Skywatching Archives

March 31, 2014December 30, 2015 by David Dickinson

Observing Alert: Watch the Moon Cross the Hyades This Week

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

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

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

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

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

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

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

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

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

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

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

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

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

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

March 28, 2014May 25, 2023 by David Dickinson

Adventures in (Radio) Amateur Astronomy

Is there truly anything new under the Sun? Well, when it comes to amateur astronomy, many observers are branching out beyond the optical. And while it’s true that you can’t carry out infrared or X-ray astronomy from your backyard — or at least, not until amateurs begin launching their own space telescopes — you can join in the exciting world of amateur radio astronomy.

We’ll admit right out the gate that we’re a relative neophyte when it comes to the realm of radio astronomy. We have done radio observations of meteor showers in tandem with optical observations, and have delved into the trove of information on constructing radio telescopes over the years. Consider this post a primer of sorts, an intro into the world of radio amateur astronomy. If there’s enough interest, we’ll follow up with a multi-part saga, constructing and utilizing our own ad-hoc “redneck array” in our very own backyard with which to alarm the neighbors and probe the radio cosmos.

Repurposing a TV Dish for amatuater astronomy. Credit: NSF/NRAO/Assoc. Universities, Inc. — The “Itty-Bitty Array”- Re-purposing a TV Dish for amateur astronomy. Credit: NSF/NRAO/Assoc. Universities, Inc.

…And much like our exploits in planetary webcam imaging, we’ve discovered that you may have gear kicking around in the form of an old TV dish – remember satellite TV? – in your very own backyard. A simple radio telescope setup need not consist of anything more sophisticated than a dish (receiver), a signal strength detector (often standard for pointing a dish at a satellite during traditional installation) and a recorder. As you get into radio astronomy, you’ll want to include such essentials as mixers, oscillators, and amplifiers to boost your signal.

Frequency is the name of the game in amateur radio astronomy, and most scopes are geared towards the 18 megahertz to 10,000 megahertz range. A program known as Radio-SkyPipe makes a good graphic interface to turn your laptop into a recorder.

Radio astronomy was born in 1931, when Karl Jansky began researching the source of a faint background radio hiss with his dipole array while working for Bell Telephone. Jansky noticed the signal strength corresponded to the passage of the sidereal day, and correctly deduced that it was coming from the core of our Milky Way Galaxy located in the constellation Sagittarius. Just over a decade later, Australian radio astronomer Ruby Payne-Scott pioneered solar radio astronomy at the end of World War II, making the first ever observations of Type I and III solar bursts as well as conducting the first radio interferometry observations.

A replica of Jansky's first steerable antanta at Green Bank, West Virginia. — A replica of Jansky’s first steerable antenna at Green Bank, West Virginia. (Public Domain image)

What possible targets exist for the radio amateur astronomer? Well, just like those astronomers of yore, you’ll be able to detect the Sun, the Milky Way Galaxy, Geostationary and geosynchronous communication satellites and more. The simple dish system described above can also detect temperature changes on the surface of the Moon as it passes through its phases. Jupiter is also a fairly bright radio target for amateurs as well.

Radio meteors are also within the reach of your FM dial. If you’ve ever had your car radio on during a thunderstorm, you’ve probably heard the crackle across the radio spectrum caused by a nearby stroke of lightning. A directional antenna is preferred, but even a decent portable FM radio will pick up meteors on vacant bands outdoors. These are often heard as ‘pings’ or temporary reflections of distant radio stations off of the trail of ionized gas left in the wake of a meteor. Like with visual observing, radio meteors peak in activity towards local sunrise as the observer is being rotated forward into the Earth’s orbit.

Amateur SETI is also taking off, and no, we’re not talking about your crazy uncle who sits out at the end of runways watching for UFOs. BAMBI is a serious amateur-led project. Robert Gray chronicled his hunt for the elusive Wow! signal in his book by the same name, and continues an ad hoc SETI campaign. With increasingly more complex rigs and lots of time on their hands, it’s not out of the question that an amateur SETI detection could be achieved.

Another exciting possibility in radio astronomy is tracking satellites. HAM radio operators are able to listen in on the ISS on FM frequencies (click here for a list of uplink and downlink frequencies), and have even communicated with the ISS on occasion. AMSAT-UK maintains a great site that chronicles the world of amateur radio satellite tracking.

Amateur radio equipment that eventually made its way to to ISS aboard STS-106. (Credit: NASA).

Old TV dishes are being procured for professional use as well. One team in South Africa did just that back in 2011, scouring the continent for old defunct telecommunications dished to turn them into a low cost but effective radio array.

Several student projects exist out there as well. One fine example is NASA’s Radio JOVE project, which seeks student amateur radio observations of Jupiter and the Sun. A complete Radio Jove Kit, to include receiver and Radio-SkyPipe and Radio-Jupiter Pro software can be had for just under 300$ USD. You’d have a tough time putting together a high quality radio telescope for less than that! And that’s just in time for prime Jupiter observing as the giant planet approaches quadrature on April 1^st (no fooling, we swear) and is favorably placed for evening observing, both radio and optical.

Fearing what the local homeowner’s association will say when you deploy your very own version of Jodrell Bank in your backyard? There are several online radio astronomy projects to engage in as well. SETI@Home is the original crowd sourced search for ET online. The Zooniverse now hosts Radio Galaxy Zoo, hunting for erupting black holes in data provided by the Karl Jansky Very Large Array and the Australia Telescope Compact Array. PULSE@Parkes is another exciting student opportunity that lets users control an actual professional telescope. Or you can just listen for meteor pings online via NASA’s forward scatter meteor radar based out of the Marshall Space Flight Center in Huntsville, Alabama. Adrian West also hosts live radio meteor tracking on his outstanding Meteorwatch website during times of peak activity.

Forward Scatter — A diagram of a basic forward scatter radar system for meteor observing. Credit: NASA

Interested? Other possibilities exist for the advanced user, including monitoring radio aurorae, interferometry, catching the hiss of the cosmic microwave background and even receiving signals from more distant spacecraft, such as China’s Yutu rover on the Moon.

Think of this post as a primer to the exciting world of amateur radio astronomy. If there’s enough interest, we’ll do a follow up “how-to” article as we assemble and operate a functional amateur radio telescope. Or perhaps you’re an accomplished amateur radio astronomer, with some tips and tricks to share. There’s more to the universe than meets the eye!

-Also be sure to check out SARA, the Society of Amateur Radio Astronomers.

March 24, 2014December 23, 2015 by David Dickinson

Ready, Set, Messier Marathon: A 2014 Guide

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

Have YOU seen all 110?

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Good luck!

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

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

March 20, 2014December 23, 2015 by Bob King

Happy Equinox! – A Perfect Time to See the Zodiacal Light

Zodiacal light tilts upward from the western horizon and points at the Pleiades star cluster in this photo taken March 19, 2009. Clouds at bottom reflect light pollution from nearby Duluth, Minn. U.S. Credit: Bob King

Welcome to the first day of spring! If you have a clear night between now and April 1, celebrate the new season with a pilgrimage to the countryside to ponder the eerie glow of the zodiacal light. Look for a large, diffuse, tapering cone of light poking up from the western horizon between 90 minutes and two hours after sunset. While the zodiacal light appears only as bright as the Milky Way, you’re actually looking at the second brightest object in the night sky. No kidding. If you could crunch it all into a little ball, it would shine at magnitude -8.5, far brighter than Venus and bested only by the full moon.

The zodiacal (Zo-DIE-uh-cull) light is centered on the plane of the solar system called the ecliptic. On late March nights, you can trace it from near the western horizon more than 45 degrees (halfway up the sky). Stellarium — The zodiacal (Zo-DIE-uh-cull) light is centered on the plane of the solar system called the ecliptic. This is the same band of sky where you’ll find the planets and zodiac constellations, hence the name. On late March nights, you can trace it from near the western horizon more than 45 degrees (halfway up the sky). Created with Stellarium

Sunlight reflecting off countless dust particles shed by comets and spawned by asteroid collisions creates the luminous cone of light. First time observers might think they’re looking at skyglow from light pollution but the tapering shape and distinctive tilt mark this glow as interplanetary dust.

This image of coronal and zodiacal light (CZL) was taken by the Clementine spacecraft, when the sun was behind the moon. The white area on the edge of the moon is the CZL, and the bright is Venus. (Credit: NASA) — Photo of coronal and zodiacal light taken by the Clementine spacecraft when the sun was hidden by the moon. At right is Venus. Clementine measured the brightness of the light to arrive at an integrated magnitude of -8.5. It also estimated dust particle sizes and origin. Credit: NASA

Like the planets, the dust resides in the plane of the solar system. In spring, that plane (called the ecliptic) tilts steeply up from the western horizon after sunset, “lifting” the chubby thumb of light high enough to clear the horizon haze and stand out against a dark sky for northern hemisphere observers. In October and November the ecliptic is once again tilted upright, but this time before dawn. While the zodiacal light is present year-round, it’s usually tipped at a shallow angle and camouflaged by horizon haze. No so for skywatchers in tropical and equatorial latitudes. There the ecliptic is tilted steeply all year long, and the light can be seen anytime there’s no moon in the sky.

The combined glow of dust particles in the plane of the solar system reaching from the sun's vicinity to beyond Mars is responsible for creating the zodiacal light. Planets are shown as colored disks. Illustration: Bob King — The combined glow of dust particles in the plane of the solar system reaching from the sun’s vicinity out to at least Jupiter is responsible for creating the zodiacal light. Dust closest to the sun glow more brightly, the reason the bottom of the zodiacal light cone is brighter than the tip. Planets are shown as colored disks. Illustration: Bob King

Now through April 1 and again from April 17-30 are the best nights for viewing because the moon will be absent from the sky. The cone is widest near the western horizon and narrows as you direct your gaze upward and to the left. At its apex, where it touches the V-shape Hyades star cluster, it continues into the even fainter zodiacal band and gegenschein, but more about that in a moment. Sweep your gaze in broad strokes back and forth across the western sky to help you discern the Z-light’s distinctive conical shape. And be sure to look for something HUGE. This thing is a monster – indeed, one of the largest entities in the solar system.

Scanning electron microscope photo of an interplanetary dust particle collected by a high-altitude plane. It measures about 8 microns across or a little less than twice the size of a human red blood cell. Scientists recently discovered that dust particles can act as tiny factories to built water molecules. Credit: Donald Brownlee and Elmar Jessberger

Observers fortunate enough to live under or with access truly dark skies can trace the zodiacal light all the way across the sky as the zodiacal band.

Midway along its length, 180 degrees opposite the sun, a slightly brighter circular patch called the gegenschein (German for ‘counter glow’) embedded in the band.

Dust particles there get an extra brightness boost because they face the sun square on, much like the moon does when full. While I usually see only a section of the zodiacal band from my dark observing site, the gegenschein is often visible as a diffuse, hazy patch of light about 6 degree across a little brighter than the sky background.

Incredible 360-degree-wide view of morning and evening zodiacal light cones (far left and right), the fainter zodiacal band and the brighter spot of gegenschein. Click to enlarge. Credit: Miloslav Druckmuller and Shadia Habbal — Incredible 360-degree-wide view of morning and evening zodiacal light cones (far left and right), the fainter zodiacal band and the brighter spot of gegenschein (center) and the Milky Way photographed from Mauna Kea. Click to enlarge. Credit: Miloslav Druckmuller and Shadia Habbal

Dutch astronomer H. C. van de Hulst determined that the dust particles responsible for the zodiacal light and its cousins the zodiacal band and gegenschein are about 0.04 inch (1 mm) in diameter and separated, on average, by about 5 miles (8 km).

The gegenschein, an oval shaped brighter spot within the faint zodiacal band, is easiest to when due south and highest in the sky at local midnight (1 a.m. Daylight Saving Time). Currently it's in northern Virgo. Since the 'counter glow' will always be opposite the sun, it will slide down closer to Spica in April. Created with Stellarium — The gegenschein, an oval shaped brighter spot within the faint zodiacal band, is easiest to when due south and highest in the sky at local midnight (1 a.m. Daylight Saving Time). Currently it’s in northern Virgo. Since the ‘counter glow’ will always be opposite the sun, it will slide down closer to Spica in April. Created with Stellarium

The particles form a low density, lens-shaped cloud of dust that’s thickest within the plane of the solar system but in reality covers the entire sky but ever so thinly. Sunlight absorbed by the particles is re-emitted as invisible infrared (heat) radiation. This re-radiation robs the dust of energy, causing the particles to spiral slowly into the sun. Fresh dust from the vaporization of cometary ices as well as collisions of asteroids replenishes the cloud.

Zodiacal light cones in the fall morning sky (left) and in late March. Both times of year, we see the plane of the solar system tipped at high angle in the sky. Credit: Bob King — Zodiacal light cones in the fall morning sky (left) and in late March. Both times of year we see the plane of the solar system tipped at a high angle in the sky. Credit: Bob King

According to a study by Joseph Hahn and colleagues of the Clementine Mission data, comet dust accounts for the majority of the zodiacal dust within 1 a.u. (93 million miles) of the sun; a mix of asteroidal and comet dust makes up the remainder.

Stepping out on a spring evening to look at the zodiacal light, we can appreciate how small things can come together to create something grand.

March 19, 2014April 26, 2016 by Bob King

Clouds May Scotch Tomorrow’s Rare Erigone-Regulus Occultation

The bright star Regulus will disappear for observers living along the path between the red lines. The disappearance is longest - up to 14 seconds - along the center green line. Credit: Google Maps / IOTA

North America’s brightest predicted asteroid occultation may be one-upped by a much bigger occultation – a solid blanket of clouds. Asteroid 163 Erigone will cover or occult the bright star Regulus shortly after 2 a.m. Eastern Daylight Time tomorrow morning March 20. Observers along a 45-mile-wide (73-km) belt stretching from the wilderness of Nunavut to the salty seas of Bermuda could see the star vanish for up to 14 seconds. Provided they can find a hole in the clouds.

ggggggg — National forecast map for 8 p.m. EDT tonight March 19. A low pressure region is expected to bring rain and snow to the Northeast and Ontario today and overnight with clearing skies later tomorrow. Click for latest New York City weather forecast. Credit: NOAA

Overcast skies with a mix of rain or snow are predicted along virtually the entire track from the tiny berg of Cochrane in northern Ontario south through New York City, Connecticut and New Jersey. A sluggish cold front isn’t expected to clear skies until … no surprise here … after the event is over.

Bermuda, perhaps the best place to watch the occultation, crosses the eastern edge of the asteroid's shadow. The red line marks — Bermuda, perhaps the best place to watch the occultation, crosses the eastern edge (blue line) of the asteroid’s shadow. The red line marks one sigma of uncertainty in the shadow edge. Credit: Google Maps/IOTA

But there is one place where maybe, just maybe, the clouds may part to let Erigone do its job. Bermuda. The Bermuda Weather Service forecast calls for highs in the low 70s mid-week, but that balmy air may come packaged with a partly to mostly cloudy sky at the time of the occultation. A few determined observers are on their way there right now, hoping for better weather. In case the islands are socked in, some plan to rent planes to rise above the low-lying clouds typical this time of year and revel in the shadow of an asteroid. Even if clear, Bermuda lies near the eastern edge of the path. Any occultation there will be brief.

Illustration showing asteroid 163 Erigone about to cover Leo’s brightest star Regulus around 2:07 Eastern Daylight Time Thursday morning March 20, 2014. As the asteroid’s shadow passes over the ground, observers will see Regulus disappear for up to 14 seconds. Illustration: Bob King with help from photos by the ESO/NASA - — Illustration showing asteroid 163 Erigone about to cover Leo’s brightest star Regulus around 2:07 Eastern Daylight Time Thursday morning March 20, 2014. As the asteroid’s shadow passes over the ground, observers will see Regulus briefly disappear. Illustration: Bob King with ESO/NASA images

Yes, there will be more occultations, but bright ones that the public can enjoy with the naked eye are rare.

Skywatchers are nothing if not hopeful. We believe in the sucker hole, the name given to rogue clearings in an otherwise overcast sky. We are patient and steadfast when it comes to glimpsing the rarest of the rare. I know this because my friends and I have stood outside on winter mornings staring at the western sky, waiting for clouds to peel back that we might glimpse a Martian dust storm or new comet.

To find Regulus, face southwest shortly before 2 a.m. The star will be about 40 degrees high (four ‘fists’ held at arm’s length against the sky). Brilliant Jupiter shines well to its lower right. You may also notice a ‘coathangar’ or ‘backwards question mark’ shape of stars above Regulus called the Sickle of Leo. Stellarium — If it does clear tomorrow, face southwest shortly before 2 a.m. to find Leo’s brightest star Regulus. The star will be about 40 degrees high (four ‘fists’ held at arm’s length against the sky). Above is the the Sickle of Leo, shaped like a backwards question mark. Brilliant Jupiter shines well to its lower right. Stellarium

If there’s an astronomer’s credo, it’s this: “The sky might clear yet!” The latest weather word (9 a.m. March 19) for U.S. and Canadian observers indicates thinner clouds along the southern end of the track in New Jersey. Many of us considered driving to the event but changed our minds because of work, worries about weather and other commitments. Assuming the credo holds true, you’ll be able to watch Regulus disappear live from the comfort of your home thanks to the efforts of several observers planning to stream the event on the Web.

Here’s a list of streamers so far:

* Brad Timerson plans to go live with audio at 2 a.m. at a rest area along I-90 just west of Syracuse, NY.

* Ted Blank on UStream

* Steve Preston will broadcast an image of his camcorder screen

* Vagelis Tsamis will try to broadcast from Canada

* SLOOH

As always, everything depends on the weather. Let’s hope Mother Nature loses focus and lets a little clear sky slip by.

March 17, 2014December 23, 2015 by David Dickinson

Get Set For Comet K1 PanSTARRS: A Guide to its Spring Appearance

Comet c/2012 K1 PanSTARRS as imaged by Dan Crowson on February 22nd, 2014. Image credit: Dan Crowson, used with permission.

Get those binoculars ready: an icy interloper from the Oort cloud is about to grace the night sky.

The comet is C/2012 K1 PanSTARRS, and it’s currently just passed from the constellation Hercules into Corona Borealis and presents a good target for observers high in the sky in the hours before dawn. In fact, from our Tampa based latitude, K1 PanSTARRS is nearly at the zenith at around 6 AM local.

Observers currently place K1 PanSTARRS at magnitude +10.5 and brightening and showing a small condensed coma. Through the eyepiece, a comet at this stage will often resemble a fuzzy, unresolved globular star cluster.

And the good news is, K1 PanSTARRS will continue to brighten, headed northward through the early morning and then into the evening sky before reaching solar conjunction on August 9th, when it’ll actually pass behind the Sun for a few hours as seen from from our vantage point. We actually get two good apparitions of Comet K1 PanSTARRS: one for the northern hemisphere in the Spring and one for the southern hemisphere after it reaches perihelion and crosses south of the ecliptic plane in August.

And it’ll be worth keeping an eye out for K1 PanSTARRS online as well, as it passes into the view of SOHO’s LASCO C3 camera on August 2 before exiting its 15 degree field of view on August 16th.

This actually means the comet will reach opposition twice from our Earthbound vantage point: once on April 15^th, and again on November 7^th. And, as is often the case, this comet arrives six months early –or late, depending how you look at it- to be a fine naked eye object. Had K1 PanSTARRS reached perihelion in January, we’d have really been in for a show, with the comet only around 0.05 Astronomical Units (about 7.7 million kilometers) from the Earth!

The orbit of comet K1 PanSTARRS. — The orbit of comet K1 PanSTARRS through the inner solar system. The yellow arrows denote the motion of the planets and the comet as seen from north of the ecliptic plane. Credit-NASA/JPL Horizons Solar System Dynamics generator.

But alas, such was not to be. At its best, K1 PanSTARRS will be hidden by the glare of the Sun at its very best, to emerge into the southern sky. The comet has a steeply inclined 142 degree retrograde orbit, and thus approaches the inner solar system from high above the ecliptic plane.

These coming last weeks of March are a great time to search out K1 PanSTARRS as the Moon reaches Last Quarter this weekend and heads towards New on March 30^th, beginning a two week “moonless period for AM observing in early April. Projections by veteran comet observer Seiichi Yoshida suggest that K1 PanSTARRS will begin to brighten dramatically towards +8^th magnitude through April. We first picked up the now posthumous comet ISON with binoculars around this magnitude last Fall. Keep in mind, like nebula and galaxies, the apparent brightness of a comet is spread out over its surface area. This can make a +10^th magnitude comet much tougher to spot than a pinpoint +10 magnitude star.

We actually prefer our trusty Canon 15x45IS image stabilized binoculars for comet hunting… they’re powerful and easy to deploy on a cold March morning!

Here’s a handy list of notable events to watch for as Comet C/2012 K1 PanSTARRS crosses the springtime sky. Only passages of less than one degree near stars greater than magnitude +6 are mentioned except where otherwise noted:

March 17^th: Comet C/2012 K1 PanSTARRS passes into the constellation Corona Borealis.

March 21^st: Passes the +5.8 magnitude star Upsilon Coronae Borealis.

March 29^th: Passes the +5.4 magnitude star Rho Coronae Borealis.

March 30^th: The Moon reaches New phase.

The path of comet K1 PanSTARRS through March and April — The path of comet K1 PanSTARRS in one week intervals through March and April. Created using Stellarium.

April 2^nd: Passes the +4.8 magnitude star Kappa Coronae Borealis.

April 7^th: Passes the +5.2 magnitude star Mu Coronae Borealis.

April 10^th: Passes into the constellation of Boötes.

April 10^th: Passes the +5 magnitude wide binary pair Nu Boötis.

April 15^th: Comet K1 PanSTARRS reaches opposition, rising opposite to the setting Sun and moving into the evening sky.

April 20^th: K1 PanSTARRS becomes circumpolar for observers above 45 degrees north until May 25th.

April 26^th: Passes into the constellation Ursa Majoris.

April 29^th: Passes the bright +1.9^th magnitude star Alkaid in the handle of the Big Dipper asterism. This is the brightest star that K1 PanSTARRS will pass near for this apparition, and Alkaid will make a great “finder” to spot the comet.

April 29^th: The Moon reaches New phase.

April 30^th: Approaches the +4.7 magnitude star 24 Canum Venaticorum.

Path of comet K1 PanSTARRS Credit: Starry Night Education Software — The Spring path of comet K1 PanSTARRS from mid-March through late June. Credit: Starry Night Education Software.

May 1^st: Passes into the constellation Canes Venatici.

May 1^st: Passes less than 2 degrees from the galaxy M51… photo op!

May 3^rd: Passes the 5.1 magnitude star 21 Canum Venaticorum.

May 6^th: K1 PanSTARRS Reaches a maximum declination of 49.5 degrees north.

May 11^th: Passes the 5.3 magnitude star 3 Canum Venaticorum.

May 14^th: Passes into the constellation Ursa Major.

May 17^th: Another great photo ops awaits astrophotographers, as the comet passes the +3.7 magnitude star Chi Ursae Majoris and the +12 magnitude galaxy NGC 3877.

May 25^th: Passes the 3^rd magnitude star Psi Ursae Majoris.

May 28^th: The Moon reaches New phase.

May 28^th: Passes the 4.7 magnitude star Omega Ursae Majoris.

June 7^th Passes into the constellation Leo Minor.

June 15^th: Passes the +4.5 magnitude star 21 Leo Minoris.

June 22^nd: Passes into the constellation Leo.

July 1- Passes to within 40 degrees elongation from the Sun.

And from there, Comet K1 PanSTARRS reaches perihelion just outside of the Earth’s orbit at 1.05 A.U. on August 27, and plunges south across the celestial equator on September 15.

Video animation of comet C/2012 K1 PanSTARRS over the span of an evening. Credit: Dan Crowson of Dardenne Prairie Missouri, used with permission.

It’s also worth noting that K1 PanSTARRS will make its first of two approaches at a minimum distance of 1.471 A.U.s from Earth May 4^thand will be moving at about a degree a day – twice the diameter of the Full Moon – before receding from us once more for a closer 1.056 A.U. approach to Earth on August 25^th.

Discovered on May 19^th, 2012 by the PanSTARRS telescope based on the island of Maui, Comet K1 PanSTARRS was first spotted at 8.7 A.U.s distant, well past the orbit of Jupiter. The PanSTARRS survey has been a prolific discoverer of asteroids and comets, including the brilliant comet C/2011 L4 PanSTARRS that graced dusk skies in March of last year.

Comet K1 PanSTARRS will join the ranks of comets reaching binocular observability later this year which includes C/2013 V5 Oukaimeden, Comet C/2013 A1 Siding Spring, and the recently discovered C/2014 E2 Jacques, which may reach +7^th magnitude as it nears perihelion this coming July.

And those are just the binocular comets that are scheduled to perform… remember, the next “big one” could come barreling in towards the inner solar system at any time to put on a memorable performance worthy of another comet Hyakutake or Hale-Bopp… just not TOO close!

– Be sure to send those comet pics in to Universe Today.

March 17, 2014December 23, 2015 by Bob King

Till Hellas Freezes Over – See Frost and Clouds in Mars’ Largest Crater

Mars photographed during part of its rotation from Melbourne, Australia on March 8. The bright "cap" marks Hellas, now covered in wintertime frost and clouds. Credit: Maurice Valimberti

Earth’s changing weather always makes life interesting. Seeing weather on other planets through a telescope we sense a kinship between our own volatile world and the fluttering image in the eyepiece. With the April 8 opposition of Mars rapidly approaching, you won’t want to miss a striking meteorological happening right now on the Red Planet.

Map showing the most prominent dark features on Mars. Hellas is at upper right. To its north is the Africa-shaped windswept volcanic plain Syrtis Major. Credit: A.L.P.O. — Map showing the most prominent dark features on Mars. Hellas is at upper right. Credit: A.L.P.O.

Winter’s already well underway in the planet’s southern hemisphere and there’s no better place to see it than over Hellas, Mars’ biggest impact crater. Hellas formed some 4 billion years when a small asteroid crashed into the young planet and left a scar measuring 1,400 miles (2,300 km) wide and 26,465 feet (7,152 meters) deep. Point your telescope in its direction in the next few weeks and you’ll see what looks at first like the planet’s south polar cap. Don’t be deceived. That’s Hellas coated in dry ice frost and filled with wintertime clouds.

The Hellas impact basin, also known as Hellas Planitia. After Mars' Utopia Planitia and the moon's South Pole-Aitken Basin, Hellas is the third largest confirmed crater in the solar system. — The Hellas impact basin, also known as Hellas Planitia, is 1,400 miles wide. After Mars’ Utopia Planitia and the moon’s South Pole-Aitken Basin, Hellas is the third largest confirmed crater in the solar system.

Right now, Mars’ northern hemisphere, along with the north polar cap, are tipped our way. Though the cap is rapidly vaporizing as the northern summer progresses, you can still spot it this month as a small dab of white along the northern limb in 6-inch (15 cm) and larger telescopes. Use a magnification upwards of 150x for the best views. The south polar cap can’t be seen because it’s tipped beyond the southern limb.

Mars from Athens, Greece on March 14, 2014 with Hellas (top), Syrtis Major and both morning and evening limb water clouds. Credit: Manos Kardasis — Mars from Athens, Greece on March 14, 2014 with Hellas (top), Syrtis Major and both morning and evening limb water clouds. The winter-whitened Hellas impact basin is best seen using magnifications of 150x or higher. Credit: Manos Kardasis

Along with nearby Syrtis Major, Hellas was one of the first features discovered with the telescope. Even in summer its pale floor stands out against the darker volcanic features of the planet. Though windswept and bitter cold now, Hellas’ great depth makes it one of the warmest places on Mars during the summer months. Mid-summer atmospheric pressure has been measured at more than 10 millibars, more than twice the planet’s mean. Afternoon high temperatures reach near the freezing point (32 F / 0 C) with nighttime lows around -50 F (-45 C). Winter temperatures are much more severe with lows around -22o F (-140 C). Carbon dioxide condenses as frost and whitens the floors of many craters during this time.

Mars photographed by the Mars Global Surveyor shows the equally prominent Syrtis Major and the Hellas impact basin. Credit; NASA/JPL/Malin Space Systems — Mars photographed by the Mars Global Surveyor shows the equally prominent Syrtis Major and the Hellas impact basin. Syrtis Major is an ancient, low relief shield volcano. Credit; NASA/JPL/Malin Space Systems

We can only see Hellas when that hemisphere is turned in our direction; this happens for about a week and a half approximately once a month. European observers are favored this week with Hellas well placed near the planet’s central meridian from 1 – 4 a.m. local time. Why the outrageous hour? Mars rises around 10 p.m. but typically looks soft and mushy in the telescope until it’s high enough to clear the worst of atmospheric turbulence 2 – 3 hours later. North and South American observers will get their turn starting this Saturday March 22nd around 12:30 – 1 a.m. Good Hellas viewing continues through early April.

Mars at 1 a.m. CDT on successive nights starting March 21, 2014. Notice how planetary features appear to rotate to the east night to night. Created with images from Meridian — Mars at 1 a.m. CDT on successive nights starting March 21, 2014. Notice how planetary features appear to rotate slowly eastward night to night. Created with images from Meridian

Like Earth, Mars revolves from west to east on its axis, but because it rotation period is 37 minutes longer than Earth’s, Hellas and all Martian features appear to drift slowly eastward with each succeeding night. A feature you observed face-on at midnight one night will require staying up until 2:30 a.m. a week later for Mars to “rotate it back” to the same spot. To keep track of the best times to look for Hellas or anything else on Mars, I highly recommend the simple, free utility called Meridian created by Claude Duplessis. Set your time zone and you’ll know exactly the best time to look.

Mars on March 8, 2014 shows not only clouds over Hellas but evening limb clouds. Credit: W.L. Chin — Mars on March 8, 2014 shows clouds over Hellas and evening limb clouds. Credit: Chin Wei Loon

While you’re out watching the Martian winter at work, don’t forget to also look for the shrinking north polar cap and bright, patchy clouds along the planet’s morning (east) and evening limbs. You can use the map above to try and identify the many subtle, gray-toned features named after lands in classic antiquity by 19th century Italian astronomer and Mars aficionado Giovanni Schiaparelli.

I will you success in seeing Hellas and encourage you to share your observations with us here at Universe Today.

March 12, 2014December 23, 2015 by David Dickinson

Astronomers Identify the Largest Yellow “Hypergiant” Star Known

A stellar monster lurks in heart of the Centaur.

A recent analysis of a star in the south hemisphere constellation of Centaurus has highlighted the role that amateurs play in assisting with professional discoveries in astronomy.

The find used of the European Southern Observatory’s Very Large Telescope based in the Atacama Desert in northern Chile — as well as data from observatories around the world — to reveal the nature of a massive yellow “hypergiant” star as one of the largest stars known.

The stats for the star are impressive indeed: dubbed HR 5171 A, the binary system weighs in at a combined 39 solar masses, has a radius of over 1,300 times that of our Sun, and is a million times as luminous. Located 3,600 parsecs or over 11,700 light years distant, the star is 50% larger than the famous red giant Betelgeuse. Plop HR 5171 A down into the center of our own solar system, and it would extend out over 6 astronomical units (A.U.s) past the orbit of Jupiter.

The field around HR 5171 A (the brightest star just below center). Credit: ESO/Digitized Sky Survey 2.

Researchers used observations going back over 60 years – some of which were collected by dedicated amateur astronomers – to pin down the nature of this curious star. A variable star just below naked eye visibility spanning a magnitude range from +6.1 to +7.3, HR 5171 A also has a relatively small companion star orbiting across our line of sight once every 1300 days. Such a system is known as an eclipsing binary. Famous examples of similar systems are the star Algol (Alpha Persei), Epsilon Aurigae and Beta Lyrae. The companion star for HR 5171 is also a large star in its own right at around six solar masses and 400 solar radii in size. The distance from center-to-center for the system is about 10 A.U.s – the distance from Sol to Saturn – and the surface-to-surface distance for the A and B components of the system are “only” about 2.8 A.U.s apart. This all means that these two massive stars are in physical contact, with the expanded outer atmosphere of the bloated primary contacting the secondary, giving the pair a distorted peanut shape.

“The companion we have found is very significant as it can have an influence on the fate of HR 5171 A, for example stripping off its outer layers and modifying its evolution,” said astronomer Olivier Chesneau of the Observatoire de la Côte d’Azur in Nice France in the recent press release.

Knowing the orbital period of a secondary star offers a method to measure the mass of the primary using good old Newtonian mechanics. Coupled with astrometry used to measure its tiny parallax, this allows astronomers to pin down HR 5171 A’s stupendous size and distance.

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Along with luminous blue variables, yellow hypergiants are some of the brightest stars known, with an absolute magnitude of around -9. That’s just 16x times fainter than the apparent visual magnitude of a Full Moon but over 100 times brighter than Venus – if you placed a star like HR 5171 A 32 light years from the Earth, it would easily cast a shadow.

Astronomers used a technique known as interferormetry to study HR 5171 A, which involves linking up several telescopes to create the resolving power of one huge telescope. Researchers also culled through over a decade’s worth data to analyze the star. Though much of what had been collected by the American Association of Variable Star Observers (the AAVSO) had been considered to be too noisy for the purposes of this study, a dataset built from 2000 to 2013 by amateur astronomer Sebastian Otero was of excellent quality and provided a good verification for the VLT data.

The discovery is also crucial as researchers have come to realize that we’re catching HR 5171 A at an exceptional phase in its life. The star has been getting larger and cooling as it grows, and this change can be seen just over the past 40 year span of observations, a rarity in stellar astronomy.

“It’s not a surprise that yellow hypergiants are very instable and lose a lot of mass,” Chesneau told Universe Today. “But the discovery of a companion around such a bright star was a big surprise since any ‘normal’ star should at least be 10,000 times fainter than the hypergiant. Moreover, the hypergiant was much bigger than expected. What we see is not the companion itself, but the regions gravitationally controlled and filled by the wind from the hypergiant. This is a perfect example of the so-called Roche model. This is the first time that such a useful and important model has really been imaged. This hypergiant exemplifies a famous concept!”

Indeed, you can see just such photometric variations as the secondary orbits its host in the VLTI data collected by the AMBER interferometer, backed up by observations from GEMINI’s NICI chronograph:

Credit: ESO/VLT/GEMINI/NICI — Looking at the bizarre system of HR 5171. Credit: Olivier Chesneau/ESO/VLT/GEMINI/NICI

The NIGHTFALL program was also used for modeling the eclipsing binary components.

These latest measurements place HR 5171 A firmly in the “Top 10” for largest stars in terms of size known, as well as the largest yellow hypergiant star known This is due mainly to tidal interactions with its companion. Only eight yellow hypergiants have been identified in our Milky Way galaxy. HR 5171 A is also in a crucial transition phase from a red hypergiant to becoming a luminous blue variable or perhaps even a Wolf-Rayet type star, and will eventually end its life as a supernova.

Enormous stars: From left to right, The Pistol Star, Rho Cassiopeiae, Betelgeuse and VY Canis Majoris compared with the orbits of Jupiter (in red) and Neptune (in blue). Remember, HR 5171 A is 50% larger than Betelgeuse! Credit: Anynobody under a Creative Commons Attribution Share-Alike 3.0 Unported license.

HR 5171 A is also known as HD 119796, HIP 67261, and V766 Centauri. Located at Right Ascension 13 Hours 47’ 11” and declination -62 degrees 35’ 23,” HR 5171 culminates just two degrees above the southern horizon at local midnight as seen from Miami in late March.

HR 5171 A: a finder chart. Click to enlarge. Credit: Stellarium

HR 5171 A is a fine binocular object for southern hemisphere observers.

But the good news is, there’s another yellow hypergiant visible for northern hemisphere observers named Rho Cassiopeiae:

Rho Cass is one of the few naked eye examples of a yellow hypergiant star, and varies from magnitude +4.1 to +6.2 over an irregular period.

It’s amusing read the Burnham’s Celestial Handbook entry on Rho Cass. He notes the lack of parallax and the spectral measurements of the day — the early 1960s — as eluding to a massive star with a “true distance… close to 3,000 light years!” Today we know that Rho Cassiopeiae actually lies farther still, at over 8,000 light years distant. Robert Burnham would’ve been impressed even more by the amazing nature of HR 5171 as revealed today by ESO astronomers!

– The AAVSO is always seeking observations from amateur astronomers of variable stars.

March 10, 2014April 26, 2016 by David Dickinson

How to Watch an Asteroid Occult a Bright Star on March 20th

Live in the New York City tri-state area, or anywhere near the path above? One of the most unusual big ticket astronomical events of 2014 occurs on in the morning hours of Thursday March 20th, when the asteriod 163 Erigone “blocks” or occults the bright star Regulus.

This is brightest star to be occulted by an asteroid for 2014, and has a potential to be observed by millions.

Occultations of stars by asteroids are often elusive events, involving faint stars and often occurring over remote locales. Not so with this one. In fact, the occultation of Regulus on March 20^th will result in an “asteroid shadow” passing over viewers across the populous areas of New York and adjoining states in the U.S. northeast before racing into Canada.

And unlike most asteroid occultations, you won’t need any special equipment to detect this event. Shining at magnitude +1.3, Regulus is an easy and familiar naked eye object and is the 22nd brightest star in the sky. And heck, it might be interesting just to catch a view of the constellation Leo minus its brightest star!

Asteroid 163 Erigone shines at magnitude+12.4 during the event. At 72 kilometres in diameter and 1.183 A.U.s distant during the occultation, 163 Erigone was discovered by French astronomer Henri Joseph Perrotin on April 26^th, 1876.

There’s a great potential to learn more not only about 163 Erigone during the event, but Regulus itself. Amateur observations will play a key role in this effort. The International Occultation Timing Association (IOTA) seeks observations from this and hundreds of events that occur each year. Not only can such a precise measurement help to pin down an asteroid’s orbit, but precise timing of the occultation can also paint a “picture” of the profile of the asteroid itself.

Example credit: — An example of an asteroid shape profile created by observers during the occultation of a star by asteroid 55 Pandora in 2007. Each cord represents an observer. Credit- The IOTA.

Regulus also has a faint white dwarf companion, and it’s just possible that it may be spied a fraction of a second before or after the event. Does 163 Erigone have a moon? Several asteroids are now known to possess moons of their own, and it’s just possible that 163 Erigone could have a tiny unseen companion, the presence of which would be revealed by a small secondary event. Observers along and outside the track from Nova Scotia down to Kentucky are urged to be vigilant for just such a surprise occurrence:

Wide map (credit) — A widened map of the March 20th event, noting the span over which an unseen “moon” of 163 Erigone could be potentially observed. Credit: IOTA/Ted Blank/Google Earth.

The maximum duration for the event along the centerline is 14.3 seconds, and the rank for the event stands at 99%, meaning the path is pretty certain.

The shadow touches down on Earth in the mid-Atlantic at 5:53 Universal Time (UT), and grazes the island of Bermuda before making landfall over Long Island New York, New Jersey, Connecticut and northeastern Pennsylvania just after 6:06 UT/2:06 AM EDT. From there, the shadow of the asteroid heads to the northwest and crosses Lake Ontario into Canada before passing between the cities of Ottawa and Toronto just before 6:08 UT. Finally, it crosses out over Hudson Bay and Nunavut before departing the surface of our fair planet at 6:22 UT.

The path is about 117 kilometres wide, and the “shadow” races across the surface of the Earth at about 2.8 kilometres per second from the southeast to the northwest.

Timing an occultation can be accomplished via audio or video recording, though accurate time is crucial for a meaningful scientific observation. The IOTA has a complete explanation of tried and true methods to use for capturing and reporting the event.

We had a chance to catch up with veteran asteroid occultation observer Ted Blank concerning the event and the large unprecedented effort underway to capture it.

He notes that Regulus stands as the brightest star that has been observed to have been occulted by an asteroid thus far when 166 Rhodope passed briefly in front of it on October 19^th, 2005.

“This is the best and brightest occultation ever predicted to occur over a populated area, and that covers the entire 40 years of predictive efforts,” Mr. Blank told Universe Today concerning the upcoming March 20^th event.

The general public can participate in the scientific effort for observations as well.

“We’re trying to make a “picket fence” of thousands of observers to catch this asteroid, so the best thing to do is to go out and observe. If they live anywhere near or in the path, just step outside (or watch from a warm house through a window). Make sure they are looking at the right star,” Mr. Blank told Universe Today. “If they can travel an hour or so to be somewhere in the predicted path, by all means do so – they’ll be home and back in bed well before rush hour starts! Then report what they saw at the public reporting page. If no occultation was seen, report a miss. This is more important that people think, since “miss” observations define the edges of the asteroid.”

There is also a handy “Occultation 1.0” timing app now available for IPhone users for use during the event.

Mr. Blank also plans to webcast the occultation live via UStream, and urges people to check the Regulus2014 Facebook page for updates on the broadcast status, as well as the final regional weather prospects leading up event next week. For dedicated occultation chasers, mobility and the ability to change observing locale at the last moment if necessary may prove key to nabbing this one. One of our preferred sites to check the cloud cover forecast prior to observing any event is the Clear Sky Chart.

This promises to be a historic astronomical event. Thanks to Ted Blank and Brad Timerson at the IOTA for putting the public outreach project together for this one, and be sure not to miss the occultation of Regulus on March 20^th!

March 7, 2014April 26, 2016 by Markus Pössel

See Light Pollution in Action

Like anyone else who’s ever looked up at the night sky in any but the smallest cities, I’ve seen light pollution first-hand. Like anyone else even marginally involved in amateur astronomy, I know about the fight against light pollution. And I know that, what with new LED lights and everything, it’s not going to be easy.

When, the other day, I was looking around for images demonstrating the effects of light pollution, it didn’t take me long to find some scary examples – the satellite images tracing human presence on Earth by its light pollution are rather unequivocal, and on Wikimedia Commons, there was an impressive image showing the same region of the night sky when viewed from a dark and from a lighter location:

The images were taken by Jeremy Stanley and are available via Wikimedia Commons under the CC BY 2.0 license. According to the author’s comment, he tried to match the two images’ sky brightness to his memory of how bright the sky appeared to his eyes.

What I didn’t find was an image showing a comparison of two images with the same specs (same camera and lens, same ISO, aperture and exposure time) under different viewing conditions. In the end, I found that I could produce such an example myself, using images I had taken during a trip to South Africa last spring.

During the first leg of our trip, we had visited South Africa’s national science festival, SciFest Africa, which is held annually in Grahamstown in the Eastern Cape Province. Grahamstown has a population of 70.000, and there is some visible light pollution. I took an image of the Milky Way, including the Southern Cross, from the reasonably well-lit courtyard of our hotel:

Some days later, we visited the Sutherland site of South Africa’s National Observatory SAAO, home, among other things, to the 10 m South African Large Telescope (SALT). In the small city of Sutherland, with a population of only about 3000, the observatory a mere 7 miles away and a spirit of cooperation with the astronomers’ needs, light pollution levels are low.

When we took some images of the sky from the backyard of our hotel, the biggest light pollution problem was the moon. Here’s an image that shows, among other objects, the Southern Cross, Alpha Centauri and Carina:

It was only much later that I realized that these images could be used for the light pollution comparison I was looking for. They were both taken with the same camera (Canon EOS 450D = EOS Rebel XSi), the same lens (Tokina 11-16 mm at 11 mm) with the same settings (ISO 1600, aperture 2.8, exposure time 10 seconds). Whatever difference you see is really due to the viewing conditions. To show what you can do with a dark, high-contrast sky, I added a third image. Its only difference to the second image is the exposure time (20 seconds to 10 seconds), which brings out the Milky Way much more strongly.

I combined the images, used GIMP to increase the contrast and saturation on the combined image (to make sure I treated all three images the same), and separated the images again. Here is the result:

The difference between the first two images is fairly drastic. And keep in mind that, as far as light pollution goes, Grahamstown is likely to be fairly harmless, compared with a big, brightly-lit city. (And yes, if I should get the chance, I’ll try to take an image with the same set-up in a larger city!)

This is just one of all too many examples. Through careless lighting, many of us are missing out on one of humanity’s most fundamental experiences: an unobstructed view of the enormity of what’s out there, far beyond space-ship Earth.