David Dickinson, Author at Universe Today

September 22, 2015December 23, 2015 by David Dickinson

Remembering the Vela Incident

36 years ago today, a strange event was detected over the Southern Indian Ocean that remains controversial. On September 22^nd, 1979, an American Vela Hotel satellite detected an atmospheric explosion over the southern Indian Ocean near the Prince Edward Islands. The event occurred at 00:53 Universal Time on the pre-dawn nighttime side of the Earth. Vela’s gamma-ray and x-ray detectors rang out in surprise, along with its two radiometers (known as Bhangmeters) which also captured the event.

What was it?

Even today, the source of the Vela Incident remains a mystery. Designed to detect nuclear detonations worldwide and enforce the Partial Nuclear Test Ban Treaty, the Vela satellites operated for about ten years and were also famous for discovering evidence for extra-galactic gamma-ray bursts.

Vela-5B was the spacecraft from the series that detected the mysterious flash. A Titan-3C rocket launched Vela 5B (NORAD ID 1969-046E) on May 23^rd, 1969 from Vandenberg Air Force Base in California.

One of the first things scientists realized early on in the Cold War is that the Universe is a noisy place, and that this extends across the electromagnetic spectrum. Meteors, lightning, cosmic rays and even distant astrophysical sources can seem to mimic certain signature aspects of nuclear detonations. The ability to discern the difference between human-made and natural events became of paramount importance and remains so to this day: the hypothetical scenario of a Chelyabinsk-style event over two nuclear armed states already on a political hair-trigger edge is a case in point.

Over the years, the prime suspect for the Vela Incident has been a joint South African-Israeli nuclear test. The chief piece of evidence is the characteristic ‘double-flash’ recorded by Vela, characteristic of a nuclear detonation. Said event would’ve been an approximately 3 kiloton explosion; for context, the bomb dropped on Hiroshima had a 15 kiloton yield, and the Chelyabinsk event had an estimated equivalent explosive force of 500 kilotons. As a matter of fact, the Vela Incident became a topic of discussion on the day Chelyabinsk occurred, as we sought to verify the assertion of whether Chelyabinsk was ‘the biggest thing’ since the 1908 Tunguska event.

The Carter administration played down the Vela Incident at the time, though U.S. Air Force dispatched several WC-135B surveillance aircraft to the area, which turned up naught. Though detectors worldwide reported no increase of radioactive fallout, the ionospheric observatory at Arecibo did detect an atmospheric wave on the same morning as the event.

Israel ratified the Limited Test Ban Treaty in 1964. To date, Israel has never acknowledged that the test took place or the possession of nuclear weapons. Over the years, other suspect states have included Pakistan, France and India. Today, probably the only true final confirmation would come from someone stepping forward who was directly involved with the test, as it must have required the silence of a large number of personnel.

Was it a reentry or a bolide? Again, the signature double flash seen by the Vela satellite makes it unlikely. A micrometeoroid striking the spacecraft could have caused an anomalous detection known as a ‘zoo event,’ mimicking a nuclear test. Los Alamos researchers who have analyzed the event over the years remain convinced in the assertion that the 1979 Vela Incident had all the hallmark signatures of a nuclear test.

Shortly after the Cold War, the U.S. Department of Defense made much of its atmospheric monitoring data public, revealing that small meteorites strike us much more often than realized. Sadly, this type of continual monitoring accompanied by public data release has declined in recent years mostly due to budgetary concerns, though monitoring of the worldwide environment for nuclear testing via acoustic microphone on land, sea and eyes overhead in space continues.

And it’s frightening to think how close we came to a nuclear exchange during the Cold War on several occasions. For example: in 1960, an Distant Early Warning System based in Thule, Greenland mistook the rising Moon for a Soviet missile launch (!) The United States also conducted nuclear tests in space shortly before the Test Ban Treaty went into effect, including Starfish Prime:

The Vela Incident remains a fascinating chapter of the Cold War, one where space and the geopolitical intrigue overlap. Even today, parsing out the difference between human-made explosions and the cataclysmic events that pepper the cosmos remains a primary concern for the continued preservation of our civilization.

Tactical nuclear weapons from around the world seen on display at the Nuclear Science Museum in Albuquerque, New Mexico. Image credit: Dave Dickinson

-Listen to an interesting discussion on monitoring nuclear plants worldwide via neutrino emissions.

-For a fascinating in-depth discussion on the continued relevance of the Vela Incident, check out this recent article by The Bulletin of Atomic Scientists.

September 17, 2015December 23, 2015 by David Dickinson

Adventures With Starblinker

Observational astronomy is a study in patience. Since the introduction of the telescope over four centuries ago, steely-eyed observers have watched the skies for star-like or fuzzy points of light that appear to move. Astronomers of yore discovered asteroids, comets and even the occasional planet this way. Today, swiftly moving satellites have joined the fray. Still other ‘new stars’ turn out to be variables or novae.

Now, a new and exciting tool named Starblinker promises to place the prospect of discovery in the hands of the backyard observer.

The advent of photography in the late 19^th century upped the game… you’ll recall that Clyde Tombaugh used a blink comparator to discover Pluto from the Lowell Observatory in 1930. Clyde’s mechanical shutter device looked at glass plates in quick sequence. Starblinker takes this idea a step further, allowing astro-imagers to compare two images in rapid sequence in a similar ‘blink comparator’ fashion. You can even quickly compare an image against one online from, say, the SDSS catalog or Wikipedia or an old archival image. Starblinker even automatically orients and aligns the image for you. Heck, this would’ve been handy during a certain Virtual Star Party early last year hosted by Universe Today, making the tale of the ‘supernova in M82 that got away’ turn out very differently…

Often times, a great new program arises simply because astrophotographers find a need where no commercial offering exists. K3CCD Tools, Registax, Orbitron and Deep Sky Stacker are all great examples of DIY programs that filled a critical astronomy need which skilled users built themselves.

“I started to code the software after the mid of last month,” Starblinker creator Marco Lorrai told Universe Today. “I knew there was a plugin for MaximDL to do this job, but nothing for people like me that make photos just with a DSLR… I own a 250mm telescope, and my images go easily down to magnitude +18 so it is not impossible to find something interesting…”

Starblinker is a free application, and features a simple interface. Advanced observers have designed other programs to sift through video and stacks of images in the past, but we have yet to see one with such a straight-forward user interface with an eye toward quick and simple use in the field.

“The idea came to me taking my astrophotos: many images are so rich with stars, why not analyze (them) to check if something has changed?” Lorrai said. “I started to do this check manually, but the task was very thorny, because of differences in scale and rotation between the two images. Also, the ‘blinking’ was done loading two alternating windows containing two different images… not the best! This task could be simplified if someone already has a large set of images for comparison with one old image (taken) with the same instrument… a better method is needed to do this check, and then I started to code Starblinker.”

Why Starblinker

I can see a few immediate applications for Starblinker: possible capture of comets, asteroids, and novae or extragalactic supernovae, to name a few. You can also note the variability of stars in subsequent images. Take images over the span of years, and you might even be able to tease out the proper motion of nearby fast movers such as 61 Cygni, Kapteyn’s or even Barnard’s Star, or the orbits of double stars. Or how about capturing lunar impacts on the dark limb of the Moon? It may sound strange, but it has been done before… and hey, there’s a lunar eclipse coming right up on the night of September 27/28^th. Just be careful to watch for cosmic ray hits, hot pixels, satellite and meteor photobombs, all of which can foil a true discovery.

“A nice feature to add could be the support for FITS images and I think it could be very nice that… the program could retrieve automatically a comparison image, to help amateurs that are just starting (DSLR imaging).” Lorrai said.

And here is our challenge to you, the skilled observing public. What can YOU do with Starblinker? Surprise us… as is often the case with any hot new tech, ya just never know what weird and wonderful things folks will do with it once it’s released in the wild. Hey, discover a comet, and you could be immortalized with a celestial namesake… we promise that any future ‘Comet Dickinson’ will not be an extinction level event, just a good show…

Image credit: Mike Weasner/Cassiopeia observatory

Download Starblinker here.

Think you’ve discovered a comet? Nova? A new asteroid? Inbound alien invasion fleet? OK, that last one might be tweet worthy, otherwise, here’s a handy list of sites to get you started, with the checklist of protocols to report a discovery used by the pros:

–How to Report New Variable Star Discoveries to the American Association of Variable Star Observers (AAVSO)

-The Central Bureau of Astronomical Telegrams (they take emails, too!)

–How to Report a Comet by veteran comet hunter David Levy

–How to Report a Discovery via the International Astronomical Union

-And be sure to send in those Starblinker captures to Universe Today.

September 16, 2015December 23, 2015 by David Dickinson

10 Years of Haumea

Remember the neat tidy solar system of the 20^th century? As a child of the 1970s, we remember orderly planets, with circular orbits punctuated by the occasional asteroid or comet. They say ignorance is bliss, and the modern astronomical age of discovery in the 21^st century has since revealed a cosmic terra incognita in our solar backyard.

We’re talking about the 99% of the solar system by volume out beyond the orbit Neptune, occupied by Trans-Neptunian Objects (TNO), Plutinos (the object, not the drink), Kuiper Belt Objects (KBOs) and more.

136108 Haumea — one of the strangest worlds of them all — was introduced into the solar system menagerie about ten years ago. Discovered by Mike Brown (@Plutokiller extraordinaire) and team in late December 2004 from the Palomar Observatory, Haumea (say HOW-meh) received its formal name on September 17, 2008 along with its dwarf planet designation. Remember, astronomers discovered Haumea — like Xena turned Eris — before the series of decisions by the International Astronomical Union in 2006 which led to the Pluto is a planet/is a dwarf planet/ is a Plutoid roller coaster ride.

Image credit: JPL — The orbit of 136108 Haumea. Image credit: NASA/JPL

You’ve come a long way, little ice world, as New Horizons has finally given us a view of Pluto and friends just this past summer. Thankfully, most of us weren’t on Twitter yet back in 2006… heck, you can even read the original article by Universe Today from around the time of Eris and Haumea’s discovery (really: we’ve been around that long!)

It wasn’t long before Brown and team realized they had a strange discovery on their hands, as well as a lingering controversy. First, a team from the Sierra Nevada Observatory in Spain attempted to scoop the Palomar team concerning the discovery. It was later learned that the Sierra Nevada team was accessing the Caltech logs remotely, and looking at where the telescopes were hunting in the sky, and at what times. Though the Spanish team later conceded accessing the observation logs, they maintained that they were double-checking earlier observations of the subject object from 2003. Wherever you stand on the discovery hullabaloo, Mike Brown goes into depth on the modern astronomical controversy in his book How I Killed Pluto and Why it Had it Coming.

Haumea (the ‘egg’ to the lower left) versus ESA Herschel’s population of Trans-Neptunian Objects Image credit: ESA/Herschel/PACS/SPIRE

Haumea initially earned the nickname ‘Santa Claus’ due to its discovery near the Christmas holiday. Haumea derives its formal name from the Hawaiian goddess of childbirth. Likewise, the reindeer inspired moons Rudolph and Blitzen were later named Hi’aka and Namaka after daughters of Haumea in the Hawaiian pantheon. Brown at team discovered both moons shortly after Haumea itself.

A Bizarre World

Methone_PIA14633 — Saturn’s moon Methone… a possible ‘mini-twin’ of Haumea? Image credit: NASA/JPL-Caltech/Space Science Institute

The Bizzaro homeworld of Superman mythos has nothing on Haumea. OK, maybe it’s not a perfect cube — remember, nothing’s perfect on the Bizzaro planet either — but it does have a decidedly oblate egg shape. Haumea is a fast rotator, with a ‘day’ equal to about four hours. We know this due to periodic changes in brightness. Haumea also has a high albedo of about 80%, similar to freshly fallen snow.

Models suggest that Haumea is about twice as long as it is wide, with dimensions of 2,000 kilometres along its long axis, versus 1,000 kilometres through its poles. The presence of two tiny moons allows us to estimate its mass at about 33% of Pluto, and 6% that of Earth’s Moon. With such a fast rotation, Haumea must just be barely maintaining hydrostatic equilibrium, though it’s stretching the world to its max.

Evidence of an ancient collision, perhaps? It would be fascinating to see Haumea up close. Like Pluto, however, it’s distant, with an aphelion near 51.5 AU and a perihelion near 35 AU. Orbiting the Sun once every 284 years, Haumea just passed aphelion in 1992 about a decade prior to discovery, and perhaps the time to send a New Horizons-type mission past it would be near perihelion in 2134. Interestingly, Haumea is also in a near 7:12 resonance with Neptune, meaning it completes 7 orbits around the Sun to Neptune’s 12.

The outer solar system view from Haumea. Image credit: Starry Night Education Software

A Swift Sky

Astronomy from Haumea is literally dizzying to contemplate. First, prepare yourself for that four hour day: you would easily see the rotation of the sky — to the tune of an object rising and reaching the zenith in just an hour — moving in real time. Then there’s the two moons Namaka and Hi’iaka, in 18 and 50 day orbits, respectively… both would show discernible discs and phases courtesy of the Sun, which would currently present a 38” disk shining at magnitude -18 (still about 100 times brighter than a Full Moon). Looking for Earth? It’s an easy catch at magnitude +4.8 but never strays more than 1 degree from the Sun, twice the diameter of a Full Moon.

Haumea currently shines at magnitude +17 in the constellation Boötes. Theoretically, it’s within the grab of a large amateur telescope, though to our knowledge, no backyard observer has ever manage to nab it… perhaps this will change over the next century or so towards perihelion?

Scratch that… we’ve since learned that Mike Weasner did indeed nab Haumea in 2013 from his backyard Cassiopeia observatory near Oracle, Arizona:

Awesome!

The discovery of Haumea and friends is a fascinating tale of modern astronomy, and shows us just how strange the brave new worlds of the outer solar system are. Perhaps one day, human eyes will gaze at the bizarre skies of Haumea… though keeping a telescope tracking might be a true challenge!

September 15, 2015December 23, 2015 by David Dickinson

A Minor Lunar Standstill for 2015

Think you know the Moon? Whether you love our natural neighbor in space for the lunar and solar eclipses it provides, or you simply decide to ‘pack it in’ from deep sky observing on the weeks bookending Full phase — per chance to catch up on image processing — the Moon has provided humanity with a fine crash course in Celestial Mechanics 101.

Take the Moon’s path in the Fall of 2015 as a peculiar case in point. In fact, we’re nearing what’s known as a minor lunar standstill over the next lunation, the first of the 21^st century.

The term lunar standstill is kind of a misnomer. The Moon will continue in its orbit around the Earth like it always does. What’s interesting to note, however, is how shallow the apparent path of the Moon currently is with respect to the ecliptic this year. A technical lunar standstill – the point at which the Moon seems to reverse course from north to south and vice versa – occurs twice a lunation… but not all lunar standstills are created equal.

The approximately five degree tilt of the Moon’s path around the Earth with respect to the path of the Earth around the Sun assures that the Moon can actually appear anywhere from 23.5 degrees (the tilt of the Earth’s axis with respect to the ecliptic) plus five degrees above or below the celestial equator, or 28.5 degrees declination north to south.

Such a ‘hilly year’ happens once every 18.6 years, and last occurred in 2006, and won’t take place again until 2025. This orbital phenomenon also results in what’s known as a ‘long nights moon’ when the Full Moon nearest the winter solstice rides high in the sky near the spot the summer Sun occupied six months earlier, and will do so again six months hence.

To quote Game of Thrones: “Winter is coming,” indeed.

Such is the wacky orbit of the Moon. Unlike the majority of natural satellites in the solar system, the inclination of the Moon’s orbit is not fixed in relation to its host planet’s (in this case, the Earth’s) equator, but instead, to the plane of its path around the Sun, that imaginary line known as the ecliptic. Hence, we say the Moon’s path is either steep and ‘hilly’ near a major lunar standstill, or shallow and almost flat-lined, like this year. In between years are sometimes termed ‘ecliptic-like’ and happen between standstills once every 9.3 years.

Why are the nodes of the ecliptic changing? The chief culprit is the gravitational pull of the Sun, which drags the nodes opposite in the Moon’s direction of travel once around full circle every 18.6 years. To confound things even more, the Moon’s line of apsides (the imaginary line bisecting its orbit from apogee to perigee) is moving in the opposite direction and completes one revolution every 8.85 years.

This also means that the Moon can wander off the beaten trail of the zodiac constellations well worn by the classical planets. The Moon can actually transit 18 constellations: the 12 familiar zodiacal constellations, plus Orion, Ophiuchus, Sextans, Corvus, Auriga and Cetus.

This, along with the 26,000 plus year precession of the equinoxes, also means that the stars the Moon can occult along its path are slowly changing as well.

There’s lots of evidence to suggest that ancient astronomers knew something of the cycle of lunar standstills as well. The modern term comes from archaeologist Alexander Thom’s 1971 book Megalithic Lunar Observatories. There is evidence to suggest Bronze Age cultures in the United Kingdom took note of the changing path of the Moon. The famous ‘Sun dagger’ rock alignment of Fajada Butte in Chaco Canyon, New Mexico may have also doubled as a similar sort of calendar that not only marked the yearly solstices and equinoxes, but longer periods of the cycles of the Moon as well.

Knowing the gear clock tick of the heavens gave cultures an edge, allowing them to predict when to sow, reap, hunt and prepare for the onset of winter.

The 2015 minor lunar standstill also impacts this years’ Full Harvest Moon as well. Ordinarily on most years, the evening angle of the ecliptic versus the eastern horizon near the autumnal equinox conspires to make the Moon seem to ‘freeze’ in its nightly path, rising scant minutes later on successive evenings. This effect is most dramatic as seen from mid-northern latitudes in September on years around the major lunar standstill.

Not so in 2015. The Full Harvest Moon occurs on September 28^th at 2:50 UT (10:50 PM EDT on the evening of the 27^th) about four and half days after the autumnal equinox. As seen from latitude 40 degrees north, however, the Moon will rise nearly 40 minutes later each successive evening. Check out these Moonrise times as seen from the U.S. capital near 39 degrees north latitude:

Washington D.C.

Sept 25^th 5:28 PM

Sept 26^th 6:09 PM

Sept 27^th 6:49 PM

Sept 28^th: 7:29 PM

Sept 29^th: 8:11 PM

As you can see, the minor lunar standstill of 2015 ameliorates the usual impact of the Harvest Moon… though we do have the final total lunar eclipse of 2015 to compensate.

SOHO Nears 3,000 Comet Discoveries

A fine sungrazer nears its doom as seen via SOHOs LASCO C2 camera. Image credit: NASA/ESA/SOHO/NRLSungrazers

It’s a discovery that could come any day now.

The Solar Heliospheric Observatory spacecraft known as SOHO is set to cross the 3,000 comet discovery threshold this month. Launched atop an Atlas II rocket on December 2^nd, 1995, SOHO is a joint NASA/ESA mission, and has observed the Sun now for almost 20 years from the sunward L1 lagrange point. That fact is amazing enough, as SOHO has already followed the goings on of our tempestuous host star for nearly two full solar cycles.

And though SOHO wasn’t initially designed as a comet hunter extraordinaire, it has gone on to discover far more comets than anyone—human or robotic.

soho_photo7 — SOHO on Earth. Image credit: NASA/ESA/SOHO

The U.S. Naval Research Laboratory’s (NRL) sungrazer website lists the discovery count as 2,987 as of July 31, 2015, with more comets awaiting verification daily. “In the past, SOHO has often discovered as many as four or five comets in a single day,” Karl Battams, a solar scientist at the NRL told Universe Today. “Suffice to say, it really could be any day now, given how close we are to 3,000! I actually expected it to be a month ago, so I’m surprised it’s dragging out like this. Predicting comets is fraught with uncertainty!”

Part of what gives SOHO an edge is its LASCO (the Large Angle and Spectrometric Coronagraph) C2 and C3 coronagraphs. With a field of view about 15 degrees wide, the C3 imager monitors the faint corona of the Sun, while blocking its dazzling disk. The corona is the pearly white outer atmosphere of the Sun, and is about half as bright as a Full Moon. On Earth, we only see the corona briefly during a total solar eclipse. SOHO routinely sees sungrazing comets ‘photobomb’ the view of its LASCO C3 camera, sometimes to the tune of more than 200 a year.

Comet NEAT makes its way through the field of view of SOHO's LASCO C2 camera in 2003. Image credit: NASA/ESA/NRL/Sungrazers — Comet NEAT makes its way through the field of view of SOHO’s LASCO C2 camera in 2003. Image credit: NASA/ESA/NRL/Sungrazers

SOHO has rewritten the history of sungrazers. How far we’ve come: flashback to 1979, and less than a dozen sungrazers were known, one being the famous Comet Ikeya-Seki in 1965. Early space-based platforms such as Solwind and SMM sported early coronagraphs, and paved the way for SOHO. Think about that for a moment; a vast majority of the cometary population of the solar system was simply sliding by, unobserved from the ground. And this was only a generation ago.

Most of what SOHO sees are what’s termed as Kreutz group sungrazers. First theorized by astronomer Heinrich Kreutz in 1888, SOHO has given researchers the ability to classify and characterize the orbits of these doomed comets. These sungrazers nearly always incinerate during their perihelion passage. C/2011 W3 Lovejoy was a famous exception, which passed about 140,000 kilometers from the surface of the Sun on December 16^th, 2011 and went on to become a fine southern hemisphere comet.

“We knew little of the Kreutz population, other than that it seemed there were ‘a few’ objects on the Kreutz path,” Battams said. “I would say that probably when the Sungrazer Project was launched in late 2000 was the point at which the team realized that this was something more than just seeing an occasional comet.”

The typical track of a Kreutz-group comet. Click here for the full diagram of C2/C3 tracks throughout the year. Image Credit: NASA/ESA/SOHO

Kreutz comets also have seasons and predictable directions of approach along the ecliptic as seen from SOHO’s point of view. Some periodic comets, such as 96P Machholz, — which orbits the Sun once every six years — have become old friends. To date, SOHO has observed 96P Machholz four times.

Upping the Comet Hunting Game

But here’s the amazing second half of the tale. Legions of dedicated amateurs make these discoveries, patiently combing over daily images sent back by SOHO. In many ways, SOHO has grown up with the rise of the internet. Think about it: what was your internet surfing experience like way back in 1995? Karl Battams at NRL relays these discoveries to the Central Bureau for Astronomical Telegrams, the clearing house for potential comet discoveries. Founded in 1882 and based at Harvard College Observatory since 1965, CBAT actually received its last ‘telegram’ announcing the possible discovery that would become Comet Hale-Bopp in 1995.

The rise of automated surveys and satellites such as SOHO has definitely upped the game. To date, the all-time human champ amongst comet hunters is Robert H. McNaught, with the discovery of 44 long-period and 26 short-period comets.

And I think we can all remember where we were on U.S. Thanksgiving Day 2013, as SOHO gave us a front row seat to the demise of Comet ISON. It’s been a roller coaster ride for sure, and it’s hard to imagine a time now when we didn’t have SOHO as a daily resource. Heck, it’s just fun to watch planets transit the field of view of SOHO, as they move from the dawn to dusk sky and back again.

Looking at the "SOHO Bump" and the rise of automated comet hunters in the early 21st century. Image credit: Dave Dickinson — Looking at the “SOHO Bump” and the rise of automated comet hunters in the early 21st century. Image credit: Dave Dickinson

Comet hunting via SOHO is fun and easy to do, though yes, there are lots of eyeballs out there looking, so you have some pretty dedicated competition. Patience is key, and there’s also a dedicated message board describing the latest discoveries and known objects entering the field of view that have already been identified.

“What’s the future of SOHO? “December is SOHO’s 20^th anniversary, so that’s another milestone,” Battams said. “Beyond that, who knows? Engineers designed SOHO to operate for two years, and with no intention of comet discovery; it has lasted 20 years and re-written the history books for comets. It remains the only coronagraph we have along the Sun-Earth line, so for space weather forecasting it remains a unique and valuable asset.”

Congrats, and be sure to follow Karl Battam’s @SungrazerComets account on Twitter… number 3,000 could be discovered any day now!

September 8, 2015December 23, 2015 by David Dickinson

Kicking Off Eclipse Season: Our Guide to the September 13th Partial Solar Eclipse

The March 11th, 2013 partial solar eclipse as seen from Saida, Lebanon. Image credit and copyright: Ziad El Zaatari

Eclipse season 2 of 2 for 2015 is nigh this weekend, book-ended by a partial solar eclipse on September 13^th, and a total lunar eclipse on September 28^th.

First, the bad news. This weekend’s partial solar eclipse only touches down across the very southern tip of the African continent, Madagascar, a few remote stations in Antarctica, and a few wind-swept islands in the southern Indian Ocean. More than likely, the only views afforded humanity by Sunday’s partial solar eclipse will come out of South Africa, where the eclipse will be about 40% partial around 5:30 Universal Time (UT).

It’s the curious circumstances surrounding the September 13^th eclipse that conspire to hide it from the majority of humanity. First, the Moon reaches its ascending node along the plane of the ecliptic at 4:38 UT on Monday, September 14^th, nearly 22 hours after New phase. The umbra, or dark inner core of the shadow of Earth’s Moon ‘misses’ the Earth, passing about 380 kilometres or 230 miles above the South Pole. The outer penumbra of the Moon’s shadow just brushes the planet Earth, assuring a 79% maximum obscuration of the Sun over Antarctica around 6:55 UT.

Second, the Moon also reaches its most distant apogee for 2015 on September 14^th at 11:29 UT, 406,465 kilometers from the Earth. This is just over 28 hours after New, assuring that the umbra of the Moon falls 25,000 kilometres short of striking the Earth. The eclipse would be an annular one, even if we were in line to see it.

Observers will see the eclipse begin at sunrise over South Africa and the Kalahari Desert, great for photography and catching the eclipse along with foreground objects. Observers will need to follow solar observing safety protocols during all stages of the eclipse. A high value neutral density filter will bring out the silhouette of foreground objects while preserving the image of the partially eclipsed Sun, but remember that such a filter is for photographic use only.

P1, or the first contact of the Moon’s penumbra with the Earth occurs on the morning of the 13^th over the Angola/South Africa border at 4:41 UT, and the shadow footprint races across the southern Indian Ocean to depart Earth near the Antarctic coast (P4) at 09:06 UT.

New Moon occurs on September 13^th at 6:43 UT, marking the start of lunation 1147.

For saros buffs, this eclipse is a part of saros series 125 (member 54 of 73). Saros 125 started on February 4^th, 1060 and produced just four total eclipses in the late 13^th and early 14^th centuries. Mark your calendars, as this saros will end with a brief partial eclipse on April 8^th, 2358. The final total eclipse for this particular saros crossed over central Europe on July 16^th, 1330, when an observation by monks near Prague noted “the Sun was so greatly obscured that of its great body, only a small extremity like a three night old Moon was seen.”

Missing out on the eclipse? The good folks over at Slooh have got you covered, with a live webcast set to start at 4:30 UT/12:30 AM EDT.

Planning an ad-hoc webcast of your own from the eclipse viewing zone? Let us know!

There are also some chances to nab the eclipse from space via solar observing satellites in low Earth orbit:

The European Space Agency’s Proba-2 will see eclipses on the following passes – 5:01 UT (partial)/6:31 UT (annular) 8:00 UT (partial).

And JAXA’s Hinode mission will see the same at the following times: 5:56 UT (Partial)/7:46 UT (partial). Unfortunately, there are no good circumstances for an ISS transit this time around, as the ISS never passes far enough south in its orbit.

Looking for more? You can always participate in the exciting pastime of slender moonspotting within 24 hours post or prior to the New Moon worldwide. This feat of extreme visual athletics favors the morning of Saturday, September 12^th to sight the slim waning crescent Moon the morning before the eclipse, or the evenings of September 13^th and 14^th, to spy the waxing crescent Moon on the evenings after.

And this eclipse sets us up for the grand finale: the last total lunar eclipse of the ongoing tetrad on September 28^th, visible from North America and Europe. And yes, the Moon will be near perigee to boot… expect Super/Blood Moon wackiness to ensue.

Watch for our complete guide to the upcoming lunar eclipse, with observational tips, factoids, eclipse lunacy and more!

September 2, 2015December 23, 2015 by David Dickinson

A Fiery End for Kosmos 1315 Over Hawaii

Reentry of Kosmos-1315 captured by Joshua Lambus. Click here to see the full video.

A relic of the Cold War surprised beach-goers and Hawaiian islands residents Sunday night, as Kosmos-1315 reentered the Earth’s atmosphere in a dramatic display.

The reentry occurred right around 11:00 PM Sunday night on August 30^th local time (Hawaii is 10 hours behind Universal Time). Folks in the satellite tracking community had been following the predicted reentry for some time, which was projected for August 31^st at 10:56 UT +/- an hour. That puts the Hawaii sighting right at the beginning of the window.

“We were outside, about 11:00. I have a TV outside on our lanai (deck) and we had watched the 10:00 news, when we were just wrapping it up for the evening,” Hawaiian resident Lance Owens told Universe Today. “My wife sees this unreal thing in the sky. Our first description was it looked like someone dragging a “sparkler” across our sky like those old spaceship movies. It took at least a minute to get across our skyline. It appeared to be breaking up right in front of our eyes. I did not hear any boom, but the visuals were incredible!”

Kosmos 1315 (Sometimes listed as Cosmos 1315) was an electronic signal intelligence (ELINT) satellite launched from the Plesetsk Cosmodrome in the then Soviet Union on October 13^th, 1981. First developed in the late 1960s, Kosmos 1315 was a typical Tselina-D type component of the two-satellite Tselina ELINT system. Kosmos 1315 was launched atop a Vostok-2M rocket, the booster for which still remains in orbit today as NORAD ID 1981-103B. Kosmos 1315 was in a 533 x 574 km low Earth orbit.

Long-time satellite tracker Ted Molczan has been compiling a list of reentries that goes back to the dawn of the Space Age, and notes that this was the 256^th reentry sighting he’s confirmed in his cataloging effort.

“Objects launched by Russia account for 205 sightings or 80 percent, followed by the U.S., which accounts for 40 sightings or 16 percent. China, Europe and Japan account for the remaining 4 percent,” Molczan told Universe Today. “Considering the vast areas of the Earth that have been under-reported, the total number of reentries seen during the Space Age probably is between 500 and 1000, the large majority lost to history.”

This was a fine example of a classic reentry versus a typical fireball or meteor train. Satellites typically have a slower reentry velocity, and you can see this in several of the videos captured of the event. Most fireball captures come from security and dashboard cams (remember Chelyabinsk?) or cameras that are already up and running recording another event, such as a concert or a football game. The famous Peekskill meteor in 1992 was captured in the background during a high school football game. Remember, during Chelyabinsk, the very first images of the event were from dashcams; minutes later, after everyone rushed to aim their hastily deployed mobile phone cameras at the contrail, we got the recordings of the blast wave. The very fact that several folks grabbed their phones and managed to capture the reentry in progress on Sunday night (how fast can YOU have your phone out, camera running?) speaks to the slow, stately traverse typical of a satellite reentry.

The position of Kosmos-1315 at 9:17 UT. Image credit: Orbitron

…and folks on social media often try to get in on the hype during a breaking story involving a meteor train or fireball event. Feel free to try to be creative, but trust us, we’ve seen ‘em all. Some ‘meteor wrongs’ (to paraphrase Meteorite Man Geoff Notkin) that typically get recycled and advertised as new videos are: the reentries of Mir, Hayabasa, the aforementioned Peekskill event, Chelyabinsk, and screen grabs from the film Armageddon.

A typical Tselina-D style Kosmos series satellite. Image credit: Yuzhnoye Design

“As is common with reentries, a few people reported the phenomenon as a UFO. A couple of witnesses perceived the glowing fragments as individual craft of some kind,” Molczan told Universe Today. “Satellite orbits closely follow the curvature of the Earth’s surface, and they continue to do so as they begin their final descent during reentry. As reentry proceeds, velocity is lost due to drag, causing the descent to gradually become steeper, but to an observer, the motion appears to be nearly horizontal. By the time an object descends below about 30 kilometers, it will have lost nearly all of its forward velocity, and from there, any surviving fragments will descend almost vertically to the Earth.”

This final descent is similar to what’s known as ‘dark flight’ prior to a meteorite impact.

And though we usually get a few high interest reentries such as Phobos-Grunt or UARS every year, space junk is reentering worldwide weekly. The Aerospace Corp. keeps a running list of upcoming reentries, and the See-Sat-L message board is a great source of fast-breaking news.

It’s definitely a space junk shooting gallery out there. Keep those smartphones charged up and handy, and keep watching the skies!

September 1, 2015December 23, 2015 by David Dickinson

Watch the Moon Occult Aldebaran This Weekend

How about that perigee Full Moon this past weekend? Thus begins ‘Supermoon season’ for 2015, as this month’s Full Moon occurs even closer to perigee — less than an hour apart, in fact — on September 28^th, with the final total lunar eclipse of the ongoing tetrad to boot. Keep an eye on Luna this week, as it crosses into the early AM sky for several key dates with destiny just prior to the start of the second and final eclipse season for 2015.

The big event later this week is a passage of the waning gibbous Moon through the Hyades open cluster on the morning of Saturday, September 5^th, climaxing with a dramatic occultation of the bright star Aldebaran on the same morning. This is part of a series of 49 ongoing occultations of Aldebaran by the Moon, one for each lunation extending out to September 2018.

This weekend’s event will occur at moonrise under nighttime skies for the northeastern United States and the Canadian Maritimes, and near dawn and under daytime skies for observers in Western Europe and Northern Africa eastward. We observed an occultation of Aldebaran by the Moon under daytime skies from Alaska back in the late 1990s, and can attest that the star is indeed visible near the limb of the Moon in binoculars. A good deep blue sky is key to spotting +1 magnitude Aldebaran in the daytime.

London 711 AM — The view from London UK at 7:11 AM local. Image Credit: Starry Night Education software

During waning phase, the bright edge of the Moon is always leading, meaning Aldebaran will ingress (wink out) on the bright limb of the 52% illuminated Moon, and egress (reappear) along its dark limb.

Here are some key times for ingress/egress by location (all times quoted are local and incorporate daylight saving/summer time):

Washington D.C.

Moonrise: 11:53 PM

Ingress: N/A (before Moonrise)

Egress: 12:38 AM (altitude = 8 degrees)

Boston

Moonrise: 11:22 PM

Ingress 11:57 PM (altitude = 6 degrees)

Egress: 12:41 AM (altitude = 14 degrees)

Gander, Newfoundland

Moonrise: 11:26 PM

Ingress: 1:37 AM (altitude = 20 degrees)

Egress: 2:26 AM (altitude = 28 degrees)

London

Moonrise: 11:04 PM

Ingress: 5:50 AM (altitude = 53 degrees)

Sunrise: 6:18 AM

Egress: 7:07 AM (altitude = 54 degrees)

Paris

Moonrise: 12:02 AM

Ingress: 6:53 AM (altitude = 56 degrees)

Sunrise: 7:12 AM

Egress: 8:10 AM (altitude = 57 degrees)

Occultations of bright stars by the Moon are one of the few times besides a solar or lunar eclipse when you can actually discern the one degree per every two and half hours orbital motion of the Moon in real time. The Moon moves just a little more than its own apparent diameter as seen from the Earth every hour. This also sets us up for four more fine occultations of Aldebaran by the Moon alternating between Europe and North America on October 2^nd, October 29^th, November 26^th, and December 23^rd.

The bright stars Antares, Spica and Regulus also lie along the path of the Moon, which is inclined about five degrees relative to the ecliptic. A series of occultations of Regulus by the Moon begins in late 2016.

Fun fact: The Moon used to occult the bright star Pollux in the constellation Gemini until about 2100 years ago in 117 BC. The 26,000 year cycle known as the Precession of the Equinoxes has since carried the star out of the Moon’s path.

Observations of occultations — especially dramatic grazes spied right from the edge of the path — can be used to construct a profile of the lunar limb. A step-wise ‘wink out’ of a star during an occultation can also betray the existence of a close binary.

Recording an occultation of a star by the Moon is as easy as running video while shooting the Moon. The dark limb egress of Aldebaran will be much easier to record during the September 5^th event than the ingress of the star against the bright limb. I typically run video with a DLSR directly coupled to a Celestron 8” SCT telescope, with WWV radio running in the background for a precise audio timing of the event. Remember, the Moon will also be transiting the Hyades star cluster as well, covering and uncovering many fainter stars for observers worldwide around the same time frame.

Sept 5 5UT — The Last Quarter Moon versus Aldebaran and the Hyades on September 5th at ~5:00 UT. Image credit: Stellarium

Now for the ‘wow’ factor. The Moon is about 240,000 miles (400,000 km), or 1 1/4 light seconds distant. Aldebaran is 65 light years away, and said light left the star around 1950, only to have its light ‘rejected’ during the very last second by the craggy mountains along the lunar limb. And though Aldebaran appears to be a member of the Hyades, it isn’t, as the open cluster sits 153 light years from Earth.

And watch that Moon, as it then heads for a partial solar eclipse as seen from South Africa and the southern Indian Ocean on September 13th, and a total lunar eclipse visible from North America and Europe on September 28th.

Expect more to come, with complete guides to both on Universe Today!

August 26, 2015December 23, 2015 by David Dickinson

Ice Giants at Opposition

It seems as if the planets are fleeing the evening sky, just as the Fall school star party season is getting underway. Venus and Mars have entered the morning sky, and Jupiter reaches solar conjunction this week. Even glorious Saturn has passed eastern quadrature, and will soon depart evening skies.

Enter the ice giants, Uranus and Neptune. Both reach opposition for 2015 over the next two months, and the time to cross these two out solar system planets off your life list is now.

Aug 26 — Looking east at dusk in late August, as Uranus and Neptune rise. Image credit: Stellarium

First up, the planet Neptune reaches opposition next week in the constellation Aquarius on the night of August 31^st/September 1^st. Shining at magnitude +7.8, Neptune spends the remainder of 2015 about three degrees southwest of the +3.7 magnitude star Lambda Aquarii. It’s possible to spot Neptune using binoculars, and about x100 magnification in a telescope eyepiece will just resolve the blue-grey 2.3 arc second disc of the planet. Though Neptune has 14 known moons, just one, Triton, is within reach of a backyard telescope. Triton shines at magnitude +13.5 (comparable to Pluto), and orbits Neptune in a retrograde path once every 6 days, getting a maximum of 15” from the disk of the planet.

Nep Aug-Nov Triton aug 31 — The path of Neptune from late August through early November 2015. Inset: the position of Neptune’s moon Triton on the evening of August 31st: Image credit: Starry Night Education software

Uranus reaches opposition on October 11^th in the adjacent constellation Pisces. Keep an eye on Uranus, as it nears the bright +5.2 magnitude star Zeta Piscium towards the end on 2015. Shining at magnitude +5.7 with a 3.6 arc second disk, Uranus hovers just on the edge of naked eye visibility from a dark sky site.

Credit — Uranus, left of the eclipsed Moon last October. Image credit and copyright: A Nartist

It’ll be worth hunting for Uranus on the night of September 27^th/28^th, when it sits 15 degrees east of the eclipsed Moon. Uranus turned up in many images of last Fall’s total lunar eclipse. This will be the final total lunar eclipse of the current tetrad, and the Moon will occult Uranus the evening after for the South Atlantic. This is part of a series of 19 ongoing occultations of Uranus by the Moon worldwide, which started in August 2014, and end on December 20^th, 2015. After that, the Moon will move on and begin occulting Neptune next year in June through the end of 2017.

Occultation — The visibility footprint of the September 29th occultation of Uranus by the Moon. Image credit: Occult 4.0.

Uranus has 27 known moons, four of which (Oberon, Ariel, Umbriel and Titania) are visible in a large backyard telescope. See our extensive article on hunting the moons of the solar system for more info, and the JPL/PDS rings node for corkscrew finder charts.

Uranus aug-dec moons oct12 — The path of Uranus, from late August through early December 2015. Inset: the position of the moons of Uranus on the evening of October 12th. Image credit: Starry Night Education software

The two outermost worlds have a fascinating entwined history. William Herschel discovered Uranus on the night of March 13^th, 1781. We can be thankful that the proposed name ‘George’ after William’s benefactor King George the III didn’t stick. Herschel initially thought he’d discovered a comet, until he followed the slow motion of Uranus over several nights and realized that it had to be something large orbiting at a great distance from the Sun. Keep in mind, Uranus and Neptune both crept onto star charts unnoticed pre-1781. Galileo even famously sketched Neptune near Jupiter in 1612! Early astronomers simply considered the classical solar system out to Saturn as complete, end of story.

And the hunt was on. Astronomers soon realized that Uranus wasn’t staying put: something farther still from the Sun was tugging at its orbit. Mathematician Urbain Le Verrier predicted the position of the unseen planet, and on and on the night of September 23^rd, 1846, astronomers at the Berlin observatory spied Neptune.

In a way, those early 19^th century astronomers were lucky. Neptune and Uranus had just passed each other during a close encounter in 1821. Otherwise, Neptune might’ve remained hidden for several more decades. The synodic period of the two planets—that is, the time it takes the planets to return to opposition—differ by about 2-3 days. The very first documented conjunction of Neptune and Uranus occurred back in 1993, and won’t occur again until 2164. Heck, In 2010, Neptune completed its first orbit since discovery!

To date, only one mission, Voyager 2, has given us a close-up look at Uranus and Neptune during brief flybys. The final planetary encounter for Voyager 2 occurred in late August in 1989, when the spacecraft passed 4,800 kilometres (3,000 miles) above the north pole of Neptune.

All thoughts to ponder as you hunt for the outer ice giants. Sure, they’re tiny dots, but as with many nighttime treats, the ‘wow’ factor comes with just what you’re seeing, and the amazing story behind it.

August 24, 2015December 23, 2015 by David Dickinson

Astro-Challenge: Splitting 44 Boötis

44 Bootis from the Palomar Sky Survey. Image credit: The CDS/Aladin previewer

How good are your optics? Nothing can challenge the resolution of a large light bucket telescope, like attempting to split close double stars. This week, we’d like to highlight a curious triple star system that presents a supreme challenge over the next few years and will ‘keep on giving’ for decades to come.

The location of 44 Boötis in the constellation of the Herdsman. Image credit: Stellarium click image to enlarge

The star system in question is 44 Boötis, in the umlaut-adorned constellation of Boötes the herdsman. Boötes is still riding high to the west at dusk for northern hemisphere observers in late August, providing observers a chance to split the pair during prime-time viewing hours.

Sometimes also referred to as Iota Boötis, William Herschel first measured the angular separation of the pair in 1781, and F.G.W. Struve discovered the binary nature of 44 Boötis in 1832. Back then, the pair was headed towards a maximum apparent separation of 5 arc seconds in 1870. We call this point apastron. A fast forward to 2015 sees the situation reversed, as the pair currently sits about an arc second apart, and closing. 44 Boötis will pass a periastron of just 0.23” from the primary in 2020. Can you split the pair now? How ‘bout in 2016 onward? Can you recover the split, post 2020?

The physical parameters of the system are amazing. About 42 light years distant, 44 Boötis A is 1.05 times as massive as our Sun, and shines at magnitude +4.8. The B component is in a 210 year elliptical orbit with a semi-major axis of 49 AUs (for comparison, Pluto at aphelion is 49 AUs from the Sun), and is itself a curious contact spectroscopic binary about one magnitude fainter. Though you won’t be able to split the B-C pair with a backyard telescope, they betray their presence to professional instruments due to their intertwined spectra. 44 Boötis B and C have a combined mass of 1.5 times that of our Sun, and orbit each other once every 6.4 hours at a center-to-center distance of only 750,000 miles, or only 3 times the distance from Earth to the Moon:

That’s close enough that the pair shares a merging atmosphere. It’s a mystery as to just how these types of contact binary stars form, and it would be fascinating to see 44 Boötis up close. This fast spin along our line of sight also means that 44 Boötis B-C varies in brightness by about half a magnitude over a six hour span.

An artist’s conception of the B-C pair of the 44 Boötis system, using data from the Chandra X-ray observatory. Image credit: NASA/CXC/M.Weiss

Though the visual 44 Boötis A-B pair doesn’t quite have an orbital period that the average humanoid could expect to live through, beginning amateur astronomers can watch as the pair once again heads towards a wide an easy 5” split during apastron around 2080.

Collimation, or the near-perfect alignment of optics, is key to the splitting close binaries, and also serves as a good test of a telescope and the stability of the atmosphere. A well-collimated scope will display stars with sharp round Airy disks, looking like luminescent circular ripples in a pond. We call the lower boundary to splitting double stars the Dawes Limit, and on most nights, atmospheric seeing will limit this to about an arc second.

But there’s another method that you can use to ‘split’ doubles closer than an arc second, known as interferometry. This relies on observing the star by use of a filtering mask with two slits that vary in distance across the aperture of the scope. When the mask is rotated to the appropriate position angle and the slits are adjusted properly, the ‘fringes’ of the star snap into focus. A formula utilizing the slit separation can then calculate the separation of the close binary pair. This method works with stars that are A). Closer than 1” separation, and B). Vary by not more than a magnitude in brightness difference.

44 Boötis near periastron definitely qualifies. As of this writing, our ‘cardboard interferometer’ is still very much a work in progress. We could envision a more complex version of this rig mechanized, complete with video analysis. Hey, if nothing else, it really draws stares from fellow amateur astronomers…

We promise to delve into the exciting realm of backyard cardboard interferometry once we’ve worked all of the bugs out. In the meantime, be sure to regale us with your tales of tragedy and triumph observing 44 Boötis. Revisiting double stars can pose a life-long pursuit!

– Be sure to check out another double star challenge from Universe Today, with the hunt for Sirius B.