History Archives

April 9, 2014December 23, 2015 by David Dickinson

Mars Opposition Season 2014: Images From Around the World

Mars as seen on from Aguadilla, Puerto Rico on Mars 25th, 2014, two weeks prior to opposition. Credit-Efrain Morales Rivera.

Did you see it? Last night, the Red Planet rose in the east as it passed opposition for 2014, and astrophotographers the world over were ready to greet it. And although Mars gets slightly closer to us over the coming week, opposition marks the point at which Mars is 180 degrees “opposite” to the setting Sun in Right Ascension as viewed from our Earthly vantage point and denotes the center of the Mars observing season. Opposition only comes around once about every 26 months, so it’s definitely worth your while to check out Mars through a telescope now if you can. We’ve written about prospects for observing Mars this season, and the folks at Slooh and the Virtual Telescope Project also featured live views of the Red Planet last night. We also thought we’d include a reader roundup of pics from worldwide:

Mars and Spica rising over the telescope domes at Kitt Peak, Arizona. The 2.1 metre dome is on the left, and the 0.9 metre dome is to the right. Credit-Rob Sparks @halfastro.

Even near opposition, Mars presents a challenge to observers. In 2014, Mars only reaches 15 arc seconds maximum in apparent size, a far cry from its 25″ appearance during the historic 2003 opposition. Now for the good news: we’re in a cycle of improving oppositions… the next one on May 22nd, 2016 will be better still, and the 2018 opposition will be nearly as favorable as the 2003 appearance!

Mars as seen from the Netherlands at 0:26 UT... about 3 hours past opposition. Credit- Christian Fröschlin. — Mars as seen from the Netherlands at 0:26 UT… about 3 hours past opposition. Credit- Christian Fröschlin @chrfde.

And you can see just how technology in the amateur astronomy community has improved with each successive appearance of Mars over the years. Early observers were restricted to sketching features glimpsed during fleeting moments of steady seeing. Even during the film era of photography, absurdly long focal lengths were required to yield even a tiny speck of a dot. And even then, the “graininess” of the film tended to smear and yield a blurry image with few details to be seen.

The advent of digital photography opened new vistas on planetary imaging. Now backyard astrophotographers are routinely taking images using stacking techniques and processing to “grab” and align those moments of good seeing. These images are often now better that what you’d see in a text book taken from professional observatories only a few decades ago!

And you can now easily modify a webcam to take decent planetary images that can then be stacked and processed with software freely available on the web.

…And check out this video animation also by Christian Fröschlin that shows the rotation (!) of Mars:

Mars as seen from Ottawa, Canada, taken using an IPhone 4S through a NexStar 8SE telescope on April 4th, 2014. Awesome! Credit-Andrew Symes @FailedProtostar

Shahrin Ahmad made an excellent video from Malaysia that demonstrates just what raw captured images of Mars look like before processing:

Note that the large dark triangular region is Syrtis Major.

Mars annotated, a stack of 1128 frames shot at 666x. Credit-Mike Weasner/Cassiopeia Observatory.

The northern polar cap is currently tipped towards us, as it’s northern hemisphere summertime on Mars. Many images reflect this prominent feature, as well as the orographic clouds skirting the Hellas basin that have been the hallmark of the Mars opposition of 2014. These are also apparent visually at the eyepiece. It’s worth staying up a bit towards local midnight to observe and image Mars, as it transits at its maximum elevation — and is above the murk of the sky low to the horizon — right around this time.

Mars captured through a Celestron C6 SCT telescope on April 5th, 2014. Credit: Joel Tonyan.

Mars: a study of color contrasts on the eve of opposition. Credit-Laura Austin @LAismylady

And Mars observing season doesn’t end this week. Mars makes its closest passage to the Earth for 2014 next Monday on April 14th at 0.618 Astronomical Units (A.U.s) distant. Mars will occupy the evening sky for the remainder of 2014 before finally reaching solar conjunction on June 14th, 2015. Mars will still be greater than a respectable 10″ in apparent size until June 24th and will continue to offer observers a fine view at the eyepiece.

Mars as seen from Rhode Island on the night of opposition. Credit-Cherie @KelieAna

And don’t forget, that waxing gibbous Moon is now homing in on Mars and will only sit a few degrees away from the Red Planet and Spica on the night of the April 14th/15th, 2014 during a fine total lunar eclipse. And no, a “red” planet + a “blood red” eclipsed Moon does not equal doomsday… but it’ll make a great photo op!

Mars imaged using a 150 mm scope. Credit-Sergei Golyshev under a Creative Commons Share-Alike 2.0 Generic License.

… and finally, Mars and the bright blue-white star Spica offered us a fine morning view as the storm front passed over Astroguyz HQ here in Florida this AM:

Author — Mars, Spica, and our partly cloudy terrestrial atmosphere. Photo by author.

Want something more? Have you ever seen Mars… in the daytime? Currently shining at magnitude -1.5, its just possible if you known exactly where to look for it low to the east about 10 minutes or so before local sunset. In fact, near opposition is the only time you can carry this unusual feat of visual athletics out. The best chance in 2014 is on the evening of April 13th and 14th, when the waxing gibbous Moon lies nearby:

Looking east on the evening of April 13th, just before sunset. Credit: Starry Night education software.

Good luck, and thanks to everyone who imaged Mars this season!

April 8, 2014December 23, 2015 by David Dickinson

The USAF’s Super-Secret X-37B Approaches a Milestone

An artists' conception of the X-37B in Earth orbit. Credit: The U.S. Air Force.

A secretive mission will pass a quiet milestone at the end of this month when the U.S. Air Force’s unmanned spaceplane the X-37B surpasses 500 days in space.

Launched atop an Atlas V rocket flying in a 401 configuration from Cape Canaveral Florida after several delays on December 11^th, 2012 on OTV-3, the X-37B has already surpassed its own record of 469 days in space set on OTV-2. Said milestone was crossed last month. If the current mission stays in space until April 25^th of this year, it will have surpassed 500 days in space.

Two X-37Bs were built for the USAF, and the first test mission flew in 2010. NASA performed drop glide tests with an early variant of the X-37A in 2005 and 2006, and DARPA is thought to be a primary customer for the program as well.

Measuring just 8.8 metres in length, the X-37B is tiny compared to its more famous spaceplane cousin the U.S. Space Shuttle. The X-37B has a maximum weight at liftoff of 4,990 kilograms and features a payload bay 2.1 by 1.2 metres in size.

The spacecraft itself is solar powered, as it unfurls a panel — as depicted in many artists’ conceptions — once it’s in orbit. Of course, its mission profile is classified, and the X-37B could land unannounced at any time. The previous landings occurred at Vandenberg Air Force Base in California and were only announced shortly thereafter.

Not only is this the longest continuous mission for any spaceplane, but the ATV-3 is also the smallest, lightest and only the second spaceplane to land autonomously, the first being the Russian space shuttle Buran that flew one mission and landed after one orbit at the Baikonur Cosmodrome on November 15^th, 1988.

The X-37B awaiting encapsulation for launch. Credit: U.S. Air Force.

The idea of a reusable spaceplane has been around since the dawn of the Space Age. The U.S. Space Shuttle program was the most high profile of these, having flown 135 missions from 1981 to 2011. But even the space shuttle launch system wasn’t fully reusable, expending its large orange external fuel tank after every mission and requiring extensive refurbishment for the solid rocket motors and orbiter after each and every flight. The Soviets abandoned Buran in 1988, and other examples of spaceplanes such as North American’s X-15 surpassed the 100 kilometre in altitude Kármán line marking the boundary to space, but were suborbital only. And this year, customers may get a chance to make similar suborbital hops into space aboard Virgin Galactic’s SpaceShipTwo spaceplane at $250,000 dollars a ticket.

But the most ambitious design for a true spaceplane was conceived in the 1960’s: Boeing’s X-20 Dyna-Soar, which was never built.

Classified satellites such as the X-37B are part of a longstanding and fascinating “secret space race” that has paralleled and shadowed the more well known space programs of various nations over the decades. These include the Corona program which ran from 1959 to 1972 and was only declassified in 1995, and satellites such as Lacrosse 5, which is notorious among satellite sleuths for the orbital “vanishing act” it sometimes pulls.

And speaking of which, you can track the X-37B from your backyard, tonight. Ground spotters first pegged its position in low Earth orbit during OTV-1 on May 22^nd 2010, and the spacecraft currently sits in a 392 x 296 kilometre (nearly circular) orbit in an 43.5 degree inclination, making it visible from latitudes 55 degrees north to south. On a favorable overhead pass, the X-37B is easily visible shining at greater than magnitude +1. OTV-3’s NORAD ID designation is 39025 or 2012-071A, and although – like most classified payloads – it’s not available to the public on Space-Track, Heavens-Above does list upcoming sighting opportunities. Be sure to start watching a bit early, as the X-37B has been known to maneuver a bit in its orbit on occasion.

Of course, just what the X-37B is doing in orbit is anybody’s guess. Speculation is that it’s serving as a test bed for new technologies. Certainly, the ability to place interchangeable payloads in orbit is immediately apparent. It’s also worth noting that the X-37B makes multiple daily passes on its northward apex over North Korea and China. There’s also been speculation that the X-37B was designed to keep tabs on the Chinese space station Tiangong-1, although this can easily be refuted as they both lie in different orbits. There’s no word as to what’s to become of Tiangong-1, though China had said it was set to deorbit the station at the end of 2013, and it is still in space.

Looking ahead into the future, there has been talk about a larger crewed variant known as the X-37C, which will undoubtedly fly much shorter missions. For now, we can watch and wonder what it’s up to, as the X-37B glides silently overhead. Perhaps one day, its mission will declassified, and its tale can be told.

-For more info sat-tracking, check out our how-to post and also read about the fascinating true role that amateurs played during the Cold War and Operation Moonwatch.

April 7, 2014December 23, 2015 by David Dickinson

The Science Behind the “Blood Moon Tetrad” and Why Lunar Eclipses Don’t Mean the End of the World

A mosaic of the 2003 total lunar eclipse. photos by author.

By now, you may have already heard the latest tale of gloom and doom surrounding the upcoming series of lunar eclipses.

This latest “End of the World of the Week” comes to us in what’s being termed as a “Blood Moon,” and it’s an internet meme that’s elicited enough questions from friends, family and random people on Twitter that it merits addressing from an astronomical perspective.

Like the hysteria surrounding the supposed Mayan prophecy back in 2012 and Comet ISON last year, the purveyors of Blood Moon lunacy offer a pretty mixed and often contradictory bag when it comes down to actually what will occur.

But just like during the Mayan apocalypse nonsense, you didn’t have to tally up just how many Piktuns are in a Baktun to smell a rat. December 21^st 2012 came and went, the galactic core roughly aligned with the solstice — just like it does every year — and the end of the world types slithered back into their holes to look for something else produce more dubious YouTube videos about.

Here’s the gist of what’s got some folks wound up about the upcoming cycle of eclipses. The April 15^th total lunar eclipse is the first in series of four total eclipses spanning back-to-back years, known as a tetrad. There are eight tetrads in the 21^st century: if you observed the set total lunar eclipses back in 2003 and 2004, you saw the first tetrad of the 21^st century.

The eclipses in this particular tetrad, however, coincide with the Full Moon marking Passover on April 15^th and April 4^th and the Jewish observance of Sukkot on October 8^th and September 28^th. Many then go on to cite the cryptic biblical verse from Revelation 6:12, which states;

“I watched as he opened the sixth seal. There was a great earthquake. The Sun turned black like sackcloth made of goat hair. The whole Moon turned blood red.”

Whoa, some scary allegory, indeed… but does this mean the end of the world is nigh?

I wouldn’t charge that credit card through the roof just yet.

First off, looking at the eclipse tetrads for the 21^st century, we see that they’re not really all that rare:

21^st century eclipse tetrads:

Eclipse #1	Eclipse #2	Eclipse #3	Eclipse #4
May 16^th, 2003	November 9^th, 2003	May 4^th , 2004	October 28^th, 2004
April 15^th, 2014*+	October 8^th, 2014	April 4^th, 2015*+	September 28^th, 2015
April 25^th, 2032	October 18^th, 2032	April 14^th, 2033*+	October 8^th, 2033
March 25^th, 2043*	September 19^th, 2043	March 13^th, 2044	September 7^th, 2044
May 6^th, 2050	October 30^th, 2050	April 26^th, 2051	October 19^th, 2051
April 4^th, 2061*+	September 29^th, 2061	March 25^th, 2062*	September 18^th, 2062
March 4^th, 2072	August 28^th, 2072	February 22^nd, 2073	August 17^th, 2073
March 15^th, 2090	September 8^th, 2090	March 5^th, 2091	August 29^th, 2091
*Paschal Full Moon
+Eclipse coincides with Passover

Furthermore, Passover is always marked by a Full Moon, and a lunar eclipse always coincides with a Full Moon by definition, meaning it cannot occur at any other phase. The Jewish calendar is a luni-solar based calendar that attempts to mark the passage of astronomical time via the apparent course that the Sun and the Moon tracks through the sky. The Muslim calendar is an example of a strictly lunar calendar, and our western Gregorian calendar is an example of a straight up solar one. The Full Moon marking Passover often, though not always, coincides with the Paschal Moon heralding Easter. And for that matter, Passover actually starts at sunset the evening prior in 2014 on April 14^th. Easter is reckoned as the Sunday after the Full Moon falling after March 21^st which is the date the Catholic Church fixes as the vernal equinox, though in this current decade, it falls on March 20^th. Easter can therefore fall anywhere from March 22^nd to April 25^th, and in 2014 falls on the late-ish side, on April 20^th.

To achieve synchrony, the Jewish calendar must add what’s known as embolismic or intercalculary months (a second month of Adar) every few years, which in fact it did just last month. Eclipses happen, and sometimes they occur on Passover. It’s rare that they pop up on tetrad cycles, yes, but it’s at best a mathematical curiosity that is a result of our attempt to keep our various calendrical systems in sync with the heavens. It’s interesting to check out the tally of total eclipses versus tetrads over a two millennium span:

Century	Number of Total Lunar Eclipses	Number of Tetrads	Century	Number of Total Lunar Eclipses	Number of Tetrads
11^th	62	0	21^st	85	8
12^th	59	0	22^nd	69	4
13^th	60	0	23^rd	61	0
14^th	77	6	24^th	60	0
15^th	83	4	25^th	69	4
16^th	77	6	26^th	87	8
17^th	61	0	27^th	79	7
18^th	60	0	28^th	64	0
19^th	62	0	29^th	57	0
20^th	81	5	30^th	63	1

Note that over a five millennium span from 1999 BC to 3000 AD, the max number of eclipse tetrads that any century can have is 8, which occurs this century and last happened in the 9^th century AD.

Of course, the visual appearance of a “Blood of the Moon” that’s possibly alluded to in Revelation is a real phenomena that you can see next week from North and South America as the Moon enters into the dark umbra or core of the shadow of the Earth. But this occurs during every total lunar eclipse, and the redness of the Moon is simply due to the scattering of sunlight through the Earth’s atmosphere. Incidentally, this redness can vary considerably due to the amount of dust, ash, and particulate aerosols aloft in the Earth’s atmosphere, resulting in anything from a bright cherry red eclipse during totality to an eclipsed Moon almost disappearing from view altogether… but it’s well understood by science and not at all supernatural.

The changing colors of a lunar eclipse: a mosaic of four eclipses. Photos by author.

Curiously, the Revelation passage could be read to mean a total solar eclipse as well, though both can never happen on the same day. Lunar and solar eclipses occur in pairs two weeks apart at Full and New Moon phases when the nodes of the Moon’s ecliptic crossing comes into alignment with the Sun — known as a syzygy, an ultimate triple word score in Scrabble, by the way — and this eclipse season sees a non-central annular eclipse following the April 15^th eclipse on April 29^th.

And yes, earthquakes, wars, disease, relationship breakups and lost car keys are on tap to occur in 2014 and 2015… just like during any other year. Lunar eclipses marked the fall of Constantinople in 1453 and the World Series victory of the Red Sox in 2004, but they’re far from rare. We humans love to see patterns, and sometimes this habit works against us, making us see them where none exists. This is simply a case of the gambler’s fallacy, counting the hits at the cost of the misses. We could just as easily make a case that the upcoming eclipse tetrad of April 15th, October 8^th, April 4^th and September 28th marks US Tax Day, Croatian Independence Day, The Feast of Benedict of the Moor & — Michael Scott take note — International World Rabies Day… perhaps the final 2015 eclipse should be known as a “Rabies Moon?”

So, what’s the harm in believing in a little gloom and doom? The harm in believing the world ends tomorrow comes when we fail to plan for still being here the day after. The harm comes when something like the Heavens Gate mass suicide goes down. We are indeed linked to the universe, but not in the mundane and trivial way that astrologers and doomsdayers would have you believe. Science shows us where we came from and where we might be headed. We’ve already fielded queries from folks asking if it’s safe (!) to stare at the Blood Moon during the eclipse, and the answer is yes… don’t give in to superstition and miss out on this spectacular show of nature because of some internet nonsense.

The upcoming lunar eclipse next week won’t mean the end of the world for anyone, except, perhaps, NASA’s LADEE spacecraft… be sure not to miss it!

March 31, 2014December 30, 2015 by David Dickinson

Observing Alert: Watch the Moon Cross the Hyades This Week

A photogenic grouping greets evening sky watchers this week providing a fine teaser leading up to a spectacular eclipse.

On the evening of Thursday, April 3^rd headed into the morning of the 4^th, the waxing crescent Moon crosses in front of the Hyades open star cluster. This is the V-shaped asterism that marks the head on Taurus the Bull, highlighted by the brilliant foreground star Aldebaran as the bull’s “eye”. Viewers across North America will have a ring-side seat to this “bull-fight” as the 20% illuminated Moon stampedes over several members of the Hyades in its path.

The passage of the Moon through the Hyades over a three hour span on the night of April 3rd (April 4th in Universal Time) comparing the North American locales of Tampa, Florida and Seattle, Washington. (Credit: Starry Night Education Software).

The brightest stars to be occulted are the Delta Tauri trio of stars ranging in magnitudes from +3.8 (Delta Tauri^1) to +4.8(2) and +4.3(3). Such occlusions – known in astronomy as occultations – are fun to watch, and can reveal the existence of close binary companions as they wink out behind the lunar limb. Several dozen occultations of stars brighter than +5^th magnitude by the Moon happen each year, and the best events occur when the Moon is waxing and the stars disappear against its dark leading edge. We recently caught one such event last month when the Moon occulted the bright star Lambda Geminorum:

We are currently seeing the Moon cross the Hyades during every lunation until the year 2020, though it’s a particularly favorable time to catch the event in April 2014 as the Moon is a slender crescent. Notice that you can just make out the dark limb of the Moon with the naked eye? What you’re seeing is termed Earthshine, and that’s just what it is: the nighttime side of the Moon being illuminated by sunlight that is reflected off of the Earth. Standing on the Earthward side of the Moon, an observer would see a waning gibbous Earth about two degrees across. Yutu has a great view!

Credit Occult 4.0 — The occultation footprint for Delta Tauri^1. Credit: Occult 4.0

The Moon will cross its descending node where its apparent path intersects the ecliptic on April 1^st (no joke, we swear) at 2:30 Universal Time or 10:30 PM EDT on March 31^st. The next nodal crossing now occurs in just two weeks, and the Earth’s shadow will be there to greet the Moon on the morning of April 15^th in the first of four total lunar eclipses that span 2014 and 2015. The month of April also sees the Moon’s orbit at its least eccentric, a time at which perigee – the Moon’s closest point to Earth – is at its most distant and apogee – its farthest point – is at its closest. This currently happens near the equinoxes, through the nodes slowly travel across the ecliptic completing one revolution every 18.6 years. Perigee can vary from 356,400 to 370,400 kilometres, and apogee can span a distance from 404,000 to 406,700 kilometres.

Looking west from the US SE at about 10PM local on the evening of April 3rd. Credit: Stellarium.

We’re also headed towards a “shallow year” in 2015 when the Moon has the least variability in respect to its declination. This trend will then reverse, climaxing with a “Long Nights Moon” riding high in the sky in 2025, which last occurred in 2006. The Moon will inch ever closer to Aldebaran on every successive lunation now, and begins a series of occultations of Aldebaran on January 29^th, 2015 through the end of 2018. Occultations of Aldebaran always occur near these shallow years, and will be followed by a cycle of occultations of Regulus starting in 2017. We caught an excellent daytime occultation of Aldebaran by the Moon from North Pole, Alaska during the last cycle in the late 1990s.

Photos by Author — The Moon passing between the Hyades and Pleiades in 2011 with Earthshine highlighted. Photos by author.

Now for the wow factor. Our Moon is 3,474 kilometres across and located just over one light second away. The Hyades star cluster covers about 6 ½ degrees of sky – about 7 times the size of the Full Moon – but is the closest open cluster to the Earth at 153 light years distant and has a core diameter of about 18 light years across. As mentioned previous, Aldebaran isn’t physically associated with the Hyades, but is merely located in the same direction at 65 light years distant.

The Hyades star cluster also provided early 20^thastronomers with an excellent study in galactic motion. At an estimated 625 million years in age, the Hyades are slowly getting disbanded and strewn about the Milky Way galaxy in a process known as evaporation. The Hyades are also part of a larger stellar incorporation known as the Taurus Moving Cluster. Moving at an average of about 43 kilometres a second, the members of the Hyades are receding from us towards a divergent point near the bright star Betelgeuse in the shoulder of Orion. 50 million years hence, the Hyades will be invisible to the naked eye as seen from Earth, looking like a non-descript open cluster and providing a much smaller target for the Moon to occult at 20’ across. Astronomer Lewis Boss was the first to plot the motion of the Hyades through space in 1908, and the cluster stands as an essential rung on the cosmic distance ladder, with agreeing measurements independently made by both Hubble and Hipparcos and soon to be refined by Gaia.

Photographing and documenting this week’s passage of our Moon across the Hyades is easy with a DSLR camera: don’t be afraid to vary those ISO and shutter speeds to get the mix of the brilliant crescent Moon, the fainter earthshine, and background stars just right. The more adventurous might want to try actually catching the numerous occultations of bright stars on video. And U.S. and Canadian west coast observers are well placed to catch the Moon cross right though the core of the Hyades… a video animation of the event is not out of the question!

And from there, the Moon heads on to its date with destiny and a fine total lunar eclipse on April 15^th which favors North American longitudes. We’ll be back later this week with our complete and comprehensive eclipse guide!

March 24, 2014December 23, 2015 by David Dickinson

Ready, Set, Messier Marathon: A 2014 Guide

Patiently awaiting darkness at the starting line... Credit and copyright: John Chumack.

Have YOU seen all 110?

The passage of the northward equinox last week on March 20^th means one thing in the minds of many a backyard observer: the start of Messier Marathon season. This is a time of year during which a dedicated observer can conceivably spot all of the objects in Charles Messier’s famous deep sky catalog in the span of one night.

We’ve written about some tips and tricks to completing this challenge previously, as well as the optimal dates for carrying a marathon out. Typically, the New Moon weekend nearest the March equinox is the best time of year for northern hemisphere observers to target all of the objects on Messier’s list. This works because a majority of the Messier objects are clustered into two regions: towards the core of our galaxy in Sagittarius — where the Sun sits during the December solstice — up through the summer triangle constellations of Cygnus, Aquila and Lyra, and in the bowl of Virgo asterism and its super cluster of galaxies that extends northward into the constellation of Coma Berenices. In March through early April the Sun sits in the constellation of Pisces, well away from the galactic plane.

The prospects for completing a Messier marathon in 2014 favor the last weekend on March on the 29^th-30^th. The Moon reaches New on Sunday, March 30^th at 18:45 Universal Time/2:45 PM EDT.

Messier marathons first came into vogue in the early 1970s right around the time Schmidt-Cassegrain and large Dobsonian “light bucket” telescopes came into general use.

Charles Messier began noting the curious objects that he would later incorporate into his famous catalog during the summer of 1758, with his description of the Crab Nebula in Taurus, which would become Messier object number one or M1. Messier was a prolific comet hunter and discovered 21 comets in his lifetime. The catalog was compiled over the span of 13 years from 1771 to 1784. Messier’s original list contained 45 objects, and was later expanded in subsequent editions 103, with Messier’s assistant Pierre Méchain adding six more objects to the catalog. The list is generally tallied at 110 objects, with one famous controversy being M102, which is generally cited as a re-observation of M101 or the galaxy NGC 5866.

The catalog itself contains a grab bag of open and globular clusters, galaxies, planetary and diffuse nebulae, and one double star (M40). The Messier catalog spans the sky down to M7, an object also known as the Ptolemy Cluster, which is the southernmost object on the list at latitude -34 degrees 48’ south.

The first page of Messier's third revision of his catalog describing M1 through M5. Image in th Public Domain. — The first page of Messier’s third revision of his catalog, describing M1 through M5. Image in the Public Domain.

Messier observed from Paris at latitude +48 degrees 51’ north using two primary telescopes of the almost one dozen that he owned for his discoveries: a 6.4” Gregorian reflector and a 3.5” refractor. Messier knew nothing of the nature of these “faint fuzzies” that he’d periodically stumbled across in his cometary vigil. His original intent was to compile a list of “comet imposters” in the night sky for comet hunters to be aware of in their quests. In his words:

“What made me produce this catalog was the nebula which I had seen in Taurus while I was observing the comet of that year (1758). The shape and brightness of that nebula reminded me so much of a comet, that I undertook to find more of its kind, to save astronomers from confusing these nebulae with comets.”

“Beware, here doth not lie comets,” Messier admonishes future generations of observers. Still, some peculiarities remain in the catalog: why did Messier, for example, include such obvious “non-comets” as the Pleiades (M45), but skip over the brilliant Double Cluster in Perseus?

Charles Messier's 1771 sketch of the Orion nebula, M42 in the Messier Catalog. Image in the public domain. — Charles Messier’s 1771 sketch of the Orion nebula, M42 in the Messier Catalog. Image in the public domain.

Alas, such mysteries are known only to Messier, who was interred at the famous Père Lachaise cemetery after his death in 1817. When we visit Paris, we’ll bypass Jim Morison to leave a copy of Burnham’s Celestial Handbook at Messier’s grave.

And just like the road variety, “running the Messier marathon” takes all of the stamina and pacing that a visual athlete can muster. You’ll want to grab M77 and M74 immediately after dusk, or the marathon will be over before it starts. From there, move on up north to the famous Andromeda galaxy (M31) and the scattering of objects around it before settling in for a more leisurely observing pace moving westward through the constellations of Orion, Leo and surrounding objects.

An all-sky map showing the distribution of Messier objects. (Click to enlarge). Credit: Jim Cornmell under a Wikimedia Commons Attribution-Share Alike 3.0 Unported license.

Now towards the approach of local midnight comes the first large group: the Virgo cluster of galaxies extending through Coma Berenices, rising to the east. After this batch, you can catch some quick shut-eye before bagging the Messier objects towards the galactic center and up through Cygnus in the pre-dawn. Plan ahead; M52, M2 and M30 are especially notoriously difficult in the spring dawn sky!

It’s also worth noting your “attitude versus latitude” plays a role as well. To this end, Ed Kotapish compiled this nifty perpetual chart of when the entire Messier catalog is visible from respective latitudes:

A chart calculating number of total Messier objects that are visible on the dates (vertical column in month-day format) versus north latitude (top row). Note that this chart is pertpetual for non-leap years, and does not take into account the pahse of the Moon. Click to enlarge. Credit: Edward Kotapish.

“The bounds of the chart are for a variety of objects,” Ed told Universe Today. “I used nautical twilight (when the Sun falls below -12 degrees in elevation) as the starting and ending condition.” Ed also notes that the top curve of the chart on the morning side is bounded by the difficulty in finding troublesome M30, while the left bottom evening boundary is limited by the observability of M110 and M74, which can be a problem for observers at higher latitudes.

Alternate versions of the Messier marathon exist as well, such as imaging or even sketching all 110 objects in one night.

Why complete a Messier marathon? Well, not only does such a feat hone your visual skills as an observer, but it also familiarizes you with the entire catalog… and there’s nothing that says you have to complete it all in one evening, except of course, for bragging rights at the next star party!

Good luck!

-Here’s a handy list of all 110 of the Messier objects in the catalog.

-Be sure to send those pics of Messier objects and more in to Universe Today’s Flickr forum!

March 10, 2014December 23, 2015 by Nancy Atkinson

‘Cosmos’ Reboot Starts With a (Big) Bang

Dr. Neil deGrasse Tyson contemplates the Big Bang. Image courtesy of Fox.

With much anticipation from the astronomy and science community, the opening episode of the new and updated version of Carl Sagan’s “Cosmos” series premiered to the masses on television in North America last night. This reboot – this time hosted by astrophysicist Neil de Grasse Tyson — did a wonderful job of paying homage to Sagan while showcasing the grandeur of space, as well as portraying the infinitesimally small amount of time that humanity has existed. Like its original counterpart, the first episode of the series takes viewers on a quick tour of the Solar System and Universe, showing our cosmic “address” as it were, going back to the Big Bang, but also touching on multiverses and a potentially infinite Universe.

As de Grasse Tyson said at the beginning, “from the infinitesimal to the infinite; from the dawn of time to the distant future.”

There were also – seemingly – an infinite number of commercial interruptions. You can watch the episode in its entirety below, without commercials, thankfully. Watching it on television last night was disappointing because of those commercial interruptions – sometimes only a couple of minutes apart — making one wish for the PBS-commercial-free version of the original Cosmos with Sagan.

And I wasn’t the only one feeling those sentiments:

What I miss most from the original 'Cosmos'? No commercials #Cosmos

— Wayne Hale (@waynehale) March 10, 2014

(Yes, I watched the show while keeping an eye on what the Twitterverse had to say about it.)

But airing the series on the Fox Network and its affiliated channels (I watched it on the National Geographic Channel) was a calculated move by the series’ producer Seth MacFarlane to showcase the series and the science to a population that may not otherwise be exposed to science at this “popular” level. And clearly, science and the scientific method gets top billing in this series:

“This adventure is made possible by generations of searchers strictly adhering to a general set of rules: test ideas by experiment and observation … follow the evidence where it leads and question everything,” said Tyson.

This planetary nebula's simple, graceful appearance is thought to be due to perspective: our view from Earth looking straight into what is actually a barrel-shaped cloud of gas shrugged off by a dying central star. Hot blue gas near the energizing central star gives way to progressively cooler green and yellow gas at greater distances with the coolest red gas along the outer boundary. Credit: NASA/Hubble Heritage Team — This planetary nebula’s simple, graceful appearance is thought to be due to perspective: our view from Earth looking straight into what is actually a barrel-shaped cloud of gas shrugged off by a dying central star. Hot blue gas near the energizing central star gives way to progressively cooler green and yellow gas at greater distances with the coolest red gas along the outer boundary. Credit: NASA/Hubble Heritage Team

With a combination of real images from telescopes and spacecraft, computer generated imagery and surprisingly watchable animations, most intriguing for me was the “cosmic calendar.” Those who have seen Sagan’s original series will remember his version of the cosmic calendar as a way to conceptualize the age of the Universe, compressing 13.9 billion years down to one year. Tyson’s flashier calendar also showed how January 1 would mark the Big Bang and December 31 would be the present – making each day represent about 40 million years. At this rate, humanity’s entire recorded history only occupies just the last 14 seconds of the year.

But as Tyson noted, science has provided unmatched discoveries during that short span of time: “The scientific method is so powerful that in a mere four centuries, it has taken us from Galileo’s’ first look through the telescope to knowing our place in the Universe.”

Giordano Bruno in Cosmos. Image courtesy of Fox.

When I heard there were going to be animated sequences of historical events (the original series used actor portrayals) I was disappointed, but the animations in this series premiere surprised me by being quite engaging.

They told the story of Giordano Bruno, the 16th century Italian monk turned astronomer. He had theorized that other planets existed with other lifeforms like ours. In his 1584 book “On the Infinite Universe and Worlds,” Bruno wrote : “… there is a single general space, a single vast immensity which we may freely call Void; in it are innumerable globes like this one on which we live and grow. This space we declare to be infinite… In it are an infinity of worlds of the same kind as our own.”

This was controversial for his time, but even in a church-dominated society, it wasn’t grounds for being declared a heretic. But later Bruno followed his argument to its logical conclusion: if there are an infinity of worlds, and if some worlds have sentient beings created by God, then wouldn’t these planets also need to be saved by God? The notion other Jesuses was not viewed well, and the church convicted him of heresy, and burned him at the stake.

Phil Plait talked more about this today in his review of “Cosmos” and I agree with him that this wasn’t really about showing religion in a bad light, but about making “a bigger point about suppression of thought and the grandeur of freedom of exploration of ideas.”

Other fun moments were when a CGI (but quite realistic) dinosaur fish named a Tiktaalik crawled out of the sea right next to Tyson, depicting the evolution of life on Earth. Most endearing was perhaps Tyson’s claim that “we are ALL descended from astronomers;” how our ancestors depended on the stars to know the change of seasons.

While this series premier was a quick overview, one surprise is that it showed just one theory – and the oldest and perhaps outdated — of how our Moon was formed, by a conglomeration of the same debris that make up Earth. These days it seems the theory of a Mars-sized planetary collision is the most accepted theory.

The show began and ended with the voice and words of Carl Sagan, and Tyson shared his story about his own personal interactions with Sagan. This was a very authentic part of the show, and allowed the torch to be passed from Sagan to Tyson.

If you missed it: Karma. "For Neil Tyson, With all good wishes to a future astronomer" – Carl Sagan pic.twitter.com/BQ2p6RRRys

— Steve Silberman (@stevesilberman) March 10, 2014

And then there was Tyson using Sagan’s famous “we are made star stuff” quote:

“They get so hot that the nuclei of the atoms fuse together deep within them to make the oxygen with breathe, the carbon in our muscles, the calcium in our bones, the iron in our blood,” Tyson said. “You, me, everyone: We are made of star stuff.”

Astronomer thought process: RT @Alex_Parker: S?T?A?R? ?G?U?T?S? S?T?A?R? ?R?E?F?U?S?E? S?T?A?R? ?B?E?L?L?Y?B?U?T?T?O?N? ?L?I?N?T? STAR STUFF

— Nancy Atkinson (@Nancy_A) March 10, 2014

This series premiere was a rousing tribute to science and I am definitely looking forward to more. Here’s hoping this series does what MacFarlane had in mind: get the general public to start talking about science again.

If you are feeling the need for more “Cosmos” you can watch the original series at Hulu Plus, and at the Carl Sagan website, learn more about the legend.

There is “The Seth MacFarlane collection of the Carl Sagan and Ann Druyan archive, 1860-2004” at the Library of Congress. MacFarlene supported this new Carl Sagan archive.

See more at the Cosmos Online website (there’s even an app for it.)

March 5, 2014April 26, 2016 by David Dickinson

Daylight Saving Time: A Spring Forward or a Step Back?

The tricky business of keeping time... the Astronomical Clock in Prague, Czech Republic.

The time to change clocks is once again nigh.

We’ll put our unabashed bias as a lover of the night sky right up front: we loathe Daylight Saving Time. And it’s not just because of the biannual hunt through our home for the dozen-odd non-networked clocks that it instigates twice a year. For astronomers, the shift to DST means that true darkness falls much later in the evening, marking the abrupt end of the school star party season not long after March. You don’t have to go far north to about latitude 45 degrees to find areas where it doesn’t get dark until about 11PM local towards mid-summer. And sure, we gain back an extra hour of morning darkness, albeit that too soon dwindles towards summer as well.

In 2014 we (as in a majority of North America) spring forward one hour on March 9^th at 2:00 AM local. That’s just one day shy of the earliest that we can now spring forward, as the current convention established by the Energy Policy Act of 2005 during the Bush administration that was enacted in 2007 now sets the beginning of DST as the 2^nd Sunday in March.

We’re now on DST for about roughly eight months or 67% of the calendar year. The European Union still shifts forward on the last Sunday of March, meaning that for a span of three weeks every March, the time lag between, say, Eastern Daylight Time and British Standard Time closes briefly to four hours before opening up again to five hours.

Current DST usage worldwide. Regions in blue currently use DST, orange have scrapped DST, and regions in red have never used DST. Credit: Paul Eggert under a wikimedia Creative Commons Attribution-Share Alike 3.0 Unported license. — Current DST usage worldwide. Regions in blue currently use DST, orange have scrapped DST, and regions in red have never used DST. Credit: Paul Eggert under a Wikimedia Creative Commons Attribution-Share Alike 3.0 Unported license.

And that’s just for starters.

Of course, there are holdouts even among DST observing countries worldwide. The states of Arizona and Hawaii do not observe DST, nor did a portion of Indiana until 2006. When DST is in effect, you can touch on three time zones in just a few hours’ drive from southeastern Arizona crossing southern New Mexico and into Texas east of El Paso. And you can really mix things up driving across the Navajo nation in northeastern Arizona – which observes DST, unlike the rest of the state – into the Hopi Reservation embedded within it, which rejects DST.

In Canada, most of Saskatchewan ignores DST, as do small portions of British Columbia, Quebec and Nunavut. In 2011, Russia opted to remain on Daylight Saving Time year round, and Australia is sharply divided on the issue of keeping DST. Of course, in the southern hemisphere, astronomical spring and fall are reversed, making UK/US/Australia teleconference scheduling even more confusing this time of year, not to mention the often bewildering state of affairs faced by computer programmers seeking to include every new rule and nuisance concerning local timekeeping worldwide.

1918 Poster espousing the benifits of the first DST shift for the U.S. Credit: U.S. Library of Congress image in the Public Domain. — 1918 Poster espousing the benefits of the first DST shift for the U.S. Credit: U.S. Library of Congress image in the Public Domain.

Most folks trace the notion of daylight saving time back to Benjamin Franklin, though DST saw its first implementation by Axis powers in 1916 as a cost saving measure. In the United States, the Standard Time Act of 1918 put DST into effect for the first time, and it was an on again, off again affair through most of the 20^th century.

And it’s not just your imagination: we do spring forward earlier and fall back later in the year than we used to. The Uniform Time Act was amended in 1986 to begin DST on the first Sunday in April and run until the last Sunday in October. And as mentioned previously, the Energy Policy Act of 2005 modified this even further under President George W. Bush to our present state of affairs, starting DST on the second Sunday of March through the first Sunday in November.

The primary rational behind DST use is to cut energy consumption. Studies done by the U.S. Department of Transportation during the adoption of DST during the 1970’s OPEC Oil Embargo and the energy crisis showed a small but measurable net savings during the implementation of DST, as well as a small decrease in the crime rate. On the down side, many find it difficult to adjust their body clocks to the shift, with many morning commuters now confronted with darkness.

Is DST a conspiracy of the golf crowd and/or the candy lobby? Anecdotal tales abound that some senators simply wanted few more hours on the course each evening, and “Big Sugar” (a great pro-wrestling name, BTW) was all too willing to oblige. Certainly, we do our trick-or-treating in the daylight now on the last day of October, and will soon be waiting later and later each Sunday evening for astronomical darkness and the start of the Virtual Star Party.

But there are some rumblings of change. This year, Idaho is pushing to scrap DST altogether. And, as is the norm in the often curious state of Florida, lawmakers have proposed to swing even further in the other direction, with a bill dubbed the “Sunshine Protection Act” looking to put the entire state on permanent DST year round in hopes of increasing tourism.

And just last year, a failed White House petition brought up the issue of ending DST. Perhaps their misspelling of DST as “Daylight Savings” (a frequent mistake) detracted from its credibility. What is it that makes us just want to throw that spurious “s” in there?

And that’s the wacky state of time we’re stuck with. Yes, we’ll be ferreting out those non-networked clocks around Astroguyz HQ Sunday morning, bleary from the loss of an hours’ sleep.

Our modest proposal is to do away with DST and time zones entirely, and adopt the use of Universal Time (also referred to as Zulu or Greenwich Mean Time) across the board. I know, it’s a tall order. In the meantime, we’ll be saying #DownWithDST on Twitter, as we await true astronomical darkness at an ever later hour.

And with that, we’ll open the debate up to you, the astute and intelligent readership of Universe Today. Is Daylight Saving Time worth it?

February 24, 2014April 26, 2016 by David Dickinson

Watch the Moon Meet Venus in the Dawn this Wednesday

The view of Wednesday's conjunction from selected sites based on four separate continents. Credit: Created by the author using Stellarium.

Are you ready for some lunar versus planetary occultation action? One of the best events for 2014 occurs early this Wednesday morning on February 26^th, when the waning crescent Moon — sometimes referred to as a decrescent Moon — meets up with a brilliant Venus in the dawn sky. This will be a showcase event for the ongoing 2014 dawn apparition of Venus that we wrote about recently.

This is one of 16 occultations of a planet by our Moon for 2014, which will hide every naked eye classical planet except Jupiter and only one of two involving Venus this year.

An occultation occurs when one celestial body passes in front of another, obscuring it from our line of sight. The term is used to refer to planets or asteroids blocking out distant stars or the Moon passing in front of stars or planets.

Wednesday’s event has a central conjunction time of 5:00 Universal. Viewers in northwestern Africa based in Mali and southern Algeria and surrounding nations will see the occultation occur in the dawn sky before sunrise, while viewers eastward across the Horn of Africa, the southern Arabian peninsula, India and southeast Asia will see the occultation occur in the daylight.

A comparison of Venus versus the Moon in the daytime taken by Sharin Ahmad (@shahgazer) from Malaysia during the last lunation on January 29th, 2014.

Observers worldwide, including those based in Australia, Europe and the Americas will see a near miss, but early risers will still be rewarded with a brilliant dawn pairing of the second and third brightest objects in the night sky. This will also be a fine time to attempt to spot Venus in the daytime, using the nearby crescent Moon as a guide. It’s easier than you might think! In fact, Venus is actually brighter than the Moon per apparent square arc second of surface area, owing to its higher average reflectivity (known as albedo) of 80% versus the Moon’s dusky 14%.

The International Occultation Timing Association also maintains a chart of ingress and egress times for specific locations along the track of the occultation.

Credit: Created using Occult 4.0.11. — The footprint of the Wednesday occultation of Venus by the Moon. Solid lines indicate where the occultation occurs before sunrise, while the dashed area denotes where the occultation occurs after sunrise. Credit: Created using Occult 4.1.0.11.

The Moon occults Venus 21 times in this decade. The last occultation of Venus by the Moon occurred on September 8^th, 2013, and the next occurs October 23rd 2014 over the South Pacific in daylight skies very close to the Sun, and is unobservable.

Wednesday’s event also offers a unique opportunity to catch a crescent Venus emerging from behind the dark limb of the Moon. On Wednesday, Venus presents a 34” diameter disk that is 35% illuminated and shining at magnitude -4.3, while the Moon is a 12% illuminated crescent three days from New. Fun fact: February 2014 is missing a New Moon, meaning that both January and March will each contain two!

Apparent path of Venus in relation to the Moon Wednesday morning as seen from a theoretical geocentric (Earth-centered) location. Created using Starry Night Education software.

This also means that a well positioned observer in northwestern Africa would be able to see able to catch the dark limb of Venus creeping out from behind the nighttime side of the Moon against a dark sky. Such favorable occurrences only happen a handful of times per decade, and this week would be a great time to try and briefly spot – or perhaps even video or photograph – a phenomenon know as the ashen light of Venus as the dazzling crescent daytime side of the planet lay obscured by the Moon. Is this effect reported by observers over the years a fanciful illusion, or a real occurrence?

Perhaps, due to the remote location, this chance to spy and record this elusive effect will go unnoticed this time ‘round. The next chance with optimal possibilities to catch a crescent Venus occulted by the Moon against a dark sky occurs next year on October 8th, 2015, favoring the Australian outback. Anyone out there down for an observing expedition to prove or disprove the ashen light of Venus once and for all? Astronomy road trip!

Photo by Author — April 22nd, 2009 conjunction of Venus and the Moon as seen from Hudson, Florida. The Photo by author.

This event also provides optimal circumstances as Venus heads towards greatest elongation west of the Sun on March 22^nd and the Moon-Venus pair lay 43 degrees west of the Sun during Wednesday’s event. Compare this to the impossible to observe occultation this October, when the pairing is only one degree east of the Sun! The next occultation of Venus for North America occurs next year on December 7th, 2015 and will be visible in the daytime across the extent of the track except for Alaska and Northwestern Canada.

Vexillographers may also want to take note: this week’s Venus-Moon pairing will closely emulate the familiar crescent Moon plus star pairing seen on many national flags worldwide. Did an ancient and unrecorded occultation of Venus by the Moon inspire this meme? Tradition has it that Sultan Alp Arslan settled on the star and crescent for the flag of the Turks after witnessing a close conjunction after the defeat of the Byzantine Army at the Battle of Manzikert on August 26^th, 1071 A.D. This tale, however, is almost certainly apocryphal, as no occultations of planets or bright stars by the Moon occurred on or near that date, and only two occultations of Venus by the Moon occurred that year. And Venus was less than two degrees from the Sun on that date, yet another strike against it. In fact, the only occultations of Venus by the Moon in 1071 occurred on June 29^th and November 27^th. Perhaps Arslan just took a while to decide…

Still, this week’s event provides a great photo-op to have “Fun with Flags” and capture the pair behind your favorite astronomical conjunction-depicting banner. And be sure to send those pics into Universe Today… methinks there’s a good chance of us running a post occultation photo-essay later this week!

February 19, 2014December 23, 2015 by David Dickinson

Dazzling New Views of a Familiar Cluster

Wow. It’s always amazing to get new views of familiar sky targets. And you always know that a “feast for the eyes” is in store when astronomers turn a world-class instrument towards a familiar celestial object.

Such an image was released this morning from the European Southern Observatory (ESO). Astronomers turned ESO’s 2.2-metre telescope towards Messier 7 in the constellation Scorpius recently, and gave us the star-studded view above.

Also known as NGC 6475, Messier 7 (M7) is an open cluster comprised of over 100 stars located about 800 light years distant. Located in the curved “stinger” of the Scorpion, M7 is a fine binocular object shining at a combined magnitude of about +3.3. M7 is physically about 25 light years across and appears about 80 arc minutes – almost the span of three Full Moons – in diameter from our Earthly vantage point.

One of the most prominent open clusters in the sky, M7 lies roughly in the direction of the galactic center in the nearby astronomical constellation of Sagittarius. When you’re looking towards M7 and the tail of Scorpius you’re looking just south of the galactic plane in the direction of the dusty core of our galaxy. The ESO image reveals the shining jewels of the cluster embedded against the more distant starry background.

Messier 7 is middle-aged as open clusters go, at 200 million years old. Of course, that’s still young for the individual stars themselves, which are just venturing out into the galaxy. The cluster will lose about 10% of its stellar population early on, as more massive stars live their lives fast and die young as supernovae. Our own solar system may have been witness to such nearby cataclysms as it left its unknown “birth cluster” early in its life.

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Other stars in Messier 7 will eventually mature, “join the galactic car pool” in the main sequence as they disperse about the plane of the galaxy.

But beyond just providing a pretty picture, studying a cluster such as Messier 7 is crucial to our understanding stellar evolution. All of the stars in Messier 7 were “born” roughly around the same time, giving researchers a snapshot and a chance to contrast and compare how stars mature over there lives. Each open cluster also has a unique spectral “fingerprint,” a chemical marker that can even be used to identify the pedigree of a star.

For example, there’s controversy that the open cluster Messier 67 may actually be the birth place of our Sun. It is interesting to note that the spectra of stars in this cluster do bear a striking resemblance in terms of metallicity percentage to Sol. Remember, metals in astronomer-speak is any element beyond hydrogen and helium. A chief objection to the Messier 67 “birth-place hypothesis” is the high orbital inclination of the open cluster about the core of our galaxy: our Sun would have had to have undergone a series of improbable stellar encounters to have ended up its current sedate quarter of a billion year orbit about the Milky Way galaxy.

Still, this highlights the value of studying clusters such as Messier 6. It’s also interesting to note that there’s also data in what you can’t see in the above image – dark gaps are thought to be dust lanes and globules in the foreground. Though there is some thought that this dust is debris that may also be related to the cluster and may give us clues as to its overall rotation, its far more likely that these sorts of “dark spirals” related to the cluster have long since dispersed. M7 has completed about one full orbit about the Milky Way since its formation.

Another famous binocular object, the open cluster Messier 6 (M6) also known as the Butterfly Cluster lies nearby. Messier 7 also holds the distinction as being the southernmost object in Messier’s catalog. Compiled from Parisian latitudes, Charles Messier entirely missed southern wonders such as Omega Centauri in his collection of deep sky objects that were not to be mistaken for comets. We also always thought it curious that he included such obvious “non-comets” such as the Pleiades, but missed fine northern sky objects as the Double Cluster in the northern constellation Perseus.

Finding Messier 6: the view from latitude 30 degrees north before dawn in mid-February. Credit: Stellarium.

Messier 7 is also sometimes called Ptolemy’s Cluster after astronomer Claudius Ptolemy, who first described it in 130 A.D. as the “nebula following the sting of Scorpius.” The season for hunting all of Messier’s objects in an all night marathon is coming right up in March, and Messier 7 is one of the last targets on the list, hanging high due south in the early morning sky.

Interested in catching how Messier 7 will evolve, or might look like up close? Check out Messier 45 (the Pleiades) and the V-shaped Hyades high in the skies in the constellation Taurus at dusk to see what’s in store as Messier 7 disperses, as well as the Ursa Major Moving Group.

And be sure to enjoy the fine view today of Messier 7 from the ESO!

Got pics of Messier 7 or any other deep sky objects? Send ’em, in to Universe Today!

February 18, 2014December 23, 2015 by David Dickinson

Now’s the Time to See Asteroid Pallas at its Best

Looking for something off of the beaten celestial path to observe? The coming weeks will offer telescope users a rare chance to catch a well known asteroid, as it puts on its best show for over two decades.

Over the coming weeks, 2 Pallas, one of the “big four” asteroids – or do you say minor/dwarf planet/planetoid? – reaches a favorable observing point known as opposition. Gliding northward through the constellations of Hydra and Sextans through February and March 2014, 2 Pallas presents a favorable binocular challenge for both northern and southern hemisphere observers as it rises to the east opposite to the setting Sun and transits the local meridian around midnight.

And although 2 Pallas reaches opposition roughly every 16 months as seen from our Earthly vantage point, 2014 provides a chance to catch it under exceptional circumstances. And to top it off, the other “Big 4” asteroids – 1 Ceres, 3 Juno and 4 Vesta – are all currently visible as well and reach opposition in the January through April time frame.

Pallas HST — 2 Pallas as imaged by the Hubble Space Telescope. Credit: NASA

Pallas and its brethren also have a checkered history though the course of 19^th century astronomy. The second minor planet to be discovered, Heinrich Wilhelm Olbers spied 2 Pallas near opposition on the night of March 28^th, 1802. Olbers made this discovery observing from his home rooftop observatory in Bremen, Germany using a five foot – telescopes were often measured in focal length rather than aperture in those days – Dollond refractor.

Olbers discovered 2 Pallas on the border of the astronomical constellations of Virgo and Coma Berenices shining at magnitude +7.5.

Pallas orbit — A simulation of the orbit of 2 Pallas near opposition this month. Credit: NASA/JPL Horizons.

If the name Olbers sounds familiar, it’s because he also lent it to the paradox that now bears his name. Obler’s paradox was one of the first true questions in cosmology posed in a scientific framework that asked: if the universe is actually infinite in time and space, then why isn’t the sky infinitely bright? And, on a curious side note, it was American horror author Edgar Allan Poe that delivered the answer.

But now back to our solar system. Olbers also discovered 4 Vesta just five years after Pallas.

He was definitely on a roll. The discoveries of these space rocks also grabbed the attention of Olbers contemporary, Johann Bode. Bode had formulated a law now known as the Titus-Bode Law that seemed to put the spacing of then known bodies of the solar system in tidy order. In fact, the Titus-Bode law seemed to predict that a body should lie between Mars and Jupiter, and for a brief time in the 18^th century — and again in 2006 when the International Astronomical Union let Eris and Pluto in the door before kicking them back out — Ceres, Pallas, Juno and Vesta were all considered planets.

Comparison — A size comparison of the first ten asteroids discovered compared to Earth’s moon. Wikimedia Commons graphic in the Public Domain.

Today, we now know that 2 Pallas is a tiny world about 575 kilometres in diameter. 2 Pallas orbits the Sun once every 4.62 years and has a relatively high inclination of 34.8 degrees relative to the ecliptic. Pallas has no confirmed satellites, though one was once hinted at during a May 29th, 1979 stellar occultation. And though we’ve yet to send a mission to examine Pallas up close, there were early planning considerations to send NASA’s Dawn spacecraft there after its visit to 1 Ceres.

wide — The path of 2 Pallas from February 16th though March 21st. Created by the author using Stellarium.

This month, look for 2 Pallas as a +7^th magnitude wandering star at dusk. Mid-February finds 2 Pallas in the constellation Hydra, and it crosses briefly into Sextans starting on March 22^nd until it passes just three degrees east of the 2nd magnitude Alphard (Alpha Hydrae) on March 1^st, making a good guidepost to find it at its brightest.

2 Pallas last broke +7^th magnitude visibility as seen from Earth in 1991 and won’t do so again til 2028. This is because 18.5 Earth years very nearly equals four orbits of Pallas around the Sun, bringing the two worlds back “into sync.” According to calculations by Belgian astronomer Jean Meeus, the 2014 opposition season offers the closest passage to Earth for Pallas from 1980-2060. Pallas can appear at a maximum brightness of magnitude +6.5 — just on the threshold of naked eye visibility — as seen from Earth.

Narrow — A narrow field finder chart for 2 Pallas with sample comparison magnitudes, decimal points omitted. Created by the author using Stellarium.

Opposition for Pallas occurs on February 22^nd, 2014, when the asteroid is 1.23 AUs distant from our fair planet. Watch for 2 Pallas near opposition this year moving at just under half a degree a day — about the diameter of the Full Moon — headed northward at closest approach.

Hunting asteroids at the eyepiece can be a challenge, as they visually resemble pinpoint stars and show no apparent disks even at high magnification. Sketching or photographing the field of view on successive nights is a fun and easy way to cross this object off of your life list. For those who own scopes with digital setting circles, Heavens-Above is a great quick look source for current coordinates.

2 Pallas just passed perihelion at 2.13 Astronomical Units from the Sun on December 6^th, 2013, and passes closest to Earth on February 24^th at 1.2 A.U.s distant.

Don’t miss the chance to spy this fascinating an enigmatic worldlet coming to a sky near you this season!

-Got pics of 2 Pallas and friends? Be sure to send ‘em in to Universe Today!