Tunguska Meteoroid’s Cousins Found?

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It’s a cosmic whodunit: a meteorite exploded in the air near a remote part of Russia called Tunguska in 1908, and the meteorite that caused the event all but disappeared. Where did it come from? Was it an asteroid or part of a comet? Astronomers have taken up the case, using mathematical simulations to track down the perpetrator. They even think they might even know a few of its siblings.

Tadeusz J. Jopek and his team at the Astronomical Observatory UAM in Poland – in collaboration with the Observatoire de la Côte d’Azur in France – looked for the possible origins of the Tunguska meteor by essentially running the explosion backwards, and mathematically simulating where the parent object of the event would have been before the impact.

By taking the existing forensic evidence of the impact to estimate the velocity and impact angle of the Tunguska meteorite, the team was able to simulate the possible orbit and speed of the object before it hit the earth. In doing this, they created 3311 virtual “particles” as possible origins of the object.

They then analyzed the orbits of near-earth objects that lie in the most likely region for the past 20,000 years to find possible matches with their simulated particles. It is still unclear exactly where the Tunguska meteor came from, and there are over 130 suspects.

“We believe that TCB originated as the result of a breakup of a single body : a comet or an asteroid. In our study we concluded that it is more probable that it was an asteroid. We cannot point to which one; instead we have found several candidates for the Tunguska parent, and the asteroid 2000 WK63 is an example of it,” Dr. Tadeusz said.

This is a hard case to solve indeed, as there remains little physical evidence of the original object near Tunguska, and the only tools astronomers have to work with are mathematical and statistical simulations. The question still remains whether the parent was a comet or asteroid, and indeed if the near-earth object it came from has been discovered yet.

“Such statistical conclusion gives no absolute sure [sic] that one of the presently known asteroids was indeed the Tunguska cosmic body parent. Therefore it is possible that still, the real Tunguska parent body is undiscovered.” Dr. Tadeusz said.

Source: Earth, Moon, and Planets Journal

2007 Perseid Meteor Shower Didn’t Disappoint

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So, did you heed my advice? Did you set aside Sunday evening to head out with friends and family to enjoy the Perseid meteor shower. Here in Vancouver, we had cloudy skies into the evening. But on a hunch, I set my alarm for 4 am, when the shower was at its height. What a treat.

My kids were disappointed that the sky was clouded over, and we wouldn’t be able to see the meteors Sunday evening. But incredibly, the sky cleared up over night, and it was perfectly clear when I checked outside at 4 am. So, I woke up the kids and we laid out on the back deck and watched for meteors as the skies started to brighten up. I was able to see quite a few before the rising Sun started to brighten the skies too much. All in all, it was great to see.

I’m really looking forward to the next big event: the total lunar eclipse on August 28, 2007. I can’t stress it enough. If you live in the Western North America, the Pacific, or Asia please try and make an event of this eclipse. It’s going to be great.

The European Space Agency has an interesting article about some of the science that happened during the meteor shower, as well as some tests of new equipment that could eventually be used to observer meteors… from space.

Source: ESA News Release

An Experiment to Test Panspermia

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One of most intriguing, and controversial, theories astrobiology is the concept of Panspermia. This idea proposes that life on Earth might have began on another planet, or maybe even out in interstellar space. Scientists have discovered just how hardy microbial life can be, surviving long journeys in the vacuum, cold, and radiation of space. Now an experiment has been devised to see how well microbes can withstand reentry through the Earth’s atmosphere.

The experiment, designed by Professor John Parnell from the University of Aberdeen, involves bolting a Scottish rock to the outside of an ESA research spacecraft. When the Foton M3 mission launches on Friday, September 14th, microbes in the rock will enjoy the acceleration of liftoff, 12 days of microgravity and vacuum, and then re-entry through the Earth’s atmosphere.

“The objective behind this is to look at the rock’s behaviour when it is exposed during re-entry through the Earth’s atmosphere – when temperatures are extreme. This will tell us something about the likelihood of life being transferred between planets on meteorites.

“The Orkney rock is a very robust material but it will be interesting to see if organic matter in the rock is robust enough to survive the harsh conditions endured during re-entering the Earth’s atmosphere.”

In theory, asteroid strikes in the past excavated material on other planets, hurling microbe-laden rocks into interplanetary space. The rocks would then act as lifeboats, carrying the microbes to other planets. More importantly, they should protect the bacteria as the rock plunges into the atmosphere.

This experiment will help discover if there’s anything to this idea. Bacteria might just be hardy enough to survive the complete journey from planet to planet.

Original Source:Univ. Of Aberdeen

Aurigid Meteor Shower, September 1

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What a fantastic month for skywatching. On August 12th, we’ve got the Perseid meteor shower. On August 28th there’ll be a total lunar eclipse. And on September 1st, there might be another meteor shower to enjoy: the Aurigids.

Unlike the dependable Perseids, the Aurigid meteor shower is unpredictable. They’re a stream of particles left behind by Comet Kiess (C/1911 N1). This is a long period comet that has only visited the inner solar system twice within the last two thousand years. Its last visit is believed to have been 83 BC.

On September 1, 2007, the Earth will pass through the dusty trail left behind by Comet Kiess, and it might be a spectacular show. Or it might be a non-event.

“We have so little experience with ancient debris from long-period comets,” notes Bill Cooke of NASA’s Meteoroid Environment Office (MEO) at the Marshall Space Flight Center. “Almost anything could happen—from a fizzle to a beautiful meteor shower.”

Astronomers have predicted that the peak of the shower will occur at approximately 1136 UTC (7:36 am EDT), and last for about 2 hours. It should be visible to observers in Western North America, the Pacific, and Eastern Asia.

One prediction calculated that there could be as many as 100 meteors an hour. That’s pretty good, but not at meteor storm levels, like the Leonids. One unique attribute about the Aurigids is that they leave a brilliant blue-green streak in the sky. Scientists think this might be because Comet Kiess is such a long period comet, spending much of its time in the darkness of the outer Solar System, its particles are relatively untouched by the Sun

So, I can’t guarantee anything. But the weather should still be warm on September 1st. School hasn’t started, and many of you will be looking for an excuse to enjoy the night sky with your friends and family.

Now you’ve got something to do. Go see the Aurigid meteors.

Original Source: NASA Science

Asteroid Vesta Formed Quickly, and Early

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Asteroid 4 Vesta is the second largest asteroid in the Solar System, stuck between the orbits of Mars and Jupiter. It was fully formed early on, turning solid and crystallizing within 10 million years of the Solar System’s formation. How do scientists know this? They’ve found a little piece of it right here on Earth. A Vesta meteorite discovered in Antarctica that tells the history of the early Solar System.

A study is being led by researchers from the University of Toronto. Their subject is a volcanic meteorite discovered in Antarctica during a recent survey. The space rock contains tiny zircon crystals that match the chemical makeup of Asteroid Vesta. It belongs to a class of objects called eucrites – meteorites that formed from volcanic activity.

Scientists believe that Vesta was quickly heated, and then melted into a metallic and silcate core, similar to the process that happened here on Earth billions of years ago. The radioactive decay from abundant minerals in the early Solar System was thought to provide the energy for this process.

Based on their analysis, this meteorite – and therefore Vesta – was once boiling rock that quickly turned solid and crystallized. This change, from liquid to solid happened within 10 million years of the Solar System’s formation. This information gives scientists clues about how our own planet solidified out of the Solar System’s protoplanetary disk.

Original Source:University of Toronto News Release

Another Reminder, Go See the Perseids

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My favourite meteor show is less than 2 weeks away now, so I wanted to give you all another gentle reminder to get organized and make sure that you’re able to enjoy the Perseid meteors this year – the shower will be peaking on the night of August 12, and into the next morning. It’s going to be a special event because the shower coincides with a new moon. The sky will be at its darkest, and the meteors will be at their brightest.

The shower gets its name because they will appear to originate from the constellation of Perseus. Don’t worry about finding the constellation, though, just lay on your back and stare up, you’ll see them.

On the evening of August 12, the first thing you’ll want to do is head outside shortly after sunset. If you’re lucky, you’ll see “earthgrazers”. These are some of the most beautiful meteors that you’ll see in the whole evening. Then settle down, find some satellites, and wait for the show to really get going. It you’ve got the stamina, the best viewing will happen in the early dawn hours of Monday, August 13th. At that point, you could be seeing a few dozen every hour.

To really get the best experience out of this, travel away from the lights of the city. Here in Vancouver, we need to get about 50 km away to start seeing the Milky Way above our heads. We’ve got a dark sky park in a suburb called Abbotsford that’s perfect.

So get organized. Book the evening with your friends, map out where you’re going to go. Bring hot drinks, warm clothes, and a comfortable place to sit back and enjoy the show.

And if you’re interested, Pamela and I recorded an episode of Astronomy Cast dealing with meteors and meteor showers, so you can listen in the car before you reach your viewing spot.

Enjoy, and let me know how it goes.

Set Your Calendar for the 2007 Perseids: August 12th

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My absolute favourite meteor shower every year is the Perseids. They’re not the most spectacular meteors of the year, but the weather’s nice and warm here in Canada. We always head back home to Hornby Island to visit the family at Perseid time to enjoy them with nice dark skies. We keep the kids awake as long as possible, and then lay back on a mattress, enjoying the sky show.

And this year’s going to be a great one: no moon.

That’s right, there’s going to be a new moon on Sunday, August 12th, the exact same time that the Perseid shower is peaking. Without the glare of the Moon, the meteors will be at their brightest. But to really enjoy the show, you’ll want to head outside your city, away from the glare.

Like all meteor showers, the Perseids get their name from the constellation the meteors originate from. The constellation is in the northeast. As soon as it starts to get dark, you should start seeing meteors streaking across overhead. It’ll probably just be a couple every minute, but by early morning, when the shower is peaking, you could even see a few dozen a minute.

And as a special bonus, Mars is going to be in the sky as well. It’ll appear to be a bright red star also in the northeast.

I want you to organize something for the Perseids this year. Gather together some great friends, head somewhere dark, and plan to enjoy a great show. Put it on your calendar right now.

Promise?

Original Source: NASA

Watch for the Geminids on Wednesday

Credit: Jason A.C. BrockOne of the best meteor showers of the year – the Geminids – are about to peak. If you’ve got clear skies, head out on the evening of December 13th, and you could see a few meteors an hour. Unlike most meteor showers, the source of the Geminids is a bit of a mystery, since the dust doesn’t seem to originate from a comet. A small asteroid called 3200 Phaethon has been discovered in the right orbit, but astronomers aren’t sure how it could be generating enough dust to cause such beautiful meteor showers.
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Organic Material Found in an Ancient Meteorite

NASA researchers have discovered organic material inside a meteorite the recently fell in Canada’s Tagish Lake. The meteorite is especially valuable because scientists collected it shortly after it crashed in 2000, ensuring it wasn’t contaminated by local bacteria. The meteorite seems to contain many small hollow organic globules, which probably formed in the cold molecular cloud of gas and dust that gave birth to the Solar System. Meteorites like this have been falling to Earth for billions of years, and probably seeded the early planet with organic material.
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Leonid Meteor Shower: November 19, 2006

One of the best meteor showers of the year is about to get rolling, so make sure you mark your calendar. The Leonid Meteor Shower will be peaking on Sunday, November 19, 2006, and you might be able to see as many as 100 meteors an hour. Find the darkest possible skies that you can, and wait until the constellation Leo is highest in the sky. Observers in western Europe, Africa, Brazil and the eastern parts of North America will get the best view this year.
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