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Perseid Meteor Shower Observations: 'Up All Night' With NASA!
08.12.10
 
Composite image of Perseids meteor shower in 2010 Composite Perseids view on the night of Aug. 11, 2010, combined from 39 single station events over Chickamauga, Ga. (NASA/MSFC/D. Moser, NASA's Meteoroid Environment Office)
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More Information
NASA News: Meteors
NASA Worldbook: Meteors
Wikipedia: Perseids
Hi everyone! Thanks for the AMAZING participation for the Perseid chats, especially the "Up All Night" Web chat. If you plan to do some more sky-watching as the Perseids wind down, Bill's blog post has some great information. Best conditions are a clear, dark sky away from city lights. Go outside and look straight up at the sky.

About the Chat

Looking for a little excitement as the summer draws to a close? This year's Perseid meteor shower peaks on the night of Aug. 12-13, and it promises to be one of the best displays of the year. If forecasters are correct, the shower should produce a peak display of at least 80 meteors per hour. A waxing crescent moon will set before the shower becomes active, setting a perfect stage for meteor watching -- weather permitting, of course!

On Thursday, Aug. 12, astronomer Bill Cooke from NASA's Marshall Space Flight Center answered your questions about the Perseids.

More About the Perseids

The Perseids have been observed for at least 2,000 years and are associated with the comet Swift-Tuttle, which orbits the sun once every 133 years. Each year in August, the Earth passes through a cloud of the comet's debris. These bits of ice and dust -- most over 1,000 years old -- burn up in the Earth's atmosphere to create one of the best meteor showers of the year. The Perseids can be seen all over the sky, but the best viewing opportunities will be across the northern hemisphere. Those with sharp eyes will see that the meteors radiate from the direction of the constellation Perseus.

More About Chat Expert Bill Cooke

The head of NASA's Meteoroid Environment Office, Dr. Bill Cooke specializes in the meteoroid environment and its effects on space vehicles of all sorts. While a graduate student at the University of Florida, he worked on instruments flying onboard balloons, the Space Shuttle, Giotto (European mission to Halley's Comet), and the Long Duration Exposure Facility.

After obtaining his PhD, he came to work at Marshall Space Flight Center as a member of the Space Environments Team. When not occupied with meteor observations and shower forecasts, he dabbles as a free- lance author for magazines and is a mentor for the Team America Rocketry Challenge and NASA's Student Launch Initiative rocketry programs.

Afternoon Chat Transcript Below | Link to Up All Night Chat Transcript, PDF, 754 KB)

Bill: Hi everyone! We're finalizing the chat set-up and will start answering questions in a few more minutes. Welcome to the Perseids chat!

cgrayflorida: Can we expect a good viewing from central Florida?

Bill: Yes! Check out my blog post, it provides some great information on viewing: http://blogs.nasa.gov/cm/blog/Watch%20the%20Skies/posts/post_1281630596623.html

heather_C: HI Bill - I was wondering if we will be able to see any meteors tomorrow night from the mts of North Carolina? And if so, how many per hour? Thank you-I can't wait for tonight:)

Bill: Yes, but not as many as tonight. Perhaps a rate of 30 per hour. Me, either. :)

cgrayflorida: Hi Bill. This is very exciting and I'm glad to be able to participate!!!

Bill: Glad you're here!

david: Where is the best place in etobicoke to see the Perseid meteor shower?

Bill: Go out after 10 local time. Find a dark place with clear skies. Meteor rate will increase as dawn approaches.

James: Will the meteor shower be visible from London tonight?

Bill: Yes, go out after 10 local time. Find a dark place with clear skies. Meteor rate will increase as dawn approaches.

Ron: I live in the North Shore of Mass. Where should I look for the meteors. North south east or west? Thank you

Bill: Lie flat on your back and look straight up. The meteors can appear anywhere in the sky.

Gabe: Why do the meteor showers appear the best during August?

Bill: The Perseids are one of the best annual showers because we run into material left behind by a large comet, which dumps a large amount of meteoroids.

lauraaa: Will you be able to see the meteor shower from Worcester in the UK?

Bill: Go out after 10 local time. Find a dark place with clear skies. Meteor rate will increase as dawn approaches. Also check out this blog post: http://blogs.nasa.gov/cm/blog/Watch%20the%20Skies/posts/post_1281630596623.html

brown: Since what time can we see the shower tonight?

Bill: Best time is between 3-4 a.m. your local time, but Perseids begin around 10 p.m.

(Moderator Jason): We're working to get through all of the great questions you've already asked us. Keep them coming! To submit your own question, please type it in the box at the bottom of the window and click the 'Ask' button on the right side of the box. Thanks for your patience as we answer your questions.

Patrícia_Borges: Is there any danger that some meteor get houses or people en Brazil, especially in Mato Grosso State?

Bill: No. :)

wishwithme: Here in Rhode Island we had way too many clouds to see the meteor shower. The next chance of clear skies is Saturday night into Sunday morning. Will we see a pretty good show of meteors then?

Bill: You'll see a few Perseids then, but the rate will be greatly diminished -- below 15 or so per hour.

Paula: Who lives in the South Hemisphere will see the shower?

Bill: Try this link: http://blogs.nasa.gov/cm/blog/Watch%20the%20Skies/posts/post_1281630596623.html

edgardog.morales: Good afternoon Bill!!! Can the shower be seen from Puerto Rico?

Bill: Yes, try this blog post. Good luck on the viewing! http://blogs.nasa.gov/cm/blog/Watch%20the%20Skies/posts/post_1281630596623.html

Tom: I live in Slovakia, will be there good spot to see it?

Bill: Anywhere with dark, clear skies.

finalizer: Don't you know once again a cloudy night in the N.E. (NY). I recall a few years back in Dec. on another cloudy night in the N.E. (what else is new) the meteor shower was so brilliant they were showing right through the clouds. Any chance of this happening tonight? Thank You.

Bill: It's possible that a fireball may show through the clouds, but this is EXTREMELY rare!

acarroll: Do we need to be in a flat field or can we look in our backyard, surrounded by tall trees?

Bill: You want to see as much sky as possible, so if your trees block a large amount of sky, I'd suggest going somewhere else.

joe: I read above that most of the comet debris is around 1000 years old. Isn't that kind of young for a celestial body?

Bill: Yes, it is, but remember they were part of the comet before they left it -- and the comet is billions of years old.

cacman14: Will people in western New York be able to see the shower tonight?

Bill: http://blogs.nasa.gov/cm/blog/Watch%20the%20Skies/posts/post_1281630596623.html

Up_In_Canada: What is the best way to see the Perseids in Ottawa, ON, Canada. We tried yesterday and only saw about 5 over 2 hours. We are in a rural setting with no light pollution. Where, when should we be looking in the sky? The internet is full of contradictory advice. Thanks...

Bill: The Perseid rate will be at maximum tonight just before dawn your time. Since you have a clear dark sky, I suggest you lie on your back and go out after midnight. Give your eyes about 45 minutes to dark adapt.

Josh: Hi Bill, I'm with the Stanford Astronomical Society and we'll be hosting a viewing tonight on campus

Bill: Great -- good luck with the viewing!

brown: Bill how long last the shower?

Bill: Perseids will be visible until Aug. 16 or so.

andreinaaaa06: Hello Mr. Cooke I live in Miami! Can I see the peak from the beach?

Bill: Yes, if it's clear and dark.

Marcy: Hi Bill! I Live in Brazil and wonder when would the best time to see the shower would be...Can you help me?

Bill: If you're in southern Brazil, head north and check out this blog post: http://blogs.nasa.gov/cm/blog/Watch%20the%20Skies/posts/post_1281630596623.html

Tom: Now we have 21:03 time, what time is the best to see the Perseids here? (I live in Slovakia)

Bill" Best time is 3-4 a.m. local time but you can start seeing Perseids within the hour.

Josh: If you have any tips for California/Bay Area viewing please do share!

Bill: Get away from the lights! The sky needs to be dark -- a way to know is that if you can see all the stars in the Little Dipper, then it's about dark enough. Clear skies are a must. Also, go outside and allow your eyes about 45 minutes to "dark adjust."

placer86: I know this has probably been answered before, but when is the best time of night to see them tonight? Is it necessary to stay up until the wee hours or can we catch them around 11 or midnight?

Bill: You will see a few Perseids around 11 p.m. to midnight, but best time is probably 3-4 a.m. local time.

(Moderator Jason): We're still working on answering all the questions you've asked. If you haven't seen yours yet, give us a few minutes to get to all of your questions. To submit your own question, please type it in the box at the bottom of the window and click the 'Ask' button on the right side of the box. Thanks for your patience as we answer your questions.

alienvenom: Is it possible that pieces of the Perseids may make it through our Earth's atmosphere and hit land? My local news ran a story about a Ohio man claiming to have been hit by a meteorite.

Bill: No, Perseids are tiny bits of ice and dust and hit the atmosphere at 130,000 mph. No way they can survive.

JBunny313: Is any of this actually going to impact earth?

Bill: No, everything will burn up.

mechanical_engineer: Is the 80 per hour more towards dawn? What is the rate at a time more around midnight?

Bill: Yes, towards dawn. Midnight rate is more like 30 per hour.

david: hi, can we expect a good viewing from toronto, canada

Bill: Yes, if the skies are clear. Get away from Toronto lights.

Alaa: From my place i can only see stars up to four magnitude can i see the meteor shower and at what rate?

Bill: You can see the brighter Perseids. Expect about half of what a person with clear skies would see.

Mar: Hi, i am from Venezuela and i want to know if here we will see the Perseid Metorer?

Bill: Yes, you will! http://blogs.nasa.gov/cm/blog/Watch%20the%20Skies/posts/post_1281630596623.html

AbCast: In northeastern Brazil will be able to see the meteor storm with quality?

Bill: It's a meteor shower, not a storm, and yes, you can see it from there.

matttttt: Bill is there a possibility of any of the meteors striking my house? I live in New York and I just added a three car garage.

Bill: No, they will all burn up. But congratulations on the garage expansion! :)

trevadetrev: Will i get a better view with a telescope?

Bill: No, definitely not. Use only your eyes because you need to see as much sky as possible. Telescopes have too narrow a field of view.

choi: what time will the meteor shower be visible in Calgary, Canada?

Bill: After 10 p.m., but most before dawn around 3-4 a.m. All times local.

James: Where should I look for the meteors from London?

Bill: Lie on your back and look straight up!

cgrayflorida: Can you tell us if we can record the meteor shower with a regular digital video camera? Would we get decent results? If not, what about using the night vision setting on the camera, would that help?

Bill: You need to be able to expose for several seconds or minutes. If your field of view is large enough, you may capture a meteor in the exposure. Try 5-10 minute exposures pointing straight up.

serotonin: What's the current estimated peak? I live in a town with a lot of bluffs would it be wise to get to a higher elevation for better viewing? or to go to a darker area with less light pollution

Bill: The important things are to have as few obstruction of your view of the sky as possible and minimize light pollution. Peak will be around 3-4 a.m. local time.

david: During the meteor shower will the moon be visible?

Bill: No, the moon will set before Perseid activity gets started.

andreinaaaa06: Hi my question is I will be able to see the peak of the meteors shower from the beach in Miami?

Bill: Yes, if it's clear and dark.

acarroll: Thank you! Looking forward to it. :)

Bill: So am I!

mechanical_engineer: How fast do the meteors enter our atmosphere?

Bill: Perseids enter the atmosphere at 130,000 mph.

aclassicaleducation: Hello Bill -- I am here with my 3 children and they want to know if we will be able to hear anything from the sky.

Bill: Not with your ears, but you can listen to the live stream from Marshall and hear the meteors as they show up on our meteor radar. It will be embedded on this page after the chat!

Paul_F: Why does the meteor rate increase as dawn approaches?

Bill: Because the direction the meteors come from, called the radiant, gets higher in the sky as the Earth rotates. The higher the radiant, the more meteors you'll see.

sorina: Hi, Bill! I`m from Romania. Will the meteor shower be visible from here?

Bill: Hi sorina. Yes, they will. http://blogs.nasa.gov/cm/blog/Watch%20the%20Skies/posts/post_1281630596623.html

wishwithme: The next chance of clear skies here in the Northeast is Saturday night into Sunday morning. Will there still be a good meteor shower then?

Bill: You'll see Perseids, but the rate will be greatly diminished.

brown: I am in Orlando, FL...is it good to go out around midnight?

Bill: You'll see a few then, better to go out closer to dawn.

a_neutron_star: Will those affected by moderate light pollution still have a pretty good chance of seeing some action?

Bill: You'll see brighter Perseids, but not as many as a person with clear skies.

Ron: What about in the North Shore of Mass, best time? and in what direction?

Bill: Best time close to dawn (3-4 local time) and look straight up.

Craig_Sheppard: If you can't go out at 3-4am tonight, or it is cloudy, would it be better on Thurs (8/12) evening or Fri evening (8/13)?

Bill: Thursday evening would be better than Friday evening.

James: How long will each meteor be visible for?

Bill: Meteors only last a few seconds or even as short as a fraction of a second.

perseidwatch: Hi bill can you tell me when the earth orbits through the debris how long do the showers last for

Bill: Perseids last for about two weeks. Other showers may last for a longer period of time or be of shorter duration. For example, the Draconid meteor shower lasts only a few hours. The Arieds last almost three weeks.

seleneseraph: So... you basically say we can see the Meteor showers from all over the world? I live in the Netherlands...

Bill: Yes, except for the southern part of South America, southern tip of Africa, southern part of Australia, and Antarctica.

Chuck: Is it visible in Europa?

Bill: Visible in Europe, yes. Visible on Jupiter's moon, no. :)

brown: Do u recommend a good spot around Orlando?

Bill: Anywhere with a dark, clear skies.

finalizer: cloudy in the N.E. (NY) but I remember a few years back seeing the showers through yet another cloudy night and they were brilliant. Any chance of this happening tonight?

Bill: You might see a fireball, but it's rare. It depends on the degree of cloud cover.

(Moderator Jason): We're still working on answering all the questions you've asked. If you haven't seen yours yet, give us a few minutes to get to all of your questions. To submit your own question, please type it in the box at the bottom of the window and click the 'Ask' button on the right side of the box. Thanks for your patience as we answer your questions.

Geoffrey_Heberlein: Hello Bill. With respect to the debris field are we passing along the edge of the cloud or are we passing through the middle. I know we vary year to year.

Bill: We're passing closer to the middle this year than usual.

KVerrone: Will we always run into the Perseid meteor shower each year, or eventually will the comet debris have moved/died out?

Bill: The Perseids have been going on since 36 A.D., at least according to the Chinese. It appears they'll go on for the foreseeable future.

cajko: Is there some live show?

Bill: We'll be embedding a livestream on this page after the chat!

Peter: Hi! What is the easiest / best way for a novice to identify the Perseus constellation?

Bill: Look for a W-shaped constellation -- Cassiopeia. Perseus will be the K-shaped constellation to the east of Cassiopeia.

lauraaa: Is there any danger that a Meteor can hit houses in the UK? Or endanger us?

Bill: No, they will all burn up. Enjoy the shower without fear. :)

bluejays92: I live in North Carolina. What time is peak time to see the most showers?

Bill: Just before dawn, but show starts around 10 p.m. local time.

caligurls: what direction should i look at if i'm in california?

Bill: Look straight up. Find a place with nice dark skies.

baxter30: I'm in Georgia, how well will we be able to see them tomorrow night (Friday)? Since I do have to get up early and work. :)

Bill: Tomorrow night the rate will be about half of what it is tonight.

choi: hiii Bill, can you tell me what time can i see the meteor shower in Calgary, Canada?

Bill: After midnight, best viewing is 3-4 a.m. local time.

kief12: Will you be able to see the meteor shower in Vancouver B.C?

Bill: Yes: http://blogs.nasa.gov/cm/blog/Watch%20the%20Skies/posts/post_1281630596623.html

trminton: Are this year's Perseids any better or worse than previous years?

Bill: Last year the Perseids hit a rate of over 200 per hour, so this year isn't quite as good as last year. But better than an average year. :)

Paul_F: how big are the particles that we will be able to see? are they dust sized or bigger?

Bill: The particles that create the streaks of light you see are from 1 mm to several cms in diameter.

Kasha: Are we able to see these showers during the day?

Bill: No, can't see them during the day.

aclassicaleducation: Can we hear anything?

Bill: Not with your ears, but you can hear radio signals that reflect off the ionization trails if you have a HAM radio.

Dixie_S: When was the comet that was responsible for this shower last appear and when will it be here again: And why are showers expected to be better in some years than others ?

Bill: It was last here in 1993 and won't be back for over 130 years. Some years we encounter narrow streams left behind by the comet in the recent past, and that give us a better shower (like last year).

lar: Hi Laurie and Jeff from Pa

Bill: Hi Laurie and Jeff!

Geoffrey_Heberlein: Bill if you had your choice where would you campout tonight to see the best of the storm?

Bill: Hawaii! Seriously, any warm spot with clear skies will do.

trevadetrev: If the skies are clear, and if i live on the east coast, what is the most number of meteors ill get in an hour?

Bill: Depends on when you look, but could see from 60-100 per hour near dawn.

mimi: Is there more than one way to see this event?

Bill: Best way is to use your eyes. You could listen on HAM radio tuned to a distant carrier frequency. Or, you can come back to this page and see the live stream that we'll have embedded overnight.

Mar: Hi, how meteorites pass near the earth?, thanks :)

Bill: Never calculated that -- depends on the size. But if you get really small, I suppose many millions pass by per day. I don't have a calculator with me. :) (Meteoroids are out in space -- meteorites are on the ground, and there are very few of them because the meteoroids which become meteors when they burn in the atmosphere usually never make it to the ground.)

Craig_Sheppard: At what altitude are most Perseids at when they burn up?

Bill: 56 miles

Bessy: How clear is it going to be for people in south west England?

Bill: I'm not sure -- consult your local meteorologist or go to weather.com.

cacman14: Will we be able to see around the same amount of meteors per hour tomorrow night?

Bill: No, the rate will be about half.

shirley: Will u be able to see Tampa fl?

Bill: Yes, find a clear dark sky.

Noether: How dark does it need to be for me to get a good view?

Bill: You need to be able to see lots of stars. If you can see all the stars in the Little Dipper, your sky is dark enough.

greentree: We should have beautiful clear skies in No. Utah tonight; when's the best time for viewing?

Bill: Start seeing at 10 local time, best viewing 3-4 a.m.

Rusty: Where in the world is the best place to see them?

Bill: There's really no preferred place.

Maite_Urquijo: Hey, I'm from Argentina, I just find out about this, but I'm a bit confused.... the meteor shower is today, right? @ 10pm EDT???

Bill: Yes, you'll start seeing Perseids around 10 p.m. except that a lot of Argentina is too far south to see the shower. Check this blog post: http://blogs.nasa.gov/cm/blog/Watch%20the%20Skies/posts/post_1281630596623.html

Sam: Why does this event occur around the same time every year?

Bill: Because the stream of material left behind by the comet is at the same place relative to Earth's orbit each year, so we run into it at the same time.

Rusty: where on the east coast of the US is the best place to see them or does location even matter?

Bill: Location doesn't matter. Just stay away from the cities.

serotonin: What is the expected peak of the shower tonight, I've heard estimates of 80+ meteors per hour, or 50+ an hour... which is more accurate?

Bill: 80 is more accurate, based on the activity we saw last night.

Heyam: Will the meteor shower be only visible to the people in the U.S?!

Bill: No.

meteodub: I am in southeast Europe, Croatia. What part of sky (North or South) will be most occupied by meteors? Thanks!

Bill: The Perseids can appear anywhere in your sky so look straight up to the zenith.

Maite_Urquijo: The Meteor Shower happens only once every 133 years???

Bill: No, it happens every year. The COMET only comes around once every 133 years. (Swift-Tuttle)

Patrícia_Borges: Hi Bill, this meteor Shower could be influence on pregnancy or other life's situation, like in a moon's change?

Bill: No, absolutely not. Enjoy the show without fear. :)

Alaa: Hi Bill should we focus at the radiant point or away from it?

Bill: Away from it. The farther a meteor is from the radiant, the longer it's train or trail. Meteors close to the radiant aren't very impressive.

cajko: Hello Bill! How big are this Perseids?

Bill: Perseids range from about 1 mm to several cms across.

Aspen: Hey Bill, will a camera be able to capture these meteors??

Bill: Yes, take time exposures of 5-10 minutes and point straight up. Be sure the sky is dark.

Heyam: I live in Saudi Arabia, will I be able to see it? Or is it for the U.S only??

Bill: You can see it in Saudia Arabia. Happy viewing!

donakene: Do you know of any online cams that will be available for people to view?

Bill: Yes -- we'll be embedding a feed on this page right after the chat.

Incredisci: I’m gonna have to sneak out of my house tonight, got to see this year

Bill: Be safe!

mimi: So the best way to see the showers is if your away from light?

Bill: Yes, lay on your back and look straight up.

slsmith: I know the shower peaks tonight, but will I still be able to see shooting stars tomorrow night?

Bill: Yes, but not as many, only about half the rate.

donakene: How do the meteor showers affect space stations and satellites?

Bill: The Perseids have been known to damage a couple of satellites, but the Space Station is very well protected and the Perseids pose no threat to it.

tonyphillips: Is this the best meteor shower of the year?

Bill: The Geminids are usually better, but most folks don't want to freeze on cold December nights -- so let's say the Perseids are the most COMFORTABLE shower of the year!



angelica: Hello Dr. Cooke! My name is Angelica and it's a pleasure to have the opportunity to speak with you! Comet Swift-Tuttle has quite a large orbit around the sun! Has the Hubble Space Telescope ever been able to send back images of Comit Swift-Tuttle? Will the astronauts on the ISS be able to see meteors burning up in the Earth's atmosphere? That would be awesome to see a meteor shower from space!

Bill: To answer your first question...to my knowledge, Hubble hasn't observed Swift-Tuttle, and yes, the astronauts can see Perseids in Earth's atmosphere by looking DOWN. It's a unique perspective!

perseidwatch: I seen somewhere on the internet that it's possible to see 200-400 meteors an hour during this shower is that true and at what time would be best if it is?

Bill: No, that was last year's shower. This year, 100 per hour, tops.

burk: What was the most intense shower you ever saw?

Bill: The 2001 Leonids.

Glasshouse: Have we collected any of this comet stuff? What have we learned/ could we learn from collecting this stuff?

Bill: We've collected nothing from Swift -Tuttle, but Stardust has collected material from Wild 2, so we do have pieces from a comet.

Tom: Is it possible to see the Perseids from the balcony? Not looking straight up to the sky but just out of the balcony?

Bill: You'll see a few, but you really need to be able to see the entire sky.

weeuna: Why do meteors make that singing noise?

Bill: Meteors don't sing, but if you use a HAM radio to detect them, you'll hear pinging and blipping and long, drawn-out whistling.

rickn: Are there any satellite instruments recording the meteor path through the Earth's atmosphere?

Bill: Not as far as I know.

MeredithM: What's your favorite fact about the Perseids?

Bill: The Perseids back in medieval times were called the Tears of St. Lawrence because they occurred during the festival of the Italian saint.

craighaney: Is there an easy way to recognize the difference between planets and stars in the night sky?

Bill: Stars twinkle, but planets don't.

dhall: What type of information does NASA collect on the Perseids?

Bill: We're interested in knowing their orbits, how many there are as a function of size, their speeds, and their compositions or densities.

rhys96: Why is this Meteor shower going to be better than any other in the last 5 years ?

Bill: Last year's Perseids was better - rates over 200 per hour.

seleneseraph: So you’re the only one answering questions... Bill? :)

Bill: I have lots of help with me. :)

(Moderator Jason): Keep the excellent questions coming. To submit your own question, please type it in the box at the bottom of the window and click the 'Ask' button on the right side of the box. Thanks for your patience as we answer your questions.

Tammie: How can a small particle make such a beautiful light in the night sky?

Bill: If you hit the atmosphere at 130,000 mph, I guarantee that YOU would make a beautiful light in the night sky. :)

SYIN3IRGY: What about Tucson Arizona area?

Bill: Try this blog post: http://blogs.nasa.gov/cm/blog/Watch%20the%20Skies/posts/post_1281630596623.html Bill: Hi everyone, a note to all. We have LOTS of questions about best times for viewing and locations. General advice to all: Perseids can be seen from 10 p.m. to dawn local time, with greatest number in pre-dawn hours. As far as location, the entire Northern Hemisphere and most of the Southern Hemisphere can see the shower. If you have doubts, check this blog post: http://blogs.nasa.gov/cm/blog/Watch%20the%20Skies/posts/post_1281630596623.html Advice is always get away from city lights and look straight up.

flids: This passing through the middle means more to see?

Bill: Yes, it does. The more dense the stream, the more meteors.

Alaa: what is the rate of fireballs per hour?

Bill: We saw 13 fireballs in a 4-hour period last night. I'd expect double that tonight.

Alaa: why don’t we get two meteor showers from the same comet because it have to turn around the sun and back so they must intersect our orbit twice?

Bill: The orbit of the comet must pass through the plane of Earth's orbit twice. It doesn't mean that the orbit has to pass close to Earth's orbit twice. In the case of Swift Tuttle, the Earth is close to only one plane passage (nodal crossing). Halley's Comet does product two meteor showers: the Eta Aquariids in May and the Orionids in October.

AbCast: We should look at the constellation of Perseus to see the meteor shower?

Bill: No, because the meteors close to the radiant have very short trails. Look straight up away from the radiant to see decent trails.

Jure_Atanackov: Past several nights there have been some unusually bright Perseids - in the magnitude -7 to -12 range. In my 12 years of observing Perseids this year has by far the most brilliant fireballs. Any thoughts on this?

Bill: We're obviously encountering large particles (cm size). We, too, are seeing a fair number of fireballs.

Dixie_S: The meteors burn up at 130,000 mph..how fast does the Earth orbit the sun ?

Bill: The Perseids burn up at 130,000 mph. The Earth orbits the sun at 66,700 mph.

Brandon_in_Southern_MD: How common are "fireball" meteors during the Perseids shower?

Bill: Very common. The Perseids are noted for producing bright meteors.

MaximusBeer: Setting my alarm. clear skies tonight in Southern Ontario Canada. 3 am here I come.

Bill: Enjoy the show!

michellecmh: What direction in the sky should I be looking at tonight?

Bill: Straight up toward the zenith!

AbCast: We should look at the constellation of Perseus to see the meteor shower?

Bill: No, look away from Perseus straight toward the zenith.

Brandon_in_Southern_MD: Is there any resource (satellite, or radar installation) that counts actual meteor tracks and we can see a graph of the rate?

Bill: The International Meteor Organization keeps track of visual reports and has a graph that's updated regularly. Go to: www.imo.net

SpaceMan965: Can you view the shower from Oxford, CT?

Bill: Yes, the show starts at 10 p.m. best viewing before dawn.

Paul_F: Do we know how long the comet that leaves the debris trail has been in this orbit? Has it been here for millions of years, or was it recently captured?

Bill: The Perseids showers has been observed since 36 AD, which implies that Comet Swift Tuttle has been in its current orbit for at least several millennia. I don't know of any studies that have traced its orbit back in time millions of years.

nasacompletesme: Hello Dr. Bill! Why was this meteor shower named Perseid?

Bill: Because the meteors appear to come from the Constellation Perseus. Meteor showers get their name from the constellation that is their radiant. For example, the Leonids get their name from the constellation Leo.

dhp397: Do you advise a drinking game involving a drink each time a meteor passes? lol

Bill: Not if you want to see many meteors! Drinking games are better for seeing pink elephants. :)

GP: Hi Bill, I also heard that we will be able to spot three planets tonight... How do I go about that???

Bill: Go out after sunset and look to the west. Go to this link for more information: http://blogs.nasa.gov/cm/blog/Watch%20the%20Skies/posts/post_1281630596623.html

Hummingbird9311: Do meteor showers only come in the summer?

Bill: No, there are showers throughout the year: Geminids in December, the Quadrantids in January, the Eta Aquariids in May, the Bootids in June, the Draconids and Orionids in October, and so on.

brykwoll: When you say 60-100 per hour near dawn, does that mean with completely clear skies? What would we more likely see through and urban haze thick enough to let uncounted stars come through but not the (finer) belt of the Milky Way?

Bill: Yes, completely clear skies.

sirthaddeus: what is the zenith?

Bill: It's the point in the sky straight overhead.

(Moderator Jason): We've got about bit over five minutes left for the last few questions...

ulfroland: Has any Perseids been seen or photograped from ISS?

Bill: No, but we have Perseids photographed from the Space Shuttle Discovery in 2001.

sirthaddeus: Are any other meteor showers expected to be as good this year?

Bill: The Geminids in mid-December, if you can stand the cold!

Jimmy: What is the radiant point?

Bill: It's the point from which the shower meteors appear to originate. It's called the radiant because the meteors appear to "radiate" from it.

MagaM: How aproximate long can be meteor?

Bill: A meteoroid is just a mm to a cm across. The streak of light it produces can range from the length of a battleship to miles.

JBlove: Are you excited for this?

Bill: Yes, I am. I always look forward to the Perseids. This year it will hopefully be clear in Alabama.

jbazza9: Where's the live stream?

Bill: It will be embedded on this page right after the chat ends.

jack: How do the meteorites gather the speed to stay in orbit?

Bill: Because meteoroids start off being part of the comet and when ejected, they keep that speed plus the little bit they get from being "kicked off" the surface.

(Moderator Jason): We've got a few minutes left for the last few questions...

jack: Are they moving faster or slower than the earth?

Bill: Perseids move faster than the Earth.

beaulieuv: Will those aboard the ISS be in any danger?

Bill: No.

gazer: Most of the news and website reports about the shower tonight quote times without qualifying the time zone. Should I assume that would be east coast time, and if so, what is the best viewing time range for us on the left coast?

Bill: Since the meteor rate is largely dependent on the elevation of the radiant, time zone isn't really a factor. Best time is just before dawn local time.

Space_Boy: Will you be outside watching the shower or will you watch it from the computer?

Bill: Watching from the computer! And doing the "up all night" web chat. :)

fiachre: What’s the composition of a meteor?

Bill: The Perseids are bits of ice mixed with dust from Comet Swift-Tuttle.

Erika: What determines the velocity of a meteor?? are they always traveling at a constant velocity?

Bill: No, a meteor slows down when it hits Earth's atmosphere because of drag.

riff: How large does a meteor need to be in order to actually crash on the surface of the earth?

Bill: It needs to be an asteroid. And the atmosphere protects us against most objects smaller than a football field across!

William_D: Thanks for the information Bill...

Bill: You're welcome. I appreciate all of the great questions. Don't forget, we'll be back here on this page at 11:00 p.m. EDT tonight for the "Up All Night" Perseids Web chat. And thanks to everyone for the great questions. We really want to hear from you in the overnight chat. Please stop in and chat about the Perseids!

(Moderator Jason): Thanks to all of you for the great questions, and thanks to our guest, Bill Cooke. Check back in the next day or two for a posted transcript of today’s chat. Be sure to check back here and join our “Up All Night chat tonight, starting at 11:00 p.m. EDT. Have a great afternoon. Remember to come back to this page for more info on the "Up All Night" web cast and chat: http://www.nasa.gov/connect/chat/perseids_2010.html and to see if you can see the Perseids yourself, visit this blog post: http://blogs.nasa.gov/cm/blog/Watch%20the%20Skies/posts/post_1281630596623.html
 
 
Janet Anderson, 256-544-6162
Marshall Space Flight Center, Huntsville, Ala.
Janet.L.Anderson@nasa.gov