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Geminids Meteor Shower: Nature's 'Holiday Light Show'
12.14.09
 
Star trails and a Geminid meteor over Brasstown Bald mountain, Georgia, in 1985. Star trails and a Geminids meteor over Georgia in 1985. Image credit and copyright: Jimmy Westlake The Geminids are one of the best meteor showers of the year and never seem to disappoint observers! Bill Cooke was online on Friday, Dec. 11, 2009 at 3:00 p.m. EST and for over 90 minutes fielded numerous questions about this year's Geminids Meteor Shower. Many thanks to everyone who joined us for today's chat.

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Transcript

(Moderator) Brooke: The chatroom is now open! This is a moderated chat. Please stay on topic! Our topic today is the 2009 Geminids meteor shower. Bill Cooke of the Meteoroid Environment Office at NASA's Marshall Space Flight Center will take your questions. Welcome back, Bill! What advice can you give us about seeing the Geminids this year?

Bill: Anywhere on the planet after 9:00 your local time on Sunday night, also on Monday night. Best time is right around midnight. Doesn't matter where you are, but some places may be a lot colder than others. :)

Hello: hi bill it is really great to see you again....what's different about this shower as compared to lenorads

Bill: The Geminids are a much more spectacular shower! The meteors are slower, very bright toward the end of the shower. You'll see (hopefully) many fireballs.

yasemonkey: what meteor does this shower originate from

Bill: The Geminids originate from an asteroid called Phaethon. Most meteor showers come from comets, but the Geminids come from this asteroid, and that makes them unusual.

Lilbrowneyes: where is a good place to watch the meteor shower on december 13-14 in florida

Bill: Anywhere with clear skies, after 9:00 p.m.

(Moderator) Brooke: This is a moderated chat. If you haven't seen your question answered yet, please wait a moment as it is in the queue to be answered. Many thanks for your patience.

Davidgojr: When outside observing, I've seen meteors streak across the sky in many different colors. What are the most common colors seen and what elements cause these colors as the meteors are heated in their journey through the atmosphere?

Bill: Greenish color is caused by ionized oxygen. Yellow typically is from sodium.

TXSpotter: Hi Bill! My question is, since the meteor rate has been going up decade after decade, do you think there is an indication that the meteoriods are getting larger and if so, do you think they could land on Earth?

Bill: No, the Geminids aren't getting larger. We're just running into more of them. :) Possible since Geminids come from a rocky asteroid that a large Geminid could make it to the ground.

KENOBI: Besides triangulation of the radiant, how do you tell a Geminid meteor from any other meteor?

Bill: If the meteor trail appears to come from radiant, then odds are good it's a Geminid. But you need triangulation to be absolutely sure.

Bostonshow: have they mapped the thicker fillaments like the leonids?

Bill: No…the Geminids have resisted attempts to model them in a computer.

Michael_C.: Hey Bill. Why do you think the strength of the Geminids Meteor Shower increased through most of the 20th century peaking at nearly 80 per hour by the end of the 20th century?

Bill: Because the Earth is now passing through the denser part of the stream. Jupiter's gravity has pulled the stream toward Earth and eventually will pull it away from the Earth.

RadDad: What size are the particles of the meteoroids? Sand grains, pebbles, larger...?

Bill: Sand grains to pebbles.

Fearwidg: Thanks for doing this.

Bill: You're welcome! :)

Fearwidg: You think we'll see more Fireballs this year?

Bill: Possibly. The Geminid fireball rate does vary year to year, hard to tell in advance.

depp: what happened to the asteroid to make it break up?

Bill: It's still there...but something happened about 1,000-2,000 years ago to create the Geminids we see, possibly a collision with another object. Or, the asteroid spun so fast that it threw off pieces of itself.

RadDad: How big does an object need to be to survive the ride thru the atmosphere?

Bill: A rocky object needs to be yards across to survive the atmosphere.

Erin: What makes the Geminids brighter than the Leonids? Does it have to do with the relatively recent creation of them?

Bill: Geminids are brighter because they're denser (rocky). As a result, they penetrate deeper into the atmosphere and this enhances brightness.

mythologymaster: I live in Wisconsin, when I be able to see the meteors?

Bill: Anywhere with clear skies, after 9:00 p.m.

lilbrowneyes: i heard it had to be in a dark place with no light around? can i just watch it in my backyard

Bill: If it's dark, yes. :) If many streetlights around, probably won't see many Geminids.

yasemonkey: what direction will the meteors be moving

Bill: Down :) Seriously, they'll appear to come from the constellation Gemini.

mythologymaster: will the meteors be very big?

Bill: Sand grains to pebbles

AskyFullOfStars: How much is known about Phaethon? It was once a comet?

Bill: Its nature is still in debate. Some astronomers insist it is and always has been an asteroid. Others point to the Geminids and suggest it's an extinct comet nucleus (a "dead" comet).

bostonshow: Approximately how many Geminids will reach the ground?

Bill: None in recent years.

(Moderator) Brooke: This is a moderated chat. If you haven't seen your question answered yet, please wait a moment as it is in the queue to be answered. Many thanks for your patience.

Daniel_Parra_Vento: in a city reduces the number of meteor per hour?

Bill: Yes, city lights substantially reduce the number of meteors seen.

mythologymaster: when the meteors go in the atmospher, do they spin?

Bill: They can spin -- tumbling is a better description. As they burn up, they probably orient themselves like a space capsule.

jaypatrikar: Hi Bill!! I live in Central India… can i get expect an awesome show?

Bill: You can expect as good of a show as anyone else. :) about 100 meteors per hour.

Erin: Is a reason known why showers that form from asteroids are rarer than ones from comets?

Bill: Yes. Comets shed material every time the go around the sun, and the Earth can run into this stuff. Hard to get material off an asteroid -- there can be a collision, or in the case of a "gravel pile" asteroid, they can rotate fast enough to throw off pieces.

Davidgojr: What speed are the Geminids traveling relative to the earth when they hit the atmosphere?

Bill: 35 km/second, or 80,000 mph

mythologymaster: what time can I see them in the sky?

Bill: Anywhere with clear skies, after 9:00 p.m.

Michael_C.: Thanks for taking our questions. Has the Geminids Meteor Shower ever posed a threat to any manned or unmanned American spacecraft?

Bill: There is always a slightly increased risk during the Geminids, BUT I'm not aware of any spacecraft taken out of action by one. Harrison Schmidt, the Apollo 17 astronaut, probably saw a Geminid hit the moon while orbiting it in December of 1972.

yasemonkey: what colors will most of the meteors be

Bill: White, some appear yellow or green

depp: do any of the geminids land?

Bill: No

KENOBI: Why can't you model the Geminids with a computer?

Bill: Because we don't understand how they were thrown off Phaethon.

lilbrowneyes: can i watch the meteor shower in my back yard?

Bill: Yes. Anywhere with clear skies, after 9:00 p.m. Make sure no street lights.

JJ: When is the next Shower going to happen

Bill: Quadrantids in peak on January 3.

redbodb: How does a "fireball" differ from the normal "streak" to which I believe myself accustomed?

Bill: A fireball is a BRIGHT streak, typically brighter than Venus.

Fearwidg: Is there a preferential time to see Fireballs? Leading edge of the debris stream? Centre/center? (I'm Canadian <g>) Trailing edge?

Bill: In the case of the Geminids, more fireballs are seen close to or after the peak. You might see more on Monday night.

Davidgojr: Are sounds sometimes heard as meteors like the Geminids streak through the atmosphere? If so, how large do they have to be to do this?

Bill: There are reports of low frequency -- electrophonic -- sounds from meteors. Hard data is not available. Many people who see extremely bright fireballs report hearing a sonic boom.

AskyFullOfStars: How are scientists able to predict peak rates from year to year? How do you know where the stream is, and how dense it is?

Bill: We know where the meteors come from, and in most cases, know how they're ejected. So, we track the particles in a computer until they intersect Earth. By counting the number of particles intersecting Earth as a function of time, we can determine the peak. It takes a long time -- days to months -- to do these calculations, even on fast computers.

Erin: Was it hard or easy to discover that Jupiter was the reason that the Geminids were increasing in strength, by moving them closer to Earth?

Bill: It was first noticed in the 1950s by a meteor scientist named Petr Pravec. He didn't even have a computer!

jaypatrikar: while wacthing meteor shower.. should we see at radiant or away from it?

Bill: Any meteor close to the radiant will have a very short trail. The farther away from the radiant, the longer the meteor trail. A meteor coming exactly from radiant will have no trail at all (point meteor).

mythologymaster: how many meteors will there be per hour

Bill: About 100/hour in a good dark sky

bostonshow: I forget the exact term but I've seen a couple that whistle when streaking across the sky...atmosphere grazers...are some storms suited better to this phenomena?

Bill: The Leonids in outburst are noted for producing very bright fireballs and there have been reports of noise associated with them.

Space_Buddy: I live in Iowa, the weather for the weekend is going to be cloudy, what can I expect if I watcg tonight while its clear?

Bill: Tonight, you'll see a FEW Geminids. Our cameras here at Marshall saw three last night. Should be a few more tonight.

Copernicus: Could any of the particles damage or destroy any of our satellites?

Bill: Odds are very low

rocketman44: My question is: could there be a large meteoric fragment hiding in the Geminids?

Bill: If you mean the size of a mountain, no. If you mean the size of a basketball, possibly.

ebkennedy: Is there a specific peak during the evening of Dec 13-14? Any advice for taking first-time viewers out (beyond warm drinks and bundling up!)?

Bill: Predicted peak is around 11:00 Central Time on the night of Dec. 13, but you may have to wait until midnight or 1:00 to see the most meteors. This is because the radiant needs to be high in the sky at your location. Warm drinks and bundling up are advised! :)

depp: thank you for your time

Bill: My pleasure!

maxb: hi bill, what determines the color of the meteors? i saw one last night and it looked really green.

Bill: Green indicates ionized oxygen, and the colors are produced by the different types of air molecules excited by the meteors' ablation.

lilbrowneyes: how are meteor showers created? i REALLY want to do astronomy for my career please tell me anything about our atmosphere, meteor showers anything , please. !

Bill: Meteor showers are caused when Earth runs into a stream of debris left behind by a comet or asteroid. If you want to be an astronomer, take lots of math and physics!

mythologymaster: will the meteors be blue? I saw one that had a sort of blue halo surrounding it

Bill: Different eyes interpret colors differently. I have seen meteors that looked white to me, when others saw a distinct yellow cast. Depends on your color perception.

Jimmym: What would the approximate relative speed be?

Bill: 80,000 mph/ 35km/second

yasemonkey: how many meteors per hour excpected

Bill: 100 per hour in dark skies

Erin: Since the Geminids come from an unusual, and possibly short term source, might they "burn themselves out" sooner than other showers?

Bill: The Geminids stream is being pulled away from Earth's orbit by Jupiter's gravity, and some researchers have suggested they will be gone by 2100 A.D.

jaypatrikar: can meteors be seen from india?

Bill: Anywhere with clear skies, after 9:00 p.m.

lilbrowneyes: how can i tell if im looking at a planet or a star?

Bill: The old adage that stars twinkle, planets don't can sometimes be used. Best way is to consult the Internet and find out where the planets are located.

mythologymaster: can they bounce off of the atmosphere?

Bill: Very few do. A big one bounced off the atmosphere over Utah in the 1970s.

Will the Geminids be visible from the Northeastern United States?

Bill: Yes. Anywhere with clear skies, after 9:00 p.m.

(Moderator) Brooke: Remember, if you don't see your question right away, it may be in queue. Please allow the queue enough time to catch up so you can see your question/answer!

Fearwidg: Are you after hourly counts? Started doing them when I was 9. I'm now 61. <g> Or have all-sky cameras, etc. made that manner of data-gathering obsolete?

Bill: Hourly counts are still valuable! Go to www.imo.net to find out how to submit your data to the International Meteor Organization.

Guest22: Why are the meteors from this shower increasing and becoming brighter?

Bill: We're passing through the denser part of the stream and the brightness of the Geminids varies year after year. Some years are brighter than others. The numbers are Geminids are increasing, but the average brightness remains roughly the same.

yasemonkey: what creates a fireball and what’s the difference between that and a meteor

Bill: A fireball is a very bright meteor, usually the size of a pebble or larger. A meteor is usually called a firebally if it's brighter than the panet Venus (magnitude -4).

Erin: If an near-miss asteroid were to be affected by humans in an explosive way to drive it farther from Earth, could that create a new shower? Or is there more to it than that?

Bill: If the explosion produced debris in an orbit that would intersect Earth. Better to talk to the asteroid office at JPL and they do the really big rocks. :)

AskyFullOfStars: So, asteroid collision 1000-2000 years ago and dormant comet are two separate theories? Is there any method by which scientists will be able to know for sure? Would a Phaethon mission help to answer that question?

Bill: Yes, they're two separate theories. And, hard to determine which is right. We need to get more data on Geminids before we can get an answer. A mission to Phaethon would obviously be helpful, but the asteroid passes 3x closer to the sun than Mercury.

RadDad: To what degree will the material remaining in the atmosphere after the meteors burn contribute to climate change / global warming ?

Bill: No effect

jimmyjr25: are they visible tonight or Saturday night just at lower occurences?

Bill: Yes, much lower

mythologymaster: are Geminis usaully thick, wide, or both

Bill: The meteor itself is a very small particle, but the trails of ionized gas they leave behind can be kilometers (miles) long.

Guest22: Is this meteor shower unique in that it has various color streaks?

Bill: No, most major showers have colored meteors associated with them.

AskyFullOfStars: Is it possible to see brighter meteors through thinner clouds, haze for example?

Bill: Yes, it is. I have video of some of those.

jeff44663: About how hot do the meteors get as they pass through the atmosphere? Is it comparable to, say, a returning space shuttle (which I've heard the exterior reaches about 3,000 degrees)?

Bill: About 3,000 degrees F is correct.

KENOBI: Do you personally model meteor streams/showers?

Bill: We do in my group. A colleague of mine runs the stream model. I generate the forecast.

Daniel_Parra_Vento: today there will be meteor shower ?

Bill: The Geminids are underway as we speak. Just at very low rates.

Erin: Does the gravity fields of other planets affect the meteor showers of Earth? Or does Jupiter's strong gravity negate most of any other sources?

Bill: Other planets such as Saturn influence the orbits of shower meteors but you're right in that Jupiter has the greatest effect.

Fearwidg: The Geminids always seem so much slower than the Perseids or Leonids. Is that because we're "catching up" to the stream instead of running "head-on" into the debris trail?

Bill: Yes

mythologymaster: is there any way you can guess how fast they are going by how big they are

Bill: Yes, by triangulating -- using two or more cameras that observe the same meteor at the same time.

NASA2009: Good Afternoon, Bill! What kind of a camera do you recommend to take pictures of the GMS with?

Bill: Suggest you go to the meteor galleries at spaceweather.com and note the cameras used to take some of the pictures there. Good images can be obtained with a variety of equipment.

Swhite: So the lowest one will get is probably 15 miles up into the atmosphere?

Bill: Lowest we have seen in the past few days burned up at an altitude of 37 miles.

AskyFullOfStars: How long does the Geminids peak last?

Bill: Two days.

Guest22: Have other planet's gravity affected this stream?

Bill: Jupiter's gravity is by far the strongest influence on the Geminids, but other planets -- Earth and Venus -- do exert some influence.

Michael_C.: Aside from Harrison Schmitt on Apollo XVII, has the Geminids Meteor Shower been observed by other Astronauts in space? Thank you.

Bill: Shuttle astronauts have seen Geminids in Earth's atmosphere. Don't know about astronauts in the Apollo/Gemini/Mercury programs.

Ortensio: What about using huge binoculars to watch Geminids?

Bill: No...you want to use your eyes as this gives the widest possible field of view. Field of view is everything when observing meteor showers.

lilbrowneyes: how are meteor showers formed?

Bill: Meteor showers are caused by debris shed by comets and asteroids. The particles orbit the sun and we get a meteor shower when the Earth collides with the debris.

mythologymaster: can you hear meteors after they get through the atmosphere? like if they are going the sound of sound.

Bill: Some people have reported sonic booms from very bright fireballs, like the one over Utah last month.

Erin: Why are fireballs more likely to be seen after the peak than before it?

Bill: Observations suggest we encounter bigger Geminids later in the shower and a meteor's brightness increases with size.

ebkennedy: Bill, for those who haven't seen fireballs before/wonder what they are like compared to normal meteors, this might be a decent link to post: http://apod.nasa.gov/apod/ap091015.html

Bill: Thanks for the link!

Guest22: Is it known how much "star dust" will fall to earth as the result of this shower?

Bill: I haven't seen any calculations on the amount. It could be done.

jimmyjr25: Can you see any tonight or tomorrow night around midnight? Kind of a pre-show?

Bill: You'll see a few tonight

Swhite: oh note not a question - saw a giant fireball go from south to north across eastern oklahoma about 1973 and it sounds like your hand continually going thru a hard piece of styrofoam contantly and it was really green. Big one.

Bill: You're lucky. I haven't seen anything like that.

hsd: When there's a meteor shower going on, what kind of data and information is NASA trying to gather?

Bill: we are interested in the size, density, and flux -- number of meteors per unit area per unit time -- of shower meteors. This information helps us calculate the risk to spacecraft.

jaypatrikar: what is the average magnitude of a Geminid?

Bill: I'm not sure. Possibly a magnitude of 0.

mythologymaster: was it a Gemini that hit Jupiter months ago?

Bill: No.

johnawad1: can i see it in lebanon in the middle east?

Bill: Anywhere with clear skies, after 9:00 p.m.

(Moderator) Brooke: Remember, if you don't see your question right away, it may be in queue. Please allow the queue enough time to catch up so you can see your question/answer!

AskyFullOfStars: Will NASA be monitoring the Moon for lunar Geminid impacts?

Bill: The moon will be new, and we start observing the moon a couple of days later. The moon is too close to the sun during the Geminid peak.

Erin: What kinds of computers do you run the shower predictions on?

Bill: The fastest ones we can find! :) 64-bit desktop PCs. LOTS of them.

jagoboots: is it possible,that micro meteors could be a danger to future space travel

Bill: Meteors always pose a danger, but it's usually small compared to other risks, like that posed by space debris (space junk).

ceilib: what is your favorite part of being a meteor scientist?

Bill: Waking up in the morning and having data in my email without having to lose sleep or freeze my tail off during the night. :)

Pumpkin: What makes them appear white, orange, green, etc? Do we know precisely what was the composition of the meteor?

Bill: The colors are caused by the air molecules excited by the meteors as it ablates. And meteors have different compositions. Geminids are rocky, while Leonids are like little dirty ice crystals. It's hard to measure the composition of a meteor unless a piece of it survives to the ground.

AskyFullOfStars: I've read that sometimes scientists fly higher altitude flights during meteor showers. What kind of knowledge is gained from these "up-close" observations?

Bill: NASA scientists at JSC will fly high-altitude missions to collect meteoritic dust in the atmosphere, which can be studied in the laboratory. We get density and compositional information.

Davidgojr: You've mentioned that air molecules are largely responsible for meteor color. Does the composition of the meteors also play a role?

Bill: It can, but given that the meteor is so small, this is not usually the case. Pebble-sized rock, mile-long ionization trail. Which one would you think will determine the color?

johnawad1: what's the average size of a meteor hitting earth from Geminids? and the size of the biggest one?

Bill: Geminids are generally 1 mm in size and smaller. I have no idea what the biggest recorded Geminid size might be. I'm guessing the size of a basketball?

jaypatrikar: what is going to be the peak hour in india?

Bill: The peak is December 14th at 5:00 a.m. GMT. You'll have to convert to your local time for the peak.

tbfan64: Why is the Geminids increasing and will it continue to increase throughtout the 21st century?

Bill: Jupiter's gravity has pulled the stream so that it now intersects Earth's orbit. Some modelers predict an increase in Geminids rates for the next several decades, maybe getting as high as 200/hour, whereas other models indicate the Gems may soon start to decrease.

Space_Buddy: Are there any websites with an all sky camera that can be watched during the peak period?

Bill: Actually, if you come to this page, there will be a link to a live Allsky camera that will be watching the skies over Huntsville, Alabama. Link is: www.ustream.tv/channel/marshall-space-flight-center

Guest22: Can we expect a magnitude range for these meteors?

Bill: Geminids range from magnitude 4 to -4, maybe some brighter.

Erin: Does Jupiter's gravity affect other meteor showers like it does the Geminids?

Bill: Yes. It influences the Leonids, too.

GodlessPeace: How many meteors will we see for the Capital city of Canada which is OTTAWA, in case you dont know?

Bill: 100/hour ANYWHERE in Canada with clear, dark skies.

goldfishpondmaster: what part of the world will have the best view

Bill: Anywhere in the Northern Hemisphere will have a good view, weather permitting

Angie: can the Gemenids be visible in Central Florida?

Bill: Yes. Anywhere with clear skies, after 9:00 p.m.

kc5eqm: Since there will be a New Moon would this be a good time to look for Moon impacts from a backyard tellescope

Bill: No, the moon is too close to the sun. You'll have to wait a couple of days after the peak before looking for impacts on the moon.

ceilib: how many meteors might i see if i look saturday night/sunday morning?

Bill: Up to 100/hour

jaypatrikar: till when will geminids be visible??

Bill: You'll see them Saturday and Sunday nights, after which the numbers will fall off.

Erin: A previous question mentioned hourly counts, which sounds fun. What can ordinary people do to help meteor science?

Bill: Hourly counts, being careful to estimate the brightness of the meteors and whether or not it is a Geminid are very valuable data.

Michael_C.: When the Geminids Meteor Shower was first noted in 1862 in Manchester, England did observers know it was a Meteor Shower or did they think it was something else? Thanks!

Bill: They noted a minor meteor shower, so yes, they did realize there was a shower going on.

(Moderator) Brooke: Remember, if you don't see your question right away, it may be in queue. Please allow the queue enough time to catch up so you can see your question/answer!

AskyFullOfStars: The Geminids are a fascinating shower, with their comparatively new discovery, unusual parent body, and steady increase. Do they offer scientists a better or different kind of learning opportunity about the nature of meteor showers, as opposed to "older" showers?

Bill: They're puzzling because they originate from an asteroid. We're still scratching our heads over why.

GodlessPeace: Is the space staion in any danger or satelites even?

Bill: The ISS is armored, so the danger is extremely small. Satellites aren't likely to be hit by a Geminid.

Pumpkin: How do you count the number of meteors per ours? Can we be sure that when they were first observed people at the time weren’t counting less of them and started seeing more as the science evolved?

Bill: Go to www.imo.net and check out their information on how to observe meteor showers. As far as historical observations, it's difficult to account for observer biases and possible bad technique.

jaypatrikar: which is the most impressive meteor shower of year...???

Bill: The Geminids, if you can stand the cold. :)

AskyFullOfStars: Phaethon, the parent body of the Geminids, is a known near-Earth-object (even a PHA - potentially hazardous asteroid). What is the closest that it has passed our planet?

Bill: I'm not sure. Don Yeomans at JPL could give you that answer. He's the Near Earth Objects( NEO) guy!

Guest22: Is there any chance of an unforseen outburst, 500 per hour?

Bill: No, not with the Geminids.

Erin: Thanks for taking the time to answer all our questions! :) Are there any interesting reactions between meteors and high-level clouds? Or are they too far apart to meet?

Bill: Probably too few meteors, but you would need to talk to an atmospheric chemist. I avoided chemistry like the plague in high school and college. :)

johnawad1: when is the highest rate of geminids meteors hitting?

Bill: Peak is 11:00 p.m.CST on Dec. 13. Highest visual rate should be a little after midnight.

Luiz: I live in Southern Hemisphere, can I watch the Geminids Meteor Shower?

Bill: If you can see the constellation Gemini, you can see the Geminids.

RadDad: Bill, is the 3000° F (see jeff's ?) some form of limit? The shuttle doesn't fly at 80,000 mph... slower ~27,500 (?). Is the temp a function of both mass & speed?

Bill: Yes. Temp depends on kinetic energy, which is a function of both mass and speed.

Davidgojr: How high above the earth are the visible light emitting meteor trails? At what altitude does the cooling effect of the denser atmosphere cool the meteors so they stop producing light?

Bill: Geminids are typically seen starting at heights of 60 miles/90 km and are no longer seen at heights of about 40 miles/60 km.

mythologymaster: if a meteor hit the earth and it was the size of a basketball, would it make a little explosion or just a large hole in the ground?

Bill: It would not make it to the ground, but would produce a very bright fireball in the sky.

virgo10: What determines when a meteor shower becomes a meteor storm?

Bill: If the rate of meteors exceeds 1,000/hour, we have a meteor storm.

Guest22: What percentage of the entire debris stream impacts Earth's atmosphere?

Bill: I'm not sure. We don't know exactly how many particles make up the Geminids meteor stream.

jesusfan1: Dear Bill- The article mentions the rate per hour of meteors has been increasing over the years- is there any idea why it has been happening? This year projections are for 100+ per hour? Thanks

Bill: yes. Jupiter's gravity has been pulling the densest part of the stream toward Earth, and that's why the rates have been increasing.

Angie: Can the Geminids be seen saturday night in Central Florida?

Bill: Yes, if it's clear

AskyFullOfStars: Will you give us a few moments to save this chat before closing it at session end? Very good information here.

Bill: We'll be posting a transcript on Monday, so that should help. :)

jaypatrikar: do geminids fall on moon too? can they be seen falling on moon?

Bill: yes, they do. What you will see is the flash caused by the explosion when the Geminid hits the lunar surface.

mythologymaster: would a meteor start a fire if it landed on dry wood, or slam the out of existance

Bill: meteors that strike the ground have been known to cause fires. Don't expect that to happen during the Geminids.

Guest22: Will NASA be watching/moitoing the moon for impacts?

Bill: We will start observing a couple of days after the peak. We MAY see a Geminid or two strike the moon.

mythologymaster: can the Mars rover observe meteors from a different angle with special cameras?

Bill: The rovers have cameras that are great for taking pictures on Mars, but they aren't very good for meteor observing. We tried using them a couple of year ago and didn't see anything.

BobJohnson: Where is the Geminds Meteor shower?

Bill: In the sky. :) You can view anywhere with clear skies, after 9:00 p.m.

SAT12: Will the ISS crew be observing the shower?

Bill: I know of no official plans, but they may see Geminids if they look down at Earth through one of the windows.

Daniel_Parra_Vento: with the lights of the city as many meteors can be seen

Bill: No -- need clear, dark skies

Lured: Hi. My question is: is there evidence of increased meteor showers activities in general in the last 1000 years. i.e. does earth these days have more intensity of meteor showers in terms of numbers and intensity due to increased visits by comets near earth orbit?

Bill: Given that scientific meteor observations didn't start until 1833, it's not possible to answer that question. I seriously doubt that the total number of meteors striking Earth on an annual basis has changed very much over the past few centuries.

Tiberiu: how large are the largest pieces ob debris in the geminids?

Bill: Most are smaller than 1 mm, some may be several centimeters in size.

BobJohnson: Oh far can you be to watch the Geminids

Bill: Anywhere with clear skies, after 9:00 p.m.

hamandbacon: Bill, Is there information on the web as to when and how to listen to meteors by radio? Thanks!

Bill: Yes! Go to meo.nasa.gov and click on Outeach. We have a description on how to put together your own meteor radar.

Guest22 : Will NASA will monitoring the moon for impacts?

Bill: Yes, a couple of days after the peak

thewiz: What material are the Gems made of... stony or iron in nature? Thank you Bill

Bill: Stony. Density around 3 grams/cubic cm

jimmymac_205: what is the biggest Geminid on recod?

Bill: I'm not sure.

Michael_C.: Bill, do you think this sky map would be useful to observers? http://science.nasa.gov/headlines/y2009/images/geminids2009/skymap_north.gif

Bill: Yes, very helpful!

Lured: If a meteor shower results due to non-periodic comet, for how many years we expect that metoer shower to last?

Bill: A non-periodic comet should not produce a meteor shower.

BenT: Have you seen the Geminids shower before?

Bill: MANY times. :)

Luiz: People in Southern hemisphere can see the Geminids?

Bill: If you can see Gemini, you can see the Geminids

Guest22: Bill, I've read that you can hear static for the meteors on FM frequencies, true?

Bill: Some amateurs use FM radio stations to detect the ionization trails of meteors, so yes.

Erin: Why might bigger meteors be encountered later in the shower? Could it be due to Jupiter's gravity not holding as much sway over the trajectory of higher mass objects?

Bill: The smaller particles are influenced more by non-gravitational forces such as solar radiation pressure, whereas the big ones are dominated by gravitational influences. This can cause a size gradient in the stream.

mythologymaster: what are the chances that me and my brother and Dad will be able to see big ones on Sunday?

Bill: If the weather forecast is good and sky is dark, you should see some bright Geminids.

(Moderator) Brooke: Well, we've got about 5 minutes left in the chat, so we've got time to answer a few more questions.

jaypatrikar: Thanks Bill for taking our questions.. you are really great..

Bill: Thank you! :)

BobJohnson: Will it be seen in Chicago

Bill: Anywhere with clear skies, after 9:00 p.m.

jimmymac_205: What is the Geminids light show and how will it effect earth?

Bill: The Geminids are caused by the Earth running into pieces from the asteroid Phaethon. Other than a nice light show, there will be no effect on the Earth.

mythologymaster: will the meteors be coming from Orian or more from the north star.

Bill: Meteors will come from the constellation of Gemini.

Luiz: Can I see it in Brazil in the capricornian tropic?

Bill: You should be able to see the Geminids from there.

Erin: Was NASA's meteor group set up to observe for science or spacecraft risk?

Bill: Spacecraft risk.

AskyFullOfStars: You noted that Geminids reach about 3000F traveling through atmosphere. Do faster meteors reach higher temperatures? Or is that average temperature for most meteor showers?

Bill: Faster meteors of the same size can reach higher temperatures depending on composition.

RadDad: Does the International Space Station take any action due to this meteor shower (or other showers / events)?

Bill: Not for the Geminids. During meteor storms, the astronauts don't go outside. No spacewalks.

Lured: Are there days during the year where there are no meteor showers at all even showers with very low intensity?

Bill: Yes. Mid-February has very little shower activity.

Brooke(P) We've got time for just 2 more questions before we wrap up here today.

Daniel_Parra_Vento: meteor shower can be heard on the radio? that often?

Bill: Yes. A simple ham radiocan be set up to hear over 1,000 meteors per day. Most of these are are background meteors not belonging to any meteor shower.

suleyman: i live in england doncaster what time should i look at the sky ?

Bill: Anywhere with clear skies, after 9:00 p.m.

mythologymaster: how hard are meteors comparing them to things on earth

Bill: Geminids are like pieces of rock. Leonids are like little bits of ice.

Leonardo: Before the 1860 there is no record of Geminids meteor shower at all?

Bill: There is a possible report of Geminids from a Mississippi river boat in 1834.

(Moderator) Brooke: