Earth. But if Kapteyn-b is merely a transitory flicker in the data, it also serves as a good case study in perils of exoplanet hunting as well.

There’s still a good deal of controversy, however, surrounding the existence of planets orbiting Kapteyn’s Star. One very recent paper released just last week on June 30th titled No Evidence for Activity Correlations in the Radial Velocities of Kapteyn’s Star is safely in the ‘pro- Kapteyn-b’ camp.

Discovered due to its high (8 arc seconds per year) proper motion by Dutch astronomer Jacobus Kapteyn in 1898, Kapteyn’s Star is the closest known halo star to our solar system. It’s thought that Kapteyn’s Star might be associated with the large globular cluster Omega Centauri, which itself is thought to be the remnant of a dwarf galaxy gobbled up by our own Milky Way in the distant past.

The location of Kapteyn's Star in the constellation Pictor. Image credit: Starry Night Education software
The location of Kapteyn’s Star in the constellation Pictor. Image credit: Starry Night Education software

Kapteyn-b also made our list of red dwarf stars visible in backyard telescopes.

And Kapteyn-b wouldn’t be the first exoplanet detection that turned out to be spurious, as the existence of the exoplanet Alpha Centuari Bb announced in 2012 has been called into question as well.

It’s a brave new world on exoplanet science out there for sure, and for now, the worlds of Kapteyn’s Star will remain a mystery.

Catching Earth at Aphelion

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Do you feel a little… distant today? The day after the 4th of July weekend brings with it the promise of barbecue leftovers and discount fireworks. It also sees our fair planet at aphelion, or its farthest point from the Sun. In 2015, aphelion (or apoapsis) occurs at 19:40 Universal Time (UT)/3:40 PM EDT today, as we sit 1.01668 astronomical units (AU) from the Sun. This translates to 152.1 million kilometres, or 94.5 million miles. We’re actually 3.3% closer to the Sun in early January than we are today. This also the latest aphelion has occurred on the calendar year since 2007, and it won’t fall on July 6th again until 2018. The insertion of an extra day every leap year causes the date for Earth aphelion to slowly vary between July 3rd and July 6th in the current epoch.

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Perihelion and aphelion versus the solstices and the equinoxes. Image credit: Gothika/Duoduoduo/Wikimedia commons 3.0 license

Aphelion sees the Earth 4.8 million kilometers farther from the Sun than perihelion in early January. The eccentricity of our orbit—that is, how much our planet’s orbit varies from circular to elliptical—currently sits at 0.017 or 1.7%.

It is ironic that we’re actually farther from the Sun in the middle of northern hemisphere summer. It sure doesn’t seem like it on a sweltering Florida summer day, right? That’s because the 23.44 degree tilt of the Earth’s rotational axis is by far the biggest driver of the seasons. But our variation in distance from the Sun does play a factor in long term climate as well. We move a bit slower farther from the Sun, assuring northern hemisphere summers are currently a bit longer (by about 4 days) than winters. The variation in solar insolation between aphelion and perihelion currently favors hot dry summers in the southern hemisphere.

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Perihelion and aphelion circumstances for the remainder of the decade. Credit: David Dickinson

But these factors are also slowly changing as well.

The eccentricity of our orbit varies from between 0.000055 and 0.0679 over a span of a ‘beat period’ of 100,000 years. Our current trend sees eccentricity slowly decreasing.

The tilt of our rotational axis varies between 22.1 and 24.5 degrees over 41,000 years. This value is also currently on a decreasing trend towards its shallow minimum around 11,800 AD.

And finally, the precession of the Earth’s axis and apsidal precession combine to slowly move the date of aphelion and perihelion one time around our calendar once every 21,000 years.

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The precession of the line of apsides versus the seasons. Image credit: Krishnavedala/Wikimedia commons 3.0 license.

These combine to form what are known as Milankovitch Cycles of long-term climate variation, which were first expressed by astronomer Milutin Milankovic in 1924. Anthropogenic climate change is a newcomer on the geologic scene, as human civilization does its very best to add a signal of its very own to the mix.

We also just passed the mid-point ‘pivot of the year’ on July 2nd. More than half of 2015 is now behind us.

Want to observe the aphelion and perihelion of the Earth for yourself? If you have a filtered rig set to photograph the Sun, try this: take an image of the Sun today, and take another on perihelion next year on January 2nd. Be sure to use the same settings, so that the only variation is the angular size of the Sun itself. The disk of the Sun varies from 33’ to 31’ across. This is tiny but discernible. Such variations in size between the Sun and the Moon can also mean the difference between a total solar and annular eclipse.

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A perihelion versus aphelion day Sol. Image credit: David Dickinson

Should we term the aphelion Sun a #MiniSol? Because you can never have too many internet memes, right?

And did you know: the rotational axis of the Sun is inclined slightly versus the plane of the ecliptic to the tune of 7.25 degrees as well. In 2015, the Sun’s north pole was tipped our way on March 7th, and we’ll be looking at the south pole of our Sun on September 9th.

And of course, seasons on other planets are much more extreme. We’re just getting our first good looks at Pluto courtesy of New Horizons as it heads towards its historic flyby on July 14th. Pluto reached perihelion in 1989, and is headed towards aphelion 49 AU from the Sun on the far off date in 2114 AD. Sitting on Pluto, the Sun would shine at -19th magnitude—about the equivalent of the twilight period known as the ‘Blue Hour’ here on Earth—and the Sun would appear a scant one arc minute across, just large enough to show a very tiny disk.

All thoughts to consider as we start the long swing inward towards perihelion next January.

Happy aphelion!

See Pluto for Yourself Ahead of New Horizons’ Historic Encounter

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Are you ready for July? The big ticket space event of the year is coming right up, as NASA’s New Horizons spacecraft is set to make its historic flyby targeting a pass 12,500 kilometres (7,750 miles) from the surface of Pluto at 11:50 UT on July 14th. Already, Pluto and its moons are growing sharper by the day, as New Horizons closes in on Pluto at over 14 kilometres per second.

And the good news is, this flyby of the distant world occurs just eight days after Pluto reaches opposition for 2015, marking a prime season to track down the distant world with a telescope.

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The path of Pluto through 2015. Image credit: Starry Night Education Software

Pluto and its large moon Charon are snapping into focus as we reach the two week out mark. Discovered in 1930 by astronomer Clyde Tombaugh while working at the Lowell observatory in Flagstaff Arizona, these far off worlds are about to become real places in the public imagination. It’s going to be an exciting—if tense—few weeks, as new details and features are seen on these brave new worlds, all calling out for names. Are there undiscovered moons? Does Pluto host a ring system? What is the history of Pluto?

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A wide field view of Sagittarius and Pluto with inset (see chart above) Image credit: Starry Night education software

Hunting for Pluto with a backyard telescope is difficult, though not impossible. We suggest an aperture of 10-inches or greater, though the tiny world has been reliably spotted using a 6-inch reflector. Pluto reaches opposition on July 6th at 10:00 UT/6:00 AM EDT, marking a period when it will rise opposite to the setting Sun and transit highest near local midnight. Pluto spends all of 2015 in the constellation Sagittarius. This presents two difficulties: 1). We’re currently looking at Pluto against the very star-rich backdrop towards the center of the Milky Way Galaxy, and 2). Its southerly declination means that it won’t really ‘clear the weeds’ much for northern hemisphere observers.

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The path of Pluto through July 2015. Image credit: Starry Night Education software

But don’t despair. With a good finder chart and patience, you too can cross Pluto off of your life list. In fact, the month of July sees Pluto thread its way between the 27’ wide  +4th magnitude pair Xi Sagittarii, making a great guidepost to spot the 14th magnitude world.

Don’t own a telescope? You can still wave in the general direction of New Horizons and Pluto on the evening of July 1st, using the nearby Full Moon as a guide:

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Pluto near the Full Moon on the night of July 1st. Image credit: Stellarium

Pluto orbits the Sun once every 248 years, and reaches opposition every 367 days. A testament to this slow motion is the fact that Mr. Tombaugh first spied Pluto south of the star Delta Gemini, and it has only moved as far as Sagittarius in the intervening 85 years. Pluto also passed perihelion in 1989, when it was about half a magnitude brighter than it currently is now. Pluto’s distance from the Sun varies from 30 AU to 49 AU, and Pluto will reach aphelion just under a century from now on 2114.

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Pluto versus Charon at greatest elongation. Image credit: Starry Night Education software

Up for a challenge? Hunting down Pluto’s elusive moon Charon is an ultimate feat of astronomical athletics. Amazingly, this has actually been done before, as reported here in 2008 on Universe Today.

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Pluto… and Charon! Image credit: Antonello Medugno and Daniele Gasparri

Charon reaches greatest elongation 0.8” from Pluto once every three days. Shining at +16th magnitude,  Charon is a faint catch, though not impossible. We’re already seeing supporting evidence from early New Horizons images that these two worlds stand in stark contrast, with dark Charon covered in relatively low albedo dirty water-ice and while brighter Pluto is coated with reflective methane snow.

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Greatest elongation times and dates for Charon through the month of July 2015. Credit: Ed Kotapish

The current forward-looking view from New Horizons of Pluto is amazing to consider. As of July 1st, the spacecraft is 0.11 AU (17 million kilometres) from Pluto and closing, and the world appears as a +1.7 magnitude object about 30 arc seconds across.  The views of Pluto are courtesy of New Horizons’ LORRI (Long Range Reconnaissance Imager), which in many ways is very similar to a familiar backyard 8-inch Schmidt-Cassegrain telescope. It’s interesting to note that the views we’re currently getting very closely resemble amateur views of Mars near opposition, though we suspect that will change radically in about a week.

And it will take months for all of the New Horizons data to make its way back to Earth. The real nail-biter will be the 20 hour period of close rendezvous on July 14th, a period in which the spacecraft will have to acquire Pluto and Charon, do its swift ballet act, and carry out key observations—all on its own before phoning home. This will very likely be the only mission to Pluto in our lifetimes, as New Horizons will head out to rendezvous with several Kuiper Belt Objects in the 2020 time frame before joining the Voyager I & II and Pioneer 10 & 11 spacecraft in an orbit around the Milky Way Galaxy.

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Pluto (marked) from the morning of June 25th, 2015. Image credit and copyright: Jim Hendrickson

Just think, in less than a few weeks time, science writers will (at last!) have a wealth of Plutonian imagery to choose from courtesy of New Horizons, and not just a few blurry pics and artist’s conceptions that we’ve recycled for decades… let us know of your tales of tribulation and triumph as you attempt to hunt down Pluto this summer!

A Brief History of Nukes in Space

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In just a few short weeks, NASA’s New Horizons spacecraft will make its historic flyby of Pluto and its moons. Solar panels are unable to operate in the dim nether regions of the outer solar system, and instead, New Horizons employs something that every spacecraft that has thus far ventured beyond Jupiter has carried in its tool kit: a plutonium-powered Radioisotope Thermoelectric Generator, or RTG.

The use of nuclear power to explore space is one of the few happy chapters of the post atomic age, and nuclear power may one day give us access to the stars.

In the 1950s, atomic energy was seen as a panacea as well as a curse, a sort of Sword of Damocles that both hung over the human race, while also holding the promise of its salvation. This was before the disasters in Fukushima Daiichi, Chernobyl and Three Mile Island, which would serve to sour the public to all things nuclear.

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EBR-1, The first commercial nuclear power plant to go online (EBR-1), located in Idaho. Image credit: David Dickinson

But early space pioneers also recognized the potential for nuclear energy in space exploration. One of the more bizarre proposals of the early Space Age was a plan named Project A119 which called for the United States to detonate a nuclear weapon on the Moon in full view of the Soviet Union as a show of power. Another interesting proposal dubbed Project Orion called for the construction of an interstellar spacecraft that would be propelled by atomic bombs detonated to its aft. And the very first human artifact shot into space may well have been a one ton steel plate that was accidentally propelled at high speed skyward during the Pascal B nuclear test in the Operation Plumbbob series on August 27th, 1957. And the United States did indeed detonate nuclear weapons in space before the advent of the Limited Test Ban Treaty of 1967 that later forbade such tests. One amazing (and, as a child of the Cold War, very eerie to watch) such test known as Starfish Prime was carried out over the South Pacific in 1962:

One of the first spacecraft that sported an RTG was the Transit-4A satellite launched on June 29th, 1961. Another similar satellite in the series, Transit-5BN-3, was lost shortly after launch along with its plutonium-fueled RTG, which reentered over the Indian Ocean. The Soviet satellite Kosmos 954 also reentered over the Canadian high Arctic in early 1978 along with its onboard nuclear reactor.

And when Apollo 13 returned to Earth, the crew jettisoned the Aquarius lunar landing module over the Pacific, where it reentered along with its plutonium RTG meant for the ALSEP experiments that the Apollo astronauts placed on the Moon during every mission.

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Aquarius after separation. Image credit: Apollo 13/NASA

Every launch from Cape Canaveral of a nuclear RTG is sure to draw a scattering of protesters, though NASA estimated a catastrophic launch failure involving an RTG rupture during the New Horizons launch at 1-in-360. These fears reached a crescendo during the launch of Cassini in 1997, which also featured an Earth slingshot flyby on August 18th, 1999 en route to Saturn.

A nuclear RTG works by utilizing the waste heat generated by the radioactive decay of plutonium-238. This not only has a half-life of 87.7 years, but it also generates a very respectable 560 watt-seconds per kilogram per second. Unfortunately, the stuff we weaponize for nuclear bombs is a separate isotope known as Pu-239, and it can’t be repurposed for RTG use. The production of plutonium-239 for nuclear weapons during the Cold War did, however, also assure that the capability to also create Pu-238 for spaceflight was on hand until production was ended in the United States in 1989.

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A glowing pellet of Pu-238. Image credit: NASA/DoE

A roll call of RTG-equipped spacecraft reads like a ‘Who’s Who’ of outer solar system space exploration and includes: Pioneer 10 and 11, Galileo, Cassini, the Mars Science Laboratory, Voyagers 1 and 2, Vikings 1 and 2, and the aforementioned New Horizons spacecraft bound for Pluto.

Fun Fact: the plutonium powering Curiosity as it explores Mars was actually bought by NASA from the Russians.

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A close up of MSL’s MMRTG. Image credit: NASA/LBNL

As of this writing, the Mars Rover 2020 mission is the next spacecraft to break the surly bonds that will sport, like Curiosity, a plutonium-powered MMRTG.  A proposed Uranus Orbiter mission named HORUS (This stands for—deep breath— the Herschel Orbiter for Reconnaissance of the Uranus System, because ‘Uranus Probe’ just doesn’t sound right) would have also utilized and RTG. The Europa Clipper mission to Jupiter’s moon Europa set to launch around 2025 chose solar cells over a nuclear RTG, though it’ll have to thread through the perilous radiation environment surrounding Jupiter. In fact, the Juno spacecraft set to enter orbit around the planet Jupiter next year will be the first Jovian mission that won’t utilize nuclear power, though it requires three enormous solar panels to compensate.

Just how much plutonium NASA has on hand courtesy of the Department of Energy is classified for security reasons, but it’s thought to have enough for one large and one scout-class mission remaining. New Horizons incorporates 10.9 kilograms of plutonium, and it’s interesting to note that any alien civilization that finds a human spacecraft orbiting the plane of our Milky Way galaxy millions of years hence could date its manufacture from the radioactive decay of what very little Pu-238 versus decay isotopes remains in its RTG.

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A close-up of New Horizons encapsulated in its launch fairing shortly after its RTG was installed. Image credit: KSC/NASA

NASA has announced that the US Department of Energy will indeed resume the production of plutonium to the tune of about 1.5 to 2 kilograms a year starting in 2016. On the downside, NASA did, however, halt the development of its Advanced Stirling Radioisotope Generator (ASRG) in 2013. This is a somewhat contradictory decision, fueled more by politics than practicality given the current scarcity of plutonium. The ASRG design was to be four times more efficient than current MMRTGs (MM stands for Multi-Mission) and would have thus utilized less of the dwindling stockpile of existing Pu-238.

Sadly, the lingering shortage of plutonium may have a dire impact on the future of outer solar system space exploration. As Cassini, New Horizons and the Voyager spacecraft wrap up their respective missions, our ‘eyes on the outer solar system’ may go dark, as the current golden era of planetary exploration draws to a close for now, or at least, awaits a new generation of plutonium-powered spacecraft to take up the mantle.

About Time: Is the June 30th Leap Second the Last?

Out with the old... changing out the historic coundown clock at the Kennedy Space Center, perhaps an easier 'time change' than the insertion of the leap second. Image credit: NASA/Frankie Martin

The month of June 2015 is just a tad longer than usual… but not for the reason you’ve been told.

Chances are, you’ll soon be hearing that we’re tacking on an extra second to the very end of June 30th, though the reason why is a bit more complex than the explanation you’ll be hearing.

It’s an error that comes around and is repeated about every 500 days or so, as we add a leap second to June 30th or December 31st.

‘The rotation of the Earth is slowing down,’ your local weather newscaster/website/anonymous person on Twitter will say. ‘This is why we need to add in an extra second every few years, to keep our accounting for time in sync.’

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The observed variation of the Earth’s rotation in milliseconds since the adoption of the leap second. Image credit: The United States Naval Observatory

Now, I know what you’re thinking.

Doesn’t adding a second once every 18-24 months or so add up to an awful lot? Are we really slowing down to the tune of (calculator apps out) over 11 minutes per millennium? What’s going on here?

Here’s what your weatherman won’t tell you.

The story of the second and the insertion of the modern day leap second is a curious case of modern astronomical history.

Universe Today recently covered the quirks of the Earth’s rotation on this past weekend’s June solstice. We are indeed slowing down, to the tune of an average of 2.3 milliseconds (thousands of a second) of a day per century in the current epoch, mostly due to the tidal braking action of the Moon. The advent of anthropogenic global warming will also incur variations in the Earth’s rotation rate as well.

Historically, the second was defined as 1/86,400th (60 seconds x 60 minutes x 24 hours) of a mean solar day. We’ve actually been on an astronomical standard of time of one sort or another for thousands of years, though it’s only been over the last two centuries that we’ve really needed—or could even reliably measure—time to an accuracy of less than a second. These early observations were made by astronomers using transit instruments as they watched stars ‘cross the wire’ in an eyepiece using nothing more sophisticated than a Mark-1 eyeball.

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A transit instrument on display at the Quito Observatory in Quito, Ecuador. Image credit: David Dickinson

The whole affair was addressed in 1956 by the International Committee for Weights and Measures, which defined what was known as the ephemeris, or astronomical second as a fraction—1/31,556,925.9747th to be precise—of the tropical year set at noon on January 1st 1900.

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Simon Newcomb. Image in the Public Domain

Now, this decision relied on measurements contained in Simon Newcomb’s 1895 book Tables of the Sun to describe the motion of the Earth. Extrapolating back, a day was exactly 86,400 modern seconds long… in 1820.

In the intervening 195 years, the modern day is now about an extra 1/500th (86,400.002) of an SI second long. In turn, the SI second was defined in 1967 as:

The duration of 9,192,631,770 periods of radiation corresponding to the transition between two hyperfine levels of the ground state of the Cesium-133 atom.

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An atomic clock at the Federal Office of Metrology in Bern, Switzerland. Image credit: Wikimedia Commons/Public Domain

Now, physicists love to have an SI definition that isn’t reliant on an artifact. In fact, the pesky holdout known as the kilogram is the last of the seven SI base units that is based on an object and not a constant that anyone can measure in a lab worldwide. Simply locking a second at 1/86,400th of a mean solar day would mean that the second itself was slowly lengthening, creating its own can of worms…

So the leap second came to be, as a compromise between UT1 (Astronomical observed time) and UTC (Coordinated Universal Time), which defines a day as being comprised of 86,400 SI seconds. These days, the United States Naval Observatory utilizes observations which include quasars, GPS satellites and laser ranging experiments left on the Moon by Apollo astronauts to measure UT1.

The difference between Universal and Terrestrial Time is often referred to as Delta T.

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An 1853 Universal Dial Plate depicting time worldwide before the adoption of Universal Time. Image credit: Wikimedia Commons/Public Domain image

The first leap second was inserted on June 30th 1972, and 25 leap seconds have been introduced up until the extra June 30th second next week.

But the Earth’s rotation isn’t actually slowing down a second every time we add one… this is the point most folks get wrong. Think of it this way: the modern Gregorian calendar inserts a leap day every four years to keep it in sync with the mean tropical year… but the length of the year itself doesn’t increase by a day every four years. Those fractions of a second per day just keep adding up until the difference between UT1 and UTC mounts towards one second, and the good folks at the International Earth Rotation Service  decide something must be done.

And don’t fear the leap second, though we’ve already seen many ‘Y2K redux’ cries already cropping up around the web. We do this every 18-24 months or so, and Skynet hasn’t become self-aware… or at least, not yet.

Of course, programmers hate the leap second, and much like the patchwork of daylight saving time and time zone rules, it causes a colossal headache to assure all of those exceptions and rules are accounted for. Consider, for example, how many transactions (emails, tweets, etc) fly around the globe every second. Many services such as Google instead apply what’s known as a ‘leap smear,’ which slices the leap second out into tinier micro-second sized bites.

With the current system in place, leap seconds will become ever more frequent as the Earth’s rotation continues to slow. There have been calls over the years to even do away with the astronomical standard for measuring time entirely, and go exclusively to the SI second and UTC. This would also create a curious situation of not only, say, throwing off local sunset and sunrise times, but users of GOTO telescope pointing systems would probably note errors within a few decades or so.

This coming November, The World Radiocommunication Conference being held in Geneva, Switzerland is looking to address the issue, though we suspect that, for now at least, the future of the leap second is secure… perhaps, if we did indeed go off the astronomical time standard for the first time in the history of modern human civilization, a leap hour might have to be instituted somewhere around oh say, 2600 AD.

What do you, the reader think? Should it be ‘down with the leap second,’ or should we keep our clocks in lock step with the cosmos?

Iridium NEXT Set to Begin Deployment This Year

An artist's conception of an Iridium-NEXT satellite in low Earth orbit. Credit: Iridium Communications Inc.

The skies, they are uh changin’…  I remember reading in Astronomy magazine waaaay back in the late 1990s (in those days, news was disseminated in actual paper magazines) about a hot new constellation of satellites that were said to flare in a predictable fashion.

This is the Iridium satellite constellation, a series of 66 active satellites and six in-orbit and nine ground spares. The ‘Iridium’ name comes from the element with atomic number 77 of the same name (the original project envisioned 77 satellites in low Earth orbit), and the satellites serve users with global satellite phone coverage.

A 'double Iridium flare' capture! Image credit: Mary Spicer
A ‘double Iridium flare’ capture! Image credit: Mary Spicer

Over the years, Iridium satellite flares have become a common sight in the night sky… but that may change soon.

The next generation of Iridium communications satellites begins launching later this year through 2017.

Known as Iridium-NEXT, the first launch is set for October of this year from Dombarovsky air base Russia atop a converted ICBM Dnepr rocket. The Dnepr can carry two satellites on each launch, and SpaceX has also recently agreed to deploy 70 satellites over the span of seven missions launching from Vandenberg Air Force Base in California later this year.

Both the initial Iridium satellites and Iridium NEXT are operated by Iridium Communications Incorporated. The original satellites were built by Motorola and Lockheed Martin, and the prime contract for Iridium NEXT construction went to Thales Alenia Space.

There are also several fascinating issues surrounding the history of the Iridium constellation, both past and present.

Originally fielded by Motorola in the 1990s, satellite phones were to be “the next big thing” until mobile phones took over. Conceived in the late 1980s, the concept of satellite phones was practically obsolete before the first Iridium satellite got off the ground. The high cost of satellite phone services assured they could never manage to compete with the explosive growth of the mobile phone industry, and satellite phones at best only found niche applications for remote operations worldwide.  Iridium Communications declared bankruptcy in 1999, and the $6 billion US dollar project was bought by a group of private investors for only $35 million dollars.

Airmen using an Iridium satellite phone in Antarctica. Image credit: Robert Tingle/USAF
Airmen using an Iridium satellite phone in Antarctica. Image credit: Robert Tingle/USAF

The original Iridium constellation employed a unique system of Inter-Satellite Links, enabling them to directly route signals from satellite to satellite. Iridium NEXT will use an innovative L-band phased array antenna, allowing for larger bandwidth and faster data transmission. The Iridium NEXT constellation is planned to eventually contain 81 satellites including spares, and the system will be much more robust and reliable.

The Iridium NEXT constellation will also face some stiff competition, as Google, SpaceX and OneWeb are also looking to get into the business of satellite Internet and communications. This will also place hundreds of new satellites—not to mention the growing flock of CubeSats—into an already very crowded region of low Earth orbit. The Iridium 33 satellite collision with the defunct Kosmos 2251 satellite in 2009 highlighted the ongoing issues surrounding space debris.

The company applied for a plan to deorbit the original Iridium constellation starting in 2017 as soon as the new Iridium NEXT satellites are in place.

Now, I know what the question of the hour is, as it’s one that we get frequently from other satellite spotters and lovers of artificial things that flash in the sky:

Will the Iridium NEXT satellites flare in manner similar to their predecessors?

Unfortunately, the prospects aren’t good. Missing on Iridium NEXT are the three large refrigerator-sized antennae which are the source of those brilliant -8 magnitude flares. And sure, while these flares weren’t Iridium’s sole mission purpose, they were sure fun to watch!

An 'Iridium classic...' note the trio of reflective antenae on the lower bus. Image credit: Iridium Communications inc.
An ‘Iridium classic…’ note the trio of reflective antennae on the lower bus. Image credit: Iridium Communications inc.

David Cubbage, Associate Director of NEXT Spacecraft Development and Satellite Production recently told Universe Today:

“It was very exciting when we first discovered that the Iridium Block 1 satellite vehicles (SVs) reflected the sunlight into a concentrated “flare” that could be viewed in the night sky.  The unique design of the Block 1 SV, with three highly reflective Main Mission Antennas (MMA) deployed at an angle from the SV body, is what caused that to happen.  For the Iridium NEXT constellation, the SVs will be built under a different design with a single MMA that faces the Earth — a design that requires fewer parts that do not need to be as reflective.  As a result, it will not likely produce the spectacular flares of the Block 1 design.”

But don’t despair. Though the two decade ‘Age of the Iridium flare’ may be coming to an end, lots of other satellites, including the Hubble Space Telescope, MetOp-A and B,  and the COSMO-SkyMed series of satellites can ‘slow flare’ on occasion. We recently saw something similar during a pass of the U.S. Air Force’s super-secret ATV-4 space plane currently carrying out its OTV-4 mission, suggesting that a large reflective solar panel may be currently deployed.

An Iridium flare through the constellations Orion and Lepus. Image credit: David Dickinson
An Iridium flare passing through the constellations Orion and Lepus. Image credit: David Dickinson

And though the path to commercial viability for satellite internet and communications is a tough one, we hope it does indeed take off soon… we personally love the idea of being able to stay connected from anywhere worldwide.

Be sure to catch those Iridium flares while you can… we’ll soon be telling future generations of amateur astronomers that we remember “back when…”

-Check out the chances for the next Iridium flare coming to a sky near you on Heavens-Above.