David Dickinson, Author at Universe Today

July 25, 2014December 23, 2015 by David Dickinson

Having Fun with the Equation of Time

An analemma of the Sun, taken from Budapest, Hungary over a one year span. (Courtesy of György Soponyai, used with permission).

If you’re like us, you might’ve looked at a globe of the Earth in elementary school long before the days of Google Earth and wondered just what that strange looking figure eight thing on its side was.

Chances are, your teacher had no idea either, and you got an answer such as “it’s a calendar, kid” based on the months of the year marking its border.

In a vague sense, this answer is correct… sort of. That funky figure eight is what’s known as an analemma, and it traces out the course of the Sun in the sky through the year as measured from a daily point fixed in apparent solar time.

Analemma (Wikimedia Commons image). — Ye ole analemma… perpetually lost in the South Pacific? (Wikimedia Commons image).

But try explaining that one to your 3^rd grade teacher. Turns out, measuring the passage of time isn’t as straight forward as you’d think. Our modern day clock and calendar is a sort of compromise, a method of marking the passage of time in a continuing battle to stay in sync with the heavens.

For most of history, the daily passage of time was denoted by the Sun. Solar Noon occurs when the Sun stands at its highest elevation (also known as its altitude) above the local horizon when it transits the north-south meridian. The trouble is, the passage apparent solar time doesn’t exactly match what we call solar mean time, or the 24 hour rotation of the Earth. In fact, this discrepancy can add up to as much as more than 16 minutes ahead of solar noon in late October and November and over 12 minutes behind it in February. This is worth bringing up this week because this factor, known as “The Equation of Time” — think “equation” in the sense that sundial owners must factor it in to make solar mean and apparent time “equal” — reaches its shallow minimum for 2014 this Saturday at 7:00 UT/3:00 AM EDT with a value of -6.54 minutes.

The solar analemma as plotted from the latitude of the Greenwich Observatory in England. (Wikimedia Commons/PAR/JPL Horizons).

So, what gives? Why won’t the pesky universe stay in sync?

Well, the discrepancy arises from two factors: the eccentricity of the Earth’s orbit, or how much it deviates from circular and the obliquity of the ecliptic to the celestial equator, think the tilt of Earth’s axis. Of the two, obliquity is the major factor, with eccentricity playing a minor but measurable role. And remember, we move slightly faster in our orbit in January near perihelion as per Kepler’s Laws of planetary motion than at aphelion, which occurred earlier this month , though be careful not to confuse the term “faster” with “sun fast.”

This means that were the Earth to orbit the Sun in a perfect circle with its poles perpendicular to its orbit, apparent and mean time would essentially stay in sync. Of course, no known planet has such a perfect alignment scenario, and other worlds do indeed host alien analemmas (analemmae?) of their own.

It’s also interesting to note that the two each major and minor minima of the Equation of Time roughly coincide with the four cross quarter tie in days of the year (marked by Groundhog’s Day, May Day, Lammas Day and Halloween, respectively) while the zero value points fall within a few weeks of the equinoxes and solstices.

A graph showing the flucuation of the value of the Equation of Time throughout the callendar year. (Created by the author). — A graph showing the fluctuation of the value of the Equation of Time (with minutes on the vertical axis) throughout the calendar year. (Created by the author).

In the current epoch, the deep minimum falls on February 21^st, while the highest maximum falls on November 3^rd on non-leap years. The four zero value dates are April 15^th, June 13^th, September 1^st and December 25^th respectively. The exact timing of these also slip to the tune of about a second a year, but of course, most sundials lack this sort of precision.

A "globe sundial" on the University of North Dakota at grand Forks campus. (Photo by author). — A “globe sundial” on the University of North Dakota at Grand Forks campus. (Photo by author).

So, why should we care about the Equation of Time in the modern atomic clock age? It is true that there have been calls over the past few years to “abolish the leap second” and go off of the astronomical time standard entirely… if this ever does come to pass, some future Pope Gregory will have to institute a “leap hour” circa 10,000 A.D. or so to stop the Sun from rising at 2 AM. But some modern day Sun tracking devices (think heliostats or solar panels) do in fact use mechanical timers and must take the equation of time into account to maximize effectiveness.

Impatient? You can plot your very own simulated analemma using a desktop planetarium program. (Credit: Starry Night Education software).

Want to see the Equation of Time in action? You can make your own analemma simply by photographing the position of the Sun at the same time each day. Just remember to account for the shift on and off of Daylight Saving if you live in an area that observes the archaic practice, residents of Arizona need not to take heed. Otherwise, you’ll end up with a “split analemma…” Wintertime near the December Solstice is the best time to start this project, as the Sun is at its lowest noonday culmination and this will assure that your very own personal analemma won’t fall below the local horizon.

Farther afield, the effects of the Precession of the Equinoxes will also tweak the dates of the Equation of Time values a bit. Live out a full 72 year life span, and the equinoctial points will have drifted along the ecliptic by about one degree, twice the diameter of the Full Moon. Incidentally, the failure to take Precession into account is yet another spectacular fail of modern astrology: most “houses” or “signs” have drifted in the past millennia to the point where most “Leos” are in fact “Cancers!”

Such is the challenges and vagaries of modern day astronomical time-keeping. Let us know of your tales of tragedy and triumph as you hunt down the elusive analemma.

July 18, 2014December 23, 2015 by David Dickinson

Observing Challenge: 6 White Dwarf Stars to See in Your Backyard Telescope

Dazzlimg Sirius, with its white dwarf companion to the lower left. Credit: NASA, ESA, H. Bond (STScI) and M. Barstow (University of Leicester).

Looking for something off beat to observe? Some examples of curious astronomical objects lie within the reach of the dedicated amateur armed with a moderate-sized backyard telescope. With a little skill and persistence, you just might be able to track down a white dwarf star. Unlike splashy nebulae or globular clusters, a white dwarf star will just appear as a speck, a tiny dot in the field of view of your telescope’s eyepiece. But just as in the case of observing other exotic objects such as red giants and quasars, part of the thrill of tracking down these astrophysical beasties is in knowing just what it is that you’re seeing. Heck, many amateur astronomers fail to realize that any white dwarf stars are within range of their instruments and have never tracked one down.

The astrophysical nature of white dwarf stars was first uncovered in the early 20^th century. Most of the early white dwarf stars discovered were companions in binary star systems and this allowed astronomers to gauge their mass by following the orbital motion of such pairs over time. Soon, astronomers realized that they were looking at something peculiar, a new type of compact but massive stellar object that stubbornly refused to be pigeon-holed along the main sequence of the freshly conceived Hertzsprung-Russell diagram.

Today, we know that white dwarf stars are the remnants of stars which have long since passed the Red Giant stage. We say that a white dwarf is a degenerate star, and no, this not a commentary on its moral state. The Chandrasekhar limit gives us an upper limit in size for a white dwarf at about 1.4 solar masses, beyond which electron degeneracy pressure can no longer act against the inward pull of gravity. Our Sun will one day become a white dwarf, over 6 billion years from now. Think of cramming the mass of our star into the volume of the Earth and you have some idea just how dense a white dwarf is: a cubic centimetre of white dwarf weighs 250 about tons, and two cup fulls of white dwarf would weigh more than a Nimitz-class aircraft carrier.

Think of a white dwarf as a cooling ember of a star long past its hydrogen fusing prime. And white dwarfs will cool down to infrared radiating black dwarfs over trillions of years, far longer than the present 13.7 billion year age of the universe. In fact, the age of white dwarfs currently observed is one on the underpinning tenets of modern Big Bang cosmology.

All amazing stuff. In any event, here is a baker’s half dozen of white dwarf stars that you can find with a telescope tonight. A more extensive list of the nearest white dwarfs to the Earth can be found on Sol Station.

The orbit of Sirius B. Wikimedia Commons image in the Public Domain.

Sirius B: This is the nearest white dwarf to the Earth at 8.6 light years distant. Shining at magnitude +8.5, Sirius B would be a cinch to see, if only dazzling Sirius A — the brightest star in our sky at magnitude -1.5 — were not nearby. Sirius B orbits its primary once every 50 years and will reach a maximum separation of 11.5” from its primary in 2025, a prime time to cross it off of your life list in the coming decade. Blocking the primary just out of the field of view, or using an occulting bar eyepiece is key to finding Sirius B.

Sirius B was discovered by American telescope maker Alvan Graham Clark in 1862. The Dogon people of Mali also have some curious myths surrounding the star Sirius.

Constellation: Canis Major

Right Ascension: 6 Hours 45’

Declination: -16° 43’

The apparent orbit of Procyon B through 2039. Graphic created by the author.

Procyon B: Located 11.5 light years distant, Procyon B was discovered in 1896 by John Martin Schaeberle from the Lick observatory. Shining at magnitude +10.7, the chief difficultly with spotting this white dwarf, as with Sirius B, is that it has a companion about 10 magnitudes – that’s 10,000 times brighter – nearby just 4.3” away.

Constellation: Canis Minor

Right Ascension: 7 hours 39’

Declination: +5 13’

The location of GJ 440 (HIP 57367) in the southern sky. Credit: Starry Night Education Software.

-LP145-141: Also known as GJ 440, LP145-141 is one of the best southern hemisphere white dwarf stars on the list. LP145-141 is a solitary white dwarf shining at magnitude +11.5. Located 15 light years distant, LP145-141 is thought to be a member of the nearby Wolf 219 Moving Group of stars.

Constellation: Musca

Right Ascension: 11 Hours 46’

Declination: -64° 50’

The location of Van Maanen’s Star in the constellation Pisces. Credit: Stellarium

-Van Maanen’s Star: Shining at magnitude +12.4 and located 14.1 light years distant, Van Maanen’s star is the closest solitary white dwarf to Earth and the best example of a white dwarf for small telescopes. Discovered by Ariaan van Maanen in 1917, Van Maanen’s Star also has a very high proper motion of 3” per year.

Constellation: Pisces

Right Ascension: 00 Hours 49’

Declination: 05° 23’

The 40 Omicron Eridani system. Image by Author

-40 Omicron Eridani B: This is a great one to track down. The triple system of 40 Omicron Eridani b contains a fine example of a red and white dwarf orbiting a main sequence star. Located 16.5 light years distant and shining at magnitude +9.5, Omicron Eridani was the first white dwarf star discovered in 1783 by Sir William Herschel, although its true nature wasn’t deduced until 1910. Omicron Eridani B is currently 82” from its primary, an easy split.

Constellation: Eridanus

Right Ascension: 4 Hours 15’

Declination: 7° 39’

-Stein 2051: Rounding off the list and located just over 18 light years distant, Stein 2051 is another example of a red dwarf/white dwarf pair. Stein 2051 b shines at a similar brightest to Van Maanen’s star at magnitude +12.4.

Constellation: Camelopardalis

Right Ascension: 04 Hours 31’

Declination: +58° 59’

Let us know about your trials and triumphs in hunting down these fascinating objects!

July 8, 2014December 23, 2015 by David Dickinson

Would the Real ‘SuperMoon’ Please Stand Up?

The perigee Full Moon of June 22nd, 2013. Credit: Russell Bateman (@RussellBateman1)

‘Tis the season once again, when rogue Full Moons nearing perigee seem roam the summer skies to the breathless exhortations of many an astronomical neophyte at will. We know… by now, you’d think that there’d be nothing new under the Sun (or in this case, the Moon) to write about the closest Full Moons of the year.

But love ‘em or hate ‘em, tales of the “Supermoon” will soon be gracing ye ole internet again, with hyperbole that’s usually reserved for comets, meteor showers, and celeb debauchery, all promising the “biggest Full Moon EVER…” just like last year, and the year be for that, and the year before that…

How did this come to be?

What’s happening this summer: First, here’s the lowdown on what’s coming up. The closest Full Moon of 2014 occurs next month on August 10^th at 18:11 Universal Time (UT) or 1:44 PM EDT. On that date, the Moon reaches perigee or its closest approach to the Earth at 356,896 kilometres distant at 17:44, less than an hour from Full. Of course, the Moon reaches perigee nearly as close once every anomalistic month (the time from perigee-to-perigee) of 27.55 days and passes Full phase once every synodic period (the period from like phase to phase) with a long term average of 29.53 days.

Moon rise on the evening of July 11th, 2014 as seen from latitude 30 degrees north. Credit: Stellarium.

And the August perigee of the Moon only beats out the January 1^st, 2014 perigee out by a scant 25 kilometres for the title of the closest perigee of the year, although the Moon was at New phase on that date, with lots less fanfare and hoopla for that one. Perigee itself can vary from 356,400 to 370,400 kilometres distant.

But there’s more. If you consider a “Supermoon” as a Full Moon falling within 24 hours of perigee, (folks like to play fast and loose with the informal definitions when the Supermoon rolls around, as you’ll see) then we actually have a trio of Supermoons on tap for 2014, with one this week on July 12^th and September 9th as well.

What, then, is this lunacy?

Well, as many an informative and helpful commenter from previous years has mentioned, the term Supermoon was actually coined by an astrologer. Yes, I know… the same precession-denialists that gave us such eyebrow raising terms as “occultation,” “trine” and the like. Don’t get us started. The term “Supermoon” is a more modern pop culture creation that first appeared in a 1979 astrology publication, and the name stuck. A more accurate astronomical term for a “Supermoon” is a perigee-syzygy Full Moon or Proxigean Moon, but those just don’t seem to be able to “fill the seats” when it comes to internet hype.

One of the more arcane aspects set forth by the 1979 definition of a Supermoon is its curiously indistinct description as a “Full Moon which occurs with the Moon at or near (within 90% of) its closest approach to Earth in a given orbit.” This is a strange demarcation, as it’s pretty vague as to the span of distance (perigee varies, due to the drag of the Sun on the Moon’s orbit in what’s known as the precession of the line of apsides) and time. The Moon and all celestial bodies move faster near perigee than apogee as per Kepler’s 2nd Law of planetary motion.

A photo essay comparing Full Moon sizes and appearance from one Supermoon to the next, spanning 2011-2012. Credit: Marion Haligowski/RadicalRetinscopy. Used with permission.

We very much prefer to think of a Proxigean Moon as defined by a “Full Moon within 24 hours of perigee”. There. Simple. Done.

And let’s not forget, Full phase is but an instant in time when the Moon passes an ecliptic longitude of 180 degrees opposite from the Sun. The Moon actually never reaches 100% illumination due to its 5.1 degree tilt to the ecliptic, as when it does fall exactly opposite to the Sun it also passes into the Earth’s shadow for a total lunar eclipse.

-Check out this animation of the changing size of the Moon and its tilt — known as libration and nutation, respectively — as seen from our Earthly perspective over the span of one lunation.

The truth is, the Moon does vary from 356,400 to 406,700 kilometres in its wonderfully complicated orbit about our fair world, and a discerning eye can tell the difference in its size from one lunation to the next. This means the apparent size of the Moon can vary from 29.3’ to 34.1’ — a difference of almost 5’ — from perigee to apogee. And that’s not taking into account the rising “Moon illusion,” which is actually a variation of an optical effect known as the Ponzo Illusion. And besides, the Moon is actually more distant when its on the local horizon than overhead, to the tune of about one Earth radius.

Like its bizarro cousin the “minimoon” and the Blue Moon (not the beer), the Supermoon will probably now forever be part of the informal astronomical lexicon. And just like recent years before 2014, astronomers will soon receive gushing platitudes during next month’s Full Moon from friends/relatives/random people on Twitter about how this was “the biggest Full Moon ever!!!”

Credit Stephen Rahn — The perigee Full Moon of May 5th, 2012. Credit: Stephen Rahn (@StephenRahn13)

Does the summer trio of Full Moons look bigger to you than any other time of year? It will be tough to tell the difference visually over the next three Full Moons. Perhaps a capture of the July, August and September Full Moons might just tease out the very slight difference between the three.

And for those preferring not to buy in to the annual Supermoon hype, the names for the July, August and September Full Moons are the Buck, Sturgeon and Corn Moon, respectively. And of course, the September Full Moon near the Equinox is also popularly known as the Harvest Moon.

And in case you’re wondering, or just looking to mark your calendar for the next annual “largest Full Moon(s) of all time,” here’s our nifty table of Supermoons through 2020, as reckoned by our handy definition of a Full Moon falling within 24 hours of perigee.

So what do you say? Let ‘em come for the hype, and stay for the science. Let’s take back the Supermoon.

July 3, 2014December 23, 2015 by David Dickinson

A Spectacular Set of Conjuctions on Tap for the Moon, Mars and Saturn this Weekend

Saturn passing behind the lunar limb on May 15th.

Got clear skies this July 4^th weekend? The Moon passes some interesting cosmic environs in the coming days, offering up some photogenic pairings worldwide and a spectacular trio of occultations for those well placed observers who find themselves along the footprint of these events.

The path of the Moon on July 5th, 6th and 7th. Credit: Stellarium

First, let’s look at our closest natural neighbor in space. The Moon reaches first quarter phase on Saturday, July 5^th at 11:59 Universal Time (UT)/7:59 AM EDT. First Quarter is a great time to observe the Moon, as the craters along the jagged terminator where the Sun is just starting to rise stand out in stark profile. Watch for the Lunar Straight Wall and the alphabet soup of elusive features known as the Lunar X or Purbach Cross and Lunar V on evenings right around First Quarter phase.

Mars off of the limb of the Moon as seen from North America on the evening of July 5th. Credit: Starry Night.

Our first conjunction stop on this weekend’s lunar journey is the planet Mars. Although the Moon occults — that is, passes in front of a given planet from our Earthly perspective — exactly 16 naked eye planets in 2014 (24 if you add in Uranus events and 1 Ceres and 4 Vesta on September 28^th), the Moon will only occult Mars once in 2014, on the night of July 5^th/6^th. Northern South America and southern Central America will have a front row seat, while the rest of North America will see a close pass less than one degree from the lunar limb. This will still present a fine photographic opportunity, as it’ll be possible to snag Mars and the limb of the Moon in the same field of view. The Moon will be 56% illuminated during the conjunction, and Mars will present an 88% illuminated disk 9.2” across shining at magnitude +0.3.

The occultation path for Mars. Graphics created using Occult 4.0.

Both will be 96 degrees east of the Sun during geocentric (Earth-centered) conjunction, which occurs around 1:00 UT on July 6^th or 9:00 PM EDT on the evening of the 5^th. For those positioned to catch the occultation, it’ll take about a minute for “Mars set” to occur on the lunar limb. The last occultation of Mars occurred on May 9^th, 2013 and the next won’t happen ‘til March 21^st, 2015.

Next up, the Moon occults the +4.5^th magnitude star Lambda Virginis on July 7^th centered on 8:26 UT. This event is well placed for observers in Hawaii on the evening of July 6^th. Located 187 light years distant, the light that you’re seeing departed the far-flung star on 1827, only to be interrupted by the pesky limb of our Moon a second prior to arrival on Earth. This star is also of note as it’s a spectroscopic binary, and while you won’t be able to resolve the pair at a tiny separation of just 0.0002” apart, you just might be able to see the pair “wink out” in a step wise fashion that betrays its binary nature. The Moon misses the brightest star in Virgo (Spica) this month, as it’s wrapped up a series of occultations of the star in early 2014 and won’t resume until 2024. Aldebaran, Antares and Regulus also lie along the Moon’s path on occasion, and the next cycle of bright star occultations resume with Aldebaran in January 2015. You can check out a list of fainter naked eye stars occulted by the Moon this year here courtesy of the International Occultation Timing Association.

And finally, the Moon visits Saturn, now residing just over the border in the astronomical constellation of Libra. This occultation occurs just 49 hours after the Mars event at 2:00 UT on July 8^th (10:00 PM EDT on the evening of July 7^th) and favors observers in the southernmost tip of South America. As with Mars, North America will see a close miss, although it will also be possible to squeeze Saturn in the same field of view as the Moon at low power, though it’ll sit about a degree of off its limb. We’re in a cycle of occultations of Saturn this year, with 11 occurring in 2014 and the next on August 4^th. The reason for this is that Saturn moves much more slowly across the sky than Mars from our perspective, making for a relatively sluggish moving target for the Moon. Saturn shines at +0.6 magnitude as the 75% illuminated Moon passes by and subtends 42” with rings and will take about five minutes to pass fully behind the Moon.

These events will make for some great pics and animation sequences for sure… can you spot Saturn or Mars near the lunar limb with binoculars or a telescope before sunset? Or catch ‘em in the frame during a local fireworks show? Let us know, if enough pics surface on Universe Today’s Flickr page, we may do a post weekend roundup!

June 30, 2014April 26, 2016 by David Dickinson

How to See Pluto at Opposition as New Horizons Crosses the One Year Out Mark

Pluto passing near the star cluster M25 in late 2013. Credit: Dave Walker.

Are you ready for 2015? On July 14^th, 2015 — just a little over a year from now — NASA’s New Horizons spacecraft with perform its historic flyby of Pluto and its retinue of moons. Flying just 10,000 kilometres from the surface of Pluto — just 2.5% the distance from Earth to the Moon on closest approach — New Horizons is expected to revolutionize our understanding of these distant worlds.

And whether you see Pluto as a much maligned planetary member of the solar system, an archetypal Plutoid, or the “King of the Kuiper Belt,” you can spy this denizen of the outer solar system using a decent sized backyard telescope and a little patience.

New Horizon in the clean room having its plutonium-fueled MMRTG installed. (Credit: NASA). — New Horizons in the clean room having its plutonium-fueled MMRTG installed. (Credit: NASA).

Pluto reaches opposition for 2014 later this week on Friday, July 4^th at 3:00 Universal Time (UT), or 11:00 PM EDT on July 3^rd. This means that Pluto will rise to the east as the Sun sits opposite to it in the west at sunset and transits the local meridian high to the south at local midnight. This is typically the point of closest approach to Earth for any outer solar system object and the time it is brightest.

Dusk July 4th Credit — The location of Pluto at dusk on July 4th, the night of opposition. Credit: Stellarium.

But even under the best of circumstances, finding Pluto isn’t easy. Pluto never shows a resolvable disk in even the largest backyard telescope, and instead, always appears like a tiny star-like point. When opposition occurs near perihelion — as it last did in 1989 — Pluto can reach a maximum “brilliancy” of magnitude +13.6. However, Pluto has an extremely elliptical orbit ranging from 30 to 49 Astronomical Units (A.U.s) from the Sun. In 2014, Pluto has dropped below +14^th magnitude at opposition as it heads back out towards aphelion one century from now in 2114.

Pluto from July-Dec — The path of Pluto from July to December 2014. Created using Starry Night Education Software.

Another factor that makes finding Pluto challenging this decade is the fact that it’s crossing through the star-rich plane of the galaxy in the direction of the constellation Sagittarius until 2023. A good finder chart and accurate pointing is essential to identifying Pluto as it moves 1’ 30” a day against the starry background from one night to the next.

In fact, scouring this star-cluttered field is just one of the challenges faced by the New Horizons team as they hunt for a potential target for the spacecraft post-Pluto encounter. But this has also meant that Pluto has crossed some pretty photogenic regions of the sky, traversing dark Bok globules and skirting near star clusters.

Pluto (marked) imaged by Jim Hendrickson on the morning of June 29th. — Pluto (marked) imaged by Jim Hendrickson @SkyscraperJim on the morning of June 28th.

You can use this fact to your advantage, as nearby bright stars make great “guideposts” to aid in your Pluto-quest. Pluto passes less than 30” from the +7^th magnitude pair BB Sagittarii on July 7^th and 8^thand less than 3’ from the +5.2 magnitude star 25 Sagittarii on July 21^st… this could also make for an interesting animation sequence.

Though Pluto has been reliably spotted in telescopes as small as 6” in diameter, you’ll most likely need a scope 10” or larger to spot it. We’ve managed to catch Pluto from the Flandrau observatory situated in downtown Tucson using its venerable 14” reflector.

June 28th-August 8th (inverted) — The path of Pluto June 28th-August 8th. (click here for an inverted white background view). Created using Starry Night Education Software.

Pluto was discovered by Clyde Tombaugh from the Lowell Observatory in 1930 while it was crossing the constellation Gemini. It’s sobering to think that it has only worked its way over to Sagittarius in the intervening 84 years. It was also relatively high in the northern hemisphere sky and headed towards perihelion decades later during discovery. 2014 finds Pluto at a southern declination of around -20 degrees, favoring the southern hemisphere. Had circumstances been reversed, or Pluto had been near aphelion, it could have easily escaped detection in the 20^th century.

We’re also fortunate that Pluto is currently relatively close to the ecliptic plane, crossing it on October 24^th, 2018. Its orbit is inclined 17 degrees relative to the ecliptic and had it been high above or below the plane of the solar system, sending a spacecraft to it in 2015 might have been out of the question due to fuel constraints.

The current location of New Horizons. (Credit: NASA/JPL).

And speaking of spacecraft, New Horizons now sits less than one degree from Pluto as seen from our Earthly vantage point. And although you won’t be able to spy this Earthly ambassador with a telescope, you can wave in its general direction on July 11^th and 12^th, using the nearby waxing gibbous Moon as a guide:

The Moon, Pluto and New Horizons as seen on July 11th. (Created Using Starry Night Education Software).

All eyes will be on Pluto and New Horizons in the coming year, as it heads towards a date with destiny… and we’ll bet that the “is Pluto a planet?” debate will rear its head once more as we get a good look at these far-flung worlds.

And hey, if nothing else, us science writers will at last have some decent pics of Pluto to illustrate articles with, as opposed to the same half-dozen blurry images and artist’s renditions…

June 26, 2014December 23, 2015 by David Dickinson

The Making of the Pillars of Creation

It’s one of the most iconic images of the modern Space Age. In 1995, the Hubble Space Telescope team released an image of towering columns of gas and dust that contained newborn stars in the midst of formation. Dubbed the “Pillars of Creation,” these light-years long tendrils captivated the public imagination and now grace everything from screensavers to coffee mugs. This is a cosmic portrait of our possible past, and the essence of the universe giving birth to new stars and worlds in action.

Now, a study out on Thursday from the 2014 National Astronomy Meeting of the Royal Astronomical Society has shed new light on just how these pillars may have formed. The announcement comes out of Cardiff University, where astronomer Scott Balfour has run computer simulations that closely model the evolution and the outcome of what’s been observed by the Hubble Space Telescope.

The ‘Pillars’ lie in the Eagle Nebula, also known as Messier 16 (M16), which is situated in the constellation Serpens about 7,000 light years distant. The pillars themselves have formed as intense radiation from young massive stars just beginning to shine erode and sculpt the immense columns.

The location of Messier 16 and the Pillars of Creation in the night sky. Credit: Stellarium.

But as is often the case in early stellar evolution, having massive siblings nearby is bad news for fledgling stars. Such large stars are of the O-type variety, and are more than 16 times as massive as our own Sun. Alnitak in Orion’s belt and the stars of the Trapezium in the Orion Nebula are examples of large O-type stars that can be found in the night sky. But such stars have a “burn fast and die young” credo when it comes to their take on nuclear fusion, spending mere millions of years along the Main Sequence of the Hertzsprung Russell diagram before promptly going supernova. Contrast this with a main sequence life expectancy of 10 billion years for our Sun, and life spans measured in the trillions of years — longer than the current age of the universe — for tiny red dwarf stars. The larger a star you are, the shorter your life span.

Such O-Type stars also have surface temperatures at a scorching 30,000 degrees Celsius, contrasted with a relatively ‘chilly’ 5,500 degree Celsius surface temperature for our Sun.

This also results in a prodigious output in energetic ultraviolet radiation by O-type stars, along with a blustery solar wind. This carves out massive bubbles in a typical stellar nursery, and while it may be bad news for planets and stars attempting to form nearby any such tempestuous stars, this wind can also compress and energize colder regions of gas and dust farther out and serve to trigger another round of star formation. Ironically, such stars are thus “cradle robbers” when it comes to potential stellar and planetary formation AND promoters of new star birth.

In his study, Scott looked at the way gas and dust would form in a typical proto-solar nebula over the span of 1.6 million years. Running the simulation over the span of several weeks, the model started with a massive O-type star that formed out of an initial collapsing smooth cloud of gas.

That’s not bad, a simulation where 1 week equals a few hundred million years…

As expected, said massive star did indeed carve out a spherical bubble given the initial conditions. But Scott also found something special: the interactions of the stellar winds with the local gas was much more complex than anticipated, with three basic results: either the bubble continued to expand unimpeded, the front would expand, contract slightly and then become a stationary barrier, or finally, it would expand and then eventually collapse back in on itself back to the source.

The study was notable because it’s only in the second circumstance that the situation is favorable for a new round of star formation that is seen in the Pillars of Creation.

“If I’m right, it means that O-type and other massive stars play a much more complex role than we previously thought in nursing a new generation of stellar siblings to life,” Scott said in a recent press release. “The model neatly produces exactly the same kind of structures seen by astronomers in the classic 1995 image, vindicating the idea that giant O-type stars have a major effect in sculpting their surroundings.”

Such visions as the Pillars of Creation give us a snapshot of a specific stage in stellar evolution and give us a chance to study what we may have looked like, just over four billion years ago. And as simulations such as those announced in this week’s study become more refined, we’ll be able to use them as a predictor and offer a prognosis for a prospective stellar nebula and gain further insight into the secret early lives of stars.

June 23, 2014December 23, 2015 by David Dickinson

Observing Challenge: The Moon Brushes Past Venus and Covers Mercury This Week

The summer astronomical action heats up this week, as the waning crescent Moon joins the inner planets at dawn. This week’s action comes hot on the tails of the northward solstice which occurred this past weekend, which fell on June 21^st in 2014, marking the start of astronomical summer in the northern hemisphere and winter in the southern. This also means that the ecliptic angle at dawn for mid-northern latitude observers will run southward from the northeast early in the morning sky. And although the longest day was June 21^st, the earliest sunrise from 40 degrees north latitude was June 14^th and the latest sunset occurs on June 27^th. We’re slowly taking back the night!

The dawn patrol action begins tomorrow, as the waning crescent Moon slides by Venus low in the dawn sky Tuesday morning. Geocentric (Earth-centered) conjunction occurs on June 24^th at around 13:00 Universal Time/9:00 AM EDT, as the 8% illuminated Moon sits 1.3 degrees — just shy of three Full Moon diameters — from -3.8 magnitude Venus. Also note that the open cluster the Pleiades (Messier 45) sits nearby. Well, nearby as seen from our Earthbound vantage point… the Moon is just over one light second away, Venus is 11 light minutes away, and the Pleiades are about 400 light years distant.

Jun 24 5AM Starry Night — Looking east the morning of Tuesday, June 24th at 5:00 AM EDT from latitude 30 degrees north. Created using Starry Night Education software.

And speaking of the Pleiades, Venus will once again meet the cluster in 2020 in the dusk sky, just like it did in 2012. This is the result of an eight year cycle, where apparitions of Venus roughly repeat. Unfortunately we won’t, however, get another transit of Venus across the face of the Sun until 2117!

Can you follow the crescent Moon up in to the daytime sky? Tuesday is also a great time to hunt for Venus in the daytime sky, using the nearby crescent Moon as a guide. Both sit about 32 degrees from the Sun on June 24^th. Just make sure you physically block the dazzling Sun behind a building or hill in your quest.

From there, the waning Moon continues to thin on successive mornings as it heads towards New phase on Friday, June 27^th at 8:09 UT/4:09 AM EDT and the start of lunation 1132. You might be able to spy the uber-thin Moon about 20-24 hours from to New on the morning prior. The Moon will also occult (pass in front of) Mercury Thursday morning, as the planet just begins its dawn apparition and emerges from the glare of the Sun.

Unfortunately, catching the event will be a challenge. Mercury is almost always occulted by the Moon in the daytime due to its close proximity to the Sun. The footprint of the occultation runs from the Middle East across North Africa to the southeastern U.S. and northern South America, but only a thin sliver of land from northern Alabama to Venezuela will see the occultation begin just before sunrise… for the remainder of the U.S. SE, the occultation will be underway at sunrise and Mercury will emerge from behind the dark limb of the Moon in daylight.

Mercury and the Moon sit 10 degrees from the Sun during the event. Stargazer and veteran daytime planet hunter Shahrin Ahmad based in Malaysia notes that while it is possible to catch Mercury at 10 degrees from the Sun in the daytime using proper precautions, it’ll shine at magnitude +3.5, almost a full 5 magnitudes (100 times) fainter than its maximum possible brightness of -1.5. The only other occultation of Mercury by the Moon in 2014 favors Australia and New Zealand on October 22^nd.

This current morning apparition of Mercury this July is equally favorable for the southern hemisphere, and the planet reaches 20.9 degrees elongation west of the Sun on July 12^th.

You can see Mercury crossing the field of view of SOHO’s LASCO C3 camera from left to right recently, along with comet C/2014 E2 Jacques as a small moving dot down at about the 7 o’clock position.

And keep an eye on the morning action this summer, as Jupiter joins the morning roundup in August for a fine pairing with Venus on August 18^th.

The Moon will then reemerge in the dusk evening sky this weekend and may just be visible as a 40-44 hour old crescent on Saturday night June 28^th. The appearance of the returning Moon this month also marks the start of the month of Ramadan on the Islamic calendar, a month of fasting. The Muslim calendar is strictly based on the lunar cycle, and thus loses about 11 days per year compared to the Gregorian calendar, which strives to keep the tropical and sidereal solar years in sync. On years when the sighting of the crescent Moon is right on the edge of theoretical observability, there can actually be some debate as to the exact evening on which Ramadan will begin.

Don’t miss the wanderings of our nearest natural neighbor across the dawn and dusk sky this week!

June 17, 2014December 23, 2015 by David Dickinson

Asteroid-Turned-Comet 2013 UQ4 Catalina Brightens: How to See it This Summer

Though ISON may have fizzled in early 2014, we’ve certainly had a bevy of binocular comets to track this year. Thus far in 2014, we’ve had comets R1 Lovejoy, K1 PanSTARRS, and E2 Jacques reach binocular visibility. Now, and asteroid-turned-comet is set to put on a fine show this summer for northern hemisphere observers.

Veteran stargazer and Universe Today contributor Bob King told the tale last month of how the asteroid formerly known as 2013 UQ4 became comet 2013 UQ4 Catalina. Discovered last year on October 23^rd 2013 during the routine Catalina Sky Survey searching for Near Earth Objects based outside of Tucson Arizona, this object was of little interest until early this year.

As it rounded the Sun, astronomers recovered the asteroid and discovered that it had begun to sprout a fuzzy coma, a very un-asteroid-like thing to do. Then, on May 7^th, Taras Prystavski and Artyom Novichonok — of Comet ISON fame — conducted observations of 2013 UQ4 and concluded that it was indeed an active comet.

Hovering around +13^th magnitude last month, newly rechristened 2013 UQ4 Catalina was a southern hemisphere object visible only from larger backyard telescopes. That should change, however, in the coming weeks if activity from this comet holds up.

Light curve — The light curve of UQ4 Catalina with current observations (dots) noted. Credit: Seiichi Yoshida/Aerith.net.

2013 UQ4 belongs to a class of objects known as damocloids. These asteroids are named after the prototype for the class 5335 Damocles and are characterized as long-period bodies in retrograde and highly eccentric orbits. These are thought to be inactive varieties of comet nuclei, and other asteroids in the damocloid series such as C/2001 OG 108 (LONEOS) and C/2002 VQ94 (LINEAR) also turned out to be comets. Damocloids also exhibit the same orbital characteristics of that most famous inner solar system visitor of them all; Halley’s Comet.

The path of Comet 9PM 30deg north — The path of Comet UQ4 Catalina looking towards the NE at 9PM local in early July from latitude 30 degrees north. Credit: Stellarium.

The good news is, 2013 UQ4 Catalina is brightening on schedule and should be a binocular object greater than +10^th magnitude by the end of June. Recent observations, including those made by Alan Hale (of comet Hale-Bopp fame) place the comet at magnitude +11.9 with a bullet. The comet is currently placed high in the east in the constellation Pisces at dawn, and will soon speed northward and vault across the sky as it crosses the ecliptic plane this week. In fact, comet 2013 UQ4 Catalina reaches perihelion on July 6th only four days before its closest approach to the Earth at 47 million kilometres distant, when it may well reach a peak magnitude of +7. At that point, the comet will have an apparent motion of about 7 degrees a day — that’s the span of a Full Moon once every 1 hour and 42 minutes — as it rises in the constellation Cepheus to the northeast at dusk in early July. A fine placement, indeed. And speaking of the Moon, our natural satellite reaches New phase later this month on June 27^th, another good reason to begin searching for 2013 UQ4 Catalina now.

Here’s a list of notable events to watch out for and aid you in your quest as comet 2013 UQ4 Catalina crosses the summer sky:

June 16^th: The comet crosses north of the ecliptic plane.

June 20^th: The waning crescent Moon passes 3 degrees from the comet.

starry nite — The celestial path of the comet from June 16th to July 15th… Credit: Starry Night Education software.

June 29^th: Crosses into the constellation of Andromeda.

July 1^st: Passes less than one degree from the +2^nd magnitude star Alpheratz.

July 2^nd: Crosses briefly into the constellation Pegasus before passing back into Andromeda.

July 6^th: The comet reaches perihelion or its closest point to the Sun at 1.081 A.U.s distant.

July 7^th: Crosses into the constellation of Lacerta and passes the deep sky objects NGCs 7296, 7245, 7226.

July 8^th: Crosses into the constellation Cepheus and across the galactic plane.

July 9^th: Passes a degree from the Elephant Trunk open star cluster.

July 10^th: Passes less than one degree from the stars Eta (magnitude +3.4) and Theta (magnitude +4.2) Cephei.

July 10^th: Passes 2 degrees from the +7.8 magnitude Open Cluster NGC 6939.

July 10^th: Passes closest to Earth at 0.309 A.U.s or 47 million kilometres distant.

July 11^th: Crosses into the constellation Draco.

July 11^th: Reaches its most northerly declination of 64 degrees.

July 12^th: Photo op: the comet passes 3 degrees from the Cat’s Eye Nebula.

July 15th- August 20th — … and the path of the comet from July 15th to August 20th. Credit: Starry Night.

July 17^th: The comet passes into the astronomical constellation of Boötes.

July 31^st: Passes just 2 degrees from globular cluster NGC5466 (+9^th magnitude) and 6 degrees from the famous globular cluster Messier 3.

From there on out, the comet drops below naked eye visibility and heads back out in its 470 year orbit around the Sun. Be sure to check out comet 2013 UQ4 Catalina this summer… what will the Earth be like next time it passes by in 2484 A.D.?

June 13, 2014December 23, 2015 by David Dickinson

It’s Hurricane Season and NASA is Ready Like Never Before

A member of NASA's Global Hawk fleet takes to the air. Credit: NASA/Armstrong Spaceflight Research Center.

What’s in the cards weather-wise for the 2014 Atlantic hurricane season? Although the start of astronomical summer for the northern hemisphere is still over a week away on June 21^st, meteorological summer has already begun and with it, hurricane season, which runs from June 1^st to November 30^th.

This year, NASA is deploying its latest weapons in its hurricane-hunting arsenal to study tropical storms like never before, including two new Earth observing satellites and two uncrewed Global Hawk aircraft.

The Global Hawk flights are set to begin on August 26^th from NASA’s Wallops Flight Facility based along the Virginia coast and run through September 29th. This coincides with the peak of the Atlantic hurricane season, when storm activity should be in full swing. The campaign is part of NASA’s airborne Hurricane and Severe Storm Sentinel mission, also known as HS3.

“This year, we’re going full-force into tropical cyclone research,” stated HS3 mission principal investigator Scott Braun in a recent press release from NASA’s Goddard Space Flight center headquartered at Greenbelt, Maryland. “We’ll have two Global Hawks equipped with six instruments. The new NASA-JAXA Global Precipitation Measurement (GPM) Core Observatory will be providing much higher quality data than previously available on rain structure in tropical cyclones in all ocean basins. The surface-wind monitoring ISS-RapidScat instrument to be launched to the International Space Station this season will provide valuable information on surface winds and storms.”

One of the key mysteries that the HS3 program is targeting is the role that a dry hot air phenomenon known as the Saharan Air Layer or SAL plays in hurricane formation and subsequent intensification. Some studies suggest the SAL feeds and triggers hurricane formation off of the north African coast —a mainstream view held by many meteorologists — while other studies imply that it may actually suppress it. HS3 will also give researchers the enhanced capability to monitor and track the formation of thunderstorms near the core of hurricanes and tropical storms and follow their progression.

To accomplish this, the HS3 Global Hawk aircraft will deploy devices that measure humidity, temperature and wind speeds known as dropsondes. All of the dropsondes to be deployed by NASA in the 2014 season are managed by the National Oceanic and Atmospheric Administration.

Global Hawk aircraft are ideal for hurricane tracking and hunting because they can stay aloft for up to 26 hours and fly at altitudes of over 18,000 metres. HS3 mission control for the Global Hawks is based out of NASA’s Wallops Flight Facility.

The first Global Hawk will provide data on the storm’s environment. The gear it uses to accomplish this will include the Cloud Physics Lidar (CPL), the Advanced Vertical Atmospheric Profiling System (AVAPS), and the Scanning High-resolution Interferometer Sounder (S-HIS).

Global Hawk number two will analyze the core storm regions to gauge temperature, humidity, surface winds and precipitation. It will use an array of instruments to accomplish this, including the High-Altitude Monolithic Microwave Integrated Circuit Sounding Radiometer (HAMSR), the Hurricane Imaging Radiometer (HIRAD), and Doppler Radar.

The dramatic night launch of the GPM satellite from Tanegashima, Japan. Credit: NASA/JAXA

In orbit, the Global Precipitation Mission (GPM) will continue with the legacy of the Tropical Rainfall Measuring Mission (TRMM) and follow hurricanes through all phases of formation and decay. A joint NASA/JAXA mission, GPM was launched atop an H-IIA rocket earlier this year on February 27^th from Tanegashima Space Center located on the southern tip of Kyushu Island in Japan. Of particular interest to GPM researchers is the formation of deep thunderstorms known as hot towers near the hurricane eyewall. GPM is located in an 65° degree inclination in low Earth orbit and will be able to track hurricanes and study hot tower formation as they move out of the tropics.

Newsflash- no sooner than we finished this article than we noticed that a rocket booster associated with the GPM launch is set to reenter soon on June 17th.

A diagram of RapidScat's future home on the ISS. Credit: NASA/JPL-Caltech/Johnson Spaceflight Center. — A diagram of RapidScat’s future home on the ISS. Credit: NASA/JPL-Caltech/Johnson Spaceflight Center.

And finally, RapidScat is set to head to the International Space Station later this year. Set to be mounted on the exterior of the Columbus module of the ISS, RapidScat will be an invaluable tool for monitoring ocean surface winds and is a cost effective replacement for the QuickScat satellite that ceased operation in 2009. RapidScat is set to launch on a SpaceX Falcon-9 rocket as part of the CRS-4 Dragon resupply mission slated for sometime this August.

These assets will give NASA the ability to study hurricanes that form during the 2014 season like never before. And speaking of the ISS, the live camera that now broadcasts HD images 24 hours a day will make for some interesting views of hurricanes online from space.

And what’s on tap for the 2014 Atlantic season? Well, forecast models out of Colorado State University suggest that an anomalous cooling early on in the Atlantic will lead to fewer than usual named storms, with perhaps only 9, as opposed to the usual average number of 12. Of these, perhaps 1-2 will reach category 3 or higher, as opposed to the average number of 3. A leading factor in this weakened trend is the possibility of a moderate to strong El Nino event earlier this year. Keep in mind through, that it only takes one destructive hurricane to wreak havoc, and these still can and do occur, even on off years.

Whatever the case, NASA and the NOAA will have all their tools at their disposal ready to study these powerful storms as the season rolls on.

June 11, 2014December 23, 2015 by David Dickinson

An Astronomical Eloping: How Rare is a “Friday the 13th Honey Moon?”

The June 2012 "Honey Moon" rising. Photo credit: Stephen Rahn.

Ah, Friday the 13^th. Whether you fear it or it’s just your favorite slasher flick, it’s coming right around the bend later this week. And while it’s pretty much a non-event as far as astronomy is concerned, there’s bound to be some woo in the works, because the June Full Moon — dubbed the “Honey Moon” — falls on the same date.

Well, sort of. We made mention of this month’s Full Moon falling on Friday the 13^th in last week’s post on the occultation of Saturn by Earth’s Moon. We’re not out to alarm any triskaidekaphobics, but we always love the chance to have some fun with calendars in the name of astronomy.

What we’re seeing here is merely the intersection of three cycles of events… and nothing more. These sorts of things can be fun to calculate and can provide a teachable moment, even when that well meaning but often misinformed relative/coworker/stranger on Twitter sends it your way . Hey, some people golf or collect steel pennies, this is our shtick.

A “Friday the 13^th Honey Moon” is basically the subset of: 1. Fridays that fall on the 13^th day of the month (OK, that’s two input parameters, we know) that also 2. Fall in the month of June, and 3. Occur on a Full Moon.

Friday the 13^th occurs from one to three times a calendar year, so you can already see that one will occasionally happen to land on a Full Moon date fairly frequently… but how ‘bout in June? To this end, we compiled this handy listing of “Full Moons that fall on the 13th day of the month” — 15 in all — that occur from 1990 to 2030:

Full Moon's that fell on the 13th from 1990-2030 as reckoned in Universal Time. Only one (March 1998) fell on a Friday the 13th. Chart by author. — Full Moons that fell on the 13th from 1990-2030 as reckoned in Universal Time. Only two (March 1998 and June 2014) fall on a Friday the 13th. Chart by author.

That’s about one every two to three years. But you have to go aaaaall the way back to June 13^th, 1919 to find a Full Moon that fell on a Friday the 13^th in the month of June. This will next occur on June 13^th, 2098.

Of course, this is just an interesting intersection concerning the vagaries and nuances of our Gregorian calendar and the lunar cycle. You could just as easily see significance where there is none in the Full Moon coinciding with the next Superbowl or Academy Awards. Humans love to pick out patterns where often none exist.

(Fun homework assignment: When is the last/next total lunar eclipse that occurs on Friday the 13^th?)

And keep in mind, the instant of the Full Moon this week occurs on Friday at 4:13 UT… this means that from the U.S. Central time zone westward, the Full Moon actually falls on Thursday the 12^th.

The rising Moon just hours before Full on Thursday June 12th. Note Saturn to the upper right. Created using Stellarium.

Fun fact: the 13^th falls on a Friday more than any other day of the month! It’s true… in a span of 400 years following the institution of the Gregorian calendar in 1582, Friday fell on the 13^th a total of 688 times, while Thursday and Saturday the 13^th fell in last place at 684.

But there’s is something else that’s special about the June Full Moon. It also falls closest to the June solstice, marking the start of astronomical northern hemisphere summer and winter in the southern. This means that the Full Moon nearest the June solstice rides at its lowest to the southern horizon for northern hemisphere observers, but is high in the sky for observers south of the equator.

The June 2012 Full Honey (or do you say Strawberry?) Moon. Photo by author.

The June solstice this year falls on Saturday, June 21^st at 10:51 UT /6:51 AM EDT. The Full Moon closest to the June solstice is nearly, but not always, in June… It can occur up to July 6^th, and the last time it fell in July is 2012 and the next is 2015. The July Full Moon is known as the Full Buck Moon.

Our good friends over at Slooh will be webcasting the Full Honey Moon this Friday the starting at 1:30 UT/9:30 PM EDT (Thursday June 12^th) for two hours from its Canary Islands site and the Pontificia Universidad Católica de Chile observatory near Santiago, Chile. The broadcast will be hosted by Slooh astronomer Geoff Fox, astronomer and author of The Sun’s Heartbeat Bob Berman, and Slooh engineer Paul Cox.

Is there a connection between late spring weddings, the June Full Moon and the modern term “honeymoon”? Well, the rising June Full Moon certainly takes on an amber color for northern hemisphere observers as it rises low through the sultry summer skies. The Moon’s orbit is actually tilted five degrees relative to the ecliptic, which means it alternates from “flat” to “hilly” about every 9 years varying from 18 to 28 degrees relative to the celestial equator. We’re approaching a flat year — known as minimum or minor lunar standstill — in 2015, after which the Moon’s apparent path across the sky will begin to widen once again towards 2024.

The ~9 year variation between major and minor lunar standstill. Credit Wikimedia Commons graphic in the Public Domain.

Bob Berman has this to say about the origin of the term: “Is this Full Moon of June the true origin of the word honeymoon, since it is amber, and since weddings were traditionally held this month? That phrase dates back nearly half a millennium to 1552, but one thing has changed: weddings have shifted, and are now most often held in August or September. The idea back then was that a marriage is like the phases of the Moon, with the Full Moon being analogous to a wedding. Meaning, it’s the happiest and ‘brightest’ time in a relationship.”

It’s also worth noting the June Full Moon was known as the Strawberry Moon to the Algonquin Indians of North America. Huh… and here we thought most weddings were in May.

Whatever the case, you can get out enjoy the rising Full Moon with that significant other this week… and don’t fear the Honey Moon.