Posted on by David Dickinson

Water-Trapped Worlds Possible Around Red Dwarf Stars?

An artist's concept of a rocky world orbiting a red dwarf star. (Credit: NASA/D. Aguilar/Harvard-Smithsonian center for Astrophysics).

Hunters of alien life may have a new and unsuspected niche to scout out.

A recent paper submitted by Associate Professor of Astronomy at Columbia University Kristen Menou to the Astrophysical Journal suggests that tidally-locked planets in close orbits to M-class red dwarf stars may host a very unique hydrological cycle. And in some extreme cases, that cycle may cause a curious dichotomy, with ice collecting on the farside hemisphere of the world, leaving a parched sunward side. Life sprouting up in such conditions would be a challenge, experts say, but it is — enticingly — conceivable.

The possibility of life around red dwarf stars has tantalized researchers before. M-type dwarfs are only 0.075 to 0.6 times as massive as our Sun, and are much more common in the universe. The life span of these miserly stars can be measured in the trillions of years for the low end of the mass scale. For comparison, the Universe has only been around for 13.8 billion years. This is another plus in the game of giving biological life a chance to get underway. And while the habitable zone, or the “Goldilocks” region where water would remain liquid is closer in to a host star for a planet orbiting a red dwarf, it is also more extensive than what we inhabit in our own solar system.

Gliese 581- an example of a potential habitable zone around a red dwarf star contrasted with our own solar system. (Credit: ESO/Henrykus under a Wikimedia Creative Commons Attribution 3.0 Unported license).
Gliese 581- an example of a potential habitable zone around a red dwarf star contrasted with our own solar system. (Credit: ESO/Henrykus under a Wikimedia Creative Commons Attribution 3.0 Unported license).

But such a scenario isn’t without its drawbacks. Red dwarfs are turbulent stars, unleashing radiation storms that would render any nearby planets sterile for life as we know it.

But the model Professor Menou proposes paints a unique and compelling picture. While water on the permanent daytime side of a terrestrial-sized world tidally locked in orbit around an M-dwarf star would quickly evaporate, it would be transported by atmospheric convection and freeze out and accumulate on the permanent nighttime side. This ice would only slowly migrate back to the scorching daytime side and the process would continue.

Could these types of “water-locked worlds” be more common than our own?

The type of tidal locking referred to is the same as has occurred between the Earth and its Moon. The Moon keeps one face eternally turned towards the Earth, completing one revolution every 29.5 day synodic period. We also see this same phenomenon in the satellites for Jupiter and Saturn, and such behavior is most likely common in the realm of exoplanets closely orbiting their host stars.

The study used a dynamical model known as PlanetSimulator created at the University of Hamburg in Germany. The worlds modeled by the author suggest that planets with less than a quarter of the water present in the Earth’s oceans and subject to a similar insolation as Earth from its host star would eventually trap most of their water as ice on the planet’s night side.

Kepler data results suggest that planets in close orbits around M-dwarf stars may be relatively common. The author also notes that such an ice-trap on a water-deficient world orbiting an M-dwarf star would have a profound effect of the climate, dependent on the amount of volatiles available. This includes the possibility of impacts on the process of erosion, weathering, and CO2 cycling which are also crucial to life as we know it on Earth.

Thus far, there is yet to be a true “short list” of discovered exoplanets that may fit the bill. “Any planet in the habitable zone of an M-dwarf star is a potential water-trapped world, though probably not if we know the planet possesses a thick atmosphere.” Professor Menou told Universe Today. “But as more such planets are discovered, there should be many more potential candidates.”

Hard times in harsh climes-an artist's conception of the daytime side of a world orbiting a red dwarf star.
Hard times in harsh climes-an artist’s conception of the daytime side of a world orbiting a red dwarf star. (Credit: NASA/JPL-Caltech).

Being that red dwarf stars are relatively common, could this ice-trap scenario be widespread as well?

“In short, yes,” Professor Menou said to Universe Today. “It also depends on the frequency of planets around such stars (indications suggest it is high) and on the total amount of water at the surface of the planet, which some formation models suggest should indeed be small, which would make this scenario more likely/relevant. It could, in principle, be the norm rather than the exception, although it remains to be seen.”

Of course, life under such conditions would face the unique challenges. The daytime side of the world would be subject to the tempestuous whims of its red dwarf host sun in the form of frequent radiation storms. The cold nighttime side would offer some respite from this, but finding a reliable source of energy on the permanently shrouded night side of such as world would be difficult, perhaps relying on chemosynthesis instead of solar-powered photosynthesis.

On Earth, life situated near “black smokers” or volcanic vents deep on the ocean floor where the Sun never shines do just that. One could also perhaps imagine life that finds a niche in the twilight regions of such a world, feeding on the detritus that circulates by.

Some of the closest red dwarf stars to our own solar system include Promixa Centauri, Barnard’s Star and Luyten’s Flare Star. Barnard’s star has been the target of searches for exoplanets for over a century due to its high proper motion, which have so far turned up naught.

The closest M-dwarf star with exoplanets discovered thus far is Gliese 674, at 14.8 light years distant. The current tally of extrasolar worlds as per the Extrasolar Planet Encyclopedia stands at 919.

This hunt will also provide a challenge for TESS, the Transiting Exoplanet Survey Satellite and the successor to Kepler due to launch in 2017.

Searching for and identifying ice-trapped worlds may prove to be a challenge. Such planets would exhibit a contrast in albedo, or brightness from one hemisphere to the other, but we would always see the ice-covered nighttime side in darkness. Still, exoplanet-hunting scientists have been able to tease out an amazing amount of information from the data available before- perhaps we’ll soon know if such planetary oases exist far inside the “snowline” orbiting around red dwarf stars.

Read the paper on Water-Trapped Worlds at the following link.

Posted on by Tammy Plotner

Pulled Apart By Black Hole Heart

New observations from ESO’s Very Large Telescope show for the first time a gas cloud being ripped apart by the supermassive black hole at the centre of the galaxy. Shown here are VLT observations from 2006, 2010 and 2013, coloured blue, green and red respectively. Credit: ESO/S. Gillessen

If you thought all was reasonably quiet at the center of the Milky Way, you’d be wrong. Of course, you knew there was a black hole waiting… but did you know the ESO’s Very Large Telescope has seen a cloud of gas being ripped apart by its influence? Thanks to new observations, we’re able to see – in real time – a gaseous region so stretched that its leading edge has reached the event horizon and it’s retreating from the black hole at more than 10 million km/h while the trailing end is still falling inward!

Just two years ago, the VLT observed a gas cloud several times the mass of Earth making haste towards the Milky Way’s central black hole… an oblivion which dwarfs the cloud by about a trillion times. Right now the plucky cloud has reached its closest approach and “spaghettification” has began. The vaporous vagabond is being stretched out of proportion by the black hole’s gravitational field.

“The gas at the head of the cloud is now stretched over more than 160 billion kilometres around the closest point of the orbit to the black hole. And the closest approach is only a bit more than 25 billion kilometres from the black hole itself — barely escaping falling right in,” explains Stefan Gillessen (Max Planck Institute for Extraterrestrial Physics, Garching, Germany) who led the observing team. “The cloud is so stretched that the close approach is not a single event but rather a process that extends over a period of at least one year.”

At this point, the gas cloud is becoming so thin that its light is difficult to detect. However, by using the SINFONI instrument on the VLT, researchers took 20 hours of exposure time with the integral field spectrometer and were able to measure the velocity of various regions of the gas cloud as it blazes by the black hole.

“The most exciting thing we now see in the new observations is the head of the cloud coming back towards us at more than 10 million km/h along the orbit — about 1% of the speed of light,” adds Reinhard Genzel, leader of the research group that has been studied this region for nearly twenty years. “This means that the front end of the cloud has already made its closest approach to the black hole.”

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Where the gas cloud originated is anyone’s guess – but there are suggestions. Possibilities include jets from the galactic center, or stellar winds from orbiting stars. There may have once been a star in the center of the cloud, and the gas may have been a product of its winds or even a protoplanetary disk. In any circumstance, these new observations help to sort out the variety of possibilities.

“Like an unfortunate astronaut in a science fiction film, we see that the cloud is now being stretched so much that it resembles spaghetti. This means that it probably doesn’t have a star in it,” concludes Gillessen. “At the moment we think that the gas probably came from the stars we see orbiting the black hole.”

It’s an exciting time to be an astronomer. Through the “eyes” of the VLT, researchers the world over are able to watch a very unique event as it happens and not after the fact. ” This intense observing campaign will provide a wealth of data, not only revealing more about the gas cloud, but also probing the regions close to the black hole that have not been previously studied and the effects of super-strong gravity.”

As this drama at the heart of the Milky Way unfolds, astronomers are able to witness its many changes – “from purely gravitational and tidal to complex, turbulent hydrodynamics.”

Original Story Source: ESO News Release.

Posted on by David Dickinson

Seeing Red: Hunting Herschel’s Garnet Star

Mu Cephei (arrowed) in the constellation Cepheus the King. (Photo & graphic by author).

Quick, what’s the reddest star visible to the naked eye?

Depending on your sky conditions, your answer may well be this week’s astronomical highlight.

Mu Cephei, also known as Herschel’s Garnet Star, is a ruddy gem in the constellation Cepheus near the Cygnus/Lacerta border. A variable star ranging in brightness by a factor of about three-fold from magnitudes 5.0 to 3.7, Mu Cephei is low to the northeast for mid-northern latitude observers in July at dusk, and will be progressively higher as summer wears on. Continue reading “Seeing Red: Hunting Herschel’s Garnet Star”

Posted on by Dan Majaess

Citizen Scientists Hunt for Impact Craters in Persia

The UNESCO World Heritage Site of Persopolis, Iran (image credit: Oshin D. Zakarian/TWAN).

Citizen scientists have discovered planets beyond our Solar System and established morphological classifications for thousands of galaxies (e.g., the Planet Hunters and Galaxy Zoo projects).  At an upcoming meeting of planetary scientists, Hamed Pourkhorsandi from the University of Tehran will present his efforts to mobilize citizens to identify impact craters throughout Persia.   Pourkhorsandi said he is recruiting volunteers to identify craters using Google Earth, while continuing to seek sightings of fireballs cited in ancient books and among rural folk.  Discovering impact craters is an important endeavour, since it helps astronomers estimate how many asteroids of a particular size strike Earth over a given time (i.e., the impact frequency).  Indeed, that is especially relevant in light of the recent meteor explosion over Russia this past February (see the UT article here), which hints at the potentially destructive nature of such occurrences.

Satellite images have facilitated the detection of impact sites such as the Kamil and Puka craters, which were identified by V. de Michele and D. Hamacher using Google Earth, respectively (see the UT article here).  Pourkhorsandi noted that, “Free access to satellite images has led to the investigation of earth’s surface by specialists and nonspecialists, attempts that have led to the discovery of new impact craters around the globe.   [Yet] few researches on this topic have been done in the Middle East.”  Incidentally, citizens are likewise being recruited to classify craters and features on other bodies in the Solar System (e.g., the Moon Zoo project).

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The Kamil impact crater in Egypt was discovered by V. de Michele using Google Earth, and H. Pourkhorsandi is recruiting volunteers to discover such structures throughout Persia following a similar approach (image credit: L. Folco).

In his paper, Pourkhorsandi describes examples of two targets investigated thus far: “1. a circular structure with a diameter of 200 m (33°21’57”N 58°14’24”E).  [However,] there is no sign of … meteoritic fragments in the region that are primary diagnostic indicators for small size impact craters.”  The second target is tied to an old tale, and note that the Puka crater in Australia was identified by following-up on an old Aboriginal story.  However, Pourkhorsandi states that a field study of the second target (28°24’52” N 60°34’44” E) revealed that the crater is not associated with an impactor from space.

“Beside these structures, field studies on other craters in Persia are in progress, the outcomes of which will be announced in the near future,” said Pourkhorsandi.



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Pourkhorsandi underscores that numerous meteorites have been found in desert regions throughout the world, yet scant attention has been given to Persian deserts (e.g., the Lut desert).  The Lut desert in Persia extends over several thousand square kilometres and is one of the hottest places on Earth (featuring land surface temperatures upwards of 70 degrees Celsius).  Pourkhorsandi noted that in 2005 a ‘curious stone’ was recovered in the Lut desert and subsequent work revealed its extraterrestrial origin.

He went on to remark that, “Three recent short field trips to the central Lut desert led to the collection of several meteoritic fragments, which points to large concentrations of meteoritic materials in the area.”  Some of those fragments are shown in the figure below, and the broader region is likely a pertinent place for citizen scientists to continue the hunt for impact craters in Persia.

Pourkhorsandi concluded by telling the Universe Today, “In the future we aim to expand our efforts with the help of additional people, and will direct individuals to scan other regions of the planet.  Simultaneously, we have commenced a comprehensive analysis of meteorites in the Lut desert with fellow European scientists.”

"Fragments of a H5 chondrite in the field. The scale." from Pour/arXiv.
H chondrite fragments found in the Lut desert (in Persia) are argued to be extraterrestrial in origin (image credit: Fig. 3 in Pourkhorsandi 2013/LPI).

H. Pourkhorsandi’s findings were shown at the 44th Lunar and Planetary conference in Texas, and will be presented at the upcoming Large Meteorite Impact and Evolution V conference.  That latter conference will feature the latest results concerning the cratering process, and a description of the science program is available here.  Copies of H. Pourkhorsandi and H. Mirnejad’s conference submissions are available via the LPI and arXiv.   Those readers interested in joining H. Pourkhorsandi’s effort, or desiring additional information, may also find the following pertinent: the Earth Impact Database, Rampino and Haggerty 1996, “Collision Earth! The Threat from Outer Space” by P. Grego, NASA’s projects for Citizen Scientists.

Posted on by Bob King

Amateur Astronomer Discovers Comet C/2013 N4 (Borisov) During a Star Party

Gennady Borisov, who lives in Naunchniy near the Crimean Observatory in the Ukraine, discovered the comet C/2013 N4 on July 8. He's shown here with his two telescopes. Credit: Oleg Bruzgalov

Ukrainian amateur astronomer Gennady Borisov discovered a brand new comet on July 8 near the bright star Capella in the constellation Auriga. The comet was confirmed and officially christened C/2013 N4 (Borisov) on July 13. At the time of discovery, Borisov was attending the Russian-Ukrainian “Southern Night” star party in Crimea, Ukraine. He nabbed the comet – his first – using an 8-inch (20-cm) f/1.5  wide field telescope of his own design equipped with a CCD camera.

Comet Borisov is the fuzzy spot with a brighter central region in this recent photo. Credit: Oleg Bruzgalov
Comet Borisov is the fuzzy spot with a brighter central region in this recent photo. Credit: Oleg Bruzgalov

The new comet is on the faint side, appearing as a small, fuzzy patch of 13th magnitude with a brighter center. To see it you’ll need at least a 10-inch (25-cm) telescope and the fortitude to rise in the wee hours before dawn. The reason for the early hour is Borisov’s location in Auriga, a constellation that doesn’t clear the horizon until shortly before the start of morning twilight. Faintness and low altitude will combine to make Comet Borisov an enticing if challenging object for amateur astronomers.

Animation of Comet Borisov compiled from multiple images. Credit: http://astronomamator.narod.ru/cometes/comet_anim.gif
Animation of Comet Borisov compiled from multiple images. Credit: http://astronomamator.narod.ru/cometes/comet_anim.gif

C/2013 N4 is currently traveling through Auriga not far from the easy-to-spot naked eye star Beta and will slowly brighten as it approaches perihelion – closest point to the sun – on August 20 at a distance of 113.5 million miles (182.7 million km). Unfortunately its elongation or separation from the sun will be slowly shrinking in the coming weeks, causing the comet to drop lower in the sky as it approaches perihelion. Our fuzzy visitor misses Earth by a comfortable 192.5 million miles (310 million km) on August 11. It’s likely Comet Borisov won’t get much brighter than 12th magnitude. Astronomers are still working out the details of its orbit, so it’s possible brightness predictions could change in the near future.

C/2013 N4 (Borisov) tracks through northern Auriga not far from Capella in the coming nights. Positions are shown every 5 days around 3 a.m. CDT. The comet is faint and will require a more detailed chart and telescope to see. Created with Stellarium
C/2013 N4 (Borisov) tracks through northern Auriga not far from Capella in the coming nights. Positions are shown every 5 days at 3 a.m. CDT. The comet is faint and will require a more detailed chart and telescope to see. Created with Stellarium

Aside from how prominent or not Gennady’s comet will become, the most amazing thing is that he beat the automated surveys to the punch. These days nearly all comets and many asteroids are found by professional astronomers using robotic telescopes hooked up to sensitive cameras and computers. Large areas of the sky are covered each clear night. If a fuzzy, moving object is detected by the computer, astronomers are alerted, follow-up observations are made and the new object receives a letter, number and the survey’s name.  That’s why there are a plethora of comets in the past 15 years with names like LINEAR (Lincoln Near-Earth Asteroid Survey), Pan-STARRS (Panoramic Survey Telescope & Rapid Response System), LONEOS (Lowell Observatory Near-Earth-Object Search) and others.

By dint of persistence, a smart plan and a keen eye, Gennady Borisov has made his mark in the sky. For that he deserves a well-deserved congratulations and round of applause!

Amateurs who wish to plot the comet on a star map using a star charting software program can get  Comet Borisov’s orbital elements HERE. To follow the latest developments, check out Leonid Elenin’s blog. You might recall it was Elenin in 2010 who discovered famed comet C/2010 X1 (Elenin), blamed for everything from earthquakes to future world catastrophes. Instead, the comet proved so friable, it disintegrated as it approached the sun. Let’s see how Comet Borisov fares.

Posted on by Shannon Hall

Jets Boost — Not Hinder — Star Formation in Early Galaxies, New Study Suggests

An artist's conception of jets protruding from a quasar. Credit: ESO/M. Kornmesser

Understanding the formation of stars and galaxies early in the Universe’s history continues to be somewhat of an enigma, and a new study may have turned our current understanding on its head. A recent survey used archival data from four different telescopes to analyze hundreds of galaxies. The results provided overwhelming evidence that radio jets protruding from a galactic center enhance star formation – a result that directly contradicts current models, where star formation is hindered or even stopped.

All early galaxies consist of intensely luminous cores powered by huge black holes.  These so-called active galactic nuclei, or AGN for short, are still the topic of intense study. One specific mechanism astronomers are studying is known as AGN feedback.

“Feedback is the astronomer’s slang term for the way in which an AGN – with its large amount of energy release – influences its host galaxy,” Dr. Zinn, lead researcher on this study, recently told Universe Today. He explained there is both positive feedback, in which the AGN will foster the main activity of the galaxy: star formation, and negative feedback, in which the AGN will hinder or even stop star formation.

Current simulations of galaxy growth invoke strong negative feedback.

“In most cosmological simulations, AGN feedback is used to truncate star formation in the host galaxy,” said Zinn. “This is necessary to prevent the simulated galaxies from becoming too bright/massive.”

Zinn et al. found strong evidence that this is not the case for a large number of early galaxies, claiming that the presence of an AGN actually enhances star formation. In such cases the total star formation rate of a galaxy may be boosted by a factor of 2 – 5.

Furthermore the team showed that positive feedback occurs in radio-luminous AGN. There is strong correlation between the far infrared (indicative of star formation) and the radio.

Now, a correlation between the radio and the far infrared is no stranger to galactic astronomy. Stars form in extremely dusty regions. This dust absorbs the starlight and re-emits it in the far infrared. The stars then die in huge supernova explosions, causing powerful shock-fronts, which accelerate electrons and lead to the emission of strong synchrotron radiation in the radio.

This correlation however is a stranger to AGN studies. The key lies in the radio jets, which penetrate far into the host galaxy itself.  A “jet which is launched from the AGN hits the interstellar gas of the host galaxy and thereby induces supersonic shocks and turbulence,” explains Zinn. “This shortens the clumping time of gas so that it can condense into stars much more quick and efficiently.”

This new finding conveys that the exact mechanisms in which AGN interact with their host galaxies is much more complicated than previously thought. Future observations will likely shed a new understanding of the evolution of galaxies.

The team used data primarily from the Chandra Deep Field South image
 but also data from Hubble, Herschel and Spitzer.

The results will be published in the Astrophysical Journal (preprint available here).

Posted on by David Dickinson

How to Spot and Track Satellites

A 10 second exposure of a bright pass of the International Space Station. (Photo by Author).

It’s a question we get all the time.

Watch the sky closely in the dawn or dusk hours, and you’ll likely see a moving “star” or two sliding by. These are satellites, or  “artificial moons” placed in low Earth orbit. These shine via reflected sunlight as they pass hundreds of kilometres overhead.

Many folks are unaware that you can see satellites with the naked eye. I always make an effort  to watch for these during public star parties and point them out. A bright pass of the International Space Station if often as memorable as anything that can be seen through the eyepiece. But after this revelation, “the question” soon follows- “What satellite is that?”

Welcome to the wonderful and highly addictive world of satellite tracking. Ground observers have been watching the skies since Sputnik 1 and the first satellite launch in October 1957. Armies of dedicated volunteers even participated in tracking the early launches of the Space Age with Operation Moonwatch.

Depiction of the apparent motion of a typical satellite overhead with respect to the observer. (Graphic created by author).
Depiction of the apparent motion of a typical satellite overhead with respect to the observer. (Graphic created by author).

The Internet has offered a wealth of information for satellite hunters. Every time I write about “how to spot the ISS,” someone amazes me with yet another new tracker App that I hadn’t heard of. One of my favorites is still Heavens-Above. It’s strange to think that we’ve been visiting this outstanding website daily for a decade and a half now. Heavens-Above specializes in satellites, and will show you a quick listing of passes for brighter satellites once configured with your location. A nifty “quick check” for possibly resolving a mystery satellite is their link for “Daily Predictions for brighter satellites” Which will generate a list of visible passes by time.

Screenshot of a typical list of bright satellite passes from Heavens-Above.
Screenshot of a typical list of bright satellite passes from Heavens-Above filtered by brightness, time and location .

Looking at the time, direction, and brightness of a pass is crucial to satellite identification. No equipment is needed to start the hunt for satellites tonight, just a working set of eyes and information. We sometimes use a set of Canon image-stabilized 15x 45 binoculars to hunt for satellites too faint to see with the naked eye. We’ve seen the “Tool Bag” lost during an ISS EVA a few years back, as well as such “living relics” of the early Space Age as Canada’s first satellite Alloutte-1, and the Vanguards (Yes, they’re STILL up there!) using binocs.

A comparision of typical satellite orbits. (Credit
A comparison of typical satellite orbits. (Credit: Cmglee, Geo Swan graphic under a Creative Commons Attribution -Share Alike 3.0 unported license).

The trick to catching fainter satellites such as these is to “ambush” them. You’ll need to note the precise time that the selected satellite is going to pass near a bright star. Clicking on a selected satellite pass in Heavens-Above will give you a local sky chart with a time-marked path. I use a short wave portable AM radio tuned to WWV out of Fort Collins, Colorado for an accurate audible time signal. Just sit back, listen to the radio call out the time, and watch for the satellite to pass through the field of view near the target star.

Another great site for more advanced trackers is CALSky. Like Heavens-Above, CALSky will give you a customized list for satellite passes over your location. One cool extra feature on CALSky is the ability to set alerts for passes of the ISS near bright planets or transiting the Sun or Moon. These are difficult events to capture, but worth it!

The International Space Station transiting the Moon as captured by Mike Weasner from Cassiopeia Observatory in Arizona.
The International Space Station transiting the Moon as captured by Mike Weasner from Cassiopeia Observatory in Arizona.

A great deal of what’s up there is space junk in the form of discarded hardware. Many satellites are on looping elliptical orbits, only visible to the naked eye when they are near perigee. Many satellites are located out at geosynchronous or geostationary orbits 35,786 kilometres distant and are invisible to the naked eye all together. These will often show up as streaks in astrophotos. An area notorious for geosynchronous satellites exists near the direction of M42 or Orion Nebula. During certain times of year, satellites can be seen nearby, nodding slowly north to south and back again. Around the March and September equinox seasons, geostationary satellites can be eclipsed by the shadow of the Earth. This can also cause communications difficulties, as many geo-sats also lie sunward as seen from the Earth around these times of year.

Probably one of the simplest satellite trackers for casual users is Space Weather’s Satellite Flybys page. North American users simply need to enter a postal code (worldwide users can track satellites via entering “country-state-city”) and a list of passes for your location is generated.

It’s a basic truism of satellite tracking that “aircraft blink; satellites don’t”. Know, we’re going to present an exception to this rule.

Some satellites will flash rhythmically due to a tumbling motion. This can be pretty dramatic to see. What you’re seeing is an expended booster, a cylinder tumbling due to atmospheric drag end-over-end. Some satellites can flash or flare briefly due to sunlight glinting off of reflective surfaces just right. Hubble, the ISS and the late NanoSail D2 can flare if conditions are just right.

The most dramatic of these are Iridium flares. The Iridium constellation consists of 66 active satellites used for satellite phone coverage in low-Earth orbit. When one of their three refrigerator-sized  antennas catch the Sun just right, they can flare up to magnitude -8, or 40 times brighter than Venus. CALSky and Heavens-Above will also predict these events for your location.

Didn’t see a predicted satellite pass? Light pollution or bright twilight skies might be to blame. Keep in mind, passes lower to the horizon also fall prey to atmospheric extinction, as you’re looking through a thicker layer of the air than straight overhead.  Some satellites such as the ISS or the USAF’s X-37B spy space plane even periodically boost or modify their orbits, throwing online prediction platforms off for a time.

More advanced satellite trackers will want to check out Celestrak and SAT-Flare Tracker 3D.

A screenshot example of TLE's for the ISS & Tiangong-1 from Celestrak.
A screenshot example of TLE’s for the ISS & Tiangong-1 from Celestrak.

I use a free tracking platform created by Sebastian Stoff known as Orbitron. Orbitron lets you set your observing location and tailor your view for what’s currently over head. You can run simulations and even filter for “visual only” passes, another plus. I also like Orbitron’s ability to run as a stand-alone system in the field, sans Internet connection. Just remember, for it to work properly, you’ll need to periodically update the .txt file containing the Two-Line Element (TLE) sets. TLE’s are data element sets that describe the orbital elements of a satellite. Cut and paste TLEs are available from Heavens-Above and Celestrak.

Orbitron screenshot for visible satellites using 'radar' mode... there's lots up there! (Credit: Orbitron).
Orbitron screenshot for visible satellites using ‘radar’ mode… there’s lots up there! (Credit: Orbitron).

For serious users, NORAD’s Space-Track is the best site for up-to-date TLEs.  Space-Track requires a login and user agreement to access, but is available to satellite spotters and educators as a valuable resource. Space-Track also hosts a table of upcoming reentries, as does the Aerospace Corporation’s Center for Orbital & Reentry Debris Studies.

The SeeSat-L mailing list is also an excellent source of discussion among satellite trackers worldwide. Increasingly, this discussion is also moving over to Twitter, which is ideal for following swiftly evolving  action in orbit. @Twisst, created by Jaap Meijers,will even Tweet you prior to an ISS pass!

And there’s always something new or strange in the sky for the observant. Satellites such as those used in the Naval Ocean Surveillance System (NOSS) were launched in groups, and are eerie to watch as they move in formations of 2 or 3 across the sky. These are difficult to catch, and all three of our sightings thus far of a NOSS pair have been surreptitious. And we’ve only had the camera ready to swing into action once to nab a NOSS pair;

A NOSS pair captured by the author. The multi-colored trail bisecting the path is an aircraft. Note a bit of "jitter" at the beginning of the exposure- I had to swing the camera into action quickly!
A NOSS pair captured by the author. The multi-colored trail to the left of the path is an aircraft. Note a bit of “jitter” at the beginning of the exposure- I had to swing the camera into action quickly!

Another bizarre satellite to catch in action is known as the Cloud-Aerosol LiDAR & Infrared Pathfinder Satellite for Observations, or CALIPSO. Part of the “afternoon A-Train” of sun-synchronous Earth observing satellites, you can catch the green LiDAR flashes of CALIPSO from the ground with careful planning, just as Gregg Hendry did in 2008-2009:

A CALIPSO LIDAR pass imaged by Gregg Hendry in 2008. My Hendry mentions that, "The hollow nature of the spots is likely due to some spherical aberration in the camera lens coupled with imperfect focus and is not representative of the laser beam's optical quality."
A CALIPSO LiDAR pass imaged by Gregg Hendry in 2008. My Hendry mentions that, “The hollow nature of the spots is likely due to some spherical aberration in the camera lens coupled with imperfect focus, and is not representative of the laser beam’s optical quality.” (Credit: Gregg Hendry, used with permission).

NASA even publishes a prediction table for CALIPSO lidar passes. I wonder how many UFO sightings CALIPSO has generated?

Artist's depiction of the A-Train constellation of Earth-Observing satellites. (Credit: NASA).
Artist’s depiction of the A-Train constellation of Earth-Observing satellites. (Credit: NASA).

And speaking of photography, it’s easy to catch a bright pass such as the ISS on camera. Shooting a satellite pass with a wide field is similar to shooting star trails; just leave the shutter open for 10-60 seconds with a tripod mounted camera. Modern DSLRs allow you to do several test exposures prior to the pass, to get the ISO, f/stop, and shutter speed calibrated to local sky conditions.

You can even image the ISS through a telescope. Several sophisticated rigs exist to accurately track and image the space station through a scope, or you could use our decidedly low-tech but effective hand-guided method;

And that’s a brief overview of the exciting world of sat-spotting… let us know of your tales of triumph and tragedy as you sleuth out what’s going on overhead!

Posted on by Bob King

Auroras Dance Over Northern U.S. Last Night, May Return Tonight

A thick green arc of aurora settled in for the night last night. It was about 5 degrees thick and some 10 degrees high. A faint but colorful diffuse aurora glowed above it. All photos taken with a 16-35 mm lens at f/2.8 and 30-second time exposure. Credit: Bob King

A burst of energetic particles from the Sun called a coronal mass ejection peppered Earth’s magnetic field yesterday afternoon sparking a modest but beautiful all-night display of the aurora borealis. Another light show may be in the offing tonight for skywatchers living in the northern U.S.,  Canada and northern Europe.

Around 1 a.m. the arc became more active, sending up occasional rays that lasted from about a minute before fading away and being replaced by another. Credit: Bob King
Around 1 a.m. the arc became more active, sending up occasional rays that lasted from about a minute before fading away and being replaced by another. Credit: Bob King

Pale green fingers of light splayed across the northern sky at twilight’s end came as a surprise. NOAA space weather forecasters had predicted little activity. These soon faded but a thick, fuzzy arc persisted throughout the night. It arched from horizon to horizon across the northern sky like a pallid, monochromatic rainbow. Such arcs are common. Often the aurora never gets past this stage and simmers quietly or even fades away during the night.

Not this one. Around local midnight (1 a.m. CDT) here in Duluth, Minn. small bright spots and a series of tall, faint rays punctuated the arc and over the span of a half-hour completely reshaped it into loopy rayed arcs resembling a crown.

I wasn't alone when the northern lights peaked about 1:20-2 a.m. At upper left you'll see the trails of a couple of fireflies. Credit: Bob King
I wasn’t alone when the northern lights peaked about 1:20-2 a.m. At upper left you’ll see the trails of a couple of fireflies. Credit: Bob King

To the eye, the brightest parts of the aurora appeared green, but the taffy-stretched rays were colorless. The camera’s sensitivity coupled with a 30-second time exposure revealed striking pinks and hints of blue. Both pink and green colors are caused by the emission of light from oxygen atoms.

An especially beautiful ray sticks up above the arc. Shorter exposures coupled with shorter shutter speeds are the best way to capture fine details of a northern lights display. Credit: Bob King
An especially beautiful ray sticks up above the arc. Shorter exposures coupled with shorter shutter speeds are the best way to capture fine details of a northern lights display. Credit: Bob King

Bombarded by high-speed solar wind electrons and protons, they get jazzed into higher energy states. When the atoms return to rest, each spits out a photon of green or red light. All those tiny flashes add up. Multiplied by the billions of atoms that exist even in the rarefied air at the aurora’s typical 60-150 mile (100-250 km) altitude and you get heavenly eye candy.

When we see an auroral arc - and associated rays - we really seeing a small section of the much larger, permanent aurora called the auroral oval. The northern oval is centered over the geomagnetic north pole located in northern Canada. Credit: NASA
When we see an auroral arc – and associated rays – we really seeing a small section of the much larger, permanent aurora called the auroral oval. The northern oval is centered over the geomagnetic north pole located in northern Canada. Credit: NASA

I started watching the northern lights at 11 from home then took a drive to darker skies. Even at dawn’s 3 a.m. start, the green arc held its own shot through with rays that occasionally towered halfway up the northern sky. While this display wasn’t a grand spectacle like some auroras, it possessed a certain majesty the same way a long, slow movement concludes a great symphony.

Chances for more of the same continues through tonight and possibly into tomorrow, so keep a watch on the northern sky before you hit the hay tonight. If you see something green and glowing it you might be in for a treat.

In another installment, I’ll share tips on how best to see the northern lights and share several excellent tools you can use for predicting when they might occur.

Posted on by David Dickinson

Conjunctions to Watch For in July

The waxing crescent Moon joins the evening sky early this week. (Photo by author).

The planets are slowly returning into view this month, bashfully peeking out from behind the Sun in the dawn & dusk sky. This month offers a bonanza of photogenic conjunctions, involving the Moon, planets and bright stars.

The action begins tonight on July 8th, as the waxing crescent Moon joins the planet Venus in the dusk sky. The razor thin Moon will be a challenge on Monday night, as it just passed New on the morning of the 8th at 3:14AM EDT/7:14 Universal Time (UT). The record for spotting the thin crescent with the naked eye currently stands at 15 hours and 32 minutes, completed by Stephen O’Meara on May 1990. Binoculars help considerably in this endeavor.  Wait until 15 minutes after local sunset, and then begin patiently sweeping the horizon.

Mr. Thierry Legault completed an ultimate photographic challenge earlier today, capturing the Moon at the precise moment of  New phase!

The Moon & Venus on the evening of July 9th from latitude 30 degrees north, about 30 minutes after sunset. (Created by the author using Stellarium).
The Moon & Venus on the evening of July 9th as seen from latitude 30 degrees north, about 30 minutes after sunset. (Created by the author using Stellarium).

This week  marks the start of lunation 1120. The Moon will be much easier to nab for observers worldwide on Tuesday night, July 9th for observers worldwide. The sighting of the waxing crescent Moon will also mark the start of the Muslim month of Ramadan for 2013. Due to the angle of the ecliptic in July, many northern hemisphere observers may not spot the Moon until Wednesday night on July 10th, about 6.7 degrees south west of -4.0 magnitude Venus.

Did you know? There are Guidelines for the Performance of Islamic Rites for Muslims aboard the International Space Station. It’s interesting to note that the timing of the rituals follows the point from which the astronaut originally embarked from the Earth, which is exclusively the Baikonur Cosmodrome in Kazakhstan for the foreseeable future of manned spaceflight.

Malaysia’s first astronaut, Sheikh Muszaphar Shukor observed Ramadan aboard the International Space Station in 2007.

From there, the crescent Moon fattens, meeting up with Saturn and Spica on the evenings of July 15th and 16th. The Moon will actually occult (pass in front of) the bright star Spica on the evening of July 15/16th at ~3:33UT/11:33PM EDT (on the 15th) for observers in Central America and western South America. The rest of us will see a near miss worldwide.

The waxing crescent Moon nearing Spica on the evening of the 15th at 10PM EDT. The Moon reaches 1st Quarter on the same evening at 11:18PM EDT. (Created by the author using Starry Night).
The waxing crescent Moon nearing Spica on the evening of the 15th at 10PM EDT. The Moon reaches 1st Quarter phase on the same evening at 11:18PM EDT. (Created by the author using Starry Night).

This is the 13th in a cycle of 18 occultations of Spica by our Moon spanning 2012-2013. Spica is one of four stars brighter than magnitude +1.4 that lie close enough to the ecliptic to be occulted by our Moon, the others being Antares, Regulus and Aldebaran. Saturn will lie 3 degrees from the Moon on the evening of July 16th.

Can you nab Spica and Saturn near the Moon with binoculars in the daytime around the 15th? It can be done, using the afternoon daytime Moon as a guide. Crystal clear skies (a rarity in the northern hemisphere summertime, I know) and physically blocking the Sun behind a building or hill helps.

The waxing gibbous Moon will also occult +2.8 Alpha Librae for South Africa on July 17th around 17:09UT & +4.4th magnitude Xi Ophiuchi for much of North America on the night of July 19th-20th.

And speaking of Regulus, the brightest star in the constellation Leo lies only a little over a degree (two Full Moon diameters) from Venus only the evenings of July 21st & the 22nd. 77.5 light years distant, Regulus is currently over 100 times fainter at magnitude +1.4. Can you squeeze both into the field of view of your telescope at low power? Venus’s mythical ‘moon’ Neith lives!

Venus can even occult Regulus on rare occasions, as last occurred on July 7th, 1959 and will happen next on October 1st, 2044.

But there’s morning action afoot as well. The planets Mars and Jupiter have emerged from solar conjunction on April 18th and June 19th, 2013 respectively, and can now be seen low in the dawn skies about 30 minutes before sunrise.

Mars and Jupiter in a close conjunction on the morning of July 22nd, about 30 minutes before sunrise as seen from latitude 30 degrees north. (Created by the author using Starry Night).
Mars and Jupiter in a close conjunction on the morning of July 22nd, about 30 minutes before sunrise as seen from latitude 30 degrees north. (Created by the author using Starry Night).

Mars approaches Jupiter in the dawn until the pair is only 0.79 degrees (about 48 arc minutes) apart on Monday, July 22nd. Mars shines at magnitude +1.6 and shows a tiny 3.9” disk, while Jupiter displays a 32.5” disk shining at magnitude -1.9 on this date. Conjunction occurs at about 7:00 UT/3:00 AM EDT, after which the two will begin to race apart. Mercury is visible beginning its morning apparition over 5 degrees to the lower right of the pair (see above).

Jupiter will reach opposition and reenter the evening sky on January 5th, 2014, while Mars won’t do the same until April 8th of next year. Weird factoid alert: neither Jupiter or Mars reach opposition in 2013! What effect does this have on terrestrial affairs? Absolutely none, well unless you’re a planetary imager/observer…

Mars also reaches its most northern declination of 2013 of 24 degrees in the constellation Gemini on July 16th at 7:00 AM EDT/11:00 UT.  Mars can wander as far as declination 27 degrees north, as last happened in 1993.

Finally, are you observing from southern Mexico this week and up for a true challenge? The asteroid 238 Hypatia occults a +7.4 magnitude star from 10:13-10:49 UT on July 10th in the constellation Pisces for up to 29 seconds. This event will be bright enough to watch with binoculars- check out our best prospects for asteroid occultations of stars in 2013 here and here.

Good luck, clear skies, and be sure to post those astro-pics in the Universe Today’s Flickr community!