David Dickinson, Author at Universe Today

July 7, 2015December 23, 2015 by David Dickinson

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 224^th 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.

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 30^th 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.

July 6, 2015December 23, 2015 by David Dickinson

Catching Earth at Aphelion

Do you feel a little… distant today? The day after the 4^th 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 6^th again until 2018. The insertion of an extra day every leap year causes the date for Earth aphelion to slowly vary between July 3^rd and July 6^th in the current epoch.

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.

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.

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.

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 7^th, and we’ll be looking at the south pole of our Sun on September 9^th.

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 14^th. 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!

June 30, 2015December 23, 2015 by David Dickinson

See Pluto for Yourself Ahead of New Horizons’ Historic Encounter

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 14^th. 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.

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?

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 6^th 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.

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 +4^th magnitude pair Xi Sagittarii, making a great guidepost to spot the 14^th 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 1^st, using the nearby Full Moon as a guide:

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.

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.

Charon reaches greatest elongation 0.8” from Pluto once every three days. Shining at +16^th 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.

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 1^st, 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 14^th, 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.

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!

June 25, 2015October 17, 2016 by David Dickinson

A Brief History of Nukes in Space

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.

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 27^th, 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 29^th, 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.

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 18^th, 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.

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.

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.

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.

June 23, 2015September 16, 2016 by David Dickinson

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 30^th, 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 30^th or December 31^st.

‘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.’

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 1/86,400^th (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.

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 1^st 1900.

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 1/500^th (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.

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 1/86,400^th 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.

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

June 18, 2015December 23, 2015 by David Dickinson

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

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.

June 17, 2015December 23, 2015 by David Dickinson

Comet C/2013 US10 Catalina: A Preview for Act I

Comet C/2013 US10 Catalina imaged on June 22nd, 2013. Image credit and copyright: Efrain Morales

Live in (or planning on visiting) the southern hemisphere soon? A first time visitor to the inner solar system is ready to put on the first of a two part act starting this month, as Comet C/2013 US10 Catalina breaks +10^th magnitude and crosses southern hemisphere skies.

Though we’ve overdue for a this generation’s ‘great comet,’ we’ve had a steady stream of fine binocular comets in 2015, including 2014 Q2 Lovejoy, 2014 Q1 PanSTARRS, and 2015 G2 MASTER. US10 Catalina looks to follow this trend, topping out at just above naked eye visibility in late 2015 going into early 2016.

Discovered by the Catalina Sky Survey on Halloween 2013, the comet received its unusual ‘US10’ designation as it was initially thought to be an asteroid early on in a periodic six year orbit, until a longer observation arc was completed. This is not an unusual situation, as new objects are often lost in the Sun’s glare before their orbit can be refined.

Recent images of US10 Catalina from may 18th, 2015. Image credit and copyright: Joseph Brimacombe — Recent images of US10 Catalina from May 18th, 2015. Image credit and copyright: Joseph Brimacombe

We now know that US10 Catalina is on a million year long journey from the distant Oort Cloud. Most likely, it was disturbed by an unrecorded close stellar passage long ago. We say that such comets are dynamically new, and this passage will eject US10 Catalina from the solar system. The comet also has a highly inclined orbit tilted almost 149 degrees relative to the ecliptic, and was at +19^th magnitude and 7.7 AU from the Earth when it was discovered, suggesting an intrinsically bright comet.

Prospects for US10 Catalina currently favor latitude 35 degrees north southward in late June, though that’ll change radically as the comet makes the plunge south this summer. As of this writing, US10 Catalina was at +11 magnitude ‘with a bullet’ and currently sits in the constellation Sculptor at a declination -30 degrees in the southern sky.

Binoculars are our favorite tools for observing comets, as they’ve easy to sweep the skies with on our cometary quest. As with nebulae and deep sky objects, keep in mind that quoted magnitude for a comet is spread out over its apparent surface area, causing them to appear fainter than a star of the same magnitude.

Here’s a blow-by-blow for Act I for Comet C/2013 US10 Catalina over the next few months:

(Unless otherwise noted, we documented stellar passages below that are within 2 degrees of stars brighter than +5^th magnitude, and fine NGC deep sky objects brighter than +8^th magnitude)

July 1^st: May break binocular visibility, at +10^th magnitude.

July 6^th: Crosses into the constellation of Phoenix.

July 23^rd: Crosses into the constellation Grus.

July 25^th: Crosses into the constellation Tucana.

July 26^th: Passes the +4^th magnitude star Gamma Tucanae.

The path of Comet US10 Catalina as seen from 30 degrees south. Image credit: Created using Starry Night Education software

August 1^st: Reaches opposition.

August 2^nd: Passes the +4.5^th magnitude star Delta Tucanae.

August 4^th: Crosses into the constellation Indus.

August 6^th: Photo op: Passes 12 degrees from 47 Tucanae and the Small Magellanic Cloud.

August 8^th: Crosses into the constellation Pavo.

August 12^th: Passes the +4^th magnitude star Epsilon Pavonis.

August 14^th: Reaches its greatest declination south at almost -74 degrees.

August 15^th: Sits at 1.1 AU from the Earth.

August 17th: Crosses into the constellation Apus.

August 19^th: Passes 5 degrees from the +7.7 magnitude globular cluster NGC 6362.

August 22^nd: Crosses into the constellation Triangulum Australe and passes the +1.9 magnitude star Atria.

August 28^th: Passes the +2.8 magnitude star Beta Trianguli Australis.

August 29^th: Passes 3 degrees from the +5^th magnitude open cluster NGC 6025.

September 1^st: Crosses into the constellation Circinus

The passage of Comet US10 Catalina through the southern sky from mid-June through September 1st. Image credit: Starry Night Education software

From there, Comet US10 Catalina heads towards perihelion 0.8229 astronomical units from the Sun on November 15^th, before vaulting up into the northern hemisphere sky in the early dawn. Like Comet Q2 Lovejoy last winter, US10 Catalina should top out at around +4th magnitude or so as it glides across the constellation Ursa Major just after New Years.

And like many comets, the discriminating factor between a ‘great’ and ‘binocular comet’ this time around is simply a matter of orbital geometry. Had C/2013 US10 Catalina arrived at perihelion in the May time frame, it would’ve passed less than 0.2 AU (30 million kilometres) from the Earth!

But that’s cosmic irony for you. Keep in mind, with Comet US10 Catalina being a dynamically new first time visitor to the inner solar system, it may well up brighten ahead of expectations.

And there’s more to come… watch for Act II as we follow the continuing adventures of Comet C/2013 US10 Catalina this coming September!

June 9, 2015October 10, 2016 by David Dickinson

NGC 2419: Wayward Globular or the Milky Way’s Own?

NGC 2419 as imaged by the Hubble Space Telescope. Image credit: NASA/STScl

Turns out, we may not know our extragalactic neighbors as well as we thought.

One of the promises held forth with the purchase of our first GoTo telescope way back in the late 1990s was the ability to quickly and easily hunt down ever fainter deep sky fuzzies. No more juggling star charts and red headlamps, no more star-hopping. Heck, it was fun to just aim the scope at a favorable target field, hit ‘identify,’ and see what it turned up.

One of our more interesting ‘discoveries’ on these expeditions was NGC 2419, a globular cluster that my AstroMaster GoTo controller (featuring a 10K memory database!) triumphantly announced was an ‘Intergalactic Wanderer…’

Or is it? The case for NGC 2419 as a lonely globular wandering the cosmic void between the galaxies is a romantic and intriguing notion, and one you see repeated around the echo chamber that is the modern web. First observed by Sir William Herschel in 1788 and re-observed by his son John in 1833, the debate has swung back and forth as to whether NGC 2419 is a true globular or—as has been also suggested of the magnificent southern sky cluster Omega Centauri—the remnant of a dwarf spheroidal galaxy torn apart by our Milky Way. Lord Rosse also observed NGC 2419 with the 72-inch Leviathan of Parsonstown, and Harlow Shapley made a distance estimate of about 163,000 light years to NGC 2419 in 1922.

The relative distances of NGC 2419, the LMC, SMC and M31. Created by author using NASA graphics.

Today, we know that NGC 2419 is about 270,000 light years from the Sun, and about 300,000 light years from the core of our galaxy. Think of this: we actually see NGC 2419 as it appeared back in the middle of the Pleistocene Epoch, a time when modern homo sapiens were still the new hipsters on the evolutionary scene of life on Earth. What’s more, photometric studies over the past decade suggest there is a true gravitational link between NGC 2419 and the Milky Way. This would mean at its current distance, NGC 2419 would orbit our galaxy once every 3 billion years, about 75% the age of the Earth itself.

This hands down makes NGC 2419 the distant of the more than 150 globular clusters known to orbit our galaxy.

At an apparent magnitude of +9 and 6 arc minutes in size, NGC 2419 occupies an area of the sky otherwise devoid of globulars. Most tend to lie towards the galactic core as seen from our solar vantage point, and in fact, there are no bright globulars within 60 degrees of NGC 2419. The cluster sits 7 degrees north of the bright star Castor just across the border of Gemini in the constellation of the Lynx at Right Ascension 7 Hours, 38 minutes and 9 seconds and declination +38 degrees, 52 minutes and 55 seconds. Mid-January is the best time to spy NGC 2419 when it sits roughly opposite to the Sun , though June still sees the cluster 20 degrees above the western horizon at dusk before solar conjunction in mid-July.

We know globular clusters (say ‘globe’ -ular, not “glob’ -ular) are some of the most ancient structures in the universe due to their abundance of metal poor, first generation stars. In fact, it was a major mystery up until about a decade ago as to just how these clusters could appear to be older than the universe they inhabit. Today, we know that NGC 2419 is about 12.3 billion years old, and we’ve refined the age of the Universe as per data from the Planck spacecraft down to 13.73 (+/-0.12) billion years.

What would the skies look like from a planet inside NGC 2419? Well, in addition to the swarm of hundreds of thousands of nearby stars, the Milky Way galaxy itself would be a conspicuous object extending about 30 degrees across and shining at magnitude -2. Move NGC 2419 up to 10 parsecs distant, and it would rival the brightness of our First Quarter Moon and be visible in the daytime shining at magnitude -9.5.

And ironically, another 2007 study has suggested that the relative velocity of Large and Small Magellanic Clouds suggest that they may not be bound to our galaxy, but are instead first time visitors passing by.

And speaking of passing by, yet another study suggests that the Milky Way and the Andromeda galaxy set on a collision course billions of years hence may be in contact… now.

Mind not blown yet?

A 2014 study looking at extragalactic background light during a mission known as CIBER suggests that there may actually be more stars wandering the universe than are bound to galaxies…

But that’s enough paradigm-shifting for one day. Be sure to check out NGC 2419 and friends and remember, everything you learned about the universe as a kid, is likely to be false.

June 4, 2015December 23, 2015 by David Dickinson

Catch Jupiter Homing in on Venus Through June

Getting closer... Venus, Jupiter, the Moon and an iridium flare on the night of May 26th, 2015. Image credit and copyright: Chris Lyons

Are you ready to hear an upswing in queries from friends/family and/or strangers on Twitter asking “what are those two bright stars in the evening sky?”

It’s time to arm yourself with knowledge against the well-meaning astronomical onslaught. The month of June sees the celestial action heat up come sundown, as the planet Jupiter closes in on Venus in the dusk sky. Both are already brilliant beacons at magnitudes -1.5 and -4 respectively, and it’s always great to catch a meeting of the two brightest planets in the sky.

Looking west on the evening of June 5th from latitude 30 degrees north… Image credit: Stellarium

Be sure to follow Venus and Jupiter through June, as they close in on each other at a rate of over ½ a degree—that’s more than the diameter of a Full Moon—per day.

…and looking west on the evening of June 20th…

Venus starts June at 20 degrees from Jupiter on the first week of the month, and closes to less than 10 degrees separation by mid-month before going on to a final closing of less than one degree on the last day of the June. Th climax comes on July 1^st, when Venus and Jupiter sit just over 20’ apart—2/3rds the diameter of a Full Moon—on July 1^st at 3:00 UT or 11:00 PM EDT (on June 30^th). This translates to a closest approach on the evening of June 30^th for North America.

… and finally, looking westward on the evening of July 1st.

Venus starts the first week of June forming a straight line equally spaced with the bright stars Castor and Pollux in the astronomical constellation Gemini. On June 12-13, Venus actually nicks the Beehive cluster M44 in the constellation Cancer, a fine sight through binoculars.

Credit: Starry night Education software — The apparent paths of Venus versus Jupiter through the month of June. Credit: Starry Night Education software

Jupiter and Venus will then be joined by the Moon on the evening of June 20^th to form a skewed ‘smiley face’ emoticon pairing. Not only is the pairing of Venus and the crescent Moon represented on many national flags, But the evening of June 20^th will also be a great time to try your hand at daytime planet spotting before sunset, using the nearby crescent Moon as a guide.

The daytime view of Venus, the Moon and Jupiter of the evening of June 20th. Image Credit: Stellarium

The Moon will actually occult Venus three times in 2015: On July 19^th as seen from the South Pacific, on October 8^th as seen from Australia and New Zealand, and finally, on December 7^th as seen from North America in the daytime.

This conjunction of Venus and Jupiter occurs just across the border in the astronomical constellation of Leo. As Venus can always be found in the dawn or dusk sky, Jupiter must come to it, and conjunctions of the two planets occur roughly once every calendar year. A wider dawn pass of the two planets occurs this year on October 25^th, and in 2019 Jupiter again meets up with Venus twice, once in January and once in November. The last close conjunction of Venus and Jupiter occurred on August 18^th, 2014, and an extremely close (4’) conjunction of Venus and Jupiter is on tap for next year on August 27^th. Check out our nifty list of conjunctions of Venus and Jupiter for the remainder of the decade from last year’s post.

The view through the telescope on the evenings June 30^th and July 1^st will be stunning, as it’ll be possible to fit a 34% illuminated 32” crescent Venus and a 32” Jupiter plus its four major moons all in the same low power field of view. Jupiter sits 6 astronomical units (AU) from Earth, and Venus is 0.5 AU away on July 1^st.

30 FoV — Looking at Jupiter and Venus on July 1st using a 30 arc minute filed of view. Image credit: Starry Night Education Software

And just think of what the view from Jupiter would be like, as Venus and Earth sit less than 3 arc minutes apart:

Venus reaches solar conjunction this summer on August 15^th, and Jupiter follows suit on August 26^th. Both enter the field of view of the European Space Agency’s Solar Heliospheric Observatory (SOHO) LASCO C3 camera in mid-August, and are visible in the same for the remainder of the month before they pass into the dawn sky.

But beyond just inspiring inquires, close conjunctions of bright planets can actually raise political tensions as well. In 2012, Indian army sentries reported bright lights along India’s mountainous northern border with China. Thought to be reconnaissance spy drones, astronomers later identified the lights as Venus and Jupiter, seen on repeated evenings. We can see how they got there; back in the U.S. Air Force, we’ve seen Venus looking like a ‘mock F-16 fighter’ in the desert dusk sky as we recovered aircraft in Kuwait. Luckily, cooler heads prevailed during the India-China incident and no shots were exchanged, which could well have led to a wider conflict…

Remember: Scientific ignorance can be harmful, and astronomical knowledge of things in the sky can save lives!

June 3, 2015December 23, 2015 by David Dickinson

Solved: The Riddle of the Nova of 1670

This chart of the position of a nova (marked in red) that appeared in the year 1670 recorded by the astronomer Hevelius and was published by the Royal Society in England in their journal Philosophical Transactions. Image credit: The Royal Society

It is a 17^th century astronomical enigma that has persisted right up until modern times.

On June 20, 1670, a new star appeared in the evening sky that gave 17^th century astronomers pause. Eventually peaking out at +3^rdmagnitude, the ruddy new star in the modern day constellation of Vulpecula the Fox was visible for almost two years before vanishing from sight.

The exact nature of Nova Vulpeculae 1670 has always remained a mystery. The event has often been described as a classic nova… but if it was indeed a garden variety recurrent nova in our own Milky Way galaxy, then why haven’t we seen further outbursts? And why did it stay so bright, for so long?

Now, recent findings from the European Southern Observatory announced in the journal Nature this past March reveal something even more profound: the Nova of 1670 may have actually been the result of a rare stellar collision.

The remnant of the nova of 1670 seen with modern instruments and created from a combination of visible-light images from the Gemini telescope (blue), a submillimetre map showing the dust from the SMA (yellow) and finally a map of the molecular emission from APEX and the SMA (red). Image credit: ESO/T. Kaminski

“For many years, this object was thought to be a nova,” said ESO researcher Tomasz Kaminski of the Max Planck Institute for Radio Astronomy in Bonn Germany in a recent press release. “But the more it was studied, the less it looked like an ordinary nova—or indeed any other kind of exploding star.”

A typical nova occurs when material being siphoned off a companion star onto a white dwarf star during a process known as accretion builds up to a point where a runaway fusion reaction occurs.

ESO researchers used an instrument known as the Atacama Pathfinder EXperiment telescope (APEX) based on the high Chajnantor plateau in Chile to probe the remnant nebula from the 1670 event at submillimeter wavelengths. They found that the mass and isotopic composition of the resulting nebula was very uncharacteristic of a standard nova event.

So what was it?

A best fit model for the 1670 event is a rare stellar merger, with two main sequence stars smashing together and exploding in a grand head on collision, leaving the resulting nebula we see today. This event also resulted in a newly recognized category of star known as a “red transient” or luminous red nova.

Universe Today caught up with Mr. Kaminski recently on the subject of red transients and the amazing find:

“In our galaxy we are quite confident that four other objects were observed in outburst owing to a stellar merger: V838 Mon (famous for its spectacular light echo, eruption 2002), V4332 Sgr (eruption 1994), V1309 Sco (observed as an eclipsing binary before its outburst in 2008), OGLE-2002-BLG-360 (recent, but most similar to CK Vul eruption, 2002).Red transients are bright enough to be observed in nearby galaxies. Among them are M31 RV (first recognized “red variable”, eruption 1989), M85 OT2006 (eruption 2006), NGC300 OT2008, etc. Very recently, a few months ago, another one went off in the Andromeda Galaxy. With the increasing number of sky surveys we surely will discover many more.”

Though astronomers such as Voituret Anthelme, Johannes Hevelius and Giovanni Cassini all noted the 1670 nova, the nebula and suspected progenitor star wasn’t successfully recovered until 1981. Often cited as the oldest and faintest observation of a nova, Hevelius referred to the 1670 apparition as ‘nova sub capite Cygni,’ or a new star located below the head of the Swan near the star Albireo the constellation of Cygnus. Astronomers of the day also noted the crimson color of the new star, also fitting with the modern red transient hypothesis of two main sequence stars merging.

This map includes most of the stars that can be seen on a dark clear night with the naked eye. It shows the small constellation of Vulpecula (The Fox), which lies close to the more prominent constellation of Cygnus (The Swan) in the northern Milky Way. The location of the exploding star Nova Vul 1670 is marked with a red circle. — This chart shows the small constellation of Vulpecula (The Fox), and the location of the exploding star Nova Vul 1670 (red circle). Image credit: ESO/IAU/Sky & Telescope

“We observed CK Vul with the hope to find some submillimeter emission, but were completely surprised by how intense the emission was and how abundant in molecules the gas surrounding CK Vul is,” Kaminski told Universe Today. “Also, we have ongoing observational programs to search for objects similar to CK Vul.”

Follow up observations of the region were also carried out by the Submillimeter Array (SMA) and the Effelsberg radio telescope in Germany. The Nova of 1670 occurred about 1,800 light years distant along the galactic plane in the Orion-Cygnus arm of our Milky Way galaxy, of which the Sun and our solar system is a member. We actually had a naked eye classical nova just last year in roughly the same direction, which was visible in the adjacent constellation of Delphinus the Dolphin.

Of course, these garden variety novae are in a distinctly different class of events from supernovae, the likes of which have not been seen in our galaxy with the unaided eye in modern times since Kepler’s supernova in 1604.

The Atacama Pathfinder Experiment (APEX) telescope on the hunt. Image credit: ESO/ Babak Tafreshi

How often do stars collide? While rogue collisions of passing stars are extremely rare—remember, space is mostly nothing—the odds go up for closely orbiting binary pairs. What would really be amazing is to witness a modern day nearby red transient in the act of formation, though for now, we’ll have to console ourselves with studying the aftermath of the 1670 event as the next best thing.

“Recent estimates give one (merger) event per 2 years in the Milky Way galaxy,” Kaminski told Universe Today. “But we currently know so little about violent merger events that this number is very uncertain.”

Previously cited as a recurrent nova, the story of the 1670 event is a wonderful example of how new methods, combined with old observations, can be utilized to solve some of the lingering mysteries of modern astronomy.