Every now and then, the Moon destroys the Sun. Okay, not destroys, covers. Well, not really covers, but from here on Earth, sitting inside the shadow of the Moon, that’s what it sure looks like. These events are called eclipses, or more precisely, transits and occultations. They occur whenever one object passes in front of another from a 3rd perspective. They’re beautiful and exciting, and deliver a tremendous amount of science as well.
The first attempt to send a rocket to the Moon via balloon hit a snag on Monday. The first test of the Aeronautics and Cosmonautics Romanian Association’s (ARCA) balloon-launched rocket (or “rockoon”) ended in failure when the “inflation arms” used to fill the balloon became entangled in the balloon itself. The arms had to be cut, and the operation – which required the use of a large naval frigate — was curtailed. ARCA hopes to compete in the Google Lunar X PRIZE, and intends on using their unusual rocket system to send an equally unique spherical lunar lander to win a $30 million prize.
Rockoons were tried and then abandoned by the US in the 1950s because they blew off course in windy conditions.
ARCA’s European Lunar Explorer (ELE) is a simple design. The super-huge balloon carrying a system of three rockets will soar to about 11 miles (18 km) up. Then the first two rocket stages will fire and boost the system into low Earth orbit, and use the final stage to boost it to the Moon. The ELE will then travel to the moon and deploy its Lunar Lander, which resembles a knobby rubber ball that uses its own rocket engine to ensure a soft landing. Watch their video of how it all will work below: (If nothing else, watch it for the great music!)
On Monday, the Romanians loaded their prototype moon-balloon rocket onto the a large Romanian naval frigate, the Constanta, which took the entire crew out to the launch site in the Black Sea.
But as the balloon started to inflate, the inflation mechanism arms got tangled, and the entire operation had to be abandoned. The giant black balloon collects heat from the sun instead of using burners like hot-air balloons normally use, so it needs to launch during the day.
The Google Lunar X PRIZE challenges participants to construct a delivery system that will get a rover to the Moon, where the robot has to drive for about 500 meters, take high-resolution pictures of its surroundings, and then send them back home.
Moments after 2:28 PM EST blast off of Space Shuttle Atlantis and six person crew on 16 November 2009 from pad 39 A at the Kennedy Space Center, Florida. Credit: Ken Kremer
(Editor’s Note: Ken Kremer is in Florida for Universe Today covering the launch of Atlantis.)
Space Shuttle Atlantis and her six person crew roared into space on Monday precisely as planned at 2:28 PM EST from the Kennedy Space Center in Florida. The yellow exhaust flames grew into a nearly blinding intensity as Atlantis ascended off the pad on a trail of crackling fire and smoke. For what felt like an eternity, it seemed like Atlantis would be engulfed in a rapidly expanding inferno emanating from her tail in mid air. The time span was in reality perhaps 5 seconds. Atlantis then dove straight upwards, arced over and finally looked like she would return back to Kennedy on a big circular loop directly through the wake of the exhaust plume. In fact that sight was just an optical illusion but the feeling was shared by other media I conversed with here at the KSC Press site.
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As Atlantis rose on 7 million pounds of liftoff thrust following ignition of the 3 space shuttle main engines and twin solid rocket boosters we saw her rotate about her vertical axis. Atlantis swiftly rising exhaust trail was clearly visible for about three minutes as she ascended northwards up the east coast of the United States for her trek into the orbital plane of the International Space Station (ISS) and carefully choreographed link up in 2 days time.
Gloomy early morning skies which were completely overcast had threatened to delay the launch. At a post-launch briefing, even senior Shuttle manager Mike Moses related how he awoke to the unexpected turn in the weather and said “What the heck happened!”.
Ken Kremer met up with a group of lucky Tweeters at the KSC press center a few minutes after Atlantis blast off. Back dropped by the world famous countdown clock, pad 39 A and US Flag, they appear to be celebrating their good fortune to be invited by NASA to witness the drama first hand and instantly transmit their experiences across all earth’s continents. Do you think they are having a blast? Credit: Ken Kremer
Perhaps an hour before launch the thick cloud layer at last dissipated and Atlantis punched through the deep blue skies, thrilling everyone at KSC including the over 100 tweeters allowed onto the press site for the very first time, some of whom I met and expressed utter joy at having the best seat in the house.
STS 129 is carrying 15 tons of critical spare parts to guard against the fast approaching day when the shuttle is retired from service in about 1 year. The shuttle is a true spaceship whose vital role and capability to transport large components and replacement equipment to the ISS will remain unmatched for decades to come.
“We appreciate all the effort making this launch attempt possible. We are excited to take this incredible vehicle for a ride to another incredible vehicle, the ISS,” Commander Charlie Hobaugh said shortly before launch.
During three spacewalks, astronauts will install two platforms to the station’s truss, or backbone which will be used to store the spare parts brought aloft and also known as Orbital Replacement Units, or ORU’s. The six person crew of Space Shuttle Atlantis walk out from crew quarters at 10:38 AM to greet the cheering crowd of media and NASA officials and then head out to pad 39 A to strap in for space launch with hours. Credit: Ken Kremer
Hobaugh is joined on Atlantis’ STS-129 mission by Pilot Barry E. Wilmore and Mission Specialists Leland Melvin, Randy Bresnik, Mike Foreman and Bobby Satcher. Atlantis will return with station resident Nicole Stott, marking the final time the shuttle is expected to rotate station crew members. Wilmore, Bresnik and Satcher are first-time space fliers. All future ISS residents will ride aboard Russian Soyuz rockets. I visited the huge Tweet Up Tent which NASA set up for the first time at the Kennedy Space Center Press center so that ordinary folks from around the world could observe a shuttle launch and share it globally straight away as events unfolded. This reminded me of a high tech command center. Credit: Ken Kremer
Type Ia supernovae are a mystery because no one can predict when or where one might occur. But astronomers are hedging their bets on V445 Puppis. A so-called “vampire white dwarf” that underwent a nova outburst after gulping down part of its companion’s matter in 2000, now, it appears this double star system is a prime candidate for exploding. “Whether V445 Puppis will eventually explode as a supernova, or if the current nova outburst has pre-empted that pathway by ejecting too much matter back into space is still unclear,” said Patrick Woudt, from the University of Cape Town and lead author of the paper reporting the results. “But we have here a pretty good suspect for a future Type Ia supernova!”
This is the first, and so far only nova showing no evidence at all for hydrogen, and provides the first evidence for an outburst on the surface of a white dwarf dominated by helium. “This is critical, as we know that Type Ia supernovae lack hydrogen,” said Danny Steeghs, from the University of Warwick, UK, “and the companion star in V445 Pup fits this nicely by also lacking hydrogen, instead dumping mainly helium gas onto the white dwarf.”
Click here to watch a movie of the expanding shell of V445 Puppis.
The astronomers have determined the system is about 25,000 light-years from the Sun, and it has an intrinsic brightness of over 10,000 times our Sun. This implies that the vampire white dwarf in this system has a high mass that is near its fatal limit and is still simultaneously being fed by its companion at a high rate.
“One of the major problems in modern astrophysics is the fact that we still do not know exactly what kinds of stellar system explode as a Type Ia supernova,” said Woudt, “As these supernovae play a crucial role in showing that the Universe’s expansion is currently accelerating, pushed by a mysterious dark energy, it is rather embarrassing.” Shell around V445 Puppis (March 2005). Credit: ESO
Woudt and his team used the ESO’s Very Large Telescope (VLT) to obtain very sharp images of V445 Puppis over a time span of two years. The images show a bipolar shell, initially with a very narrow waist, with lobes on each side. Two knots are also seen at both the extreme ends of the shell, which appear to move at about 30 million kilometers per hour. The shell — unlike any previously observed for a nova — is itself moving at about 24 million kilometers per hour. A thick disc of dust, which must have been produced during the last outburst, obscures the two central stars.
As Steeghs said, one defining characteristic of Type Ia supernovae is the lack of hydrogen in their spectrum. Yet hydrogen is the most common chemical element in the Universe. Such supernovae most likely arise in systems composed of two stars, one of them being the end product of the life of sun-like stars, or white dwarfs. When such white dwarfs, acting as stellar vampires that suck matter from their companion, become heavier than a given limit, they become unstable and explode.
The build-up is not a simple process. As the white dwarf cannibalizes its prey, matter accumulates on its surface. If this layer becomes too dense, it becomes unstable and erupts as a nova. These controlled, mini-explosions eject part of the accumulated matter back into space. The crucial question is thus to know whether the white dwarf can manage to gain weight despite the outburst, that is, if some of the matter taken from the companion stays on the white dwarf, so that it will eventually become heavy enough to explode as a supernova.
Astronaut Bob Crippen, along with John Young, made history on April 12, 1981 when they launched on one of the riskiest test flights ever, STS-1 on space shuttle Columbia. Crippen also commanded three other space shuttle missions (STS-7, STS-41C, STS-41G), and was the former director of the Kennedy Space Center and former President of Thiokol Propulsion. Crippen has always been a straight shooter — telling it like it is — and a strong supporter of human spaceflight. Personally, I will never forget the moving speech he gave after the Columbia accident, eulogizing the spacecraft itself. I had the chance to talk with Crippen today following the launch of STS-129.
Universe Today: You had the good fortune to be there for the launch today. It looked great on my little computer screen; how did it look live and in-person?
Bob Crippen: It was a beautiful launch here as well, one of those picture perfect launches where the countdown went smooth, there were no technical problems and the winds cooperated, thank goodness.
UT: I don’t remember a countdown that proceeded so trouble-free.
Crippen: We like it that way!
UT: You were there for the beginning of the space shuttle program. What are your thoughts now as you see this program coming to an end? Bob Crippen on board Columbia for STS-1. Credit: NASA
Crippen: I’m feeling somewhat nostalgic. It’s been a part of the better part of my life. It’s been a great vehicle and it’s done some great things, but I would very much like to see us go back to the Moon and beyond and the space shuttle is not the vehicle for doing that. But truthfully, my preference would have been to keep flying it until we had another vehicle to bring people to orbit. I’m not fond of the hiatus we’re going to have between the shuttle and whatever is going to follow it.
UT: What are your thoughts on the Augustine Commission Report.
Crippen: First, I applaud them for saying there wasn’t enough money for NASA to do what is on its plate, because I’ve thought that myself for quite some time. Some of the other things they proposed I’m a little bit uncomfortable with. My thought is that the program that was laid out, the Constellation Program, was a good program. It’s been underway now for a few years and to switch over to anything else, I believe, is going to take longer and cost more money.
UT: Do you think anything could be done to close the gap for our human spaceflight capability?
Crippen: I believe that given some additional funds, NASA could come pretty close to their projected timetable of 2015, of having the Ares ready. The Augustine Committee said it probably wouldn’t be until 2017. I think they were allowing for the normal problems you run into in programs. I don’t believe extra money would pull it back any earlier than 2015 at this particular juncture, so I think we’re still going to see at least a five year gap.
UT: How about commercial spaceflight. Can they contribute to human spaceflight?
Crippen: Sure. I’m all for commercial spaceflight. I think NASA has been supporting them with the programs to be able to bring up cargo to the International Space Station. I think it would be premature to rely on commercial to get the crews up there. Maybe someday that is going to happen, but I believe it is a ways down the road. We need to see what happens with cargo before we step up to human crews on those commercial flights.
UT: You’re at the launch today with a group from Coalition for Space Exploration. What kinds of things do you do to support them?
Crippen: The Coalition for Space Exploration is a group of individuals like myself and companies that strongly belive we ought to have an exploration initiative. I support is as one of their advisors by doing interviews and I’ve written some op-ed pieces so try and keep the issue in front of the public, the government and the powers that be that we should continue on the road we are on. The STS-1 crew of John Young and Bob Crippen. Credit: NASA UT: What are some of your favorite memories from your flights on the space shuttle.
Crippen: I’ve got some great ones. I like to use my friend (astronaut) John Young’s answer to that one: the part between takeoff and landing is the best part. It’s all great. All my missions were different, but all of them had some great aspects to them and I’ll always have fond memories of them.
Ever wondered what the largest telescope on the Earth is? Well, this coming Wednesday and Thursday of this week, the largest telescope ever assembled here will take observations for a whole day. How big is the telescope? About the size of the whole Earth! 35 radio telescopes on 7 continents will link together for one whole day in an effort to observe distant quasars as part of an initiative to improve the reference frame that scientists use to measure positions in the sky.
Radio telescopes in Asia, Australia, Europe, North America, South America, Antarctica, and in the Pacific will all be linked together to measure the same 243 quasars over a 24-hour period. Quasars are galaxies that have a supermassive black hole at the center, which has strong emissions in the radio spectrum. The quasars being monitored are so far away from the Earth that they appear to be motionless in the sky. This makes them a perfect candidate for setting up a grid in the sky to use as a frame of reference, against which the positions of other objects can be determined.
This monitoring session comes out of a meeting of the International Astronomical Union in August, during which it was decided to start using a set of 295 quasars as a celestial reference frame starting January 1st, 2010. This is not a new reference frame to be used by astronomers – the current one was adopted in 1998 – but an important update to the existing reference frame, the International Celestial Reference Frame.
The session, called the Very Large Astrometry Session is coordinated by the International VLBI Service for Geodesy and Astrometry. Several of the participating observatories will have live webcams running during the event (check for the observatory in your language!), and a public outreach page on the event, hosted by the Bordeaux Observatory, can be found here. The public outreach page will post images as they are taken during the session, with information about observation coordinates.
Radio telescopes like the Very Long Base Array in the United States already link together observatories that are far apart to take observations. This technique is called very long baseline radio interferometry (VLBI), and allows for the use of smaller telescopes that are distant from one another to be linked together and have the same angular resolution as if they were one larger telescope. Doing these observations all in one go will reduce some of the errors that occur when disparate observatories take images at different times.
The previous record for radio observatories linked together to create a larger telescope for one monitoring session is 23. That means that this observing session will beat that record by a whopping 12 additional observatories. Even with this unprecedented amount of observatories monitoring the quasars, there will be a few gaps in the sky, mostly in the Southern hemisphere. Only 243 of the total 295 quasars in the reference frame will be observed this week, though that will break another record for the amount of objects observed in one session using this method. The image below depicts the locations of the participating observatories.
By taking data on the 243 selected quasars, astronomers will be able to more accurately pinpoint objects in the sky in all wavelengths, and gather more precise data. For instance, many objects of scientific interest are monitored by separate telescopes operating in the visible, radio, x-ray and infrared wavelengths. Having a more accurate frame of reference to tell these different telescopes where to point in the sky will improve the ability of the different telescopes to gather information from the same place in space.
If you don’t quite have the right stuff, but always thought being an astronaut would be cool, here’s a way for you to contribute to the US space program. Go to bed. With NASA. “I would absolutely recommend it. It was one of the most amazing experiences of my life,” said Heather Archuletta, who has participated in three different studies for the Human Test Subject Facility (HTSF) at the Johnson Space Center. These ongoing studies use long-term bed rest to simulate the effects of micro-gravity an astronaut would experience during extended space flight. “This is a great opportunity for the general public to help NASA with their scientific research,” said John Foster, who works for Solitaire Creative Services, a company that promotes the studies.
“This is one of NASA’s biggest barriers for sending humans to Mars,” Archuletta told Universe Today. “If they can find a way around bone demineralization, wow, that would really boost the possibilities for human spaceflight.”
NASA is planning a series of studies that support the scientific needs of the space program. The studies will be conducted over the next ten years, and currently, NASA is looking to fill spots in 87-day bed rest studies and a lunar analog feasibility study. Participants in a NASA bed rest study. Credit: NASA
For the bed rest study, participants are placed in bed with the head of the bed tilted down at a minus-six-degree incline. The Lunar Analog Feasibility Study is a 21-day study to demonstrate if it is possible to simulate 1/6 G lunar gravity using bed rest.
“Participants are compensated for their time and expenses,” said Foster. “For example, a participant who completed a 60-day study was paid approximately $13,800.”
“I know they desperately need more healthy females,” Archuletta said. “It seems people think only guys can do these studies, so it seems harder to get women.”
Archuletta, who is also known as the “Pillow-naut” from her blog about her experiences, Pillow Astronaut, said amazingly, the studies simulate very well what astronauts experience in space. “You wouldn’t think that something as simple as tilting the body would mimic what astronauts experience, but it affects your vestibular system the same way and you get the same exact fluid shift where all the blood pools in your head. You get a little bit of muscle atrophy and some bone mineral loss, and they see the same exact lowering in plasma volume and lower heart rate. Almost everything that happens in space they can do with tilting the bed. That was major news for me.”
She said the first week of being in bed is the hardest part of the study. “When they put you in the head-down position, it kind of messes with the inner ear and your equilibrium,” Archuletta said. “They warned me about it, but I didn’t give it much credence, because I thought, ‘you’re lying down, how hard can it be?’ But you get a blood rush to the head, so my teeth were throbbing and I had a headache.” During the 90-day bed rest study, participants do everything in bed, from showering to eating to socializing with other participants. Image Credit: NASA
She also would get dizzy when she turned her head quickly, which again, mimics what many astronauts experience in space. “I have been able to talk with two different astronauts and they both said, yes, the first few days you are on orbit, the veteran astronauts tell them not to turn their head quickly because when you are weightless it messes with the vestibular system.”
Those symptoms passed in about a week, Archuletta said. “It is amazing what the body can adapt to. All of a sudden my body just said, ‘OK, this is our new reality and we’ll deal with it.’ Within a couple of weeks I felt normal and actually getting up was the hard part. You get used to lying down and it actually starts to feel normal.”
But the benefits of participating outweighed any discomforts she went through. “You have tons and tons of free time. I tore through about 30 books. You have your own room but there is a common room where we can play games and talk, but I worked a little while I was there,” said Archuletta, who works as a consultant for an IT company and also is a freelance writer. “But mostly it was nice just to catch up on a lot of things I’d wanted to do for a while.”
But don’t expect to be chosen to participate if you plan to just play video games for three months. “They are really looking for people who come in with goals,” Archuletta said, “such as one person there learned Spanish, I learned sign language, and another person brought their guitar and wrote songs. They want people who have ideas about how to keep themselves busy because they will be less likely to get restless.”
Archuletta said the question she gets asked most often is if she got bored. “Absolutely not,” she said. “It is a very busy testing schedule when you first come, so you go through a lot of physical exertion before the bed rest phase; they keep you very busy. Once you are in bed you do get a lot of free time, but you are being monitored. They take vitals a couple of times a day, and make sure you are doing OK. You stretch a couple times a day so you don’t get blood clots, but you can’t outright exercise. But you get a massage every other day – that’s definitely one of the good parts! I don’t think the astronauts get that in space!” Archuletta doing isokinetics exercises. Courtesy Heather Archuletta
The studies are done at the University of Texas Medical Branch in Galveston, Texas. Participants will live in a special research unit for the entire study and be fed a carefully controlled diet. The first 11-15 days of the 87-day study, participants undergo tests, but are not on bed rest. The next 60 days participants are constantly in bed, (except for limited times for specific tests) with their head tilted downward slightly. Then there are 14 days to recover, to allow the body to get back to normal.
Participants must be nonsmokers who are in good health with no history of cardiovascular, neurological, gastrointestinal, or musculoskeletal problems.
The exoplanet HAT-P-7b has been observed to have a very curious orbit. It either has a highly tilted orbit – passing almost over the poles of its parent star, HAT-P-7 – or a retrograde orbit; that is, orbiting in the opposite direction of its parent star. Two teams of researchers, both using the Subaru Telescope in Japan, have published papers on the bizarre properties of this planet, the second exoplanet ever observed to have a retrograde orbit.
In our Solar System, the planets calmly rotate in the same direction as that of their parent star, in our case the Sun. This is called a prograde orbit, and the Earth has the most inclined orbit with regard to the equator of the Sun, of 7.15 degrees. The planet HAT-P-7b, however, has an orbit that is the opposite of the rotation of its parent star but in the same plane as the equator (effectively a 180 degree incline). This is called a retrograde orbit. It may also be the case that it is inclined to at least 86 degrees of the equator of its Sun, so as to have almost a polar orbit. The researchers have yet to determine the true rotation of the star HAT-P-7, and thus which scenario is true for the exoplanet.
“There is a large range of uncertainty because we have not measured the true angle between the orbit and the stellar equator. Instead we can only measure the angle that we see from our perspective on Earth,” said Winn in a MIT press release.
HAT-P-7b is about 1.4 times as wide and 1.8 times as massive as Jupiter, and lies approximately 1,000 light years from the Earth.
A Japanese collaboration led by Norio Narita of the National Astronomical Observatory of Japan, and a team led by MIT assistant professor of physics Joshua Winn both published papers detailing their studies of HAT-P-7b. These studies were published in the Publications of Astronomical Society of Japan Letters October 25, 2009 and the Astrophysical Journal Letters for October 1, 2009, respectively. The paper by the Japanese team is available for your perusal on Arxiv here.
Both research teams used the Subaru Telescope’s High Dispersion Spectrograph instrument to observe the star HAT-P-7. The spectrograph allowed the researchers to monitor the redshift or blueshift of light as the planet orbited the star. In planets with a prograde orbit, their transit in front of the star blocks the blue shifting of the light from the star first, then blocks the redshift of the light, making the star appear to move more that it actually is.
In the case of HAT-P-7b the effect was reversed – that is, the redshifted light appeared bluer, then the blueshifted light appeared redder, making it apparent that the orbit of the planet was not in the same direction of that of HAT-P-7. This effect is called the Rossiter-McLaughlin effect, illustrated below.
The Rossiter McLaughlin effect makes a star appear to have a greater radial velocity than it actually does because of a transiting planet. Image Credit: Nicholas Shanks, WikiMedia Commons
The odd orbit of HAT-P-7b could have been caused by a number of different factors, and theorists that model the formation of exoplanetary systems will not have to “go back to the drawing boards”. The general consensus is that planets form out of a large disk of material orbiting the star, and thus all orbit in the same direction as the disk out of which they formed.
Multiple planets could have formed in an unstable configuration around the star, and their proximity to each other could have caused a rather chaotic series of gravitational billiards to boot HAT-P-7b into its current orbit. Another explanation is the presence of a third object in the system, such as another massive planet or companion star, that is tilting the orbit of HAT-P-7b due to what’s known as the Kozai effect.
The announcement of the retrograde orbit of HAT-P-7b came only one day after the announcement on August 12th, 2009 that the planet WASP-17b orbits opposite its parent star. HAT-P-7b is also one of the first exoplanets to be studied by the Kepler mission, which studied the planet’s orbit over 10 days. Kepler will take further images of the star during its mission, and by observing the rotation of spots on the surface of the star, nail down the orbital direction, after which we’ll know whether HAT-P-7b is orbiting “backwards” or around the poles of the star.
The Dawn spacecraft – which is on a course to study the asteroid Vesta and dwarf planet Ceres – has taken up permanent residence in the asteroid belt as of November 13th. Dawn is officially the first human-made object to become a part of the asteroid belt, which is sandwiched between the orbits of Mars and Jupiter.Dawn didn’t move in without checking the place out first, though; this is the second visit for the craft, which remained there for 40 days in June of 2008. The lower boundary of the asteroids belt is defined as the furthest Mars gets away from the Sun during its orbit – 249,230,000 kilometers, or 154,864,000 miles.
Dawn, which was launched in September 2007, is on an eight-year, 4.9-billion kilometer (3-billion mile) journey to study the asteroid Vesta and the dwarf planet Ceres. By studying these members of the asteroid belt, NASA scientists hope to learn more about the formation of our Solar System. Because Vesta and Ceres are some of the largest members of the ring of asteroids between Mars and Jupiter, they are the most intact from when they were formed, and should act as a ‘time capsule’ to preserve information about what the early Solar System was like.
Dawn got a gravity assist from Mars in February of 2009, which propelled it past the planet and into the asteroid belt.
The spacecraft is expected to visit Vesta in August of 2011. Vesta is believed to be the source of most of the asteroid-origin meteorites that fall to ground here on Earth, and further study of the asteroid should confirm this.
In May of 2012, Dawn will make its way to Ceres, which lies further out in the asteroid belt. It will arrive there in July of 2015, where it will spend the remainder of its mission studying the icy dwarf planet, which may even have a tenuous atmosphere.
If you want to keep tabs on Dawn in its new home, the mission web site has a tool updated hourly, found here, which allows you to see where Dawn is right now. The tool includes simulated views of the Earth, Mars, Sun and Vesta from the vantage point of the spacecraft.
The annual Leonid Meteor Shower is about to light up the night… And the time to start watching is now. The year 2009 will not see a Leonid storm, but an outburst for sure. There are still some uncertainties regarding the time of maximum of the 1466 trail. For those of you seeking a definitive date and time, it isn’t always possible, but we can learn a whole lot about when and where to look.
The Leonid Meteor Shower belongs to the debris shed by comet 55/P Tempel-Tuttle as it passes our Sun in its 33.2 year orbit. Although it was once assumed it would simply be about 33 years between the heaviest “showers,” we later came to realize the debris formed a cloud which lagged behind the comet and dispersed irregularly. With each successive pass of Tempel-Tuttle, new filaments of debris are left in space along with the old ones, creating different “streams” the orbiting Earth passes through at varying times, which makes blanket predictions unreliable at best. Each year during November, we pass through the filaments of its debris – both old and new ones – and the chances of impacting a particular stream from any one particular year of Tempel-Tuttle’s orbit becomes a matter of mathematical estimates. We know when it passed… We know where it passed… But will we encounter it and to what degree? Traditional dates for the peak of the Leonid meteor shower occur as early as the morning of November 17 and as late as November 19.
So what can we expect this year? According to NASA’s 2009 predictions a significant shower is expected this year when Earth crosses the 1466-dust and 1533-dust ejecta of comet 55P/Tempel-Tuttle. According to J. Vaubaillon, the narrow (about 1-hr) shower is expected to peak on November 17, 2009, at 21:43 (1466) and 21:50 (1533) UT, perhaps 0.5 to 1.0 hour later based on a mis-match in 2008, with rates peaking at about ZHR = 115 + 80 = 195/hr (scaled to rates observed in 2008). E. Lyytinen, M. Maslov, D. Moser, and M. Sato all predict similar activity from both trails, combining to about ZHR = 150 – 300 /hr. P. Jenniskens notes that if the calculated trail pattern is slightly shifted in the same manner as observed before, then the 1533-dust trail would move in Earth’s path and its rates would be higher (the 1466-dust trail would move away). However, the 1533-dust trail is distorted in the models, and because of that it is not clear how much higher that would be. This remains a rare opportunity to study old dust trails from comet 55P/Tempel-Tuttle. In such old trails, the model of Lyytinen and Nissinen predicts wide trails, which can be tested by measuring the width of the outburst profile.
Let’s take a closer look at the at how the two centuries old trails will affect our observing, beginning with the one created in the year 1466. The exact same trail will be encountered again this year with its maximum rate of up to 115 meteors per hour occurring at 21:43 UT (may be 0.5-1hr later). “The trail will be much closer to the Earth, explaining why we expect a quite high zenith hourly rate.” say J. Vaubaillon (et al), “However the discrepancy between the expected time of maximum remains, as well as a general higher expected ZHR. Among the possible explanations are: sensitivity to initial conditions (given that the trail is 16 Rev. old) or change of cometary activity (impossible to verify unfortunately).”
But don’t count on only this single trail, because the year 1533 trail will encounter the Earth at almost the same time as the 1466 trail. Its maximum time of arrival is expected to be at 21:50 UT on the 17th of November, with a zenith hourly rate of 80 – for a combined rate of perhaps 200 meteors per hour. “The total level of the shower (ZHR~200/hr) was callibrated using the 2008 observations of the 1466 trail, but nothing is known from the 1533 trail. As a consequence, it will be very interesting to check.” comments Vaubaillon, “In particular there might be a difference of up to 1 hour between the 1466 and 1533 trail, or they might even be late together, giving us some insight about how well/poorly we know comet 55P’s orbit.”
Let’s take a closer look with 3D-view of the two trails may have evolved between 1466 and 2009…
Dr. Vaubaillon’s colleagues from MSFC (D. Moser and B. Cooke) pointed out that the best location to view the outburst caused by the 1466 and 1533 trails will be centered around India and includes: Nepal, Thailand, Western China, Tadjikistan, Afghanistan, Eastern Iran, South Central Russia, etc. Dr. P. Atreya (IMCCE), citizen of Nepal, is currently organizing an international Leonid observation campaign in his home country. This campaign will involve many amateurs and researchers from Nepal and other countries. The climate conditions in Nepal at this time of the year makes it an excellent spot.
We may never know precisely where and when the Leonids might strike, but we do know that a good time to look for this activity is well before dawn on November 17, 18 and 19. Where do you look? For most of us, the best position will be to face east and look overhead. With the Moon out of the picture, even if you don’t see a huge amount of meteoric activity, chances are that even a few minutes of your time will bring a bright and happy reward!
Many thanks to John Chumack for sharing his early 2009 Leonid image and to NASA, Dr. Vaubaillon and colleagues for the illustrations and 3D animation!
