David Dickinson, Author at Universe Today

March 18, 2013December 23, 2015 by David Dickinson

Stalking the Lunar X

The Lunar X, captured by the author on June 8th, 2011.

This week offers observers a shot at capturing a fascinating but elusive lunar feature.

But why study the Moon? It’s a question we occasionally receive as a backyard astronomer. There’s a sort of “been there, done that” mentality associated with our nearest natural neighbor in space. Keeping one face perpetually turned Earthward, the Moon goes through its 29.5 synodic period of phases looking roughly the same from one lunation to the next. Then there’s the issue of light pollution. Many deep sky imagers “pack it in” during the weeks surrounding the Full Moon, carefully stacking and processing images of wispy nebulae and dreaming of darker times ahead…

But fans of the Moon know better. Just think of life without the Moon. No eclipses. No nearby object in space to give greats such as Sir Isaac Newton insight into celestial mechanics 101. In fact, there’s a fair amount of evidence to suggest that life arose here in part because of our large Moon. The Moon stabilizes our rotational axis and produces a large tidal force on our planet. And as all students of lunar astronomy know, not all lunations are exactly equal.

A daytime capture of the Lunar X. (Photo by Author).

This week, we get a unique look at a feature embedded in the lunar highlands which demonstrates this fact. The Lunar X, also sometimes known as the Purbach cross or the Werner X reaches a decent apparition on March 19^th at 11:40UT/7:40EDT favoring East Asia and Australia. This feature is actually the overlapping convergence of the rims of Blanchinus, La Caille and Purbach craters. The X-shaped feature reaches a favorable illumination about six hours before 1^st Quarter phase and six hours after Last Quarter phase. It is pure magic watching the X catch the first rays of sunlight while the floor of the craters are still immersed in darkness. For about the span of an hour, the silver-white X will appear to float just beyond the lunar terminator.

Visibility of the Lunar X for the Remainder of 2013.
Lunation	Date	Time	Phase	Favors
1116	March 19^th	11:40UT/7:40EDT	Waxing	East Asia/Australia
1116	April 3^rd	3:20UT/23:20EDT*	Waning	Africa/Europe
1117	April 17^th	23:47UT/19:47EDT	Waxing	Eastern North America
1117	May 2^nd	16:19UT/12:19EDT	Waning	Central Pacific
1118	May 17^th	10:51UT/6:51EDT	Waxing	East Asia/Australia
1118	June 1^st	4:31UT/0:31EDT	Waning	Western Africa
1119	June 15^th	21:21UT/17:21EDT	Waxing	South America
1119	June 30^th	16:04UT/12:04EDT	Waning	Western Pacific
1120	July 15^th	7:49UT/3:49EDT	Waxing	Australia
1120	July 30^th	3:16UT/23:16EDT*	Waning	Africa/Western Europe
1121	August 13^th	18:50UT/14:50EDT	Waxing	South Atlantic
1121	August 28^th	14:27UT/10:27EDT	Waning	Central Pacific
1122	September 12^th	9:50UT/5:50EDT	Waxing	East Asia/Australia
1122	September 27^th	2:00UT/22:00EDT*	Waning	Middle East/East Africa
1123	October 11^th	19:52UT/15:52EDT	Waxing	Atlantic Ocean
1123	October 26^th	14:12UT/10:12EDT	Waning	Central Pacific
1124	November 10^th	10:03UT/5:03EST	Waxing	East Asia/Australia
1124	November 25^th	3:14UT/22:14EST*	Waning	Africa/Europe
1125	December 10^th	00:57UT/19:57EST	Waxing	Western North America
1126	December 24^th	17:07UT/12:07EST	Waning	Western Pacific
Times marked in bold* denote visibility in EDT/EST the evening prior.

Fun Factoid: All lunar apogees and perigees are not created equal either. The Moon also reaches another notable point tonight at 11:13PM EDT/ 3:13 UT as it arrives at its closest apogee (think “nearest far point”) in its elliptical orbit for 2013 at 404,261 kilometres distant. Lunar apogee varies from 404,000 to 406,700 kilometres, and the angular diameter of the Moon appears 29.3’ near apogee versus 34.1’ near perigee. The farthest and visually smallest Full Moon of 2013 occurs on December 17^th.

The first sighting of the Lunar X feature remains a mystery, although modern descriptions of the curious feature date back to an observation made by Bill Busler in June 1974. As the Sun rises across the lunar highlands the feature loses contrast. By the time the Moon reaches Full, evidence of the Lunar X vanishes all together. With such a narrow window to catch the feature, many longitudes tend to miss out during successive lunations. Note that it is possible to catch the 1^st and Last Quarter Moon in the daytime.

A 1st Quarter Moon with the Lunar X (inset). (Photo by Author).

Compounding the dilemma is the fact that the lighting angle for each lunation isn’t precisely the same. This is primarily because of two rocking motions of the Moon known as libration and nutation. Due to these effects, we actually see 59% of the lunar surface. We had to wait for the advent of the Space Age and the flight of the Soviet spacecraft Luna 3 in 1959 to pass the Moon and look back and image its far side for the first time.

We actually managed to grab the Lunar X during a recent Virtual Star Party this past February. Note that another fine example of lunar pareidolia lies along the terminator roughly at the same time as the Lunar X approaches favorable illumination. The Lunar V sits near the center of the lunar disk near 1^st and Last Quarter as well and is visible right around the same time. Formed by the confluence of two distinct ridges situated between the Mare Vaporum and Sinus Medii, it is possible to image both the Lunar X and the Lunar V simultaneously!

A simultaneous capture of the Lunar X & the Lunar V features. (Photo by Author).

This also brings up the interesting possibility of more “Lunar letters” awaiting discovery by keen-eyed amateur observers… could a visual “Lunar alphabet be constructed similar to the one built by Galaxy Zoo using galactic structures? Obviously, the Moon has no shortage of “O’s,” but perhaps “R” and “Q” would be a bit more problematic. Let us know what you see!

-Thanks to Ed Kotapish for providing us with the calculations for the visibility of the Lunar X for 2013.

March 15, 2013April 26, 2016 by David Dickinson

Citizen Science, Old-School Style: The True Tale of Operation Moonwatch

An Operation Moonwatch team in action based out of Terre Haute, Indiana. (Courtesy of Keep Watching the Skies! Author Patrick McCray, used with Permission).

Amateur astronomers have done more than just watch the skies, they’ve been a national security asset. In the mid-1950’s, it was realized that the reality of the Space Age was at best only a decade away. Sub-orbital German V-2 rockets captured by the Soviets and the United States were reaching higher and higher altitudes, and it was only a matter of time before orbital velocity would be achieved.

Keep in mind, this was the age of backyard bomb shelters, “duck and cover” drills, and civil preparedness as Cold War fever reached a heightened pitch. Ground Observer Corps encouraged and trained citizen groups how to spot and report enemy bombers approaching the U.S coast in preparation for a nuclear confrontation. And remember, there was no reason to think that this build up wouldn’t extend to the militarization of space. It was in this era that Operation Moonwatch was born.

Conceived by Harvard astronomer Fred Whipple, Operation Moonwatch was the “Galaxy Zoo” of its day. The idea was simple; teams of observers around the world would track, time and record satellite passes over their location and feed this data back to the computation center at Cambridge, Massachusetts (telephone, Western Union or ham radio were the methods of the day) This data would give engineers information as to where to point their enormous Baker-Nunn cameras. These instruments were wide-field Schmidt cameras that could cover large swaths of the sky. They were to be positioned at 12 locations worldwide to keep tabs on satellites in low Earth orbit (LEO).

A Baker-Nunn satellite tracking camera ready for action. (Credit: NASA).

To be sure, there were obstacles to overcome. The Baker-Nunn cameras were well behind schedule, and the entire system was struggling to come online by mid-1958 in time for the International Geophysical Year (IGY). School and community groups had to be organized, trained, and equipped. Knowing precise location in the pre-GPS era had to be addressed. Many purchased optical kits available from Radio Shack, while many teams built their own. Then there was the dilemma of what a satellite would actually look like to an observer on the ground. Could a trained spotter even see it? Civil Air Patrol groups experimented with various trial substitutions, such as following aircraft, flocks of birds and bats at dusk and even tracking pebbles tossed into the sky!

Operation Moonwatch was also to play a part of the 1958 International Geophysical Year. Many doubted to effectiveness of amateur groups, but public interest ran high. Then on October 4th 1957, the world was caught off guard as Sputnik 1 lifted off from the Baikonur Cosmodrome.

The metal ball that started it all... Sputnik 1. (Credit: NASA/Asif A. Siddiqi). — The metal ball that started it all… Sputnik 1. (Credit: NASA/Asif A. Siddiqi).

The world was stunned that the Soviets had beaten the West into space. The National Advisory Committee for Aeronautics (later to become NASA in 1958) had yet to achieve a successful orbital launch, and the United States Naval Research Laboratory was still floundering to get the Vanguard program off the pad. The launch of Sputnik found a scant few Moonwatch teams at the ready to catch its first dusk passes over the United States. Keep in mind, the Sputnik satellite was too small and faint to see with the naked eye. What most casual observers in the general public saw (remember the opening scenes in the movie October Sky?) was actually the rocket booster that put Sputnik into space.

Moonwatch teams would “look up by looking down” using a bench mounted telescope that looked at a reflective plate aimed skyward. With observers arranged in a row aimed at a picket line, they would call out when the target satellite crossed the local meridian. This would in turn be documented by an onsite recorder for transmission.

A classic Operation Moonwatch bench instrument sold by Edmund Scientifc. (Credit: The Smithsonian Natinal Air & Space Museum). — A classic Operation Moonwatch bench instrument sold by Edmund Scientific (Credit: The Smithsonian National Air & Space Museum).

With Sputnik, the Operation Moonwatch volunteers found themselves thrust into the spotlight. Newspapers & radio shows clamored to interview volunteers, as the public suddenly became obsessed with space. Moonwatchers followed and documented to launch of the dog Laika aboard Sputnik 2 on November 3^rd, 1957, and when the U.S. finally launched its first satellite Explorer I on February 1^st 1958 Operation Moonwatch tracked it. Magazines such as National Geographic and Boys Life ran articles on the project and told teams how they could participate. When Sputnik 4 reentered over the U.S. on September 1962, it was data from Operation Moonwatch observers that proved vital in its recovery.

How Operation Moonwatch fit into the hierarchy. (Credit: NASA archives, The Role of the NAS & TPESP). — How Operation Moonwatch fit into the hierarchy. Note how amateur groups were associated with this press. (Credit: NASA archives, *The Role of the NAS & TPESP*).

Moonwatch was disbanded in 1975, but many volunteers continued tracking satellites and sharing data on their own. I always think that it’s fascinating that three very early satellites from the early days of Operation Moonwatch are still in orbit and can been seen with a good pair of binoculars and a little patience , Vanguards 1, 2 & 3. It could be argued that Operation Moonwatch provided a civilian means to monitor the goings on of governments in low Earth orbit and may have contributed to the Outer Space Treaty outlawing the use of nuclear weapons in space. Another fortunate occurrence of the era was the establishment of a civilian space agency in the U.S., argued for successfully by Dr. James Van Allen. How different would the course of history have been if the U.S. space program had become a “fourth branch” of the military?

Cincinnati plaque commemorating Operation Moonwatch. (Brian Van Flandern Public Domain image).

Today, modern satellite trackers still follow, image and share information on satellites worldwide. This effort transcends borders; when hazardous payloads such as Russia’s failed Mars mission Phobos-Grunt reentered in early 2012 satellite trackers documented its final passage, and efforts are still underway to keep tabs on the USAF’s X-37 spy satellite. One can also see a stark contrast between the efforts to enlist civilian effort during the Cold War and the modern Global War on Terrorism. Interest in science was at an all-time high in the 1950’s, as it was realized the West might be lagging behind in science education. In a post-9/11 era, there almost seems to be a movement to isolate participation. Many model rocketry groups are under increased restriction, and even amateur astronomers may see essential tools such as green laser pointers restricted for use.

Image of Space Shuttle Discovery on STS-119 captured from the ground… note the NASA “Blue Meatball” logo on the wing! (Credit: Ralf Vandebergh, used with permission).

But the good news is, anyone can still track a satellite from the comfort of their own backyard all in the spirit of Operation Moonwatch. DARPA announced a project last year which may resurrect a program similar to Operation Moonwatch. Named SpaceView, this program seeks to augment the U.S. Air Force’s Space Surveillance Network. Keep an eye on the sky, and remember a dedicated few amateur observers that played a crucial role in modern history as you watch satellites drift silently by in the twilight skies.

For more on the fscinating hostory of Operation Moonwatch, read Patrick McCray’s Keep Watching the Skies!

See more of Ralf Vandebergh’s outstanding work at his site Telescopic Spaceflight Images.

March 13, 2013April 26, 2016 by David Dickinson

WISE Nabs the Closest Brown Dwarfs Yet Discovered

WISE J104915.57-531906 from NASA's WISE survey (centered) and resolved to should its binary nature by the Gemini Observatory (inset). (Credit: NASA/JPL/Gemini Observatory/AURA/NSF).

We now know our stellar neighbors just a little better, and a new discovery may help tell us how common brown dwarfs are in our region of the galaxy. Early this week, researchers at Pennsylvania State University announced the discovery of a binary brown dwarf system. With a parallax measurement of just under 0.5”, this pair is only 6.5 light years distant making it the third closest system to our own and the closest example of the sub-stellar class of objects known as brown dwarfs yet discovered.

Named WISE J104915.57-531906, the system was identified by analysis of multi-epoch astrometry carried out by NASA’s Wide-field Infrared Survey Explorer (WISE). The discovery was made by associate professor of astronomy and astrophysics at Penn State’s Center for Exoplanets and Habitable Worlds Kevin Luhman. The system’s binary nature and follow up observations were confirmed by spectroscopic analysis carried out by the Gemini Observatory’s Multi-Object Spectrographs (GMOS).

Animation showing the motion of WISE 1049-5319 across the All-WISE, 2MASS & Sloan Digital Sky Survyies from 1978 to 2010. (Credit: NASA/STScI/JPL/IPAC/University of Massachusetts.) — Animation showing the motion of WISE 1049-5319 across the All-WISE, 2MASS & Sloan Digital Sky Surveys from 1978 to 2010. (Credit: NASA/STScI/JPL/IPAC/University of Massachusetts.)

This find is also the closest stellar system discovered to our own solar system since the discovery of Barnard’s star by astronomer E.E. Barnard in 1916. Incidentally, Barnard’s star was the center of many spurious and controversial claims of extrasolar planet discoveries in the mid-20^th century. Barnard’s star is 6 light years distant, and the closest star system to our own is Alpha Centauri measured to be 4.4 light years distant in 1839. In 1915, the Alpha Centauri system was determined to have a faint companion now known as Proxima Centauri at 4.2 light years distant. The Alpha Centauri system also made headlines last year with the discovery of the closest known exoplanet to Earth. WISE 1506+7027 is the closest brown dwarf to our solar system yet discovered. This also breaks the extended the All-WISE survey’s own previous record of the closest brown dwarf released in 2011, WISE 1506+7027 at 11.1 light years distant.

When looking for nearby stellar suspects, astronomers search for stars displaying a high proper motion across the sky. The very first parallax measurement of 11 light years distant was obtained by Friedrich Bessel for the star 61 Cygni in 1838. 61 Cygni was known as “Piazzi’s Flying Star” for its high 4.2” proper motion across the sky. To giving you an idea of just how tiny an arc second is, a Full Moon is about 1800” in diameter. With a proper motion of just under 3” per year, it would take WISE 1049-5319 over 600 years to cross the same apparent distance in the sky as viewed from the Earth!

An artist's conception of looking back at Sol from the binary brown dwarf system WISE 1049-5319, 6.5 light years distant. (Credit: Janella Williams, Penn State University). — An artist’s conception of looking back at Sol from the binary brown dwarf system WISE 1049-5319, 6.5 light years distant. (Credit: Janella Williams, Penn State University).

“Based on how this star system was moving in images from the WISE survey, I was able to extrapolate back in time to predict where it should have been located in older surveys,” stated Luhman. And sure enough, the brown dwarf was there in the Deep Near-Infrared Survey of the Southern Sky (DENIS), the Two Micron All-Sky Survey (2MASS) and the Sloan Digitized Sky Survey (SDSS) spanning a period from 1978 to 1999. Interestingly, Luhman also points out in the original paper that the pair’s close proximity to the star rich region of galactic plane in the constellation Vela deep in the southern hemisphere sky is most likely the reason why they were missed in previous surveys.

The discovery of the binary nature of the pair was also “an unexpected bonus,” Luhman said. “The sharp images from Gemini also revealed that the object actually was not just one, but a pair of brown dwarfs orbiting each other.” This find of a second brown dwarf companion will go a long way towards pinning down the mass of the objects. With an apparent separation of 1.5”, the physical separation of the pair is 3 astronomical units (1 AU= the Earth-Sun distance) in a 25 year orbit.

Size comparison of stellar vs substellar objects. (Credit: NASA/JPL-Caltech/UCB).

Brown dwarfs are sub-stellar objects with masses too low (below ~75 Jupiter masses) to sustain the traditional fusion of hydrogen into helium via the full proton-proton chain process. Instead, objects over 13 Jupiter masses begin the first portion of the process by generating heat via deuterium fusion. Brown dwarfs are thus only visible in the infrared, and run a spectral class of M (hottest), L, T, and Y (coolest). Interestingly, WISE 1049-5319 is suspected to be on the transition line between an L and T-class brown dwarf. To date, over 600 L-type brown dwarfs have been identified, primarily by the aforementioned SDSS, 2MASS & DENIS infrared surveys.

General location of WISE 1049-5319 in the constellation Vela. Note its proximity to the galactic plane. (Created by the author using Starry Night).

This discovery and others like it may go a long ways towards telling us how common brown dwarfs are in our region of the galaxy. Faint and hard to detect, we’re just now getting a sampling thanks to surveys such as WISE and 2MASS. The James Webb Space Telescope will do work in the infrared as well, possibly extending these results. Interestingly, Luhman notes in an interview with Universe Today that the potential still exists for the discovery of a brown dwarf closer to our solar system than Alpha Centauri. “No published study of the data from WISE or any other survey has ruled out this possibility… WISE is much more capable of doing this than any previous survey, but the necessary analysis would be fairly complex and time consuming. It’s easier to find something than to rule out its existence.” Said Luhman. Note that we’re talking a nearby brown dwarf that isn’t gravitationally bound to the Sun… this discussion is separate from such hypothetical solar companions as Nemesis and Tyche…and Nibiru conspiracy theorists need not apply!

The WISE 1049-5319 system is also a prime target in the search for nearby extra-solar planets. “Because brown dwarfs have very low masses, they exhibit larger reflex motions due to orbiting planets than more massive stars, and those larger reflex motions will be easier to detect.” Luhman told Universe Today. Said radial surveys for exoplanets would also be carried out in the IR band, and brown dwarfs also have the added bonus of not swamping out unseen planetary companions in the visible spectrum.

Congrats to Mr. Luhman and the Center for Exoplanets and Habitable Worlds on the discovery. You just never know what’s lying around in your own stellar backyard!

Read this original discovery paper here.

March 11, 2013April 26, 2016 by David Dickinson

Update: Comet PANSTARRS Makes Its Northern Hemisphere Debut

Comet PANSTARRS as seen from Arizona on March 10, 2013. Credit and copyright: Chris Schur.

The first of three bright comets anticipated in 2013 became visible to North American observers this past weekend. Comet C/2011 L4 PanSTARRS is now currently visible low to the southwest at dusk, if you know exactly where to look for it.

Observers in the southern hemisphere have been enjoying this comet for the past few weeks as it reached naked eye visibility above 6^th magnitude around late February and began its long trek northward. Comet PanSTARRS is on a 106,000+ year orbit with a high inclination of 84.2° with respect to the ecliptic. This also means that PanSTARRS is currently moving roughly parallel to the “0 Hour” line in Right Ascension (The same point occupied by the Sun during next week’s Vernal Equinox on March 20^th) and is only slowly gaining elevation on successive evenings.

CometPANSTARRS from Michael Zeiler on Vimeo.

Observers in Hawaii and Mexico picked up PanSTARRS late last week, and scattered reports of sightings from the southern continental United States started trickling in Saturday night on the evening of March 9^th. We managed to grab Comet PanSTARRS low to the southwest on Sunday evening on March 10^th, about 30 minutes after local sunset.

Comet PanSTARRS seen from Hudson Florida on the evening of March 10th (Photo by Author).

We were surprised by the star-like appearance of the coma, about +1^stto 2^nd magnitude with a tiny fan-shaped tail. The comet was visible in binoculars only (I used our trusty pair of Canon 15×45 Image-Stabilized binocs for the task) and I couldn’t yet pick out the comet with the naked eye.

Several sightings westward followed. Clay Davis based in Santa Fe, New Mexico noted a visual magnitude of -0.5, saying that PanSTARRS was “Brighter than Mars” at magnitude +1 but “A challenge to keep in view.” Note that observer estimations of the brightness of comets can vary based on local sky conditions. Also, unlike a pinpoint star, the brightness of comets extends over its visible surface area, much like a faint nebula. The first sightings of the comet for many observers has been contingent on the weather, which can trend towards overcast for much of North America in early March. From our +28.5° northern latitude vantage point here just north of Tampa Bay Florida we had about a 10 minute window from when the sky was dark enough to spy PanSTARRS before it set below the local horizon.

Here are a few more images from Universe Today readers:

Comet Pan-STARRS as imaged by Robert Sparks (@HalfAstro) on the night of March 10th from Tucson, Arizona. All Rights Reserved, part of the Universe Today photo gallery. — Comet PanSTARRS as imaged by Robert Sparks (@HalfAstro) on the night of March 10th from Tucson, Arizona. All Rights Reserved, part of the Universe Today photo gallery.

First views of Comet PANSSTARRS from Tucson, Arizona. Credit and copyright: Adam Block/Mount Lemmon SkyCenter.

Comet PANSTARRS from Puerto Rico on March 10, 2013. Credit and copyright: Efrain Morales.

To see the comet we suggest;

A clear uncluttered southwestern horizon;
A reasonably clear sky;
Binoculars.

First naked eye sightings of the comet for U.S. and European latitudes should be forthcoming over the next few evenings. PanSTARRS just passed perihelion yesterday on March 10^th at 0.3 Astronomical Units from the Sun (or 46.5 million kilometres, just inside the orbit of Mercury).

Comet PanSTARRS looking west at 8PM EDT from latitude 30 degrees north. (Created by the author using Starry Night). — Comet PanSTARRS looking west at 8PM EDT the evening of March 12th from latitude 30 degrees north. (Created by the author using Starry Night).

And Comet PanSTARRS may put on its best show over the next few nights. The Moon reaches New phase today at 3:51PM EDT/ 19:51 UT and starts lunation number 1116. On the next few evenings, the slim crescent Moon will slide by Comet PanSTARRS. Look for the 2% illuminated Moon 5° to the lower right of the comet on the evening of Tuesday March 12^th. On the next evening, the 5% illuminated Moon will be 9° above Comet PanSTARRS on Wednesday, March 13^th. The age of the Moon will be 28 hours old on Tuesday evening and 52 hours on Wednesday the 13^th respectively, an easy catch. The Moonwatch website is a great place to check for those early lunar crescent sighting possibilities worldwide. Note that Comet PanSTARRS also passes less than 30’ from the planet Uranus (about the diameter of the Full Moon) on the evening of the 12^th at 8 PM EDT/24UT. +6^th magnitude Uranus may just be visible near the head of the comet using binoculars or a small telescope. Keep in mind, they just appear to be close as seen from our Earthly vantage point. PanSTARRS is currently 1.1 A.U.s from the Earth, while Uranus is on the other side of the solar system at 21 A.U.s distant!

Comet PanSTARRS looking west at 8PM EDT from latitude 30 degrees north on the evening of March 13th. (Created by the author using Starry Night).

PanSTARRS also crosses the Celestial Equator today on March 11^th and the Ecliptic on March 13^th. Observers from dark sky sites may get the added bonus of the zodiacal light, a true photographic opportunity!

Spacecraft studying the Sun are also giving us views of Comet PanSTARRS from a different perspective. NASA’s twin STEREO A & B spacecraft are positioned to monitor the Sun from different vantage points along the Earth’s orbit. Often, they see comets as an added bonus. Comet PanSTARRS has just moved into the field of view of STEREO-B’s Heliospheric Imager and has given us amazing views of the comet and the Earth in the distance over the past week.

The view of Comet PanSTARRS from NASA's STEREO Behind observatory. (Credit: NASA/SECCHI). — The view of Comet PanSTARRS from NASA’s STEREO Behind observatory. (Credit: NASA/SECCHI).

From STEREO, the remarkable fan-shaped dust tail of PanSTARRS stands out in profile. The dust tail of a comet always points away from the Sun. Driven by the solar wind, a comet’s tail is actually in front of it as it heads back out of the solar system! An ultimate animation of Comet PanSTARRS just came to our attention today via @SungrazerComets on Twitter;

Animation of comet 2011 L4 PanSTARRS entering STEREO-B's HI camera, note the twin ion/dust tail reminiscent of Hale-Bopp! (Credit: NASA/STEREO/NRL). — Animation of comet 2011 L4 PanSTARRS entering STEREO-B’s HI camera, note the twin ion/dust tail reminiscent of Hale-Bopp! (Credit: NASA/STEREO/NRL).

As of this writing, PanSTARRS seems to be performing as per predictions with an observed magnitude of around +1. The comet will continue on its northward trek, becoming a circumpolar object for observers based around latitude 50° north on April 2nd. Comet PanSTARRS should dip back below +6^th magnitude around April 15th.

Comet PanSTARRS as imaged by Mike Weasner from Cassiopeia Observatory in southern Arizona on the night of March 10th. Used with permission.

But this is but Act One in a forecasted three act cometary saga for 2013. Comet C/2012 F6 Lemmon will grace early dawn skies in April for northern hemisphere observers, and then all eyes will be on Comet C/2012 S1 ISON for the hoped for grand finale later this year. Interestingly, ESA’s Solar Heliospheric Observatory will get a look at this sungrazing comet as it passes through its LASCO C3 camera’s field of view. Clear skies, and may 2013 go down as the Year of the Comet!

-Check out photos of Comet PanSTARRS and more being added daily to the Universe Today’s Flickr gallery.

March 8, 2013April 26, 2016 by David Dickinson

12 Star Party Secret Weapons

We’ve all been there. Well OK, all public star party telescope operators have been there. You’re set up and you’ve got a stunning view of Saturn centered in the field of view. But then the first member of the viewing public takes a quick glance and steps back from the eyepiece, stating “yeah, I saw that through the last four ‘scopes…”

What do you do when every telescope down the row is aimed at the same object? Or worse yet, what do you aim at when there is no Moon or bright planets above the horizon? Every seasoned telescope operator has a quick repertoire of secret favorites, little known but sure-fire crowd pleasers. Sure, Saturn is awesome and you should see it through a telescope… but it’s a big universe out there.

I’ve even seen clubs assign objects to individual telescopes to avoid having everyone point at the same thing, but this method is, well, boring for the scope operators themselves. Most backyard astronomers can simply look at a tube pointed at Orion and know the neighboring telescope is aimed at the Orion Nebula. What follows is our very own highly subjective (but tested in the field!) list of secret star party faves. Yes, it is mid-northern latitude-centric. It also covers a span of objects of all types, as well as a handy information chart of where in the sky to find ‘em and a few surprises. We also realize that many public star parties often take place downtown under light polluted skies, so a majority of these are brighter objects. Don’t see your favorite? Drop us a line and let us know!

12. The Double Cluster: Straddling the border of the constellations Perseus and Cassiopeia, this pair of clusters is a fine sight at low power. The technical designation of the pair is NGC 884 and NGC 869 respectively and the clusters sit about 7000 light years distant. You can just see the pair with the naked eye under suburban skies.

The location of Herschel 3945 in Canis Major. (Created by Author in Starry Night).

11. Herschel 3945: A popular summer-to-fall star party target is the colored double star Albireo is the constellation Cygnus. But did you know there’s a similar target visible early in the year as well? I call Herschel 3945 the “winter Albireo” for just this reason. This 27” split pair of sapphire and orange stars offers a great contrast sure to bring out the “ohs” and “ahs.” Continue reading “12 Star Party Secret Weapons”

March 6, 2013April 26, 2016 by David Dickinson

Giant Ancient Impact Crater Confirmed in Iowa

3-D perspective map of the Decorah impact feature looking northward. (Credit: USGS/Adam Kiel graphic/Northeast Iowa RC&D).

A monster lurks under northeastern Iowa. That monster is in the form of a giant buried basin, the result of a meteorite impact in central North America over 470 million years ago.

A recent aerial survey conducted by the state of Minnesota Geological Survey and the United States Geological Survey (USGS) confirms the existence of an impact structure long suspected near the eastern edge of the town of Decorah, Iowa. The goal of the 60 day survey was a routine look at possible mineral and water resources in the region, but the confirmation of the crater was an added plus. Continue reading “Giant Ancient Impact Crater Confirmed in Iowa”

March 5, 2013December 23, 2015 by David Dickinson

Why This Weekend is Perfect for a Messier Marathon

To 'scopes, get set, marathon! (A homemade 14" Gregorian reflector, photo by author).

This coming weekend presents the first window for 2013 to complete a challenge in the realm of backyard astronomy and visual athletics. With some careful planning, persistence, and just plain luck, you can join the vaunted ranks of those seasoned observers who’ve seen all 110 objects in the Messier catalog… in one night.

Observing all of the objects in Messier’s catalog in a single night has become a bit of a sport over the last few decades for northern hemisphere observers, and several clubs and organizations now offer certificates for the same. The catalog itself was a first attempt by French astronomer Charles Messier to catalog the menagerie of “faint fuzzies” strewn about the northern hemisphere sky.

Not that Charles knew much about the nature of what he was seeing. The modern Messier catalog includes a grab bag collection of galaxies, nebulae, open and globular clusters and more down to magnitude +11.5, all above declination -35°. Charles carried out his observations from Paris France at latitude +49° north. Unfortunately, this also means that Messier catalog is the product of Charles Messier’s northern-based vantage point. The northernmost objects in the catalog are Messiers 81 & 82 at declination +69°, which never get above the horizon for observers south of latitude -21°. His initial publication of the catalog in 1774 contained 45 objects, and his final publication contained 103, with more objects added based on his notes after his death in 1817. (Fun fact: Messier is buried in the famous Père Lachaise Cemetery in Paris, site of other notable graves such as those of Chopin and Jim Morrison).

M51, the Whirlpool Galaxy, one of the more photogenic objects in the Messier catalog. (Credit: NASA/Hubble Heritage Project).

There’s a fair amount of controversy on Messier’s motivations and methods for compiling his catalog. The standard mantra that will probably always be with us is that Messier was frustrated with stumbling across these objects in his hunt for comets and decided to catalog them once and for all. He eventually discovered 13 comets in his lifetime, including Comet Lexell which passed only 2.2 million kilometres from Earth in 1770.

No one is certain where the modern tradition of the Messier Marathon arose, though it most likely had its roots in the amateur astronomy boom of the 1970s and was a fixture of many astronomy clubs by the 1980s. There are no Messier objects located between right ascension 21 hours 40 minutes and 23 hours 20 minutes, and only one (M52) between 23 hours 20 minutes and 0 hours 40 minutes. With the Sun reaching the “0 hour” equinoctial point on the March Vernal Equinox (falling on March 20^th as reckoned in Universal Time for the next decade), all of the Messier objects are theoretically observable in one night around early March to early April. Taking into account for the New Moon nearest to the March equinox, the best dates for a weekend Messier marathon for the remainder of the decade are as follows;

Optimal Messier marathon dates for the remainder of the decade. (Compiled by author).

Note that this year’s weekend is very nearly the earliest that it can occur. The optimal latitude for Messier marathoning is usually quoted as 25° north, about the latitude of Miami. It’s worth noting that 2013 is one of the very few years where the primary weekend falls on or before our shift one hour forward to Daylight Saving time, occurring this year on March 10^th for North America.

Students of the Messier catalog will also know of the several controversies that exist within the list. For example, one wide double star in Ursa Major made its way into the catalog as Messier 40. There’s also been debate over the years as to the true identity of Messier 102, and most marathoners accept the galaxy NGC 5866 in its stead. Optics of the day weren’t the most stellar (bad pun intended) and this is evident in the inclusion of some objects but the omission of others. For example, it’s hard to imagine a would-be comet hunter mistaking the Pleiades (M45) for an icy interloper, but curiously, Messier omits the brilliant Double Cluster in Perseus.

M42, the Orion Nebula. (Photo by Author, taken back in the days of ye ole film!)

It’s vital for Messier marathoners to run through objects in proper sequence. Most visual observers run these in groups, although Alex McConahay suggests in a recent April 2013 Sky & Telescope article that folks running a photographic marathon (see below) beware of wasting precious time crossing the celestial meridian (a maneuver which requires a telescope equipped with a German Equatorial mount to “flip” sides) hunting down objects. The unspoken “code of the skies” for visual Messier marathoners is that “Go-To” equipped scopes are forbidden. Part of the intended purpose of the exercise is to acquaint you with the night sky via star hopping to the target.

Most observers complete Messier objects in groups. You’ll want to nab M77 and M74 immediately after local dusk, or the marathon will be over before it starts. You’ll then want to move over to the Andromeda Galaxy and the collection of objects in its vicinity before scouring Orion and environs. From that point out, you can begin to slow down a bit and pace yourself through the galaxy groups in Coma Berenices and the Bowl of Virgo asterism. Another cluster of objects stretch out in the sky past midnight along the plane of our Milky Way Galaxy from Sagittarius to Cygnus, and the final (and often most troublesome) targets to bag are the Messier objects in Aquarius and M30 in Capricornus just before dawn. Remember, dark skies, warm clothes, and hot coffee are your friends in this endeavor!

There have been alternate rules or versions of Messier marathons over the years. Some imagers complete one-night photographic messier marathons. There are even abbreviated or expanded versions of the feat. It is also possible to nab most of the Messier catalog with a good pair of binoculars under clear skies. Probably the most challenging version we’ve heard of is sketching all 110 Messier objects in one evening… you might be forgiven for using a Go-To enabled telescope to accomplish this!

Finally, just like running marathons, the question we often get is why. Some may eschew transforming the art of dark sky observing into a task of visual gymnastics. We feel that to run through this most famous of catalogs in an evening is a great way to learn the sky and practice the fast-disappearing art of star hopping. And hey, no one’s saying you can’t take a year or three to finish the Messier catalog… its a big universe, and the New General Catalog (NGC) and Index Catalog (IC) containing thousands of objects will still be waiting. Have YOU seen all 110?

– A perpetual listing of Messier marathon visibility by latitude by Tom Polakis.

– An All Sky Map of the Messier catalog.

– A handy priority list for a Messier marathon compiled by Don Machholz.

February 27, 2013December 23, 2015 by David Dickinson

Pulsar Jackpot Scours Old Data for New Discoveries

Space Shuttle Atlantis passes behind the Parkes radio telescope after final undocking from the International Space Station in July 2011. (Image Copyright: John Sarkissian; used with permission).

Chalk another one up for Citizen Science. Earlier this month, researchers announced the discovery of 24 new pulsars. To date, thousands of pulsars have been discovered, but what’s truly fascinating about this month’s discovery is that came from culling through old data using a new method.

A pulsar is a dense, highly magnetized, swiftly rotating remnant of a supernova explosion. Pulsars where first discovered by Jocelyn Bell Burnell and Antony Hewish in 1967. The discovery of a precisely timed radio beacon initially suggested to some that they were the product of an artificial intelligence. In fact, for a very brief time, pulsars were known as LGM’s, for “Little Green Men.” Today, we know that pulsars are the product of the natural death of massive stars.

The data set used for the discovery comes from the Parkes 64-metre radio observatory based out of New South Wales, Australia. The installation was the first to receive telemetry from the Apollo 11 astronauts on the Moon and was made famous in the movie The Dish. The Parkes Multi-Beam Pulsar Survey (PMPS) was conducted in the late 1990’s, making thousands of 35-minute recordings across the plane of the Milky Way galaxy. This survey turned up over 800 pulsars and generated 4 terabytes of data. (Just think of how large 4 terabytes was in the 90’s!)

Artist's conception of a pulsar. (Credit: NASA/GSFC). — Artist’s conception of a pulsar. (Credit: NASA/GSFC).

The nature of these discoveries presented theoretical astrophysicists with a dilemma. Namely, the number of short period and binary pulsars was lower than expected. Clearly, there were more pulsars in the data waiting to be found.

Enter Citizen Science. Using a program known as Einstein@Home, researchers were able to sift though the recordings using innovative modeling techniques to tease out 24 new pulsars from the data.

“The method… is only possible with the computing resources provided by Einstein@Home” Benjamin Knispel of the Max Planck Institute for Gravitational Physics told the MIT Technology Review in a recent interview. The study utilized over 17,000 CPU core years to complete.

Einstein@Home screenshot. (Credit: LIGO Consortium).

Einstein@Home is a program uniquely adapted to accomplish this feat. Begun in 2005, Einstein@Home is a distributed computing project which utilizes computing power while machines are idling to search through downloaded data packets. Similar to the original distributed computing program SETI@Home which searches for extraterrestrial signals, Einstein@Home culls through data from the LIGO (Laser Interferometer Gravitational Wave Observatory) looking for gravity waves. In 2009, the Einstein@Home survey was expanded to include radio astronomy data from the Arecibo radio telescope and later the Parkes observatory.

Among the discoveries were some rare finds. For example, PSR J1748-3009 Has the highest known dispersion measure of any millisecond pulsar (The dispersion measure is the density of free electrons observed moving towards the viewer). Another find, J1750-2531 is thought to belong to a class of intermediate-mass binary pulsars. 6 of the 24 pulsars discovered were part of binary systems.

These discoveries also have implications for the ongoing hunt for gravity waves by such projects as LIGO. Specifically, a through census of binary pulsars in the galaxy will give scientists a model for the predicted rate of binary pulsar mergers. Unlike radio surveys, LIGO seeks to detect these events via the copious amount of gravity waves such mergers should generate. Begun in 2002, LIGO consists of two gravity wave observatories, one in Hanford Washington and one in Livingston Louisiana just outside of Baton Rouge. Each LIGO detector consists of two 2 kilometre Fabry-Pérot arms in an “L” configuration which allow for ultra-precise measurements of a 200 watt laser beam shot through them. Two detectors are required to pin-point the direction of an incoming gravity wave on the celestial sphere. You can see the orientation of the “L’s” on the display on the Einstein@Home screensaver. Two geographically separate detectors are also required to rule out local interference. A gravity wave from a galactic source would ripple straight through the Earth.

Arial view of LIGO Livingston. (Image credit: The LIGO Scientific Collaboration).

Such a movement would be tiny, on the order of 1/1,000^th the diameter of a proton, unnoticed by all except the LIGO detectors. To date, LIGO has yet to detect gravity waves, although there have been some false alarms. Scientists regularly interject test signals into the data to see if system catches them. The lack of detection of gravity waves by LIGO has put some constraints on certain events. For example, LIGO reported a non-detection of gravity waves during the February 2007 short gamma-ray burst event GRB 070201. The event arrived from the direction of the Andromeda Galaxy, and thus was thought to have been relatively nearby in the universe. Such bursts are thought to be caused by neutron star and/or black holes mergers. The lack of detection by LIGO suggests a more distant event. LIGO should be able to detect a gravitational wave event out to 70 million light years, and Advanced LIGO (AdLIGO) is set to go online in 2014 and will increase its sensitivity tenfold.

The control room at LIGO Livingston. (Photo by Author).

Knowledge of where these potential pulsar mergers are by such discoveries as the Parkes radio survey will also give LIGO researchers clues of targets to focus on. “The search for pulsars isn’t easy, especially for these “quiet” ones that aren’t doing the equivalent of “screaming” for our attention,” Says LIGO Livingston Data Analysis and EPO Scientist Amber Stuver. The LIGO consortium developed the data analysis technique used by Einstein@Home. The direct detection of gravitational waves by LIGO or AdLIGO would be an announcement perhaps on par with CERN’s discovery of the Higgs Boson last year. This would also open up a whole new field of gravitational wave astronomy and perhaps give new stimulus to the European Space Agencies’ proposed Laser Interferometer Space Antenna (LISA) space-based gravity wave detector. Congrats to the team at Parkes on their discovery… perhaps we’ll have the first gravity wave detection announcement out of LIGO as well in years to come!

-Read the original paper on the discovery of 24 new pulsars here.

-Amber Stuver blogs about Einstein@Home & the spin-off applications of gravity wave technology at Living LIGO.

-Parkes radio telescope image is copyrighted and used with the permission of CSIRO Operations Scientist John Sarkissian.

-For a fascinating read on the hunt for gravity waves, check out Gravity’s Ghost.

February 26, 2013December 23, 2015 by David Dickinson

Spotting the Dragon: How to See SpaceX on Approach to the ISS This Weekend

Capture of the Dragon during the October 2012 CRS-1 mission. (Credit: NASA/ISS).

SpaceX’s Dragon spacecraft may be appearing in a backyard sky near you this weekend. Scheduled to launch this Friday on March 1^st at 10:10 AM Eastern Standard Time (EST)/15:10 Universal Time (UT), this will be the 3^rd resupply flight for the Dragon spacecraft to the International Space Station (ISS). And the great news is, you may just be able to catch the spacecraft as it chases down the ISS worldwide.

The Space Shuttle and the ISS captured by the author as seen from Northern Maine shortly after undocking in June, 2007.

Catching a satellite in low Earth orbit is an unforgettable sight. Satellites appear as moving “stars” against the background sky, shining steadily (unless they’re tumbling!) in the sunlight overhead in the dawn or dusk sky. Occasionally, you may catch a flare in brightness as a reflective panel catches the sunlight just right. The Hubble Space Telescope and the Iridium constellation of satellites can flare in this fashion.

At 109 metres in size, the ISS is the largest object ever constructed in orbit and is easily visible to the naked eye. It has an angular diameter of about 50” when directly overhead (about the visual size of Saturn plus rings near opposition). I can just make out a tiny box-like structure with binoculars when it passes overhead. If the orientation of the station and its solar panels is just right, it looks like a tiny luminous Star Wars TIE fighter as viewed through binoculars!

Dragon in the processing hangar at Cape Canaveral. (Credit: NASA/Kim Shiflett).

But what’s even more amazing is to watch a spacecraft rendezvous with the ISS, as diligent observers may witness this weekend. Your best bet will be to use predictions for ISS passes from your location. Heavens-Above, CALSky and Space Weather all have simple trackers for sky watchers. More advanced observers may want to use an application known as Orbitron which allows you to manually load updated Two-Line Element sets (TLEs) from Celestrak or NORAD’s Space-Track website for use in the field sans Internet connection. Note that Space-Track requires permission to access; they welcome amateur sat-spotters and educators, but they also want to assure that no “rogue entities” are accessing the site! Continue reading “Spotting the Dragon: How to See SpaceX on Approach to the ISS This Weekend”

February 25, 2013April 26, 2016 by David Dickinson

Light-travel-time Effect Finds New Astronomical Applications

Io and Jupiter as seen by New Horizons during its 2008 flyby. (Credit: NASA/Johns Hopkins University APL/SWRI).

Sometimes the tried and true methods are still the best, even in observational astronomy. Researchers at the University of Prague demonstrated this recently in a study of the eclipsing binary system V994 Herculis (V994 Her).

Researchers P. Zasche and R. Uhla used a method known as the Light-travel-time Effect to verify that V994 Her is actually a double binary. If that method sounds familiar to any astronomy historians out there, that’s because it was first used by 17^th century astronomers to gauge the speed of light.

V994 Her is a rarity in the skies. While many eclipsing binaries are known, V994 Her is one of only six quadruple eclipsing binary stars discovered. An eclipsing binary star is a system where the two stars pass one in front of the other from our line of sight. Although too close to be split visually, eclipsing binaries rise and fall in brightness periodically. One famous example is the star Algol (Beta Persei) in the constellation Perseus. Algol means the “Demon Star” in Arabic, which suggests that its curious nature was known to Arab astronomers in pre-telescopic times.

Continue reading “Light-travel-time Effect Finds New Astronomical Applications”