This plot of data captured by NASA's Nuclear Spectroscopic Telescope Array, or NuSTAR, shows X-ray light streaming from regions near a supermassive black hole known as Markarian 335. Credit: NASA
NASA’s Nuclear Spectroscopic Telescope Array (NuSTAR) has captured a spectacular event: a supermassive black hole’s gravity tugging on nearby X-ray light.
In just a matter of days, the corona — a cloud of particles traveling near the speed of light — fell in toward the black hole. The observations are a powerful test of Einstein’s theory of general relativity, which says gravity can bend space-time, the fabric that shapes our universe, and the light that travels through it.
“The corona recently collapsed in toward the black hole, with the result that the black hole’s intense gravity pulled all the light down onto its surrounding disk, where material is spiraling inward,” said coauthor Michael Parker from the Institute of Astronomy in Cambridge, United Kingdom, in a press release.
The supermassive black hole, known as Markarian 335, is about 324 million light-years from Earth in the direction of the constellation Pegasus. Such an extreme system squeezes about 10 million times the mass of our Sun into a region only 30 times the diameter of the Sun. It spins so rapidly that space and time are dragged around with it.
NASA’s Swift satellite has monitored Mrk 335 for years, recently noting a dramatic change in its X-ray brightness. So NuSTAR was redirected to take a second look at the system.
NuSTAR has been collecting X-rays from black holes and dying stars for the past two years. Its specialty is analyzing high-energy X-rays in the range of 3 to 79 kiloelectron volts. Observations in lower-energy X-ray light show a black hole obscured by clouds of gas and dust. But NuSTAR can take a detailed look at what’s happening near the event horizon, the region around a black hole form which light can no longer escape gravity’s grasp.
Specifically, NuSTAR is able to see the corona’s direct light, and its reflected light off the accretion disk. But in this case, the light is blurred due to the combination of a few factors. First, the doppler shift is affecting the spinning disk. On the side spinning away from us, the light is shifted to redder wavelengths (and therefore lower energy), whereas on the side spinning toward us, the light is shifted to bluer wavelengths (and therefore higher energy). A second effect has to do with the enormous speeds of the spinning black hole. And a final effect is from the gravity of the black hole, which pulls on the light, causing it to lose energy.
All of these factors cause the light to smear.
Intriguingly, NuSTAR observations also revealed that the grip of the black hole’s gravity pulled the corona’s light onto the inner portion of the accretion disk, better illuminating it. NASA explains that as if somebody had shone a flashlight for the astronomers, the shifting corona lit up the precise region they wanted to study.
“We still don’t understand exactly how the corona is produced or why it changes its shape, but we see it lighting up material around the black hole, enabling us to study the regions so close in that effects described by Einstein’s theory of general relativity become prominent,” said NuSTAR Principal Investigator Fiona Harrison of the California Institute of Technology. “NuSTAR’s unprecedented capability for observing this and similar events allows us to study the most extreme light-bending effects of general relativity.”
The new data will likely shed light on these mysterious coronas, where the laws of physics are pushed to their limit.
The article has been published in the Monthly Notices of the Royal Astronomical Society and is available online.
The last dawn pairing of Venus, Jupiter and the crescent Moon in the dawn sky in 2012... this month's will be much tighter! Credit: Tavi Greiner.
“What are those two bright stars in the morning sky?”
About once a year we can be assured that we’ll start fielding inquires to this effect, as the third and fourth brightest natural objects in the sky once again meet up.
We’re talking about a conjunction of the planets Jupiter and Venus. Venus has been dominating the dawn sky for 2014, and Jupiter is fresh off of solar conjunction on the far side of the Sun on July 24th and is currently racing up to greet it.
We just caught sight of Jupiter for the first time for this apparition yesterday from our campsite on F.E. Warren Air Force Base in Cheyenne, Wyoming. We’d just wrapped up an early vigil for Perseid meteors and scrambled to shoot a quick sequence of the supermoon setting behind a distant wind farm. Jupiter was an easy catch, first with binoculars, and then the naked eye, using brilliant Venus as a guide post.
The view looking eastward at dawn on August 18th, including a five degree telrad (red circles) and a one degree telescopic field of view (inset). Created using Stellarium.
And Jupiter will become more prominent as the week progresses, climaxing with a fine conjunction of the pair on Monday, August 18th. This will be the closest planet versus planet conjunction for 2014. At their closest — around 4:00 Universal Time or midnight Eastern Daylight Saving Time — Venus and Jupiter will stand only 11.9’ apart, less than half the diameter of a Full Moon. This will make the pair an “easy squeeze” into the same telescopic field of view at low power. Venus will shine at magnitude -3.9, while Jupiter is currently about 2 magnitudes or 6.3 times fainter at magnitude -1.8. In fact, Jupiter shines about as bright as another famous star just emerging into the dawn sky, Sirius. Such a dawn sighting is known as a heliacal rising, and the first recovery of Sirius in the dawn heralded the flooding of the Nile for the ancient Egyptians and the start what we now term the Dog Days of Summer.
To the naked eye, enormous Jupiter will appear to be the “moon” that Venus never had next weekend. The spurious and legendary Neith reported by astronomers of yore lives! You can imagine the view of the Earth and our large Moon as a would-be Venusian astronomer stares back at us (you’d have to get up above those sulfuric acid clouds, of course!)
Said conjunction is only a product of our Earthly vantage point. Venus currently exhibits a waxing gibbous disk 10” across — three times smaller than Jupiter — but Venus is also four times closer to Earth at 1.61 astronomical units distant. And from Jupiter’s vantage point, you’d see a splendid conjunction of Venus and the Earth, albeit only three degrees from the Sun:
Earth meets Venus, as seen from Jupiter on August 18th. Note the Moon nearby. Created using Starry Night Education Software.
How often do the two brightest planets in the sky meet up? Well, Jupiter reaches the same solar longitude (say, returns back to opposition again) about once every 13 months. Venus, however, never strays more than 47.1 degrees elongation from the Sun and can thus always be found in either the dawn or dusk sky. This means that Jupiter pairs up with Venus roughly about once a year:
A list of Venus and Jupiter conjunctions, including angular separation and elongations (west=dawn, east=dusk) from now until 2020. Created by author.
Note that next year and 2019 offer up two pairings of Jupiter and Venus, while 2018 lacks even one. And the conjunction on August 27th, 2016 is only 4’ apart! And yes, Venus can indeed occult Jupiter, although that hasn’t happened since 1818 and won’t be seen again from Earth until – mark your calendars – November 22nd, 2065, though only a scant eight degrees from the Sun. Hey, maybe SOHO’s solar observing successor will be on duty by then…
Venus has been the culprit in many UFO sightings, as pilots have been known to chase after it and air traffic controllers have made furtive attempts to hail it over the years. And astronomy can indeed save lives when it comes to conjunctions: in fact, last year’s close pairing of Jupiter and Venus in the dusk sky nearly sparked an international incident, when Indian Army sentries along the Himalayan border with China mistook the pair for Chinese spy drones. Luckily, Indian astronomers identified the conjunction before shots were exchanged!
Earth strikes back… firing a 5mw green laser at the 2013 conjunction of Jupiter and Venus. Photo by author.
Next week’s conjunction also occurs against the backdrop of Messier 44/Praesepe, also known as the “Beehive cluster”. It’ll be difficult to catch sight of M44, however, because the entire “tri-conjunction” sits only 18 degrees from the Sun in the dawn sky. Binocs or a low power field of view might tease out the distant cluster from behind the planetary pair.
And to top it off, the waning crescent Moon joins the group on the mornings of August 23rd and 24th, passing about five degrees distant. Photo op! Can you follow Venus up into the daytime sky, using the Moon as a guide? How about Jupiter? Be sure to block that blinding Sun behind a hill or building while making this attempt.
The Moon photobombs the conjunction of Venus and Jupiter on the weekend of August 23rd. Credit: Stellarium.
The addition of the Moon will provide the opportunity to catch a skewed “emoticon” conjunction. A rare smiley face “:)” conjunction occurred in 2009, and another tight skewed tri-conjunction is in the offering for 2056. While many national flags incorporate examples of close pairings of Venus and the crescent Moon, we feel at least one should include a “smiley face” conjunction, if for no other reason than to highlight the irony of the cosmos.
A challenge: can you catch a time exposure of the International Space Station passing Venus and Jupiter? You might at least pull off a “:/” emoticon image!
Don’t miss the astronomical action unfolding in a dawn sky near you over the coming weeks. And be sure to spread the word: astronomical knowledge may just well avert a global catastrophe. The fate of the free world lies in the hands of amateur astronomers!
An artist's conception of a distance exomoon blocking out a star's light. Credit: Dan
I firmly believe that our next greatest discovery will be detecting an exomoon in orbit around a distant exoplanet. Although no one has been able to confirm an exomoon — yet — the hunt is on.
Now, a research team thinks following a trail of radio wave emissions may lead astronomers to this groundbreaking discovery.
The difficulty comes in trying to spot an exomoon using existing methods. Some astronomers think that hidden deep within the wealth of data collected by NASA’s Kepler mission are miniscule signatures confirming the presence of exomoons.
If an exomoon transits the star immediately before or just after the planet does, there will be an added dip in the observed light. Although astronomers have searched through Kepler data, they’ve come up empty handed.
So the team, led by Ph.D. student Joaquin Noyola, from the University of Texas at Arlington, decided to look a little closer to home. Specifically, Noyola and colleagues analyzed the radio wave emissions that result from the interaction between Jupiter, and it’s closest moon, Io.
During its orbit, Io’s ionosphere interacts with Jupiter’s magnetosphere — a layer of charged plasma that protects the planet from radiation — to create a frictional current that emits radio waves. Finding similar emissions near known exoplanets could be the key to predicting where moons exist.
“This is a new way of looking at these things,” said Noyola’s thesis advisor, Zdzislaw Musielak, in a press release. “We said, ‘What if this mechanism happens outside of our Solar System?’ Then, we did the calculations and they show that actually there are some star systems that if they have moons, it could be discovered in this way.”
The team even pinpointed two exoplanets — Gliese 876b, which is about 15 light-years away, and Epsilon Eridani b, which is about 10.5 light-years away — that would be good targets to begin their search.
With such a promising discovery on the horizon, theoretical astronomers are beginning to address the factors that may deem these alien moons habitable.
“Most of the detected exoplanets are gas giants, many of which are in the habitable zone,” said coauthor Suman Satyal, another Ph.D. student at UT Arlington. “These gas giants cannot support life, but it is believed that the exomoons orbiting these planets could still be habitable.”
Of course one look at Io shows the drastic effects a nearby planet may have on its moon. The strong gravitational pull of Jupiter distorts Io, causing its shape to oscillate, which generates enormous tidal friction. This effect has led to over 400 active volcanoes.
But a moon at a slightly further distance could certainly be habitable. A second look at Europa — Jupiter’s second-most inner satellite — demonstrates this facet. It’s possible that life could very well exist under Europa’s icy crust.
Exomoons may be frequent, habitable abodes for life. But only time will tell.
The findings have been published in the Aug. 10 issues of the Astrophysical Journal and are available online.
Artist concept of matter swirling around a black hole. (NASA/Dana Berry/SkyWorks Digital)
Black holes one billion times the Sun’s mass or more lie at the heart of many galaxies, driving their evolution. Although common today, evidence of supermassive black holes existing since the infancy of the Universe, one billion years or so after the Big Bang, has puzzled astronomers for years.
How could these giants have grown so massive in the relatively short amount of time they had to form? A new study led by Tal Alexander from the Weizmann Institute of Science and Priyamvada Natarajn from Yale University, may provide a solution.
Black holes are often mistaken to be monstrous creatures that suck in dust and gas at an enormous rate. But this couldn’t be further from the truth (in fact the words “suck” and “black hole” in the same sentence makes me cringe). Although they typically accumulate bright accretion disks — swirling disks of gas and dust that make them visible across the observable Universe — these very disks actually limit the speed of growth.
First, as matter in an accretion disk gets close to the black hole, traffic jams occur that slow down any other infalling material. Second, as matter collides within these traffic jams, it heats up, generating energy radiation that actually drives gas and dust away from the black hole.
A star or a gas stream can actually be on a stable orbit around the black hole, much as a planet orbits around a star. So it is quite a challenge for astronomers to think of ways that would make a black hole grow to supermassive proportions.
Luckily, Alexander and Natarajan may have found a way to do this: by placing the black hole within a cluster of thousands of stars, they’re able to operate without the restrictions of an accretion disk.
Black holes are generally thought to form when massive stars, weighing tens of solar masses, explode after their nuclear fuel is spent. Without the nuclear furnace at its core pushing against gravity, the star collapses. While the inner layers fall inward to form a black hole of only about 10 solar masses, the outer layers fall faster, hitting the inner layers, and rebounding in a huge supernova explosion. At least that’s the simple version.
The erratic path of the black hole through the gas (black line) is randomized by the surrounding stars (yellow circles). Meanwhile, dense cold gas (green arrows) flows toward the center of the cluster (red cross). Credit: Weizmann Institute of Science.
The team began with a model of a black hole, created from this stellar blast, embedded within a cluster of thousands of stars. A continuous flow of dense, cold, opaque gas fell into the black hole. But here’s the trick: the gravitational pull of many nearby stars caused it to zigzag randomly, preventing it from forming an accretion disk.
Without an accretion disk, not only is matter more able to fall into the black hole from all sides, but it isn’t slowed down in the accretion disk itself.
All in all, the model suggests that a black hole 10 times the mass of the Sun could grow to more than 10 billion times the mass of the Sun by one billion years after the Big Bang.
An array of Earth-like planets. Image Credit: NASA
Since 1995, astronomers have detected thousands of worlds orbiting nearby stars, sparking a race to find the one that most resembles Earth. The discovery of habitable exoplanets and even extraterrestrial life is often referred to as the Holy Grail of science. So with the gold rush of exoplanet discoveries these days, it’s pretty tempting in news articles to lose readers in a fantastical narrative.
This month I’m launching a project on Beacon — a new independent platform for journalism — that will go behind the sensational headlines covering the search for Earth 2.0.
But I can’t do it without your help. In order to commit to writing about this on a regular basis, I need to raise $4,000 from subscribers who are willing to support my work over this month. Don’t worry, subscriptions are available for only $5 per month. This will supply the funding necessary to write for six months.
By Kepler’s definition, to be Earth-like a planet must be both Earth-size (less than 1.25 times Earth’s radius and less than twice Earth’s mass) and must circle its host star within the habitable zone: the band where liquid water can exist.
Image Credit: xkcd
This simple, and yet variant, definition is a crucial starting point. But one glance at our Solar System (namely Venus and Mars) demonstrates that just because a planet is Earth-like doesn’t mean it’s an Earth twin.
So even if we do find Earth-like planets, we still don’t have the ability to know if they’re water worlds with luscious green planets and civilizations peering back at us.
But should we scale our definition of Earth-like planets up or down? Examples in the Solar System suggest that we should scale it down. Maybe planets located nearer to the center of the habitable zone are more congenial to life.
But can we base our definition on a single example — even if it’s the only example we know — alone? Theoretical astronomers suggest the picture is much more complicated. Life might arise on larger worlds, ones up to three times as massive as Earth, because they’re more likely to have an atmosphere due to more volcanic activity. Or life might arise on older worlds, where there’s simply more time for life to evolve.
It’s a crucial debate in astronomy research today, and it’s one that the media needs to handle with care. I am proud to be a part of Universe Today’s team, bringing readers up-to-date with the on goings in our local Universe. And Beacon will allow me to spend even more time, focusing on such a critical topic.
For each article, I will gather news, opinions and commentary from astronomers in the field. Not only do I have training as an astronomer, but my graduate school research focused on detecting exoplanet atmospheres from ground-based telescopes. With this deep-rooted understanding of the field at hand, I am able to parse complex information by directly reading peer-reviewed journal articles and interviewing astronomers I’ve met through my previous research.
But I really do need your help. Subscriptions are available for only $5 per month, and there are special rewards — such as gorgeous astronomy photos printed on canvas and gift subscriptions for friends — for people who subscribe at higher levels. You can directly subscribe here.
But here’s the best part: when you subscribe to my work, you’ll get access not only to all the stories I write, but the work of over 100 additional writers, based all over the world. This month Beacon is launching a series of astronomy projects, including one by Universe Today writer Elizabeth Howell.
Hubble infrared image showing CL J1449+0856, the most distant mature cluster of galaxies found. Color data was added from ESO’s Very Large Telescope and the NAOJ’s Subaru Telescope. Credit: NASA, ESA, R. Gobat (Laboratoire AIM-Paris-Saclay, CEA/DSM-CNRS–)
The Universe is big, but how big is it? That all depends on whether the Universe is finite or infinite. Even the word “big” is tough to get clear. Are we talking about the size of the Universe we can see, or the Universe’s actual size right now?
The Universe is big, but how big is it? And what the heck kind of question is that? Are elephants big? Trucks? Dinosaurs? Cheese? Is cheese big? How big is cheese? How big is big?
The word “big” is tough to get clear. Are we talking about the size of the Universe we can see, or the Universe’s actual size right now? This becomes even more complicated when we are trying to work under assumptions of either the Universe is finite or the Universe is infinite.
One difficulty with talking about the size, is that the Universe is expanding. Light takes time to travel from distant galaxies, and while that light travels, the Universe continues to expand. So our problem with talking about how big it is, is that there is no single meaning to distance when it comes to the universe. For this reason, astronomers usually don’t worry about the distance to galaxies at all, and instead focus on redshift, which is measured by z. The bigger the z, the more redshift, and the more distant the galaxy.
As an example, consider one of the most distant galaxies we’ve observed, which has a redshift of 7.5. Using this, we can determine distance by calculating how long the light has traveled to reach us. With a redshift of 7.5, that comes out to be about 13 billion years. You might think that means it’s 13 billion light years away, but 13 billion years ago the universe was smaller, so it was actually closer at the time the light left that galaxy. Using this, if you calculate that distance, it was only a short 3.4 billion light years away.
Now the galaxy is much farther than that. After the light left the galaxy, the galaxy continued to move away from us. It is now about 29 billion light years away. Which is definitely more than 13, and quite a bit more than its original 3.4.
Usually it is this big distance that people mean when they ask for the size of the universe. This is known as the co-moving distance. Of course, we can only see so far. So, how far can we see? The most distant light we are able to observe is from the cosmic microwave background, which has a redshift of about z = 1,000.
This means the co-moving distance of the cosmic background is about 46 billion light years. Sticking us at the center of a massive sphere, the currently observable universe has a diameter of about 92 billion light years. Even with this observed distance, we know that it extends much further than that. If what we could see was all there is, we would see galaxies tend to gravitate towards us, which we don’t observe.
Artist concept of the multiverse. Credit: Florida State University
In fact we don’t see any kind of galaxy clumping to a particular point at all. So as far as we know the universe could extend forever. It could be even stranger than that. Despite some media controversy, if the BICEP2 detection of early inflation is correct, it is likely the Universe undergoes a type of inflation with the intimidating moniker of “eternal inflation”. If it is the case, our observable universe is merely one bubble within an endless sea of other bubble universes. This is otherwise referred to as… the multiverse.
So, in the immortal words of Douglas Adams, “Space,” it says, “is big. Really big. You just won’t believe how vastly, hugely, mindbogglingly big it is. I mean, you may think it’s a long way down the road to the chemist’s, but that’s just peanuts to space”
What do you think? Does the Universe go on for ever? Tell us in the comments below. And if you like what you see, come check out our Patreon page and find out how you can get these videos early while helping us bring you more great content!
The "super moon" of August 2014 captured by Expedition 40's Oleg Artemyev on the International Space Station. Credit: OlegMKS / Twitter
With the full Moon approaching just a little bit closer than Earth to usual, a cosmonaut on the International Space Station took a few moments of his time to capture a few shots of it setting behind the Earth. Oleg Artemyev was just a shade closer to that Moon than the rest of us, and the sequence of pictures (below the jump) is stunning.
As Universe Today’s David Dickinson explained last week, the so-called “supermoon” refers to a phenomenon where the full Moon falls within 24 hours of perigee (closest approach to the Earth.) We’re in a cycle of supermoons right now, with this weekend’s the second in a three-part cycle this year.
The Moon appears about 14% bigger between its furthest and closest approaches to Earth. While the difference is subtle in the sky, it does produce higher tides on Earth (with an example being Hurricane Sandy in 2012.)
Technically the perigee happened August 10 at 6:10 p.m. UTC (2:10 p.m. EDT), but people (including Artemyev) took several pictures of the moon a bit before and after that time. One example from our Universe Today Flickr pool is at the bottom of this post. You can see more examples on Flickr.
An Illustration of the ISEE-3 trajectory around the Earth, Moon and Sun. (Credits: Google Creative Labs, Skycorp Inc., Space Exploration Engineering)
The journey began on August 12, 1978 from Cape Canaveral on a Delta II launch vehicle. Now after 36 years and 30 billions miles of travel around the Sun — as well as a crowd-funded reboot of the spacecraft and a foiled attempt to put it into Earth orbit — the ISEE-3 has completed a return visit to the Earth-Moon system.
The spacecraft made its closest approach to the Earth on August 9 and flyby of the Moon, August 10, 2014. Closest approach was 15,600 km (9693 miles) from the Moon’s surface. With the lunar flyby, Skycorp, Inc. of Mountain View, California, with help from Google Creative Labs, has announced a revised mission for ISEE-3 to deliver science to the public domain.
ISEE-3 has marked several important milestones and achievements for NASA over the five decades in which it has traveled and monitored the particles and fields between the Earth and the Sun. Its latest milestone – returning to Earth, was planned and refined over 30 years ago. However, with NASA no longer interested in recovering the spacecraft because of the limitations of its present budgets, its impending return would be with no fanfare, no commanding, no recovery into Earth orbit and no new mission. With the news that NASA could not afford a recovery, space enthusiasts began to talk. Retired and active aerospace engineers began to exchange ideas with avid HAM radio operators around the World. Finally, one group took charge. They revived the vintage spacecraft and has now designed a new mission for the it.
NASA illustration of the ISEE-3 fly by the Moon, 1982. On August 10, 2014, ISEE-3 will fly within 15,600 km (9693 miles) above the Moon’s surface.
Enter Dennis Wingo and Austin Epps of Skycorp, Inc. Residing in an abandoned McDonald’s drive-thru on Moffett Field in Mountain View, California, they began a journey in March to recover the spacecraft. First off, before any recovery attempt could be undertaken, it required original documentation, so Dennis with assistance from Keith Cowing began contacting original ISEE-3 engineers, calling, knocking on NASA doors and finally began signing NASA space act agreements to have the documents released into their possession. And what fascinating documents they were.
Written long before the internet, before the first personal computers and when computer punch cards and main frames were the means to program and command spacecraft, most of the ISEE-3 documents resided as printed documents only, on none other than paper, yellowing and old, doomed to eventually rot away in modest storage rooms. Some had been converted to the modern archive format, Adobe’s PDF file format. This was the beginning of revival of a working knowledge to command the spacecraft. It was very sketchy but in about 90 days, documents appeared, documents were scanned to PDFs, searched and the team prepared for the recovery attempt.
Key personnel of the ISEE-3 Reboot Project. From left, Casey Harper, Cameron Woodman, Austin Epps, Jacob Gold, Balint Seeber, Keith Cowing, Dennis Wingo, Marco Colleluori and Ken Zin. (Photo credit, Google Creative Labs)
The team grew rapidly and as the Beatles song goes, Skycorp got by with a little help from their friends. Actually, a lot of help from their friends. First, there was a crowd funding effort. Thousands of individuals from around the globe contributed to a final crowd funding purse of about $160,000. This is in contrast to the $100 million or much more that is required to reach just the launch date of a NASA mission.
Next, the people that had been exchanging comments on blogs (e.g. Planetary blog post on ISEE-3) began making themselves available, no charge, providing decades of accrued experience in spacecraft design and operation and other very relevant expertise. There were original NASA engineers, Robert Farquhar and David Dunham, Warren Martin, Bobby Williams, and Craig Roberts. HAM radio operators appeared or were contacted from as far as England (AMSAT-UK), Germany(Bochum Obs.) and as nearby as the SETI Institute in Mountain View, California. All this expertise, working knowledge and capable hardware had to converge very rapidly. By the latter half of May, they were ready.
The operators of the venerable Arecibo Radio Telescope offered their expertise and its 1000 foot radio dish for communication purposes. And an absolutely critical solution was found to replace the lack of any existing transmitter that could communicate with the old 40 year old technology. NASA had retired and scrapped the original Deep Space Network equipment. So technology developed by Ettus Research Corp. of Santa Clara, California was identified as a possible replacement for the non-existent transmitter. Ettus proposed a combination of open source software called Gnu Radio configured to work with Ettus developed Universal Software Radio Peripheral (USRP) platforms as the solution. With the Skycorp team constructing the command sequences, Ettus engineers Balint Seeber and a former engineer John Marlsbury rigged the critical substitute for a hardware transmitter and with the expertise to modulate and demodulate a radio signal, a trip to Puerto Rico and the Arecibo dish was undertaken in May.
After two weeks of some waiting on hardware and trial and error, there was success. Two-way communication was achieved and ISEE-3 truly became ISEE-3 Reboot. Further hiccups unfolded by trial and error, learning to command and receive with still less than complete working knowledge. More NASA space act agreements were necessary to permit the access to achieve success. Finally, NASA provided time on the Deep Space Network, the famous Goldstone radio dish and others in the network, famous for communicating with Apollo missions and Voyagers at the edge of the Solar System. This provided further attempts at communication that helped to resolve and understand issues. Furthermore, a Bell Labs engineer, Phil Karn Jr. (KA9Q) volunteered his expertise in late night work sessions, to demodulate and decode the incoming radio signal, to convert analog signal into 1’s and 0’s. Phil provided crucial input and energy to the ISEE-3 Reboot at a key juncture.
The ultimate goal could now be attempted – command the spacecraft to fire its rocket engines to change its trajectory and become captured by the Earth’s gravitational field. Mike Loucks of Space Exploration Engineering and engineers of Applied Defense Solutions, Inc. worked quickly to provide trajectory information and revisions. Finally, commanding ISEE-3 to fire its rockets was attempted and then attempted again and again. Skycorp concluded that father time was what was truly in command of ISEE-3’s destiny. Thirty-six years in space had taken its toll and Skycorp engineers realized that the fuel tanks had lost pressure. They could command it in all necessary ways but the spacecraft could not squeeze the fuel out of the tanks.
Recovering from this disappointment, Skycorp has arrived at today with the help of the original engineers lead by Robert Farquhar of Goddard Space Flight Center, along with the thousands through crowd funding contributions and an incredible group of volunteers. And along the way, Google Creative Labs documented the adventure and created the compendium which was delivered to the public domain last week, A Spacecraft for All. This web site provides a graphic illustration of both the ISEE-3 timeline as well as its incredible journey to explore the Sun-Earth relationship, study two comets and then undertake a 30 year journey to return to Earth on August 10, 2014.
Using the radio telescope at Morehead State University, they will continue receiving the commanded telemetry stream from the remaining viable science instruments, process the data and present it to the public and to professional researchers alike for analysis. While ISEE-3 could not be recovered into an Earth orbit as Farquhar had hoped decades ago, it will continue its journey around the Sun and return to the vicinity of the Earth in 2029. How long telemetry from ISEE-3 can be received as it travels away from the Earth remains to be seen, and keeping in contact with it will be a challenge for its new operators in the months ahead.
The annual Perseid meteor shower radiates from a point in the constellation Perseus just below the W of Cassiopeia. Rates are usually about 100-120 meteors per hour from a dark, moonless sky at peak but will be cut in half due to moonlight this time around. This map shows the sky facing east around midnight Aug. 12-13. Source: Stellarium
Get ready for the darling of meteor showers this week — the Perseids. Who can deny their appeal? Not only is the shower rich with fiery flashes of meteoric light, but the meteors come in August when the weather’s couldn’t be more ideal. Peak activity is expected Tuesday night, Aug. 12-13, when up to 100 meteors an hour might be seen.
Ah, but there’s a rub. This year the moon will be only two days past full and radiant enough to drown out the fainter shower members. We’re more likely to see something like 30 meteors an hour, maybe fewer. But all it takes is one bright meteoric flash to make it all worthwhile. Nothing gets the heart pumping like a bright Perseid and the anticipation of the next.
While more meteors are surely more exciting, it’s not a number thing, but the experience of the raw event that makes all the difference. Sure beats sitting in front of a computer screen or watching the latest rerun of The Big Bang Theory, right?
A fine Perseid flashes straight out of the radiant on August 12 last year. The two bright dots above the start of the trail form the well-known Perseus Double Cluster. Credit: Bob King
Find a place away from glaring lights to allow your eyes to adapt to the darkness. That way you’ll see more meteors. While the Perseids spit out the occasional fireball, most shower members are going to be closer in brightness to the stars of the Big Dipper. Some leave “smoke” trails called meteor trains. They’re actually tubes of glowing air molecules created as the meteoroid particles speed through the atmosphere at 130,000 mph. Though ‘shooting stars’ can look surprisingly close by, they typically burn up 60-70 miles overhead.
Perseid meteors radiate from the constellation Perseus (hence the name) located a short distance below the “W” of Cassiopeia in the northeastern sky. To know for sure if you’ve seen the genuine item and not a random meteor, follow the trail backward — if it points toward the northeast, you’ve got a ringer!
A remarkable orbital view of a Perseid (right, center) burning up in Earth’s atmosphere photographed by astronaut Ron Garan on Aug. 13, 2011. The star Arcturus is directly above the bright trail. Credit: Ron Garan / ISS Expedition 28 crew / NASA
You can watch for Perseids all week long, but peak activity begins Tuesday evening and continues through dawn Wednesday. The later you stay up, the more meteors you’ll spot because the radiant or point in the sky from which the meteors appear to radiate rises higher with every hour. The higher the radiant, the fewer meteors that get cut off by the horizon.
Composite of bright Perseid meteors recorded by NASA all-sky cameras in 2011. Each is a grain of rock shed from the tail of comet 109P/Swift-Tuttle. Every year in mid-August, Earth passes through the comet’s debris trail as it orbits around the sun. Credit: NASA
The observing equipment you were born with and a comfortable chair are all you need to make the most of the event. OK, it’s nice to have a friend along, too, to share the ‘wow’ moments and keep from falling asleep. Sometimes I’m too lazy to haul out a chair and instead sprawl out on the deck or grass. Others prefer their Perseids from a steaming hot tub.
A 2010 Perseid meteor streaks over the European Southern Observatory’s Very Large Telescope (VLT). Credit: ESO
Left-behind sand, seed and pebble-sized particles from comet 109P/Swift-Tuttleare responsible for all the fun. Discovered in 1862, the comet circles the sun every 120 years. Over millennia, 109P has left a stream of debris along its orbit, which the Earth passes through every year in mid-August. Comet grit hits our atmosphere like bugs smacking a car windshield and vaporize in a flashes of light or meteors.
Normally I’d recommend facing east or southeast to watch the shower, but with the moon dominating that direction, look off to the northeast, north or southwest to keep from getting zapped by that old devil moonlight. Even a little dark adaption will help boost your Perseid count. Once situated, sit back, look up and enjoy each and every sparkler that drops from the sky.
And don’t forget to take in the big picture show rolling by. The sky’s a giant calendar that begins with the mid-summer constellations at nightfall and advances through the fall stars to the onset of winter with the rising of Orion at dawn. Let the months fall away as the Earth turns you toward the sun.
It’s hard to comprehend the vast emptiness of space. Especially when we detect odd signatures, such as luminous explosions that are neither as bright nor as long as traditional supernovae, originating in the unfathomable emptiness.
But a team of astronomers is now beginning to understand these so-called calcium-rich transients, often referred to as the Universe’s loneliest supernovae, hypothesizing that they’re created by collisions between white dwarf stars and neutron stars — both of which have been thrown out of their galaxy.
“One of the weirdest aspects is that they seem to explode in unusual places. For example, if you look at a galaxy, you expect any explosions to roughly be in line with the underlying light you see from that galaxy, since that is where the stars are” said lead author Joseph Lyman from the University of Warwick in a press release. “However, a large fraction of these are exploding at huge distances from their galaxies, where the number of stellar systems is miniscule.”
The team guessed there could be very faint dwarf galaxies, hiding beneath the limit of detection, but found nothing with our best telescopes, namely the Very Large Telescope in Chile and the Hubble Space Telescope.
“So the question becomes, how did the get there?” pondered Lyman. Roughly a third of these events occur at least 65 thousand light-years away from a potential host galaxy.
We’ve discovered dozens of so-called hypervelocity stars — single stars that escape their home galaxy, traveling rapidly throughout intergalactic space — and even one runaway globular cluster. Nature clearly has a way of kicking systems out of an entire galaxy, likely by an interaction with the supermassive black hole lurking in the center of that galaxy.
So it’s viable that the source of these supernovae was first kicked out of its host galaxy. But the second puzzle wondered what type of system could have caused such an odd explosion.
Previous studies show that calcium comprises up to half of the material thrown off in these transients, compared to only a tiny fraction in normal supernovae. It remained unclear how to explain such a calcium-rich system.
So the research team compared their data to short-duration gamma ray bursts, which are also seen to explode in remote locations with no coincident galaxy detected. We think these enigmatic bursts occur when two neutron stars collide, or when a neutron star merges with a black hole.
Alas, the research team discovered that if a neutron star collided with a white dwarf, the explosion would not only provide enough energy to generate the low luminosity of the calcium rich transients, but it would also produce calcium rich material.
“What we therefore propose is these are systems that have been ejected from their galaxy,” said Lyman. “A good candidate in this scenario is a white dwarf and a neutron star in a binary system. The neutron star is formed when a massive star goes supernova. The mechanism of the supernova explosion causes the neutron star to be ‘kicked’ to very high velocities (100s of km/s). This high velocity system can then escape its galaxy, and if the binary system survives the kick, the white dwarf and neutron star will merge causing the explosive transient.”
Any merger should also produce high-energy gamma-ray bursts, motivating further observations of any new examples.
The paper has been published today in the journal Monthly Notices of the Royal Astronomical Society and is available online.
