Screenshot from the video "Joshua Tree Nights", taken at Joshua Tree National Park. Credit: Mark 'Indy' Kochte / Vimeo
Channelling all U2 fans: this stunning timelapse above Joshua Tree National Park is a walking tourism brochure for astrophotographers. The pictures were taken in September and November 2012 (the latter during the Leonid meteor shower) and just put up on Vimeo a few days ago.
Can you spot any famous astronomical objects? Read below to see some of what was featured in these video clips.
“Due to the lateness in the year I was there, the Milky Way was setting into the light dome of Palm Springs and greater Los Angeles. Consequently, I only got one decent Milky Way sequence in the nights I shot,” wrote videographer Mark ‘Indy’ Kochte on Vimeo.
“At the time I was not traveling with a dolly rail set up, so was limited in the camera movements to using an Astrotrac astrophotography guiding system. However, the Astrotrac would only pan for about 90 minutes before reaching the end of it’s workable motion. Hence why there are a number of ‘still’, tripod-only sequences.”
It’s that time of year again, when the most famous of all meteor showers puts on its best display.
Why are the Perseids such an all ‘round favorite of sky watchers? Well, while it’s true that other annual meteor showers such as the Quadrantids and Geminids can exceed the Perseids in maximum output, the Perseids do have a few key things going for them. First, the shower happens in mid-August, which finds many northern hemisphere residents camping out under warm, dark skies prior to the start of the new school year. And second, unlike showers such as the elusive Quads which peak over just a few hours, the Perseids enjoy a broad span of enhanced activity, often covering a week or more.
The orientation of the orbital path of Comet 109P/Swift-Tuttle and the position of the Earth on August 12th. Credit: JPL-Horizons.
These are all good reasons to start watching for Perseids now. Here’s the low down on the Perseid meteors for 2014:
The History: The Perseids are sometimes referred to as “The Tears of Saint Lawrence,” who was martyred right around the same date on August 10th, 258 A.D. The source of the shower is comet 109P Swift-Tuttle, which was first identified as such by Schiaparelli in 1866. The comet itself visited the inner solar system again recently in 1992 on its 120 year orbit about the Sun, and rates were enhanced throughout the 1990s.
A 2013 Perseid pierces the plane of the Milky Way. Credit: Stephen Rahn.
Unlike most showers, the Perseids have a very broad peak, and observers and automated networks such as UKMON and NASA’s All Sky Camera sites have already begun to catch activity starting in late July.
A pair of early 2014 Perseids recently captured by UKMON’s Wilcot station. Credit: The UK-MON network.
In recent years, the rates for the Perseids have been lowering a bit but are still enhanced, with ZHRs at 91(2010), 58(2011), 122(2012), and 109(2013). It’s also worth noting that the Perseids typically exhibit a twin peak maximum within a 24 hour span. The International Meteor Organization maintains an excellent page for quick look data to check out what observers worldwide are currently seeing. The IMO also encourages observers worldwide to submit meteor counts by location. Note that the phase of the Moon was near Full in 2011, with observing circumstances very similar to 2014.
The Prospects for 2014: Unfortunately, the 2014 Perseid meteors have a major strike going against them this year: the Moon will be at waning gibbous during its peak and just two days past Full illumination. This will make for short exposure times and light polluted skies. There are, however, some observational strategies that you can use to combat this: one is to place a large building or hill between yourself and the Moon while you observe — another is to start your morning vigil a few days early, before the Moon reaches Full. The expected Zenithal Hourly Rate for 2014 is predicted to hover around 90 and arrive around 00:15 to 2:00 UT on August 13th favoring Europe, Africa and the Middle East.
The orientation of Earth’s shadow during the projected peak of the Perseids on August 13th at 00:15 Universal Time. The positions where the Sun, Moon, and radiant of the Perseids are directly overhead are also noted. Created by Author.
The Radiant: It’s strange but true: meteor shower radiants wander slightly across the sky during weeks surrounding peak activity, due mostly to the motion of the Earth around the Sun. Because of this, the radiant of the Perseids is not actually in the constellation Perseus on the date that it peaks! At its maximum, the radiant actually sits juuusst north of the constellation that it’s named for on the border of Camelopardalis and Cassiopeia. This is a great pedantic point to bring up with your friends on your August meteor vigil… they’ll sure be glad that you pointed this out to ’em and hopefully, invite you back for next year’s Perseid watch.
The actual position of the radiant sits at 3 Hours 04’ Right Ascension and +58 degrees north declination.
The movement of the radiant of the Perseids. The sky is simulated for latitude 30 degrees north at 2:00 AM local on August 13th. Credit: Starry Night Education software.
Meteor-speak: Don’t know your antihelion from a zenithal hourly rate? We wrote a whole glossary that’ll have you talking meteors like a pro for Adrian West’s outstanding Meteorwatch site a few years back. Just remember, the crucial “ZHR” of a shower that is often quoted is an ideal extrapolated rate… light pollution, the true position of the radiant, observer fatigue and limited field of view all conspire to cause you to see less than this predicted maximum. The universe and its meteor showers are indeed a harsh mistress!
Observing: But don’t let this put you off. As Wayne Gretsky said, “You miss 100% of the shots that you don’t take,” and the same is true with meteor observing: you’re sure to see exactly zero if you don’t observe at all. Some of my most memorable fireball sightings over the years have been Perseids. And remember, the best time to watch for meteors is after local midnight, as the Earth is turned forward into the meteor stream. Remember, the car windshield (Earth) gets the bugs (meteors) moving down the summer highway…
Good luck, and let us know of those tales of Perseid hunting and send those meteor pics in to Universe Today!
Comet Jacques and IC 405, better known as the Flaming Star Nebula, align to create a temporary question mark in the sky this morning July 26. Credit: Rolando Ligustri
What an awesome photo! Italian amateur astronomer Rolando Ligustri nailed it earlier today using a remote telescope in New Mexico and wide-field 4-inch (106 mm) refractor. Currently the brightest comet in the sky at magnitude 6.5, C/2014 E2 Jacques has been slowly climbing out of morning twilight into a darker sky over the last two weeks. This morning it passed the Flaming Star Nebula in the constellation Auriga. Together, nebula and pigtailed visitor conspired to ask a question of the sky in a rare display of celestial punctuation. IC 405 is a combination emission-reflection nebula. Some of its light stems from starlight reflecting off grains of cosmic dust, but the deep red results from hydrogen excited to fluorescence by powerful ultraviolet light from those same stars. The depth of field hidden within the image is enormous: the nebula lies 1,500 light years away, the comet a mere 112 million miles or 75 million times closer. Coincidentally, the comet also glows in similar fashion. The short dust tail to the left of the coma is sunlight reflecting off minute grains of dust boiled from the nucleus. The long, straight tail is primarily composed of carbon monoxide gas fluorescing in ultraviolet light from the sun.
Follow Jacques in a small telescope or binoculars in its travels across Auriga into Perseus during the next two weeks before the moonlight interferes. Comet positions are shown for 4 a.m. CDT every 5 days. Stars to magnitude +8.0. Click to enlarge. Source: Chris Marriott’s SkyMap
As Jacques swings toward its closest approach to Earth in late August, it’s gradually picking up speed from our perspective and pushing higher into the morning sky. A week ago, twilight had the upper hand. Now the comet’s some 20º high (two ‘fists’) above the northeastern horizon around 4 a.m. This morning I had no difficulty seeing it as a small, ‘fuzzy star’ in 10×50 binoculars. In my dusty but trusty 10-inch (25 cm) telescope at 76x, Comet Jacques was a dead ringer for one of those fuzzy dingle-balls hanging from a sombrero. I caught a hint of the very short dust tail but couldn’t make out the gas tail that shows so clearly in the photo. That will have to await darker skies.
A different perspective on Comet Jacques. This negative image, which emphasizes details in the comet’s tails, was shot July 26, 2014 with an 8-inch (20 cm) telescope. Credit: Michael Jaeger
Maybe you’d like to try your own eyes on Jacques. Start with a pair of 40mm or larger binoculars or small telescope and use the map above to help you spot it. Oh, and don’t forget to keep an exclamation mark handy when you get that first look.
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.
Ye ole analemma… perpetually lost in the South Pacific? (Wikimedia Commons image).
But try explaining that one to your 3rd 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 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 21st, while the highest maximum falls on November 3rd on non-leap years. The four zero value dates are April 15th, June 13th, September 1st and December 25th 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).
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.
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 20th 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!
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 10th 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 everyanomalistic 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 1st, 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 12th 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!!!”
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.
Got clear skies this July 4th 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 5th 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 28th), the Moon will only occult Mars once in 2014, on the night of July 5th/6th. 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 6th or 9:00 PM EDT on the evening of the 5th. 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 9th, 2013 and the next won’t happen ‘til March 21st, 2015.
The footprint of Lambda Virginis…
Next up, the Moon occults the +4.5th magnitude star Lambda Virginis on July 7th centered on 8:26 UT. This event is well placed for observers in Hawaii on the evening of July 6th. 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 the occultation footprint for Saturn.
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 8th (10:00 PM EDT on the evening of July 7th) 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 4th. 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!
Pluto passing near the star cluster M25 in late 2013. Credit: Dave Walker.
Are you ready for 2015? On July 14th, 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 Horizons in the clean room having its plutonium-fueled MMRTG installed. (Credit: NASA).
Pluto reaches opposition for 2014 later this week on Friday, July 4th at 3:00 Universal Time (UT), or 11:00 PM EDT on July 3rd. 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.
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 +14th magnitude at opposition as it heads back out towards aphelion one century from now in 2114.
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 @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 +7th magnitude pair BB Sagittarii on July 7th and 8th and less than 3’ from the +5.2 magnitude star 25 Sagittarii on July 21st… 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.
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 20th century.
We’re also fortunate that Pluto is currently relatively close to the ecliptic plane, crossing it on October 24th, 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 11th and 12th, 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…
Ceres and Vesta are converging in Virgo not far from Mars and Spica. On July 5, the duo will be just 10' apart and visible in the high power telescope field of view. Positions are shown every 5 days for 10 p.m. EDT and stars to magnitude +8.5. Created with Chris Marriott's SkyMap software
I bet you’ve forgotten. I almost did. In April, we reported that Ceres and Vesta, the largest and brightest asteroids respectively, were speeding through Virgo in tandem. Since then both have faded, but the best is yet to come. Converging closer by the day, on July 5, the two will make rare close pass of each other when they’ll be separated by just 10 minutes of arc or the thickness of a fat crescent moon.
Vesta (left) and Ceres. Vesta was photographed up close by the Dawn spacecraft from July 2011-Sept. 2012, while the best views we have to date of Ceres come from the Hubble Space Telescope. The bright white spot is still a mystery. NASA will plunk Dawn into orbit around Ceres next February. Credit: NASA
Both asteroids are still within range of ordinary 35mm and larger binoculars; Vesta is easy at magnitude +7 while Ceres still manages a respectable +8.3. From an outer suburban or rural site, you can watch them draw together in the coming two weeks as if on a collision course. They won’t crash anytime soon. We merely see the two bodies along the same line of sight. Vesta’s closer to Earth at 164 million miles (264 million km) and moves more quickly across the sky compared to Ceres, which orbits 51 million miles (82 million km) farther out.
Ceres and Vesta lie near an easy naked eye star, Zeta Virginis, which forms an isosceles triangle right now with Mars and Spica. The map shows the sky around 10 p.m. local time tonight facing southwest. Stellarium
Right now the two asteroids are little more than a moon diameter apart not far from the 3rd magnitude star Zeta Virginis. Happily, nearby Mars and Spica make excellent guides for finding Zeta. Once you’re there, use binoculars and the more detailed map to track down Ceres and Vesta.
Virgo will be busy Saturday night July 5, 2014 when the waxing moon passes about 1/2 degree from Mars as Ceres and Vesta squeeze closest. Stellarium
In early July they’ll look like a wide double star in binoculars and easily fit in the same high power telescopic view. Vesta has always looked pale yellow to my eye. Will its color differ from Ceres? Sitting side by side it will be easier than ever to compare them. Vesta is a stony asteroid with a surface composed of solidified (and meteoroid-battered) lavas; Ceres is darker and covered with a mix of water ice and carbonaceous materials.
On the night of closest approach, it may be difficult to spot dimmer Ceres in binoculars. By coincidence, the 8-day-old moon will be very close to the planet Mars and brighten up the neighborhood. We’ll report more on that event in a future article.
With so much happening the evening of July 5, let’s hope for a good round of clear skies.
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.
A capture from the simulation, showing a cross-section 25 by 25 light years square and 0.2 light years thick. The simulation shows how the O-type star “sculpts” its surroundings over the span of 1.6 million years, carving out, in some cases, the famous “pillars”. Credit: S. Balfour/ University of Cardiff.
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.
