Posted on by Tammy Plotner

Lunar Eclipse – Saturday, December 10, 2011

Aligning his camera on the same star for nine successive exposures, Sky & Telescope contributing photographer Akira Fujii captured this record of the Moon’s progress dead center through the Earth’s shadow in July 2000. Credit: Sky & Telescope / Akira Fujii

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Are you ready for some good, old-fashioned observing fun? Although you might not want to get up early, it’s going to be worth your time. This Saturday, December 10, 2011, marks the last total lunar eclipse event for the western portion of the Americas until 2014. While a solar eclipse event has a very small footprint where it is visible, a lunar eclipse has a wide and wonderful path that encompasses a huge amount of viewers. “We’re all looking at this together,” says Sky & Telescope senior editor Alan MacRobert.

How much of the dawn lunar eclipse will be visible for you? For your location, this map tells what stage the eclipse will have progressed to by the time the Moon sets below your west-northwestern horizon. Credit: Sky & Telescope
If you live in the eastern portion of the Americas, sorry… You’ll miss out on this one. In the Central time zone, the Moon will be setting while it is partially eclipsed. However, beginning in a line that takes in Arizona and the Dakotas you’ll be treated to the beginning of the lunar eclipse, totality, and it will set as it is beginning to come out of eclipse. If you live in the western portion of the US or Canada? Lucky you! You’ll get to enjoy the Moon as it goes through the initial states of eclipse, see totality and even might catch the phases as it slips out of Earth’s shadow again – just as the Sun begins to rise. For Skywatchers in Hawaii, Australia, and East Asia, you’ll have it better. Seen from there, the whole eclipse happens high in a dark sky from start to finish. For Europe and Africa, the eclipsed Moon will be lower in the east during or after twilight on the evening of the 10th.

When exactly does the event begin? The lunar eclipse will be total from 6:05 to 6:57 a.m. Pacific Standard Time. The partial stage of the eclipse begins more than an hour earlier, at 4:45 a.m. PST. Be sure to watch the southern lunar edge, too. Because the Moon will be skimming by the southern edge of the Earth’s shadow, it will remain slightly brighter and add to the dimensional effect you’ll see. Enjoy the coppery colors from the refracted sunlight! The Moon won’t be black – but it will most certainly be a very photogenic experience.

“That red light on the Moon during a lunar eclipse comes from all the sunrises and sunsets around the Earth at the time,” explains Sky & Telescope editor in chief Robert Naeye. “If you were an astronaut standing on the Moon and looking up, the whole picture would be clear. The Sun would be covered up by a dark Earth that was ringed all around with a thin, brilliant band of sunset- and sunrise-colored light — bright enough to dimly illuminate the lunar landscape around you.”

May clear skies be yours!

Original News Source: Sky and Telescope News Release. Image Credits: Sky and Telescope.

Posted on by Nancy Atkinson

Popular Astronomy App Supports Astronomers Without Borders

The constellations Sagittarius and Scorpius (highligted) as mythical figures, near the center of the Milky Way. Credit: Southern Stars.com

he constellations Sagittarius and Scorpius (highlited) as mythical figures, near the center of the Milky Way. Credit: Southern Stars.com

You can support a great organization, Astronomers Without Borders, by purchasing a popular astronomy app for Apple and Mac devices. SkySafari 3 is a “revolutionary” app that can completely cover your observing/educational needs. During a special promotion that is available until December 8, 40% of proceeds from all SkySafari sales will be donated to Astronomers Without Borders to support their global programs. Some significant discounts are also being offered, so you can get a great price and help build AWB’s worldwide astronomy community at the same time.

You’ve probably heard of some of AWB’s project, such as The World at Night, Global Astronomy Month, and 100 Hours of Astronomy. AWB nobly works to foster understanding and goodwill across national and cultural boundaries by creating relationships through the universal appeal of astronomy. They provide and share resources, information and inspiration.

With all the great work they are doing, AWB needs some help to continue their outreach. “Interest and demand have really outstripped our start-up, volunteer, grass-roots organization,” AWB President Mike Simmons told Universe Today. “So we’re starting a fund-raising campaign that we hope will get us over the hump so we can keep up with all the opportunities there are.”

If you are considering getting an astronomy app for yourself or someone else for the holidays, consider SkySafari 3, the latest version of this popular app – and you can support AWB at the same time. But hurry – this offer ends on Dec. 8, 2011.

You can also support AWB even if you don’t need an app.

More info:
Continue reading “Popular Astronomy App Supports Astronomers Without Borders”

Posted on by VirtualAstro

Coming Attraction: Geminid Meteor Shower 2011

Credit: Wally Pacholka

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It’s the finale of this year’s meteor showers: The Geminids will start appearing on Dec. 7 and should reach peak activity around the 13th and 14th. This shower could put on a display of up to 100+ meteors (shooting stars) per hour under good viewing conditions.

However, conditions this year are not ideal with the presence of a waning gibbous Moon (which will be up from mid-evening until morning). But seeing meteors every few minutes is quite possible. Geminid meteors are often slow and bright with persistent coloured trails which can linger for a while after the meteor has burned up.

There is something unusual about the Geminid meteor shower, as normally meteor showers are caused by the Earth ploughing through the debris streams created by comets and their tails. But the object that created the specific stream of debris associated with the Geminids is not a dusty icy comet, but a rocky asteroid called Phaethon 3200.

Phaethon 3200 belongs to a group of asteroids whose orbit cross the Earth’s. It turns out to be an unusual member of that group: Not only does it pass closer to the Sun than the others but it also has a different colour, suggesting a different composition to most asteroids.

Credit: Adrian West

One of the curious things about the Geminid particles is that they are more solid than meteoroids known to come from comets. This is good for meteor watchers; giving us brighter meteors.

Observations by astronomers over decades have shown that meteor rates have increased as we reach denser parts of the stream.

It is not known exactly when the asteroid was deflected into its current orbit, but if it was originally a comet it would have taken a long time for all the ices to have been lost. However, it is possible that it may have been a stony asteroid with pockets of ice.

We are unsure of the origins and appearance of Phaethon 3200, but its orbit has left us with a unique legacy every December, with little steaks of light known as the Geminid meteor shower.

You will only need your eyes to watch the meteor shower, you do not need telescopes binoculars etc, but you will need to be patient and comfortable. See this handy guide on how to observe meteors

During a meteor shower, meteors originate from a point in the sky called the radiant and this gives rise to the showers name e.g. The Geminids radiant is in Gemini, Perseids radiant is in Perseus etc.

Don’t be mislead by thinking you have to look in a particular part of or direction of the sky, as meteors will appear anywhere and will do so at random. You will notice that if you trace back their path or trajectory it will bring you to the meteor showers radiant. The exception to this rule is when you see a sporadic or rogue meteor.

Tell your friends, tell your familly and tell everyone to look up and join in with the Geminid meteorwatch on the 12th to the 14th December 2011. Use the #meteorwatch hashtag on twitter and visit meteorwatch.org for tips and guides on how to see and enjoy the Geminids and other meteor showers.

Credit: Wally Pacholka

Posted on by Nancy Atkinson

Comet Curiosity? MSL Looks Like a Comet as it Heads Toward Mars

Visible at the bottom of the image is the venting of gases, probably from the Mars Science Laboratory Centaur rocket stage, as seen from the Sir Thomas Brisbane Planetarium in Australia. The Orion Nebula is at the top. Photo by Duncan Waldron.

What does a spacecraft look like as it lights-out for another world? This incredible time-lapse video was taken by astronomers at the Sir Thomas Brisbane Planetarium in Australia. The sequence shows a plume drifting against the background stars, probably caused by venting from the Centaur rocket stage that sent the Mars Science Laboratory/Curiosity Rover on its way to the Red Planet, after it carried out a burn over the Indian Ocean on November 26, 2011.

Brisbane Planetarium Curator Mark Rigby said that he and photographer/amateur astronomer Duncan Waldron, along with another planetarium staff member were likely the only people who saw this amazing sight, as they have received no other reports of similar observations.

Rigby said they are “are over the Moon – or higher” from seeing the departure of the Mars Science Laboratory, its rocket stage and plume above Australia on Sunday. “It is a real shame that we couldn’t have woken up everyone that didn’t have clouds,” Rigby wrote on the Planetarium’s Facebook page. “Even we didn’t expect to see such a spectacle. Can you imagine the feeling if there had been a crew onboard heading for Mars?”

Rigby first saw the plume at 2:15am local time, (16:15 UT) and said it was “a one-degree elongated cloud of VERY easy naked eye brightness.” Duncan Waldron also saw it starting at about 2:30pm and began to photograph it until it faded. Nonetheless, he captured a unique timelapse covering 21 minutes until 3am.

Here is one of Waldron’s images, below:

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The coordinates of the observing site: -27.630779,152.966324, altitude 40m approx.

Congrats to the Sir Thomas Brisbane Planetarium team for capturing such an amazing and historical sight!

Posted on by Ray Sanders

Telescope Review: Orion SkyQuest XT8 Classic Dobsonian Reflector

Orion XT8 Dobsonian reflector in front of the author's observatory. Photo Credit: Ray Sanders

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Orion SkyQuest XT8 Classic Dobsonian Telescope, (MSRP $349.99) Orion Telescopes.

For many astronomers who are just getting started, dobsonian reflector telescopes are a popular choice. While many newcomers to Astronomy seek out computerized “go-to” telescopes, some prefer the “no-frills” setup a dobsonian telescope offers.

The Orion XT8 dobsonian is a mid-range reflector telescope. There are a few smaller and less expensive models available in Orion’s classic dobsonian series, and there are a few larger, more expensive models as well. The XT8 offers a good balance between portability, price and performance. In this review we’ll look at the build quality of the XT8, along with how it performs at planetary and “dark sky” objects.

For starters, let’s look at the raw specifications for the XT8. The XT8 features an 8″ (203mm) primary mirror. With a focal length of 1200mm, this gives a focal ratio of f/5.9. Advanced observers will enjoy the XT8’s 2″ focuser, which allows for larger eyepieces, or even a “T” adapter for short-exposure astrophotography. New observers (or those on a budget) will find the included 2″ to 1.25″ eyepiece adapter allows the use of 1.25″ eyepieces with no noticeable wiggle/slop.

The XT8 does come with a 25mm 1.25″ Plossl eyepiece which performs well as a medium-power eyepiece in the XT8. The XT8 features Orion’s EZ Finder II sight. While the EZ Finder II isn’t a terribly bad “red-dot” finder, some observers may see fit to replace the stock finder with something like a “correct image” finder scope, a laser pointer, or even a Telrad non-magnified finder.

Orion ships the XT8 in two boxes. One for the optical tube, and a second for the dobsonian mount base. The shipping box for the mount base was well thought out, minimizing potential damage to the base components. The shipping box for the optical tube was adequate, but as with any piece of delicate equipment – there can never be enough padding.

Assembling the XT8 took about half an hour by myself. With a helper, the XT8 could probably be assembled in ten minutes. Once assembled the mount base is quite sturdy and allowed for smooth rotation of the optical tube, due to the Teflon azimuth bearings. Adjusting the optical tube in altitude was equally effortless and the tension springs provided enough tension to maintain position (even pointed at the horizon) without making the tube difficult to raise or lower.

The mount base does include a carrying handle. At around 40lbs total weight, some users of the scope may prefer to carry the optical tube and base assemblies separately. Once assembled and put in place at an observing location, operation of the XT8 is fairly straight forward. Depending on what finder setup is used, aligning the finder may take just a few minutes, or slightly longer. Generally, using a very bright object (newcomers may want help with this step) in the finder makes the process of alignment easier and faster. When setting up the XT8 for this review, I aligned my Telrad finder and the telescope itself with Jupiter.

After aligning the finder, using the XT8 is simply a matter of moving the optical tube to whatever objects are desired. Once the telescope is pointed at an object, making focus and/or eyepiece adjustments are fairly trivial. The eyepiece holder features thumbscrews which do a good job of holding eyepieces in place. The focuser offers smooth operation with very little image “wobble”.

Putting the XT8 through a short observing session, I was able to obtain great views of the Moon, Jupiter, the Orion Nebula (M42), and the Andromeda Galaxy (M31). At the time of testing, the Moon was in a waning crescent phase and the XT8 brought out some great views of lunar craters near the terminator. Despite being close to the horizon, the view of lunar craters in the eyepiece were crisp and clear. Moving eastward to Jupiter revealed a delightful view of a few of Jupiter’s atmospheric bands, as well as the Galilean moons. While the view from an 8″ telescope can’t compare to the views of Jupiter from Voyager or the Hubble, the detail revealed is still quite impressive.

Saving the best for last, I pointed the XT8 at M42 (Orion Nebula) and M31 (Andromeda Galaxy). Star-hopping to M31 was fairly trivial, via Alpheratz (In Pegasus). I did switch from the stock 25mm to a lower power 40mm eyepiece, as M31 does tend to benefit from lower power eyepieces, at least visually. The view of M31 provided a fuzzy patch that clearly stood out from the background stars. Moving eastward to M42, the views were breathtaking for such a relatively small telescope. Significant detail (albeit without much color) of the gas and dust was visible, along with a bright trapezium.

In Summary, the Orion XT8 is a great mid-range telescope which balances price and performance quite well. Despite Orion classifying this telescope as an “Intermediate” telescope, the XT8 would be an excellent choice for a beginning astronomer, or even an experienced observer looking to add a new scope to their fleet.

Assembling the XT8 was a trivial task with the included wrenches, and after assembly the telescope felt very sturdy. At around 40lbs, most people will have little to no trouble carrying the XT8 from their car to their observing spot, or from the house to a spot in their backyard. The included 25mm eyepiece works well as a mid-range eyepiece, but some users may want to invest in additional eyepieces, or at the very least a 2X barlow lens.

Some users of the XT8 may choose to replace the stock finder with one of their own choosing, but the included red-dot sight is fairly adequate. With a scope as powerful as the XT8, those planning to regularly perform lunar observations may want to consider purchasing a lunar filter. Any users who choose to perform solar observations can easily obtain a glass filter lens for the XT8 at a cost of around $100.

Posted on by VirtualAstro

Beginner’s Guide To Binoculars

Credit: opticsreviewer.com

Before you consider buying expensive equipment for viewing the wonders of the night sky, binoculars are one piece of equipment every amateur astronomer should have.

Many beginners to astronomy (especially around the holiday period) are sometimes dead-set on getting a telescope, but many aren’t aware that a good pair of binoculars can outperform many entry level telescopes for a similar cost, or much less.

Binoculars are simplicity in themselves — maintenance free, instantly available for use and very versatile, as they can be used for daytime, or “terrestrial viewing” just as well. It is difficult to say the same for with most telescopes.

Go into any photographic store, or website that sells binoculars and you will be met with literally hundreds of different makes, types and sizes – confusing for the beginner, but with a few pointers it can be easy to choose.

Credit: astronomybinoculars.com

So how do you choose a pair of binoculars that will give good results with astronomy?

When choosing binoculars for astronomy, the only variables you need to think about are size of the optics and weight.

Too small and they won’t be powerful enough or let enough light in; too big and heavy means they are almost impossible to use without a support or tripod. Beginners need to find a pair of binoculars which are just right.

The key is to get as much light into the binoculars as possible without making them too heavy. This will give sharp views and comfort when used.

Size and weight come hand in hand, the more light gathered, the heavier the binoculars will be.

All binoculars are measured or rated by two numbers, for example: 10 X 25 or 15 X 70. The first number is the magnification and the second number is the “objective diameter” which is the diameter of the objective lens and this determines how much light can be gathered to form an image.

Credit: Halfblue Wikipedia

The second number or objective diameter is the most important one to consider when buying binoculars for astronomy, as you need to gather as much light as possible.

As a rule of thumb, binoculars with an objective diameter of 50mm or more are more suited to astronomy than smaller “terrestrial” binoculars. In many cases a larger objective also gives better eye relief (larger exit pupil) making the binoculars much more comfortable to use.

For the beginner or general user, don’t go too big with the objective diameter as you are also making the binoculars physically larger and heavier. Large binoculars are fantastic, but — again — almost impossible to keep steady without a support or tripod.

Celestron Skymaster 15 X 70 Binoculars

Good sizes of binoculars for astronomy start at around or just under 10 X 50 and can go up to 20 X 80, but any larger and they will need to be supported when using them. Some very good supported binoculars have objective diameters of more than 100mm. Theses are fantastic, but not as portable as their smaller counterparts.

Binoculars are one of the most important items a new or seasoned astronomer can buy. They are inexpensive, easy to choose, use and will last a very long time.

Enjoy your new binoculars!

Posted on by Ray Sanders

Are Pulsars Giant Permanent Magnets?

The Vela Pulsar, a neutron star corpse left from a titanic stellar supernova explosion, shoots through space powered by a jet emitted from one of the neutron star's rotational poles. Now a counter jet in front of the neutron star has been imaged by the Chandra X-ray observatory. The Chandra image above shows the Vela Pulsar as a bright white spot in the middle of the picture, surrounded by hot gas shown in yellow and orange. The counter jet can be seen wiggling from the hot gas in the upper right. Chandra has been studying this jet so long that it's been able to create a movie of the jet's motion. The jet moves through space like a firehose, wiggling to the left and right and up and down, but staying collimated: the "hose" around the stream is, in this case, composed of a tightly bound magnetic field. Image Credit:

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Some of the most bizarre phenomena in the universe are neutron stars. Very few things in our universe can rival the density in these remnants of supernova explosions. Neutron stars emit intense radiation from their magnetic poles, and when a neutron star is aligned such that these “beams” of radiation point in Earth’s direction, we can detect the pulses, and refer to said neutron star as a pulsar.

What has been a mystery so far, is how exactly the magnetic fields of pulsars form and behave. Researchers had believed that the magnetic fields form from the rotation of charged particles, and as such should align with the rotational axis of the neutron star. Based on observational data, researchers know this is not the case.

Seeking to unravel this mystery, Johan Hansson and Anna Ponga (Lulea University of Technology, Sweden) have written a paper which outlines a new theory on how the magnetic fields of neutron stars form. Hansson and Ponga theorize that not only can the movement of charged particles form a magnetic field, but also the alignment of the magnetic fields of components that make up the neutron star – similar to the process of forming ferromagnets.

Getting into the physics of Hansson and Ponga’s paper, they suggest that when a neutron star forms, neutron magnetic moments become aligned. The alignment is thought to occur due to it being the lowest energy configuration of the nuclear forces. Basically, once the alignment occurs, the magnetic field of a neutron star is locked in place. This phenomenon essentially makes a neutron star into a giant permanent magnet, something Hansson and Ponga call a “neutromagnet”.

Similar to its smaller permanent magnet cousins, a neutromagnet would be extremely stable. The magnetic field of a neutromagnet is thought to align with the original magnetic field of the “parent” star, which appears to act as a catalyst. What is even more interesting is that the original magnetic field isn’t required to be in the same direction as the spin axis.

One more interesting fact is that with all neutron stars having nearly the same mass, Hansson and Ponga can calculate the strength of the magnetic fields the neutromagnets should generate. Based on their calculations, the strength is about 1012 Tesla’s – almost exactly the observed value detected around the most intense magnetic fields around neutron stars. The team’s calculations appear to solve several unsolved problems regarding pulsars.

Hansson and Ponga’s theory is simple to test – since they state the magnetic field strength of neutron stars cannot exceed 1012 Tesla’s. If a neutron star were to be discovered with a stronger magnetic field than 1012 Tesla’s, the team’s theory would be proven wrong.

Due to the Pauli exclusion principle possibly excluding neutrons aligning in the manner outlined in Hansson and Ponga’s paper, there are some questions regarding the team’s theory. Hansson and Ponga point to experiments that have been performed which suggest that nuclear spins can become ordered, like ferromagnets, stating: “One should remember that the nuclear physics at these extreme circumstances and densities is not known a priori, so several unexpected properties might apply,”

While Hansson and Ponga readily agree their theories are purely speculative, they feel their theory is worth pursuing in more detail.

If you’d like to learn more, you can read the full scientific paper by Hansson & Pong at: http://arxiv.org/pdf/1111.3434v1

Source: Pulsars: Cosmic Permanent ‘Neutromagnets’ (Hansson & Pong)

Posted on by Amy Shira Teitel

Do-It-Yourself Guide to Measuring the Moon’s Distance

The Moon. Photo credit: NASA.

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When the distance from the Earth to the Moon comes up, the common figure thrown around is 402,336 km (or 250,000 miles). But have you every wondered how astronomers got that figure? And how exact it really is? There are a couple of ways you can measure the distance of the Moon that don’t require lasers or any instruments. All you need are your eyes, a clear sky, and someone else willing to stand outside all night with you. 

There are two ways to measure the distance from the Earth to the Moon on your own: using a Lunar eclipse and using parallax. Let’s look at eclipses first.

The phases of a Lunar eclipse. Photo credit: Keith Burns for NASA/JPL

The Ancient Greeks used Lunar eclipses – the phenomena of the Earth passing directly between the sun and the Moon – to determine the distance from the Earth to its satellite. It’s a simple matter of tracking and timing how long it takes the Earth’s shadow to cross over the Moon.

Start with the few knowns. We know, as did the Ancient Greeks, that the Moon travels around the Earth at a constant speed – about 29 days per revolution. The diameter of the Earth is also known to be about 12,875 km or 8,000 miles.By tracking the movement of the Earth’s shadow across the Moon, Greek astronomers found that the Earth’s shadow was roughly 2.5 times the apparent size of the Moon and lasted roughly three hours from the first to last signs of the shadow.

From these measurements, it was simple geometry that allowed Aristarchus (c. 270 BC) to determined that the Moon was round 60 Earth radii away (about 386,243 km or 240,000 miles). This is quite close to the currently accepted figure of 60.3 radii.

You can follow Aristarchus’ method in your own backyard if you have a clear view of a Lunar eclipse. Track the movement of the Earth’s shadow on the Moon by drawing the changes and time the eclipse. Use your measurements to determine the Moon’s distance.

Lunar parallax: the moon as observed from Italy and China at the same time during a lunar eclipse. Photo credit: measurethemoon.org/wordpress

For the second method, you’ll need a friend to help out. The Ancient Greeks also knew about parallax, an object’s apparent change in position when seen from two different viewpoints. You can experience parallax by holding a pen out at arm’s length and looking at it with one eye at a time. As you switch between your left and right eye, the pen will appear to move back and forth.

The same thing can be seen on a giant scale. Two observers in different parts of the world (at least 3,200 km or 2,000 miles apart) will see the Moon’s position as different from where calculations say it should be in the night sky.

To find the distance of the Moon from the Earth, you and a friend stand 3,200 km apart and each take a picture of the Moon at exactly the same time. Then, compare your images. The Moon will be in a different spot, but the background stars will be in the same place. What your images have given you is a triangle. You know the base (the distance between you and your friend), and you can find the angle at the top (the point of the Moon in this triangle). Simple geometry will give you a value for the distance of the Moon.

It might be a little more labour intensive than searching the internet, but determining the Moon’s distance yourself is sure to be more fun! If you really want to get involved, check out International Measure the Moon Night on Dec. 10, 2011. Join participants around the world who register their own events and share their images and observations!

A graph showing which parts of the world have the best chance of measuring the moon's distance using these two methods. Regions in red can see full eclipses while regions covered in red bars are best suited to measurements using parallax. Photo credit: measurethemoon.org/wordpress
Posted on by Tammy Plotner

Leonid Meteor Shower Peaks – November 17-19, 2011

Leonid meteors seen from 39,000 feet aboard an aircraft during the 1999 Leonids Multi-Instrument Aircraft Campaign (Leonid-MAC). Comet Tempel-Tuttle provides the cometary debris for the Leonid meteor storm, which takes place in mid-November. Credit: NASA/ISAS/Shinsuke Abe and Hajime Yano

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Are you ready for a good, predictable meteor shower? Then break out your favorite skywatching gear because the 2011 Leonid meteor shower is already sparkling the skies…

In the pre-dawn hours on the mornings of November 17-19th, the offspring of Comet Temple/Tuttle will be flashing through our atmosphere at speeds of up to 72 kilometers per second – and enticing you to test your meteor watching skills against partially moonlit skies. Although the waning Moon will greatly interfere with fainter meteor trails, don’t let that stop you from enjoying early evening observations, or enjoying your morning coffee with a handful of “shooting stars” which will be emanating outward from the constellation of Leo.

Where in the skies do you look? For all observers the constellation of Leo is along the ecliptic plane and will be near its peak height during best viewing times. When? Because of the Moon, earlier evening observations are favored (before local midnight), but just a couple of hours before local dawn is the best time to watch. Why? Read on!

Although it has been a couple of years since Temple/Tuttle was at perihelion, don’t forget that meteor showers are wonderfully unpredictable and the Leonids are sure to please with fall rate of around 20 (average) per hour. Who knows what surprises it may bring! Each time the comet swings around our Sun it loses some of its material in the debris trail. Of course, we all know that is the source of a meteor shower, but what we don’t know is just how much debris was shed and where it may lay.

“The Moon is going to be a major interference, but we could see a rate of about 20 per hour,” said Bill Cooke, head of NASA’s Meteoroid Environments Office at NASA’s Marshall Space Flight Center in Huntsville, Alabama. “Some models, including ours, indicate that particles may encounter Earth on November 16 at around 5:30 p.m. EST [2230 GMT], where we could see anywhere from 100 to 200 meteors per hour. So, we could get a Leonid outburst, but unfortunately it is not favorably placed for viewing from the United States.”

As our Earth passes through the dusty matter, it may encounter a place where the comet let loose with a large amount of its payload – or it may pass through an area where the “comet stuff” is thin. We might even pass through an area which produces an exciting “meteor storm” like the Leonids produced in 1883! For those in the know, the Leonid meteor shower also made a rather incredible appearance in 1866 and 1867 – dumping up to 1000 (not a typo, folks) shooting stars recorded even with a Moon present! It erupted again in 1966 and in 1998 and produced 3000 (yep. 3000!) video recorded meteors during the years of 2001 and 2002. But remember, human eyes may only be able to detect just a few. So what’s a realistic guess?

According to Cooke; “We could see rates of about five meteors per hour,” he explained. “If people want to see the Leonids, it might be good to watch the nights of November 16th and 17th. Instead of just going out one night, you might want to go out twice.”

Chart Courtesy of "Your Sky"

And to make this year’s show twice as nice, you’ll have a hard time not being distracted with the Moon and Mars being right on the radiant! You won’t be able to miss the Red Planet as the Moon slides along south… First to Mars’ west and then to the east on the nights of November 18th and 19th.

What a terrific show!

Posted on by Ray Sanders

Was a Fifth Giant Planet Expelled from Our Solar System?

Artist’s impression of a fifth giant planet being ejected from the solar system. Image credit: Southwest Research Institute

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Earth’s place in the “Goldilocks” zone of our solar system may be the result of the expulsion of a fifth giant planet from our solar system during its first 600 million years, according to a recent journal publication.

“We have all sorts of clues about the early evolution of the solar system,” said author Dr. David Nesvorny of the Southwest Research Institute. “They come from the analysis of the trans-Neptunian population of small bodies known as the Kuiper Belt, and from the lunar cratering record.”

Nesvorny and his team used the clues they had to build computer simulations of the early solar system and test their theories. What resulted was an early solar system model that has quite a different configuration than today, and a jumbling of planets that may have given Earth the “preferred” spot for life to evolve.


Researchers interpret the clues as evidence that the orbits of Jupiter, Saturn, Uranus and Neptune were affected by a dynamical instability when our solar system was only about half a billion years old. This instability is believed to have helped increase the distance between the giant planets, along with scattering smaller bodies. The scattering of small bodies pushed objects both inward, and outward with some objects ending up in the Kuiper Belt and others impacting the terrestrial planets and the Moon. Jupiter is believed to have scattered objects outward as it moved in towards the sun.

One problem with this interpretation is that slow changes to Jupiter’s orbit would most likely add too much momentum to the orbits of the terrestrial planets. The additional momentum would have possibly caused a collision of Earth with Venus or Mars.

“Colleagues suggested a clever way around this problem,” said Nesvorny. “They proposed that Jupiter’s orbit quickly changed when Jupiter scattered off of Uranus or Neptune during the dynamical instability in the outer solar system.”

Basically if Jupiter’s early migration “jumps,” the orbital coupling between the terrestrial planets and Jupiter is weaker, and less harmful to the inner solar system.

Animation showing the evolution of the planetary system from 20 million years before the ejection to 30 million years after. Five initial planets are shown by red circles, small bodies are in green.
After the fifth planet is ejected, the remaining four planets stabilize after a while, and looks like the outer solar system in the end, with giant planets at 5, 10, 20 and 30 astronomical units.
Click image to view animation. Image Credit: Southwest Research Institute

Nesvorny and his team performed thousands of computer simulations that attempted to model the early solar system in an effort to test the “jumping-Jupiter” theory. Nesvorny found that Jupiter did in fact jump due to gravitational interactions from Uranus or Neptune, but when Jupiter jumped, either Uranus or Neptune were expelled from the solar system. “Something was clearly wrong,” he said.

Based on his early results, Nesvorny added a fifth giant planet, similar to Uranus or Neptune to his simulations. Once he ran the reconfigured simulations, everything fell into place. The simulation showed the fifth planet ejected from the solar system by Jupiter, with four giant planets remaining, and the inner, terrestrial planets untouched.

Nesvorny concluded with, “The possibility that the solar system had more than four giant planets initially, and ejected some, appears to be conceivable in view of the recent discovery of a large number of free-floating planets in interstellar space, indicating the planet ejection process could be a common occurrence.”

If you’d like to read Nesvorny’s full paper, you can access it at: http://arxiv.org/pdf/1109.2949v1

Source: Southwest Research Institute Press Release