On the Road to One Thousand Exoplanets

Planets everywhere. So where are all the aliens? Credit: ESO/M. Kornmesser

A quiet milestone in modern astronomy may soon come to pass.  As of today, The Extrasolar Planets Encyclopedia lists a current tally of 998 extrasolar planets across 759 planetary systems. And although various tabulations differ slightly, very soon we should be living in an era where over one thousand exoplanets are known.

The history of exoplanet discovery has paralleled the course of the modern age of astronomy. It’s strange to think that a generation has already grown up over the past two decades in a world where knowledge of extrasolar planets is a given. I remember hearing of the promise of such detections growing up in the 1970’s, as astronomers put the odds at detection of planets beyond our solar system in our lifetime at around 50%.

A "Periodic Table of Exoplanets" Credit: PHL @ UPR Arecibo.
A “Periodic Table of Exoplanets” Credit: PHL @ UPR Arecibo.

Sure, there were plenty of false positives long before the first true discovery was made. 70 Ophiuchi was the site of many claims, starting with that of W.S. Jacob of the Madras Observatory way back in 1855. The high proper motion exhibited by Barnard’s Star at six light years distant was also highly scrutinized throughout the 20th century for claims of an unseen companion causing it to wobble. Ironically, Barnard’s Star still hasn’t made it into the pantheon of stars boasting planetary worlds.

A portrait of the HR8799 planetary system as imaged by the Hale Telescope. (Credit: NASA/JPL-Caltech/Palomar Observatory).
A portrait of the HR8799 planetary system as imaged by the Hale Telescope. (Credit: NASA/JPL-Caltech/Palomar Observatory).

But the first verified claim of an exoplanetary system came from a bizarre and unexpected source: a pulsar known as PSR B1257+12, which was discovered to host two worlds in 1992. This was followed by the first discovery of a world orbiting a main sequence star, 51 Pegasi in 1994. I still remember getting my hands on the latest issue of Astronomy magazine— we got our news, often months later, from actual paper magazines in those days —announcing “Planet Discovered!” on the cover.

Most methods and techniques used to discover exoplanets rely on either radial velocity or dips in the light output of a star from a transiting world. Both have their utility and drawbacks. Radial velocity looks for shifts in the star’s spectra as an unseen companion tugs it around a common center of mass. Though effective, it can only place a lower limit on the planet’s mass… and it’s biased towards worlds in short orbits. This is one reason that “hot Jupiters” have dominated the early exoplanet catalog: we hadn’t been looking for all that long.

Another method famously employed by surveys such as the Kepler space telescope is the transit detection method. This allows a much more refined estimate of a planet’s mass and orbit, assuming it transits the disk of its host star as seen from our Earthly vantage point in the first place, which most don’t.

A size comparision of exoplanets versus composition. (Credit: Marc Kuchner/NASA/GSFC).
A size comparision of exoplanets versus composition. (Credit: Marc Kuchner/NASA/GSFC).

Direct detection via occulting the host star is also coming of age. One of the first exoplanets directly imaged was Fomalhaut b, which can be seen changing positions in its orbit from 2004 to 2006.

Gravitational microlensing has also bared planetary fruit, with surveys such as MOA (Microlensing Observations in Astrophysics) and OGLE (the Optical Gravitational Lensing Experiment) catching brief lensing events as an unseen body passes in front of a background star. Distant free-ranging rogue planets can only be detected via this method.

More exotic techniques also exist, such as relativistic beaming (sounding like something out of Star Trek). Other methods include searches for tiny light variations as an illuminated planet orbits its host star, deformities caused by ellipsoidal variations as massive planets orbit a star, and infrared detections of circumstellar disks. We’re always amazed at the wealth of data that can be teased out of a few dim photons of light.

A scatter plot of exoplanet discoveries as of 2010 mass versus semi-major axis. Select exoplanets are labeled. A majority were detected via radial velocity (blue) and the transiting method (green). The remainder were detected by other methods (click here for a full discription). Graph in the Public Domain.
A scatter plot of exoplanet discoveries as of 2010 displaying mass versus semi-major axis. Select exoplanets are labeled. A majority were detected via radial velocity (blue) and the transiting method (green). The remainder were detected by other methods (click here for a full description). Graph in the Public Domain.

Universe Today has grown up with exoplanet science, from reporting on the hottest, fastest, and other notable “firsts”. A bizarre menagerie of worlds are now known, many of which defy the imagination of science fiction writers of yore. Want a world made of diamond, or one where it rains glass? There’s now an “exoplanet for that”.

Exoplanet news has almost gone from the incredible to the routine, as Tatooine-like worlds orbiting binary stars and systems with worlds in bizarre resonances are announced with increasing frequency.

Exoplanet surveys also have a capacity to peg down that key fp factor in the famous Drake equation, which asks us “what fraction of stars have planets”. It’s been long suspected that stars with planets are the rule rather than the exception, and we’re just now getting hard data to back that assertion up.

Missions, such as NASA’s Kepler space telescope and CNES/ESA CoRoT space telescope have swollen the ranks of extrasolar worlds. Kepler recently ended its career staring off in the direction of the constellations Cygnus, Hercules and Lyra and still has over 3,200 detections awaiting confirmation.

Exoplanet discoveries by year as of October 2013, color coded by method. Blue=radial velocity, Green=transiting, Yellow=timing, Red=direct imaging, Orange=microlensing
Exoplanet discoveries by year as of October 2013, color coded by method. Blue=radial velocity, Green=transiting, Yellow=timing, Red=direct imaging, Orange=microlensing

But is a given world Earthlike, or just Earth-sized? That’s the Holy Grail of modern exoplanet detection: an Earth-sized world orbiting in a star’s habitable zone. We’re cautious every time the latest “Earth-twin” makes its way into the headlines. From the perspective of an intergalactic astronomer, Venus in our own solar system might appear to fit the bill, though I wouldn’t bank the construction of an interstellar ark on it and head there just yet.

Exoplanet science has definitely come of age, allowing us to finally begin characterization of solar systems and give us some insight into solar system formation.

But perhaps what will be the most enduring legacy is what the discovery of extrasolar planets tells us about ourselves. How common (or rare) is the Earth? How typical is the story of our solar system? If the “first 1,000” are any indication, we strongly suspect that terrestrial planets come in enough distinct varieties or ”flavors” to make Baskin Robbins envious.

And the future of exoplanet science looks bright indeed. One proposed mission, known as the Fast INfrared Exoplanet Spectroscopy Survey Explorer, or FINESSE, would target exoplanet atmospheres, if given the go ahead for a 2017 launch. Another proposal, known as the Wide Field Infrared Survey Telescope, or WFIRST, would search for microlensing events starting in 2023. A mission that scientists would love to fly that always seems to be shelved is known as the Terrestrial Planet Finder.

But the exoplanet hunting mission that’s closest to launch is the Transiting Exoplanet Survey Satellite, or TESS. Unlike Kepler, which stares at a single patch of sky, TESS will be an all-sky survey looking at a half million stars.

We’re also just approaching an era where spectroscopy may allow us to detect exomoons and the chemistry taking place on these far off exoworlds. An example of an exciting discovery would be the detection of a chemical such as chlorophyll, a chemical that we know on Earth only exists as the result of life. But what a tantalizing discovery a blip on a graph would be, when what we humans really want to see is the vista of those far-flung alien forests!

Such is the exciting era we live in. Congratulations, humanity, on detecting 1,000 exoplanets… here’s to a thousand more!

This Week’s Penumbral Lunar Eclipse and the Astronomy of Columbus

(Photo by Author)

You can always count on an eclipse to get you out of a delicate situation. Today is Columbus Day in the United States and Thanksgiving north of the border in Canada. Later this week also marks the start of the second eclipse season for 2013. Today, we thought we’d take a look at the circumstances for the first eclipse of the season kicking off this coming Friday night, October 18, as well as the fascinating role that eclipses played in the life and times of Christopher Columbus.

Friday’s event is a penumbral lunar eclipse, meaning that the Full Moon will only pass through the outer bright rim of the Earth’s shadow. Such events are subtle affairs, as opposed to total and partial lunar eclipses, which occur when the Moon enters the dark inner core, or umbra, of the Earth’s shadow. Still, you may just be able to notice a slight dusky shading on the lower southern limb of the Moon as it flirts with the umbra, barely missing it around the time of central eclipse at 23:51 Universal Time/ 7:51 PM Eastern Daylight Saving Time. Friday night’s penumbral is 3 hours and 59 minutes in duration, and 76.5% of the disk of the Moon will be immersed in the penumbra at maximum eclipse.

eclipse
The visibility footprint and circumstances of this week’s penumbral lunar eclipse. (Credit: Fred Espenak/NASA/GSFC).

Key Events occurring on Friday, October 18th:

21:50UT/5:50PM EDT: 1st contact with the Earth’s shadow.

23:51UT/7:51PM EDT: Mid-eclipse.

01:49UT(Oct 19th)/9:49PM EDT: Last contact. Eclipse ends.

The eclipse will be underway at moonrise for North and South America and occur at moonset for central Asia— Africa and Europe will see the entire eclipse. Standing on Earth’s Moon, an observer on the nearside would see a partial solar eclipse.

A simulation of Friday's lunar eclipse, looking back from Earth Moon at mid-eclipse. (Credit:
A simulation of Friday’s lunar eclipse, looking back from Moon at mid-eclipse. (Wikimedia Commons graphic in the Public Domain).

This eclipse is the 3rd and final lunar eclipse of 2013, and the 5th overall. It’s also the first in a series of four descending node eclipses, including the total lunar eclipse of October 8th next year.   It’s also the 52nd eclipse of 72 in the lunar saros series 117, which started on April 3rd, 1094 and will end with a final lunar eclipse on May 15th, 2356. Saros 117 produced its last total lunar eclipse in 1815 and its final partial in 1941.

Though penumbrals are slight events, we’ve been able to notice an appreciable difference before, during and after the eclipse photographically:

Penumbral I
Can you spy the difference? The May 18th, 2002 penumbral lunar eclipse before (left) and during mid-eclipse (right). Photos by Author.

Be sure to use identical exposure settings to catch this effect. Locations where the Moon rides high in the sky also stand the best chance of imaging the faint penumbral shading, as the Moon will be above the discoloring effects of the thicker air mass low to the horizon.

The Moon reaches descending node along the ecliptic about 20 hours after the end of the eclipse, and reaches apogee just over six days later on October 25th. The October Full Moon is also known as the Hunter’s Moon, providing a bit of extra illumination on the Fall hunt.

And this sets us up for the second eclipse of the season the next time the Moon crosses an ecliptic node, a hybrid (annular-total) solar eclipse spanning the Atlantic and Africa on November 3rd. More to come on that big ticket event soon!

In Columbus’s day, the Moon was often used to get a rough fix of a ship’s longitude at sea. Columbus was especially intrigued with the idea of using lunar eclipses to determine longitude. If you can note the position of the Moon in the sky from one location versus a known longitude during an event— such as first contact of the Moon with the Earth’s umbra during an eclipse —you can gauge your relative longitude east or west of the point. The sky moves 15 degrees, or one hour of right ascension overhead as we rotate under it. One of the earliest records of this method comes to us from Ptolemy, who deduced Alexander the Great’s position 30 degrees (2 hours) east of Carthage during the lunar eclipse of September 20th, 331 B.C. Alexander noted that the eclipse began two hours after sunset from his locale, while in Carthage it was recorded that the eclipse began at sunset.

A Jacob's crossstaff, a simple tool for measuring angles in the sky. (Photo by Author).
A Jacob’s cross staff, a simple tool for measuring angles in the sky. (Charles Towne Landing Historic Site Museum, Photo by Author).

Columbus was a student of Ptolemy, and used this method during voyages to and from the New World during the lunar eclipses of September 14th, 1494 and February 29, 1504. Of course, such a method is only approximate. The umbra of the Earth often appears ragged and indistinct on the edge of the lunar disk at the start of an eclipse, making it tough to judge the actual beginning of an eclipse by more than ten of minutes or so. And remember, you’re often watching from the pitching deck of a ship to boot!

Another problem also plagued Columbus’s navigation efforts: he favored a smaller Earth than we now know is reality. Had he listened to another Greek astronomer by the name of Eratosthenes, he would’ve gotten his measurements pretty darned close.

An eclipse also saved Columbus’s butt on one occasion. The story goes that tensions had come to a head between the locals and Columbus’s crew while stranded on the island of Jamaica in 1504. Noting that a lunar eclipse was about to occur on March 1st  (the evening of February 29th for North America), Columbus told the local leader that the Moon would rise “inflamed with wrath,” as indeed it did that night, right on schedule. Columbus then made a great show of pretending to pray for heavenly intersession, after which the Moon returned to its rightful color.  This kept a conniving Columbus and his crew stocked in supplies until a rescue ship arrived in June of that year.

A depiction of the 1504 lunar eclipse from the 1879 text Astronomie Populare by Camille Flammarion.
A depiction of the 1504 lunar eclipse from the 1879 text Astronomie Populare by Camille Flammarion.

Be sure to check out this Friday’s penumbral eclipse, and amaze your friends with the prediction of the next total lunar eclipse which occurs on U.S. Tax Day next year on April 15th, 2014. Can you do a better job of predicting your longitude than Columbus?

Is Iran REALLY Planning on Sending a Cat Into Space?

Space Cat

“I’m going where?”

No, this isn’t The Onion… as a concerned consumer of all that is space news, you have indeed arrived at the cyber-doorstep of Universe Today.

I’ll admit though, that we did do a double take about a week back when a peculiar claim came our way via the Iranian Space Agency. Yes, there is an Iranian Space Agency, and it’s kind of frightening that they remain open for business while NASA is largely shutdown.

In mid-September, senior Iranian space program official Mohammad Ebrahimi issued a statement that Iran will attempt another bio-capsule launch “within 45 days”. The unwilling occupant: a Persian cat.

Apparently, a rabbit, a mouse, and another “Space Monkey” were also in the running. Iran’s space program is shrouded in secrecy, and most launches are only announced after they’ve been conducted. This is a convenient political strategy for hiding launch failures that harkens back to the early days of the Cold War. You’re right in guessing that the Iranian Space Agency probably won’t hold a Tweetup for this one. Many western analysts see the Iran’s space effort as a thinly veiled attempt to develop its long range ballistic missile technology. Along with Israel, Iran remains the only Middle Eastern country with the proven technology to conduct indigenous satellite launches.

Iran has stated that it hopes to put an astronaut in orbit by 2019.  The Pishgam (or “Pioneer” in Farsi) 2 bio-capsule launch could occur from a mobile launcher at Semnan Space Center as early as October 15th.  Satellite sleuths are also expecting activity at Semnan to pick up this month, with the possible launch of SharifSat atop a Safir 1-B rocket, and Iran’s Toulou satellite aboard a rumored new launch vehicle.

Iran successfully became a space-faring nation with the launch of its 27 kilogram Omid satellite on February 2nd, 2009. It isn’t immediately clear if the upcoming launch will be an orbital launch or a sub-orbital ballistic shot. If Pisgam-2 achieves orbit, said “Space Cat” would become the first feline to circle the Earth. If recovery is attempted —again, Iran is always nebulous as to their intentions— it would also be the first time they’ve achieved a return from orbit.

But is “Space Cat” even a reality?

Iran has been caught red-handed before playing a shell game with the media in terms of its space program. Earlier this year, “Monkey-gate” erupted, as before-and-after images from the Pisgam-1 bio-capsule suborbital launch clearly showed two different monkeys before and after the flight:

Monkey business? Iran displayed a decidedly different looking monkey before, during, and after launch earlier this year! (Credit: Iran News Agency).
Monkey business? Iran displayed a decidedly different looking monkey before, during, and after launch earlier this year! (Credit: Iran News Agency).

Clearly, Iran and other ‘Axis of Evil’ countries definitely need to sharpen their Photoshop, or at least their monkey-switching skills. Either said monkey launch never actually occurred, or (more likely), the unwilling Iranian space primate never survived the flight.

Perhaps this is why Iran decided on a feline occupant this time around, for possible ease of replacement?

PETA, the People for the Ethical Treatment of Animals, have also issued a statement concerning the impending launch of “Space Cat” by Iran, calling the action an “archaic experiment, a throwback to the primitive techniques of the 1950’s.”

NASA did entertain the idea of "Catronauts" early in the space program. (Credit: NASA).
NASA did entertain the idea of “Catronauts” early in the space program. (Credit: NASA).

The U.S. and the Soviet Union launched animals into space as a prelude to human spaceflight. On November 3rd, 1957, Laika the dog became the first animal to orbit the Earth. Laika perished is space due to overheating, as did several unfortunate monkeys that were launched on the first US ballistic tests.

Russia still conducts the occasional launch of animals into space, including the Bion-1M “Space Zoo” mission earlier this year. The Bion missions allow for scientists to dissect the specimens afterwards to study the effects of a month in zero-g, something you can’t do with humans.

And the U.S. did once fly cats in zero-g aboard its Convair C-131 “Vomit Comet” aircraft, as can be seen in this bizarre video:

But the first cat in space was actually launched by France atop a Veronique AGI sub-orbital rocket 50 years ago this month on October 18th, 1963. It would be ironic if Iran conducted it launch this month on the anniversary! The story goes the Felix, the original cat slated for the flight, escaped just prior to launch from the Sahara desert Hammaguir test site in Algeria, and was replaced by the “backup crew,” a female cat named Felicette. Felicette survived the 15 minute flight, reaching an apogee of 217 kilometres. A follow-up launch of a second cat six days later wasn’t so lucky.

Felicette (left) and Felix in publicity shots prior to launch.  Note the cranial electrode (!) implants.
Felicette (left) and Felix in publicity shots prior to launch. Note the cranial electrode (!) implants. (Credit: Marjorie-art Voila.net)

As always, Iran’s intentions for the future of its space program remain hidden. Their current launch capabilities remain limited, and are a far cry from being able to hoist a human into orbit anytime soon. If the launch of “Space Cat” does come to pass this month, it’ll be over protests from animal rights groups and the general public. Hey, didn’t the former Iranian president Mahmoud Ahmadinejad  say earlier this year after “Monkey-Gate” that he was willing to be “The first Iranian to be sacrificed by the scientists of my country and go into space” as the first Iranian astronaut? Is he really going to let Space Cat upstage him?

Felix and Felicette where also commemorated on several African postage stamps. (Credit:
Felix and Felicette where also commemorated on several African postage stamps. (Credit: Majorie-art.voila.net).

Read a great synopsis of the history of felines in space from Heather Archulletta @Pillownaut.

55 Years of NASA

55 Years of the National Aeronautics and Space Administration. Credit: NASA.

Today is NASA’s 55th birthday. Unfortunately, the celebration is muted due to the government shutdown, forcing much of NASA to shut down as well for the time being (see our overview of what’s still running at NASA and what’s not).

Before having to close the door (temporarily) today, NASA put together this nice graphic of the highlights of their accomplishments of the past 55 years, as well as what the hopes and plans are for the future.

The National Aeronautics and Space Administration began operating on October 1, 1958, managing the US’s burgeoning space exploration program. NASA replaced the National Advisory Committee for Aeronautics (NACA) agency, which began in 1915 to undertake and promote aeronautical research.

Now, NASA is in the midst of expanding commercial access to the International Space Station with the rendezvous of Orbital Science’s Cygnus capsule this week. While the ISS is still operating, and when full operations resume throughout NASA, they’ll continue work on exploring space, monitoring Earth, unlocking mysteries of our solar system and peering back into the beginnings of the Universe.

Our advice to you? If you are a US citizen, write your Congress-people and tell them how important you feel NASA is to the future of the nation and the world. And while you’re at it, tell them to get to work and do the job they were elected to do. Find out who represents you in the US Congress here.

More ISON Craziness: Tales of Popes, a Prophet and a Comet

Comet Halley as seen from the Kuiper Airborne Observatory in 1986. (Credit: NASA).

There’s an astronomical tall tale from the Middle Ages that seems to get recycled as factual every time a “great” comet rolls around. This week, we thought we’d look at a story that just won’t die, as well as a new twist in comet conspiracy that’s rolling around ye’ ole ‘Net.

We’ve debunked the current craziness surrounding ISON recently, but apparently our work isn’t finished! Comets seem to bring ‘em out of the woodwork. Today, we’ll discuss how that old prophet of doom Nostradamus may have “predicted” Comet ISON being part of the ‘end times,’ but first, let’s look at an astronomical tale of the past. Did a pope really excommunicate the most famous of all comets?

The mid-15th century was a trying time for Medieval Europe. The Black Death  had decimated the population of Europe a century prior, and the armies of the Ottoman Turks were advancing from the east. A bright comet could only bear ill will in the minds of the superstitious.

Pope Callixtus III: the ecommunicator of comets? (Credit:  Museo de la Catherdral de Valencia).
Pope Callixtus III: the excommunicator of comets? (Credit: Museo de la Cathedral de Valencia).

It was into this setting that Pope Callixtus III came into power in 1455. Callixtus was the first of two popes fielded by the Spanish Borgia family, which would later include his nephew Rodrigo who became Pope Alexander the VI, as depicted in the Showtime series The Borgias.

A fine the apparition of Halley’s Comet occurred in June and July 1456. Belgrade was to come under siege by the Ottoman Turks from July 4th to 22nd of that year, and the Fall of Constantinople on May 29th, 1453 to Mehmed II was still fresh on everyone’s mind.

Astronomical signs and omens were a hot topic as well. The partial lunar eclipse of May 22nd, 1453 was seen by many to have fulfilled prophecy that an eclipse would mark the fall of Constantinople. Of course, there are from 4 to 7 eclipses that can be seen on any given year, and lunar eclipses are visible from the entire moonward facing side of the Earth. It’s not too tough to find one to fit any given bill of gloom and doom.

Keep in mind, Halley’s Comet wasn’t even identified in the 15th century as the same comet that was returning once every 75.3 years. That fact wouldn’t be uncovered until Edmund Halley successfully predicted the return of the comet that now bears his name on Christmas Day 1758.

Halley’s Comet would’ve been a spectacular sight in the early summer of 1456, unfurling a tail that was said to have been 60 degrees long and spanning the constellations of Cancer and Leo. The brilliant comet would’ve been a conspicuous object for up to three hours after sunset, and it’s certain that observers around the Mediterranean, including a Rome-based pope would’ve seen it.

A depiction of the passage of Comet Halley through the constellations of Cancer & Leo in 1456. (Wikimedia Commons image in the Public Domain).
A depiction of the passage of Comet Halley through the constellations of Cancer & Leo in 1456. (Wikimedia Commons image in the Public Domain).

But did the pope actually excommunicate the comet to assuage the fears of the European populace of an invasion from the east?

While a quixotic story, the idea that a pope could’ve banned a heavenly body from salvation is apocryphal as best. The Papal Bull issued by Callixtus III on June 29th, 1456 called for prayers and penance and the ringing of church bells in light of the cruelty visited upon Eastern Europe by invaders from the east, but makes no mention of the comet. In fact, no primary source for the tale exists.

The story seems to have gotten its start with a historian named Platina, who wrote a biography of Callixtus III in 1471. Here we find the appearance of:

“A hairy reddish comet appearing for several days… Callixtus, in order to avert the wrath of God, ordered processions to be held…”

No out right excommunication per se, but the Pope and the comet were now forever linked in the eye of history.

The pitched Battle of Nandorfehervar during the 1456 Siege of Belgrade. (Wikimedia Commons scan in the Public Domain).
The pitched Battle of Nandorfehervar during the 1456 Siege of Belgrade. (Painting by Rubens in the Public Domain).

French mathematician and astronomer Pierre-Simon Laplace later gave the excommunication tale a boost in the late 18th century, and further embellishment followed from astronomer François Arago writing in 1832.

Keep in mind, these are historical works written down some years after the fact, often translated from Latin to French to English—ideas such as LaPlace’s “conjurer la comete” can easily come across as to “exorcise” or “excommunicate” a comet. Also, political satire of popes, both alive and dead, was common after the start of the Protestant Reformation. Halley’s Comet also made a fine apparition in 1835, and Arago may have been looking for something to captivate the public with in anticipation.

But although this story was debunked over a century ago, it still makes its rounds. None other than Carl Sagan repeated the excommunication story in his book Comet (sorry Carl!) although he also notes that the tale is apocryphal. Although the story of the excommunication of Halley’s Comet has been debunked time and again, a search of the Internet reveals about an even split between the credulous and the skeptical.

But there is also a current mythos being born around Comet ISON, Pope Francis and Nostradamus on ye ole web. For the most part, it has to do with — you guessed it — the end of the world. As per the usual, great comets are harbingers of catastrophic events. Combine the words of Nostradamus with the fact that 2013 has been hyped as “The Year of the Comet,” along with Pope Benedict’s unusual resignation, and that equals The End of Time.

If you don’t believe me, search of Comet/ISON/Pope and see what turns up. The gist of the prophecy cites a quatrain stating that:

 “the great star for seven days shall burn

So nakedly clear like two suns appearing

The large dog all night howling

While the great Pontiff shall change his territory.”  

Of course, the quatrains of Nostradamus, like all prophecies, are suitably vague enough that they could be interpreted almost in whatever fashion suits the reader. And again, we’re looking at the old 16th century French translated into modern English.

And like eclipses, there are a handful of comets every year. Most reach binocular visibility, and a few may go on to become visible to the naked eye. We’ve already had two comets that crossed this threshold this year, comet C/2011 L4 PanSTARRS and C/2012 F6 Lemmon.

Comet ISON as seen from the Hubble Space Telescope- no popes were harmed in the taking of this image! (credit: NASA/ESA/STScI/AURA).
Comet ISON as seen from the Hubble Space Telescope… no popes were harmed or forced to flee in the taking of this image. (credit: NASA/ESA/STScI/AURA).

And Comet ISON’s “greatness” is still very much in question. Its currently only at 12th magnitude and probably won’t be a naked eye object until at least early November. And it certainly won’t have the appearance of a second Sun!

I’ll leave it to the armchair predictors of comet doom to decipher what “the large dog howling” even means.  The chief logical fallacy evoked by the adherents of Nostradamus is what is known as retrofitting— it’s easy to take a cryptically predicted disaster and find an earthquake, eclipse, and yes, even a comet that falls roughly near the given date.

Of course, if ISON kicks into high gear, then we could really be in for a grand show, along with an accompanying upswing in comet hysteria. And thus, the tireless vigilance against comet-mania continues. Hey, we’re all after “link juice” and the almighty SEO, right? Of course, the real harm comes when something like the 1997 Heaven’s Gate mass suicide, inspired by rumors of an alien spacecraft following comet Hale-Bopp occurs.

Halleys March 9 2062
Halley’s Comet as seen on the morning of March 9th, 2062. (Created by the author using Starry Night Education software).

In short, enjoy the show as ISON approaches, read the online tales of popes and comets past… but as rapper and surreptitious promoter of skepticism Chuck D of Public Enemy implores us, don’t believe the hype.

Maybe we’ll finally be an enlightened and rational species when Halley’s Comet pays us a visit again starting  in the summer of 2061 through the spring of 2062!

-For an exhaustive look at the myth of the excommunication of Halley’s Comet, Read An Historical Examination of the Connection of Callixtus III with Halley’s Comet published in 1910.

-To see a (mostly) woo free version of the current Comet ISON versus Pope Francis mythos, (with quatrains) check out this article from news.com.au. Hey, we sift through woo so you don’t have to!

Huge Asteroid 324 Bamberga Makes a Return Visit to Earth’s Neighborhood on Friday the 13th

Starry Night

This week offers a fine chance to catch sight of a unique asteroid.

324 Bamberga reaches opposition this week in the constellation Pisces on (friggatriskaidekaphobics take note) Friday the 13th at 7AM EDT/11:00 Universal Time.

About 230 kilometres in size, 324 Bamberga reaches 0.81 astronomical units from the Earth this week. No other asteroid so large gets so close.

Discovered on February 25th, 1892 by Johann Palisa, 324 Bamberga only reaches a favorable opposition once every 22 years.

Shining at magnitude +8.1, 324 Bamberga is also one of the highest numbered asteroids visible with binoculars. Earth-crossing asteroids 433 Eros, which made a close pass last year, and 4179 Toutatis are two of the very few asteroids that possess a larger number designations that can regularly reach +10th magnitude.

Stellarium
Look east in mid-September about an hour after sunset. The inset covers the region that 324 Bamberga is currently traversing in the introductory graphic. (Created by the author using Stellarium).

So, why did it take so long for 324 Bamberga to be uncovered? One factor is its high orbital eccentricity of 0.34. This means that most of the oppositions of the asteroid aren’t favorable. 324 Bamberga orbits the Sun once every 4.395 years and only comes around to an opposition that lands near perihelion once every 22 Earth years. Perihelion this year occurs only 45 days after opposition on October 27th.

The resonance between 324 Bamberga and Earth is nearly five Earth orbits for every one circuit of the Sun for the asteroid and is offset by only 9 days, meaning that the 22 year window to see the asteroid will actually become less favorable in centuries to come. 324 Bamberga made its last favorable appearance on September 15th, 1991 and won’t surpass +10th magnitude again until September 2035.

Orbit
The orbit of 324 Bamberga. (Created using the JPL Small-Body Database Browser).

Observing asteroids requires patience and the ability to pick out a slowly moving object amidst the starry background. 324 Bamberga spends September west of the circlet of Pisces, drifting two degrees a week, or just over 17’ a day, to cross over into the constellation Pegasus in early October.

324 Bamberga will be moving too slow to pick up any motion in real time, but you can spy it by either sketching the field on successive nights or photographing the region and noting if the asteroid can be seen changing position against the background of fixed stars. Start hunting for 324 Bamberga tonight, as the Full Harvest Moon will be visiting Pisces later next week on the 19th.

Starry Night
A closeup of the path of 324 Bamberga for the week of September 10-17th. Decimal points for comparison stars are omitted. (Created by the author using Starry Night Education software).

324 Bamberga is also unique as the brightest C-type asteroid that is ever visible from Earth. The runner up in this category is asteroid 10 Hygiea, which can shine a full magnitude fainter at opposition.

It’s also remarkable that Palisa actually managed to discover 324 Bamberga while it was at 12th magnitude! Palisa was one of the most prolific visual hunters of asteroids ever, discovering 121 asteroids from 1874 to 1923. He accomplished this feat first with the use of a 6” refractor while based at the Austrian Naval Observatory in Pola (now the Croatian town of Pula) and later using the Vienna observatory’s 27” inch refractor.

The Great Refractor of the University of Vienna used to discover asteroid 324 Bamberga. (Credit: Prof. Franz Kerschbaum, Wikimedia Commons image under an Attribution-Share Alike 3.0 Unported license).
The Great Refractor of the University of Vienna used to discover asteroid 324 Bamberga. (Credit: Prof. Franz Kerschbaum, Wikimedia Commons image under an Attribution-Share Alike 3.0 Unported license).

324 Bamberga itself takes its name from the town of Bamberg in Bavaria, the site of the 1896 meeting of the Astronomische Gesellschraft.

An occultation of a star by 324 Bamberga on December 8th, 1987 allowed astronomers to pin down its approximate size. Searches have also been carried out during occultations for any possible moons of this asteroid, though thus far, none have been discovered.

It’s interesting to note that 324 Bamberga will also actually occult the star 2UCAC 3361042 tonight in the early morning hours at 8:59-9:10 UT for observers spanning a path from Florida to Oregon. The magnitude drop will, however, be very slight, as the star is actually 3 full magnitudes fainter than the asteroid itself. Dave Gee caught a fine occultation of a 7.4 magnitude star in the constellation Corvus by 324 Bamberga in 2007.

There’s also something special about this time of year and the region that 324 Bamberga is crossing. More visual discoveries of asteroids have been historically made in the month of September than any other calendar month. In fact, 344 of the first 1,940 numbered asteroids were found in September, more than twice the average. Palisa’s own track record bears this out, though 324 Bamberga was discovered in February.

One of the primary reasons for a September surge in discoveries is viewing direction. Astronomers of yore typically hunted for asteroids approaching opposition in the anti-sunward direction, which in September lies in the relatively star poor fields of Pisces.  In December and June —the months with the lowest numbers of visual discoveries at only 75 and 65 for the “first 1,940” respectively —the anti-sunward point lies in the star-rich regions of Sagittarius and Gemini. And by the way, the meteor that exploded over the city of Chelyabinsk on February 15th was sneaking up on the Earth from the sunward direction.

Be sure to catch a glimpse of this unique asteroid through either binoculars or a telescope over the coming weeks. The next chance to observe 324 Bamberga won’t roll around again until September 2035… it’ll be great to compare notes of the 2013 apparition on that far off date!

How to See Planet Neptune: Our Guide to Its 2013 Opposition

Neptune and its large moon Triton as seen by Voyager 2 on August 28th, 1989. (Credit: NASA).

If you do your own stargazing or participate in our Sunday night Virtual Star Parties, you’ve probably noticed we’re starting to lose planetary targets in the night-time sky. August and September of this year sees Venus and Saturn to the west at dusk, with the planets Mars and Jupiter adorning the eastern dawn sky just hours before sunrise.

That means there is now a good span of the night that none of the classic naked eye planets are above the horizon. But the good news is, with a little persistence, YOU can spy the outermost planet in our solar system in the coming weeks: the elusive Neptune. (Sorry, Pluto!)

A wide field view of Aquarius with Neptune's present position in late August/early September. (Created by the author i Stellarium).
A wide field view of Aquarius, with Neptune’s present position marked for late August/early September. (Created by the author in Stellarium; click on all star charts to enlarge).

The planet Neptune reaches opposition late this month in the constellation Aquarius on August 27th at 01:00 UT (9:00 PM EDT on the 26th). This means that it will rise to the east as the Sun sets to the west and will remain above the local horizon for the entire night.

If you’ve never caught sight of Neptune, these next few weeks are a great time to try. The Moon passes 6° north of the planet’s location this week on August 21st, just 10 hours after reaching Full.

neptune on the night of Opposition using a 4.4 degree field of view. (Created by the author using Stellarium).
Neptune on the night of Opposition using a 4.4 degree field of view. Magnitudes for nearby guide stars are given in red. (Created by the author using Stellarium).

Shining at magnitude +7.8, Neptune is an easy catch with binoculars from a dark sky site. Even in a large telescope, Neptune appears as a tiny blue dot, almost looking like a dim planetary nebula that refuses to come to a sharp focus. Visually, Neptune is only 2.3” across at opposition; you could stack 782 Neptunes across the breadth of the Full Moon!

It’s sobering to think that Neptune only just returned in 2011 to the position of its original discovery back in 1846. The calculation of Neptune’s position by Urbain Le Verrier was a triumph for Newtonian mechanics, a moment where the science of astronomy began to demonstrate its predictive power.

Astronomers knew of the existence of an unseen body due to the perturbations of the planet Uranus, which was discovered surreptitiously by William Herschel 65 years earlier. Using Le Verrier’s calculations, Johann Galle and Heinrich d’Arrest spied the planet on the night of September 23rd, 1846 using the Berlin observatory’s 9.6” refractor. Neptune was within a degree of the position described in Le Verrier’s prediction.

Neptune orbits the Sun once every 164.8 years, and comes back into opposition once every successive calendar year about 2 days later than the last. Those observers of yore were lucky that Neptune and Uranus experienced a close and undocumented conjunction in 1821; otherwise, Neptune may have gone undetected for a much longer span of time. And ironically, Galileo sketched the motion of Neptune near Jupiter in 1612 and 1613, but failed to identify it as a planet!

The motion of Neptune through Aquarius through late August into September. (Starry Night)
The motion of Neptune through Aquarius through late August into September. (Graphic created by author; courtesy of  Starry Night Education).

Neptune descended through the ecliptic in 2003 and won’t reach its southernmost point below it until 2045. This month, Neptune lies 1.5 degrees west of the +4.8 magnitude double star Sigma Aquarii. Neptune passes less than 4’ from +7.5 magnitude star HIP 110439 on September 9th as it continues towards eastern quadrature on November 24th.

Corkscrew chart credit:
Corkscrew chart for the elongations of Triton through early September. (Courtesy of Ed Kotapish; created using NASA/PDS Rings Node).

Up for a challenge? Neptune also has a large moon named Triton that is just within range of a moderate (8” in aperture or larger) telescope. Shining at magnitude +13.4, Triton is similar in brightness to Pluto and is 100 times fainter than Neptune. In fact, there’s some thought that Pluto may turn out to be similar to Triton in appearance when New Horizons gets a close-up look at it in July 2015.

Triton never strays more than 18” from Neptune during eastern or western elongations. This presents the best time to cross the moon off your astronomical “life list…” experienced amateurs have even managed to image Triton!

The moons of Neptune and Uranus imaged by Credit:
The moons of Neptune and Uranus imaged by Rolf Wahl Olsen using a 10″ reflector and a ToUCam Pro. An amazing catch! (Credit & Copyright: Rolf Wahl Olsen, used with permission).

Triton was discovered just 17 days after Neptune by William Lassell using a 24” reflector. Triton is also an oddball among large moons in the solar system in that it’s in a retrograde orbit.

A second moon named Nereid was discovered by Gerard Kuiper in 1949. To date, Neptune has 14 moons, including the recently discovered S/2004 N1 unearthed in Hubble archival data.

Neptune & Triton on the night of August 21st as it reaches greatest elongation. (Starry Night).
Neptune & Triton on the night of August 21st as it reaches greatest elongation. (Graphic created by author. Courtesy of Starry Night Education).

To date, Voyager 2 is the only spacecraft that has studied Neptune and its moons up close. Voyager 2 conducted a flyby of the planet in 1989. A future mission to Neptune would face the same dilemma as New Horizons: a speedy journey would still take nearly a decade to complete, which would rule out an orbital insertion around the planet. (Darn you, orbital mechanics!) In fact, New Horizons just crosses the orbit of Neptune at a distance of 30 astronomical units from the Earth in 2014.

Neptune is about four light hours away from the Earth, a distance that varies less than 20 minutes in light travel time from solar conjunction to opposition. And while Neptune and Triton may not appear like much more than dim dots through a telescope, what you’re seeing is an ice giant 3.8 times the diameter of the Earth, with a large moon 78% the size of our own.

Make sure to cross Neptune and Triton off of your bucket list… and next month, we’ll be able to do the same for the upcoming opposition of Uranus!

Apollo 15: “Stand by for a Hard Impact”

Only two of three parachutes worked correctly for the return of Apollo 15. Credit: NASA.

On this day in history, the crew of Apollo 15 returned home from their mission to the Moon. But the splashdown in the Pacific Ocean wasn’t without a little drama. One of the three parachutes failed to open fully, but astronauts Dave Scott, Al Worden, and Jim Irwin didn’t know it until they were almost ready to hit the ocean.

“Apollo 15, this is Okinawa. You have a streamed chute. Stand by for a hard impact.”

(You can read the entire transcript here.)

The recovery ship, USS Okinawa radioed to the crew that one parachute was not inflated. Technically, the Apollo capsule really only needed two chutes to land, with the third being for redundancy, but still, the landing was harder than other Apollo missions. However, no damage or injury resulted.

Experts looking at this photo say that two or three of the six riser legs on the failed parachute were missing, and after looking into the issue, it was determined that excess fuel burning from the Command Module Reaction Control System likely caused the lines to break.

Apollo 15 landed about about 320 miles (515 kilometers) north of Hawaii.

Ancient Astronomical Calendar Discovered in Scotland Predates Stonehenge by 6,000 Years

A wintertime rising gibbous Moon. (Image credit: Art Explosion).

A team from the University of Birmingham recently announced an astronomical discovery in Scotland marking the beginnings of recorded time.

Announced last month in the Journal of Internet Archaeology, the Mesolithic monument consists of a series of pits near Aberdeenshire, Scotland. Estimated to date from 8,000 B.C., this 10,000 year old structure would pre-date calendars discovered in the Fertile Crescent region of the Middle East by over 5,000 years.

But this is no ordinary wall calendar.

Originally unearthed by the National Trust for Scotland in 2004, the site is designated as Warren Field near the town of Crathes. It consists of 12 pits in an arc 54 metres long that seem to correspond with 12 lunar months, plus an added correction to bring the calendar back into sync with the solar year on the date of the winter solstice.

Diagram...
A diagram of the Warren Field site, showing the 12 pits (below) and the alignment with the phases of the Moon plus the rising of the winter solstice Sun. Note: the scale should read “0-10  metres.” (Credit: The University of Birmingham).

“The evidence suggests that hunter-gatherer societies in Scotland had both the need and sophistication to track time across the years, to correct for seasonal drift of the lunar year” said team leader and professor of Landscape Archaeology at the University of Birmingham Vince Gaffney.

We talked last week about the necessity of timekeeping as cultures moved from a hunter-gatherer to agrarian lifestyle. Such abilities as marking the passage of the lunar cycles or the heliacal rising of the star Sirius gave cultures the edge needed to dominate in their day.

For context, the pyramids on the plains of Giza date from around 2500 B.C., The Ice Man on display in Bolzano Italy dates from 3,300 B.C., and the end of the last Ice Age was around 20,000 to 10,000 years ago, about the time that the calendar was constructed.

“We have been taking photographs of the Scottish landscape for nearly 40 years, recording thousands of archaeological sites that would never have been detected from the ground,” said manager of Aerial projects of the Royal Commission of Aerial Survey Projects Dave Cowley. “It’s remarkable to think that our aerial survey may have helped to find the place where time was invented.”

The site at Warren Field was initially discovered during an aerial survey of the region.

Vince Gaffney professor of Landscape and Archaeology at University of Birmingham in Warren Field, Crathes, Aberdeenshire where the discovery was made.
Vince Gaffney, professor of Landscape and Archaeology at University of Birmingham in Warren Field, Crathes, Aberdeenshire where the discovery was made. (Credit: The University of Birmingham).

The use of such a complex calendar by an ancient society also came as a revelation to researchers. Emeritus Professor of Archaeoastronomy at the University of Leicester Clive Ruggles notes that the site “represents a combination of several different cycles which can be used to track time symbolically and practically.”

The lunar synodic period, or the span of time that it takes for the Moon to return to the same phase (i.e., New-to-New, Full-to-Full, etc) is approximately 29.5 days. Many cultures used a strictly lunar-based calendar composed of 12 synodic months. The Islamic calendar is an example of this sort of timekeeping still in use today.

However, a 12 month lunar calendar also falls out of sync with our modern Gregorian calendar by 11 days (12 on leap years) per year.

The familiar Gregorian calendar is at the other extreme, a calendar that is strictly solar-based.  The Gregorian calendar was introduced in 1582 and is still in use today. This reconciled the 11 minute per year difference between the Julian calendar and the mean solar year, which by the time of Pope Gregory’s reform had already caused the calendar to “drift” by 10 days since the 1st Council of Nicaea 325 AD.

Artist’s conception of the Warren Field site during the winter solstice. (Credit: The University of Birmingham). Credit: The University of Birmingham
Artist’s conception of the Warren Field site during the winter solstice. (Credit: The University of Birmingham). Credit: The University of Birmingham

Surprisingly, the calendar discovered at Warren Field may be of a third and more complex variety, a luni-solar calendar. This employs the use of intercalary periods, also known as embolismic months to bring the lunar and solar calendar back into sync.

The modern Jewish calendar is an example of a luni-solar hybrid, which adds an extra month (known as the 2nd Adar or Adar Sheni) every 2-3 years. This will next occur in March 2014.

The Greek astronomer Meton of Athens noted in 5th century B.C. that 235 synodic periods very nearly add up to 19 years, to within a few hours. Today, this period bears his name, and is known as a metonic cycle. The Babylonian astronomers were aware of this as well, and with the discovery at Warren Field, it seems that ancient astronomers in Scotland may have been moving in this direction of advanced understanding as well.

It’s interesting to note that the site at Warren Field also predates Stonehenge, the most famous ancient structure in the United Kingdom by about 6,000 years. 10,000 years ago would have also seen the Earth’s rotational north celestial pole pointed near the +3.9th magnitude star Rukbalgethi Shemali (Tau Herculis) in the modern day constellation of Hercules. This is due to the 26,000 year wobble of our planet’s axis known as the precession of the equinoxes.

The precession of the north celestial pole over millenia. (Credit: Wikimedia Commons graphic under a Creative Commons Attribution 2.5 Generic license. Author: Tau'olunga).
The precession of the north celestial pole over millennia. (Credit: Wikimedia Commons graphic under a Creative Commons Attribution 2.5 Generic license. Author: Tau’olunga).

The Full Moon nearest the winter solstice also marks the “Long Nights Moon,” when the Full Moon occupies a space where the Sun resides during the summer months and  rides high above the horizon for northern observers all night. The ancients knew of the five degree tilt that our Moon has in relation to the ecliptic and how it can ride exceptionally high in the sky every 18.6 years. We’re currently headed towards a ‘shallow year’ in 2015, where the Moon rides low in relation to the ecliptic. From there, the Moon’s path in the sky will get progressively higher each year, peaking again in 2024.

Who built the Warren Field ruins along the scenic Dee Valley of Scotland? What other surprises are in store as researchers excavate the site? One thing is for certain: the ancients were astute students of the sky. It’s fascinating to realize how much of our own history has yet to be told!

 

 

The Astronomy of the Dog Days of Summer

Looking east from latitude 30 north on August 3rd, 30 minutes before sunrise. (Created by the author in Stellarium).

Can you feel the heat?

It’s not just your imagination. The northern hemisphere is currently in the midst of the Dog Days of Summer. For many, early August means hot, humid days and stagnant, sultry nights.

The actual dates for the Dog Days of Summer vary depending on the source, but are usually quoted as running from mid-July to mid-August. The Old Farmer’s Almanac lists the Dog Days as running from July 3rd through August 11th.

But there is an ancient astronomical observation that ties in with the Dog Days of Summer, one that you can replicate on these early August mornings.

The sky was important to the ancients. It told them when seasons were approaching, when to plant crops, and when to harvest. Ancient cultures were keen observers of the cycles in the sky.  Cultures that were “astronomically literate” had a distinct edge over those who seldom bothered to note the goings on overhead.

The flooded Temple of Isis on the island of Philae circa 1905. (Credit: Wikimedia Commons under an Attribution-Share Alike 2.5 license. Author H.W. Dunning).
The flooded Temple of Isis on the island of Philae circa 1905. (Credit: Wikimedia Commons under an Attribution-Share Alike 2.5 license. Author H.W. Dunning).

Sirius was a key star for Egyptian astronomers. Identified with the goddess Isis, the Egyptian name for Sirius was Sopdet, the deification of Sothis. There is a line penned by the Greco-Roman scholar Plutarch which states:

“The soul of Isis is called ‘Dog’ by the Greeks.”

Political commentary? A mis-translation by Greek scholars? Whatever the case, the mythological transition from “Isis to Sothis to Dog Star” seems to have been lost in time.

These astronomer-priests noted that Sirius rose with the Sun just prior to the annual flooding of the Nile. The appearance of a celestial object at sunrise is known as a heliacal rising. If you can recover Sirius from behind the glare of the Sun, you know that the “Tears of Isis” are on their way, in the form of life-giving flood waters.

Sopdet as the personification of Sirius (note the star on the forehead)
Sopdet as the personification of Sirius (note the star on the forehead) Wikimedia Commons image under an Attribution Share Alike 3.0 license. Author Jeff Dahl).

In fact, the ancient Egyptians based their calendar on the appearance of Sirius and what is known as the Sothic cycle, which is a span of 1,461 sidereal years (365.25 x 4) in which the heliacal rising once again “syncs up” with the solar calendar.

It’s interesting to note that in 3000 BC, the heliacal rising of Sirius and the flooding of the Nile occurred around June 25th, near the summer solstice. This also marked the Egyptian New Year. Today it occurs within a few weeks of August 15th, owing to precession. (More on that in a bit!)

By the time of the Greeks, we start to see Sirius firmly referred to as the Dog Star. In Homer’s Iliad, King Priam refers to an advancing Achilles as:

“Blazing as the star that cometh forth at Harvest-time, shining forth amid the host of stars in the darkness of the night, the star whose name men call Orion’s Dog”

The Romans further promoted the canine branding for Sirius. You also see references to the “Dog Star” popping up in Virgil’s Aenid.

Over the years, scholars have also attempted to link the dog-headed god Anubis to Sirius. This transition is debated by scholars, and in his Star Names: Their Lore and Meaning, Richard Hinckley Allen casts doubt on the assertion.

Sirius as the shining "nose" of the constellation Canis Major. (Created by the author using Starry Night).
Sirius as the shining “nose” of the constellation Canis Major. (Created by the author using Starry Night).

Ancient cultures also saw the appearance of Sirius as signifying the onset of epidemics. Their fears were well founded, as summer flooding would also hatch a fresh wave of malaria and dengue fever-carrying mosquitoes.

Making a seasonal sighting of Sirius is fun and easy to do. The star is currently low to the southeast in the dawn, and rises successively higher each morning as August rolls on.

The following table can be used to aid your quest in Sirius-spotting.

Latitude north

Theoretical date when Sirius can 1st be spotted

32°

August 3rd

33°

August 4th

34°

August 5th

35°

August 6th

36°

August 7th

37°

August 8th

38°

August 9th

39°

August 10th

40°

August 11th

41°

August 12th

42°

August 13th

43°

August 14th

44°

August 15th

45°

August 16th

46°

August 17th

47°

August 18th

48°

August 19th

49°

August 20th

50°

August 21st

Thanks to “human astronomical computer extraordinaire” Ed Kotapish for the compilation!

Note that the table above is perpetual for years in the first half of the 21st century. Our friend, the Precession of the Equinoxes pivots the equinoctial points to the tune of about one degree every 72 years. The Earth’s axis completes one full “wobble” approximately every 26,000 years. Our rotational pole only happens to be currently pointing at Polaris in our lifetimes. Its closest approach is around 2100 AD, after which the north celestial pole and Polaris will begin to drift apart. Mark your calendars—Vega will be the pole star in 13,727 AD. And to the ancient Egyptians, Thuban in the constellation Draco was the Pole Star!

Near Luxor (Photo by author).
The Colossi of Memnon Near Luxor, just one of the amazing architectural projects carried out by the ancient Egyptians. (Photo by author).

Keep in mind, atmospheric extinction is your enemy in this quest, as it will knock normally brilliant magnitude -1.46 Sirius a whopping 40 times in brightness to around magnitude +2.4.

Note that we have a nice line-up of planets in the dawn sky (see intro chart), which are joined by a waning crescent Moon this weekend. Jupiter and Mars ride high about an hour before sunrise, and if you can pick out Mercury at magnitude -0.5 directly below them, you should have a shot at spotting Sirius far to the south.

And don’t be afraid to “cheat” a little bit and use binoculars in your quest… we’ve even managed on occasion to track Sirius into the broad daylight. Just be sure to physically block the Sun behind a building or hill before attempting this feat!

Sirius as seen via Hubble- can you spy Sirius B? (NASA/ESA Hubble image).
Sirius as seen via Hubble- can you spy Sirius B? (Credit: NASA/ESA Hubble image).

Of course, the heliacal rising of Sirius prior to the flooding of the Nile was a convenient coincidence that the Egyptians used to their advantage. The ancients had little idea as to what they were seeing. At 8.6 light-years distant, Sirius is the brightest star in Earth’s sky during the current epoch. It’s also the second closest star visible to the naked eye from Earth. Only Alpha Centauri, located deep in the southern hemisphere sky is closer. The light you’re seeing from Sirius today left in early 2005, back before most of us had Facebook accounts.

Sirius also has a companion star, Sirius B. This star is the closest example of a white dwarf. Orbiting its primary once every 50 years, Sirius B has also been the center of a strange controversy we’ve explored in past writings concerning Dogon people of Mali.

Sirius B is difficult to nab in a telescope, owing to dazzling nearby Sirius A. This feat will get easier as Sirius B approaches apastron with a max separation of 11.5 arc seconds in  2025.

Some paleoastronomers have also puzzled over ancient records referring to Sirius as “red” in color.  While some have stated that this might overturn current astrophysical models, a far more likely explanation is its position low to the horizon for northern hemisphere observers. Many bright stars can take on a twinkling ruddy hue when seen low in the sky due to atmospheric distortion.

Let the Dog Days of Summer (& astronomy) begin! (Photo by author).
Let the Dog Days of Summer (& astronomy) begin! (Photo by author).

All great facts to ponder during these Dog Days of early August, perhaps as the sky brightens during the dawn and your vigil for the Perseid meteors draws to an end!