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NASA Chat: Observe the Moon!
September 16, 2010

A crescent moon, backdropped against the blackness of space A waning crescent moon is featured in this image photographed by an Expedition 24 crew member on the International Space Station. (NASA)

A crescent moon, seen in the glowing edge of the atmosphere A setting, waning crescent moon amid the thin line of Earth's atmosphere. (NASA)

More Information
Worldbook@NASA: Moon
Link: NASA Moon Facts
Link: Moon FAQ
Link: Lunar Impacts
The moon is the Earth's nearest celestial neighbor and a geologic wonderland. There are mountains that are many miles high, lava flows several hundred miles long and enormous lava tubes and craters of every size. It is the brightest object in the night sky and has profoundly influenced the course of human civilization.

For early humans, the moon provided lighting for hunting and defined when crops should be planted and harvested. Markings of lunar phases appear in cave paintings in France and defined the arrangement of Stonehenge.

The 2010 International "Observe the Moon Night" is happening on Saturday, Sept. 18. On Thursday, Sept. 16, Dr. Rob Suggs of NASA's Marshall Space Flight Center in Huntsville, Ala., answered your questions about the moon and National Observe the Moon Night.

About Chat Expert Dr. Rob Suggs

Dr. Rob Suggs is the Space Environments Team Lead in the Engineering Directorate of NASA's Marshall Space Flight Center. For the past 4 years he has managed the NASA Lunar Impact Monitoring Project which has recorded over 200 meteoroid impacts on the Moon using telescopes at 2 observatories. He has a Ph.D. in Astronomy from New Mexico State University (NMSU) and was part of the NMSU team which attempted to record the LCROSS spacecraft impact on the Moon last October.

Chat Transcript

Rob: Hey everyone, welcome to the chat! We're finishing up some last-minute details and will get rolling at the top of the hour.

(Moderator Jason): Welcome to today's web chat with NASA astronomer and space scientist Dr. Rob Suggs. Our topic today is the moon, Earth's nearest celestial neighbor and a geological wonderland. In today's chat, we're going to focus on what Rob sees as he's observing the moon – and he does a lot of that since he's involved in lunar impact monitoring. Please remember to stay on topic! This is a moderated chat. It may take a few moments for the queue to catch up to your questions, so please don't leave if you don't see your question right away.

Rob: Hey everyone, the chat is open now. Welcome - please remember to stay on topic. This is a moderated chat. :)

rwerka: What further images of the Apollo 17 area, especially the crater Nansen, have been taken by various spacecraft, including LRO?

Rob: The NASA LRO site has images of all the Apollo landing areas. www.nasa.gov/lro is the link. Or lunar.gsfc.nasa.gov. The Apollo hardware is clearly visible in these images. :)

Moonstructure: Where can i find detailed highres pics from backside of the moon?

Rob: The NASA LRO site has images of the moon. www.nasa.gov/lro is the link. Or lunar.gsfc.nasa.gov has good images, too.

Akarsh_Valsan: I have heard that moon has no atmosphere. Is that true?

Rob: It has a very tenuous atmosphere that's very difficult to detect. That's part of the purpose of the landing mission, LADEE, which will launch between 2012 and 2013. www.nasa.gov/lunarquest has more information.

Akarsh_Valsan: What is the sea of tranquility?

Rob: It's a basin or mare. It's an impact basin which is filled with ancient lava flow and basaltic material.

kheervani: Hey! Actully what would have happened if there was no moon?The orbit where there would have been zero gravity would have been shifted towards which planet?

Rob: It would make the rotation of earth more chaotic and the poles and tides could change (not as much tidal activity, only solar tides). Some might argue this would make it harder for life to arise.

kheervani: Is the texture of the soil on the moon similar to that on the beach sands?If so wouldn;t it be quite difficult to actually set up labs for research over there?

Rob: It's probably more like the texture of flour - it's really jagged and sharp, but fine and sticky. There's no erosion to round out the particles. Lunar dust mitigation is a huge area of study.

Akarsh_Valsan: Who was the first person to observe Moon by a telescope?

Rob: Galileo, traditionally.

(Moderator Kim): Please remember to stay on topic. This is a moderated chat and it may take a few moments for the queue to catch up to your questions, so please don't leave if you don't see your question right away.

mangalrahul: I want to know is this true that there is black hole in moon south pole?

Rob: There are permanently shadowed regions near the lunar poles, but that's very different from the astronomical definition of a black hole.

(Moderator Jason): We're working to answer your great questions. 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.

A_Sky_Full_of_Stars: Do you have much opportunity to observe the Moon from your own backyard, through binoculars / telescope? What are your favorite lunar features to observe?

Rob: It's very easy to observe many features on the surface of the moon using binoculars or a small telescope. We use 14" telescopes to observe meteoroid impacts on the moon. A small telescope will show lots of craters, mountains, ridges, domes, and other interesting features. http://en.wikipedia.org/wiki/Observing_the_Moon My favorite lunar feature Aristarchus, because it's the brightest crater and has an interesting rille next to it.

Dell_Conagher: What got you interested in observing lunar impacts?

Rob: We were interested in the risk to astronauts and robotic equipment from the ejecta thrown up by meteoroid impacts. We've found that it's teaching us a lot about the meteoroid environment in general.

Akarsh_Valsan: As you told, we know there is no atmosphere on the Moon, and since there is no air, there is no wind. Yet how is the American flag fluttering in the wind on the moon?

Rob: This would be a good link for that. :) Debunking the Moon landing hoax: http://en.wikipedia.org/wiki/Moon_landing_conspiracy_theories

A_Sky_Full_of_Stars: Not "as much" tidal activity if we had no Moon? This means the Moon is not solely responsible for Earth's tides?

Rob: That's correct. The sun also contributes to the tidal activity on the Earth.

Akarsh_Valsan: Sir, as you answered my question " Who was the first person to observe moon by a telescope" as Galileo but my father says that some people in the world still argue that it is an english scientist Thomas Harriot. What is your opinion about this?

Rob: That's also a possibility.

(Moderator Jason): Really good questions so far. 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.

Dell_Conagher: What was the largest impact that you have ever observed?

Rob: We think the smallest impactor we can see is about the size of a golf ball. The largest we've seen to date was probably about the size of a bowling ball.

Roberto: Was there the water on the moon?

Rob: Preliminary results from LCROSS show there was water in the permanently shadowed crater Cabaeus. Other orbiting spacecraft have seen indications of water as well. www.nasa.gov/lcross

A_Sky_Full_of_Stars: Have there been any significant lunar impacts in recent years, large enough to leave a new crater?

Rob: Yes, the impacts we see leave impacts of a few meters across.

Bass_Robot: What kind of telescope do I need to observe the moon?

Rob: Any telescope or binoculars can be used to examine lunar features.

mangalrahul: What was the result of probe impact done by NASA on Moon's south pole? Did they find anything?

Rob: Preliminary results were that there was water mixed with regolith excavated by the LCROSS impact.

NickDMax: Why does one side of the mood face us all the time, is there even a slow rotation or wobble of this?

Rob: Most of the mass concentrations are on the near side, which has caused that side to tidally "lock" to the Earth. There are some small oscillations in that. It does rotate once a month, which is the same length of time it takes to orbit around the Earth. Almost any moon around a big planet is tidally locked.

ezelz: How many foreign objects (large enough to leave a mark) strike the Moon's surface each year?

Rob: Honestly, that would depend on the size of the mark you're talking about. There are down to micro-craters, and the smaller you go, the more there are. There are about 5 per hour somewhere on the moon, down to the golfball size.

Dell_Conagher: Are there different classifications of impacts that you observe, or is the study still in mostly observation and data-taking phase?

Rob: We're studying the size distribution of the impactors and trying to determine if they're from meteor showers or from sporadic, background meteoroids.

(Moderator Kim): Rob is really enjoying your questions. Please keep them coming!

A_Sky_Full_of_Stars: Are there any formal opportunities for amateurs to contribute to the NASA Lunar Impact Monitoring Project?

Rob: Yes, go to our Web site to find out how amateurs can make the same observations that we make and provide data to us: http://www.nasa.gov/centers/marshall/news/lunar/index.html

Dzhon: Are lunar impacts a significant risk to future moon construction, such as research stations?

Rob: Our study of meteoroid impacts is providing data on the magnitude of the risk due to ejecta. We don't think it's a significant risk, but, it must be considered in the design.

kheervani: How far is the moon from the internatinal space station?Would it make it easy for astronauts to reach the moon from the ISS?

Rob: It would take an enormous (impossible) amount of fuel to get the space station to the moon, so that's not a feasible plan. It's 239,000+ (363,000 km) miles to the moon.

jamaha: Does the moon have any frozen water on it? Specifically where nasa crashed the rocket?

Rob: Yes, the water that LCROSS found was frozen and mixed with the regolith (Lunar Dirt).

A_Sky_Full_of_Stars: New craters? Awesome! Is there a map of those sites, and are they visible in smaller scopes, a 10" perhaps?

Rob: The craters are too small to be seen from Earth, but there is a map of the impacts on our Web site: http://www.nasa.gov/centers/marshall/news/lunar/index.html

kheervani: What is regolith?

Rob: Basically, lunar dirt. :)

Dell_Conagher: What signals an impact? Is it a bright flash recorded on video, similar to the recent Jupiter impacts?

Rob: Yes, it's a bright flash that can last from 1/60th of a second to about 1/2 second.

ndaringer: who was the first person to see the back side of the moon?

Rob: It was first photographed by a Russian spacecraft (1958, Luna 3). The first humans that saw it were the astronauts on Apollo 8 (1968).

tesetem: What power telescope would you recomend for the backyard observer to observe the moon?

Rob: The power (magnificaiton) isn't as important as the aperture of the lens for astronomical observations.The moon is so bright that you really don't need a large telescope.

Dell_Conagher: At what phase of the moon is it easiest to observe impacts? Is there a time when it is impossible?

Rob: We observe when the moon is between a cresent phase and quarter phase. (When it's full isn't the best time.) We need to look at the night portion of the moon, and this is when the night portion is the largest.

(Moderator Jason): We're working to answer your great questions. 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.

Andy: You say that there are about 5 impacts per hour......why didn't the Astronauts or their equipment ever get struck? Was it simply a matter of luck by being in the right place at the right time?

Rob: The moon is a large place and ejecta doesn't travel that far - so it was unlikely they would have been impacted by ejecta during their brief stay on the surface. However, Apollo 17 astronaut Jack Schmitt reporting seeing an impact from lunar orbit during his mission in 1972. The small meteoroids coming directly from space were considered in the design of the spacesuits and the lunar module.

Akarsh_Valsan: What does the interior of moon look like?

Rob: This would be a good link for that: http://www.spudislunarresources.com/moon101.htm

(Moderator Kim): Great questions everybody. We're trying to get to them, so please be patient.

NickDMax: How do you estemate the size of the meteor after the imact is observed?

Rob: We look at the brightness of the flash compared to stars in the field of the view of the moon and that gives us the energy of the light output. Then, we've done lab studies to relate the brightness of the flash to the energy and thus the velocityand mass of the impactor. The mass gives us the size.

Mlittlec: Is the only risk of impact related to meteorites and their ejecta? Or is there also a risk of impact from human objects?

Rob: That's a good question. There are very few manmade objects currently in orbit around the moon. The spacecraft operators have deliberately removed them from lunar orbit, so we shouldn't expect a problem with debris raining from the sky onto unsuspecting astronauts on the moon. :)

Akarsh_Valsan: Why do we see always one side of the moon facing us?

Rob: Most of the mass concentrations are on the near side, which has caused that side to tidally "lock" to the Earth. There are some small oscillations in that. It does rotate once a month, which is the same length of time it takes to orbit around the Earth. Almost any moon around a big planet is tidally locked.

Dell_Conagher: From the impacts that you have observed, how far does the ejecta typically travel?

Rob: We don't know for sure because it depends on the velocity of the ejecta, but theoretically, some particles could make it all the way around the moon. Most will only go less than a kilometer. It depends on how fast the impactor is going. where it strikes, and how large it is.

Akarsh_Valsan: Do we experience our echoe in the moon?

Rob: There's no atmosphere to carry sound waves, so there can't be any sound echoes.

Mlittlec: Wouldn't even the impact of a micro-meteor on an astronaut knock them over (due to the high speed it's travelling at)?

Rob: The suits are designed to break up small particles and vaporize them. It wouldn't transfer a lot of momentum, so I don't think it would knock an astronaut over - more likely it would penetrate the suit.

Akarsh_Valsan: Why do we say the full moon influence the animal behaviour?

Rob: That might be a better question for an animal psychologist. :)

Dell_Conagher: Could different compositions of meteoroids affect the brightness of the impact flash?

Rob: The density of the impactor, which is related to the composition, could certainly affect the brightness flash, but we haven't studied that yet.

krim: Since people have already been to the moon, why can't we just go up again like in the good 'ol times? Why would we need to prepare a new for the next trip?

Rob: My own personal opinion - I think we should return. Watching the Apollo missions is one reason I decided I wanted to work for NASA. For now, we have to rely on robotic missions to explore the moon for us.

Akarsh_Valsan: Why do footprints on Moon last forever?

Rob: They won't last forever. Small meteoroid impacts will eventually "garden" the surface and destroy the footprints - but it will take a very long time.

Andy: Since the moon is moving away from the Earth at a rate of 1.5 inches per year, at what point will it begin to affect the Earth in terms of tides and rotation?

Rob: Earth's days lengthen by 17 microseconds (17 millionths of a second) each year, so there is already some effect.

Akarsh_Valsan: Sir, What are Breccia's?

Rob: This would be a good link for that:http://www.spudislunarresources.com/moon101.htm, also http://en.wikipedia.org/wiki/Moon.

(Moderator Jason): Join NASA for our celebration of International Observe the Moon night this Saturday. NASA centers, observatories, planetariums, and schools around the world are hosting events to observe and learn about the moon. Find one near you: NASA Goddard: http://www.nasa.gov/centers/goddard/visitor/events/observe-the-moon.html ; NASA Ames: http://lunarscience.arc.nasa.gov/articles/international-observe-the-moon-night; NASA Marshall: http://www.nasa.gov/pdf/482506main_ObservetheMoonNightEvent.pdf; and around the globe: http://observethemoonnight.org/getInvolved/attend.cfm.

Dell_Conagher: Does the composition of the area where the impact happens affect the observability of the impact?

Rob: We investigated that and we don't think that impacting the smooth mare surfaces vs the highland surfaces makes a significant difference in the number of impacts we see. It probably makes a small difference in the brightness of the flash.

Rob: Hey everyone, thanks very much for participating in the chat. Great questions. I thank you. :)

(Moderator Kim): Thanks to Dr. Rob Suggs for his time to answer questions. Rob wants to let our online audience know this Saturday, Sept. 18, is the first International Observe the Moon night. Rob plans on participating in an event here at NASA's Marshall Space Flight Center Education Training Facility. He's bringing his small telescope to let visitors view the moon and tell them what they're seeing as they peer through the lens. He's also going to present findings about the lunar impacts his team has observed over the last year. Several games and presentations are planned, so it should be a fun and educational event. You can check out the following website to see if there's an event in your area you can attend. http://observethemoonnight.org

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