Tour Guide FAQ | Stats | Inconsistencies

The questions were those that the Programs staff found that they either frequently or occasionally get which they have found either uncomfortable answering, were difficult to answer, or for which they felt they were unprepared to answer. The answers, while far from perfect, offer acceptable responses typically from several perspectives ... that is, acceptable in that the VC won't have a problem with you answering these sorts of questions in these ways. The different perspectives may help you formulate a response you're comfortable giving.

Let's consider this a document in progress ... I'm sure other questions will come up at times so please feel free to request additions to the document. As always, if you don't know the answer or feel uncomfortable answering a particular question, say that and do you best to help them find someone who might be able to better respond. (Frank Cianciolo)

What are the Marfa Lights?
Are UFOs real? Was this thing I saw an UFO?
Is there/do you believe there is life on other planets?
Will the world end in 2012? What will happen in 2012? What about that planet/comet/whatever that’s going to kill us all?
What big discoveries have been made at McDonald Observatory?
What good does astronomy do for us? Why Study Astronomy?
Why do you need these telescopes when you have Hubble? Is Hubble going to make these telescopes useless?
But my bible says the Earth is only XXXX years old…
Do astronomers believe in god? Are all astronomers/scientists atheists?
Can we go online and see pictures of what your astronomers are looking at?
Can you show me this star that I bought for my dead Aunt Martha?
Can we see the flag/equipment left on the moon?
Did we really send men to the moon?
How do we know all this?
Is global warming real? Is global warming man-made? Could the sun’s cycle cause global warming?
How does air pollution affect viewing here? Is air pollution a problem here?
What was the christmas star?
How much do astronomers pay to use the telescopes?
How far out can the telescopes see?
What is the power of these telescopes?
Why was 55 degrees chosen as the altitude angle for the HET?
How large is the drive gear on the 107" telescope?
When Betelgeuse dies, will its supernova effects threaten the Earth?
What happened to the guy that shot the mirror at the 107" telescope?
Why is there one segment missing from the HET mirror array?
What is the faintest object visible in the HET?
What is the faintest object visible in the 107"?
What level of vacuum is pulled in the 107" and 82" Aluminizing Chambers?
How much would a person weigh if they were standing on the surface of the sun?
How many professional telescopes/observatories are there in the USA and worldwide?
How cold is liquid nitrogen?
How much torque does it take to rotate the HET once the air bearings have lifted it off the pier ring?
How powerful are the motors that move the 107" Harlan J. Smith Telescope, and what pressure is exerted by the hydraulic bearings?

I heard you are working with Texas A&M on a project. Can you tell me about it?


Q: What are the Marfa Lights?

RESPONSE A:
 
This question is fairly easy to answer, but the answer frequently disappoints people, and especially people who have already been out there to see them and simply can't believe that they're capable of being fooled.
 
Here's more or less how I answer it, depending upon the way in which it was asked:
 
In terms of empirical evidence (mine and others I trust), the Marfa Lights are vehicle traffic south of Marfa, mostly along highway 67 to Presidio.
Especially over distances of tens of miles, these headlights are frequently greatly affected by terrain and changes in atmospheric density and are certainly not unique to this setting.  Despite claims that the Marfa Lights were seen in pre-automobile times, the evidence for this has yet to be made manifest. (KM)

RESPONSE B:

You may have overheard or been told directly that the Marfa Lights are a mysterious phenomenon which residents and visitors have observed in the Mitchell Flats area near Marfa for hundreds of years.  Actually, the earliest known mention of some sort of “ghost light” activity dates from an area rancher named Robert Ellison in 1883.  Unfortunately (for mystery buffs, that is), these are all second-hand accounts … his descendants claim he told them about seeing lights back then but there are no written records of these observations.  In fact, even Robert Ellison, himself, failed to make any mention of Marfa Lights in his memoirs of 1937.  It appears that the first written records are from a 1957 magazine article which stated that the phenomenon occurred only a dozen or so times per year (it would be great to actually find that article … I’ll continue to look for it) not the near-nightly activity reported these days.  The most likely explanation is that the vast majority, if not all, of the light activity is the result of the headlights of cars traveling on TX Hwy 67.  Headlights can be observed for many miles and there are many stretches of Hwy 67 visible from the traditional Marfa Lights viewing areas.  In addition to direct views, car headlights can easily be refracted by both inferior and superior mirage effects (the latter frequently referred to as a Fata Morgana inversion layer.)  Superior mirages can make a light source appear far above where it actually resides making a car headlight on the horizon appear to float above it, appear to shimmer, divide, and move in various directions … all behavior quite consistent with that attributed to Marfa Lights.
One of the more definitive studies done to date seems to be one conducted by the UT Dallas chapter of the Society of Physics Students (their study is reported at
http://www.spsnational.org/wormhole/utd_sps_report.pdf.)  Their analysis shows that all “mystery light” activity observed during their study followed a regular pattern of behavior including:  appearing/disappearing at the same location along the horizon and numbers of sightings diminishing as the night progressed in direct correlation with traffic patterns along TX Hwy 67.  Their conclusion was that all light activity can be attributed to car headlights.
For a more extensive discussion, go to
http://skeptoid.com/episodes/4038 (FC)



Q: Are UFOs Real? Was this thing I saw a UFO?

RESPONSE A:
 
This question is fairly easy to answer, but the answer frequently disappoints people, and especially people who have already been out there to see them and simply can't believe that they're capable of being fooled.
 
Here's more or less how I answer it, depending upon the way in which it was asked:
 
In terms of empirical evidence (mine and others I trust), the Marfa Lights are vehicle traffic south of Marfa, mostly along highway 67 to Presidio.
Especially over distances of tens of miles, these headlights are frequently greatly affected by terrain and changes in atmospheric density and are certainly not unique to this setting.  Despite claims that the Marfa Lights were seen in pre-automobile times, the evidence for this has yet to be made manifest. (KM)

RESPONSE B:

You may have overheard or been told directly that the Marfa Lights are a mysterious phenomenon which residents and visitors have observed in the Mitchell Flats area near Marfa for hundreds of years.  Actually, the earliest known mention of some sort of “ghost light” activity dates from an area rancher named Robert Ellison in 1883.  Unfortunately (for mystery buffs, that is), these are all second-hand accounts … his descendants claim he told them about seeing lights back then but there are no written records of these observations.  In fact, even Robert Ellison, himself, failed to make any mention of Marfa Lights in his memoirs of 1937.  It appears that the first written records are from a 1957 magazine article which stated that the phenomenon occurred only a dozen or so times per year (it would be great to actually find that article … I’ll continue to look for it) not the near-nightly activity reported these days.  The most likely explanation is that the vast majority, if not all, of the light activity is the result of the headlights of cars traveling on TX Hwy 67.  Headlights can be observed for many miles and there are many stretches of Hwy 67 visible from the traditional Marfa Lights viewing areas.  In addition to direct views, car headlights can easily be refracted by both inferior and superior mirage effects (the latter frequently referred to as a Fata Morgana inversion layer.)  Superior mirages can make a light source appear far above where it actually resides making a car headlight on the horizon appear to float above it, appear to shimmer, divide, and move in various directions … all behavior quite consistent with that attributed to Marfa Lights.
One of the more definitive studies done to date seems to be one conducted by the UT Dallas chapter of the Society of Physics Students (their study is reported at
http://www.spsnational.org/wormhole/utd_sps_report.pdf.)  Their analysis shows that all “mystery light” activity observed during their study followed a regular pattern of behavior including:  appearing/disappearing at the same location along the horizon and numbers of sightings diminishing as the night progressed in direct correlation with traffic patterns along TX Hwy 67.  Their conclusion was that all light activity can be attributed to car headlights.
For a more extensive discussion, go to
http://skeptoid.com/episodes/4038 (FC)


Q: Is there/do you believe there is life on other planets?

RESPONSE A:

Since human beings have gazed at the stars the biggest question has been: Are we alone in the universe? The Milky Way galaxy contains hundreds of billions of stars and there are billions of other galaxies. With these vast numbers it seems highly unlikely that the Earth is the only planet in the universe that supports life. In our solar system there are several bodies that may support forms of life such as Mars, Europa, and Titan, just to name a few. Within the last decade we have discovered planets orbiting many stars. To date (2/11/2015) we know of 1889 extra-solar planets. There are several current or planned missions dedicated to looking for Earth-like planets (Kepler, Terrestrial Planet Finder, etc).  I think that within a decade or so we will discover Earth-like planets. This topic has been a lifelong fascination of mine. To quote Carl Sagan: “If we are alone in the Universe, it sure seems like an awful waste of space.”

Here are some links related to this topic:

 

Extrasolar planets: http://media4.obspm.fr/exoplanets/
Kepler mission:
http://kepler.nasa.gov/
Terrestrial Planet Finder:
http://planetquest.jpl.nasa.gov/TPF/tpf_index.cfm
Is there any other life in the universe?
http://www.thekeyboard.org.uk/Extraterrestrial%20life.htm
The Drake Equation:
http://www.setileague.org/general/drake.htm (JW)

 

RESPONSE B:

Currently, scientists don’t know that for sure. There could be some type of microscopic life (or fossils) under the surface of Mars, since we now know there were shallow seas there at one time. It’s thought, too, that water is underneath its surface. Because H2O is essential for life as we know it, it would be good to send astronauts there for further studies. Similarly with Saturn's moon Titan. We know it’s very similar to Earth when it was younger, and further exploration might reveal some sort of microscopic life there. Jupiter's moon Europa has a cracked ice surface. That indicates volcanic activity underneath a water ocean below the ice.  There very well could be some sort of marine life in that ocean. As far as intelligent life and visits from aliens... if one of them lands on the White House lawn, sure, I’ll believe in them then. (MC)


Q: What about that planet/comet/whatever that’s going to kill us all? (Formerly:  Will the world end in 2012? What will happen in 2012? What about that planet/comet/whatever that’s going to kill us all? Etc.)

 

RESPONSE A:

Claims of an impending disaster that will cause the “end of the world,” are somewhat common, cropping up occasionally throughout history.  None of these predictions have come to pass. For example, doomsayers claimed an unseen planet would collide with Earth in 2003. When these folks found themselves still around in 2004, they revised their predictions to say the world would end in 2010 and then 2012. Needless to say, we are all still here.

 

Some common culprits attached to “end of the world” scenarios include:

 

ALIGNMENTS: Some claim a rare alignment of the Sun, Earth, Galactic Plane, and center of the Milky Way or some kind of alignment of the planets will cause the end of the world. This is simply not the case. There is no physical effect caused by such alignments that would prompt a cataclysm on Earth. Additionally, the alignment of the Sun, Earth and Galactic center occurs every year. An alignment of those three while the Sun passes through the galactic plane occurs over a span of 36 years, due to the apparent diameter of the sun. The center of this alignment occurred in 1998 and we are all still here.

 

PLANET X/NIBIRU: Another scenario suggested by those who believe the end of the world is nigh involves the mysterious solar system body referred to as Nibiru or Planet X. Sumerian mythology has tales of an unseen planet that is going to collide with Earth, called Nibiru. The so-called Planet X has been suggested as a solution to the perturbations observed in Pluto’s orbit, and some suggest this object is the mythical Nibiru. Most likely, these perturbations are due to small bodies beyond Pluto’s orbit, and many such objects (called Kuiper Belt objects) have already been found. However, none of these objects is actually called “Planet X,” and none pose any danger to Earth. Impacts do occur on Earth, but there is no evidence to suggest an object such as Nibiru or Planet X is on a collision course with us.

 

GEOMAGNETIC REVERSAL: The earth’s magnetic field reverses its polarity occasionally. There is evidence to support this in core samples of the Earth. The time between known reversals ranges from a few hundred years to tens of millions of years. We do not know what drives the reversals, and we don’t know enough about them to make any kind of prediction about when the next one will occur.  The good news for us is that such reversals in the past do not appear to correspond to any kind of mass extinctions or other disasters.

 

KILLER SOLAR FLARE: The sun emits extreme solar flares on occasion and the emissions from these flares can cause problems for us here on Earth. We call these X-Class flares and they emit large amounts of X-rays. There is currently no way to predict such a flare.  X-class flares have occurred in the past, and while they can heavily impact our modern technology, the flare itself would not be fatal to those on Earth.  (RF)

 

RESPONSE B:

An example of “end of the world” hype comes from the 2012 hysteria over the Mayan calendar ending at this date. Although the calendar did not really end, it did roll over to another cycle.  This was kind of like the hysteria regarding Y2K. A great article about this can be found here: http://www.universetoday.com/2008/05/19/no-doomsday-in-2012/ (JW)


Q: What big discoveries have been made at McDonald Observatory?

RESPONSE A:

Things I mention would include the discovery of several planetary satellites, the atmosphere of Titan, interstellar polarization of starlight, and, more recently, the discovery of dozens of extrasolar planets, chemical elements in at least one (transiting) extrasolar planet, and the most luminous supernova. (KM)

 

RESPONSE B:

Discoveries are made all the time at McDonald, but most of them don’t make the news. A large part of astronomy is filling in the gaps in our knowledge or advancing our knowledge by small amounts. Major discoveries are rare. Thousands of scientific papers have been published using data gathered at McDonald Observatory over its. Here is a sampling of some of the more famous discoveries:

 

1939-1949: Gerard Kuiper discovered the presence of methane in Titan’s atmosphere, thus making the first observation of an atmosphere on a moon in our solar system. Kuiper also found carbon dioxide on Mars, and discovered the 5th moon of Uranus (Miranda) and the 2nd moon of Neptune during this period.

 

1980: DeVaucaleurs discovered that the Milky Way is part of a large collection of galaxies called a supercluster. He also discovered molecular oxygen on Mars and the presence of methane ice on Pluto.

 

2000-2010: Many expolanets have been discovered using telescopes at McDonald Observatory.  Some of the more famous discoveries include the first planet found orbiting a close-in binary system, and the first exoplanetary system discovered to have four planets.  Astronomers here also made the first ever ground-based detection of the atmosphere of an exoplanet.   Also, the 2.1m Otto Struve Telescope was used in 2008 to discover a new class of White Dwarf star, known as a “pulsating carbon white dwarf.”

 

2010-Present: Astronomers continue to use telescopes at McDonald to discover and characterize exoplanetary systems, such as a multiple-planet system orbiting a binary star.  This system made headlines because of its similarity to Luke Skywalker’s home planet of Tattooine in the “Star Wars” movies.  (RF)


Q: What good does astronomy do for us? Why Study Astronomy? Etc.

RESPONSE A:

The way I answer this one is also frequently met with dissatisfaction, mostly because it's usually asked by a certain type of person who, after having finished the tour and seen everything, just thinks it's all a huge waste of money and time and won't be convinced otherwise.

Astronomy, like any pure science, is something people do simply to learn more about the world (or in this case, the universe) around them. Humans (some at least) are curious creatures, and that curiosity has contributed to our long-term survival and will in the future. Knowledge is never a bad thing, and you never know where it will lead. The technological innovations required to do research often lead to further technology that directly benefit us, although that's never the goal at the outset. Even without these "technology spinoffs", pure research is still vitally important and completely justified. In the case of astronomy, current knowledge of the universe could, and almost certainly will, be used together with the technology of tomorrow to avert a potentially disastrous asteroid or comet impact with Earth. In terms of its relationship to other research fields, research in astronomy also is a window into the physical high energy universe, allowing us to study matter and energy in states that are impossible, or only briefly possible to recreate in physics and chemistry labs on Earth. Our understanding and continued research into the dynamics of planetary atmospheres will no doubt help us to understand the degree to which global warming is happening on Earth, and possibly help us find steps to ameliorate its effects. (KM)

RESPONSE B:

It would be impossible for me to beat the fine essay by Dave Finely of the NRAO/VLBA on exactly this topic so … http://www.aoc.nrao.edu/intro/why.html

Why Do Astronomy?
Or, What do we get for our tax money?
By Dave Finley
National Radio Astronomy Observatory

The purpose of the VLA, the VLBA and of NRAO is to do fundamental research on the nature of the universe in which we live. This research seeks to answer some of the biggest questions we can ask, such as how did the universe begin (or did it begin), how big is it, how old is it, and how will it end (or will it end)? As the science that provides the framework knowledge of where we, and the planet on which we live, fit into the environment of the universe, astronomy is a vital part of the culture of all mankind. A person deprived of the broad outlines of astronomical knowledge is as culturally handicapped as one never exposed to history, literature, music or art. As astronomers communicate new discoveries about the universe, they enrich the intellectual lives of millions.

From the dawn of civilization, astronomy has provided important stepping stones for human progress. Our calendar and system of timekeeping came from astronomy. Much of today's mathematics is the result of astronomical research. Trigonometry was invented by Hipparchus, a Greek astronomer. The adoption of logarithms was driven by the needs of astronomical calculations. The calculus, the basis of all modern science and engineering, was invented by Sir Issac Newton for astronomical calculations. Astronomy provided the navigational techniques that allowed sailors and aviators to explore our planet (and today allow spacecraft to explore our solar system). Astronomy's appetite for computational power drove the development of many of the earliest electronic computers. The space age, which brought us the communication and weather satellites upon which we depend each day, would have been impossible without the fundamental knowledge of gravity and orbits discovered by astronomers. Radio astronomers led the development of low-noise radio receivers that made possible the satellite communications industry. Image-processing techniques developed by astronomers now are part of the medical imaging systems that allow non-invasive examination of patients' internal organs. At today's observatories, the needs of astronomers for better instruments continue to drive developments in such diverse fields as electronics, mechanical engineering, and computer science.

Astronomy has much yet to contribute to human knowledge and progress. From the airplane to the transistor, from radio to lasers, the developments of the Twentieth Century were based on fundamental knowledge of the physics of matter and energy. Astronomy offers scientists from a wide range of backgrounds with a nearly infinite variety of cosmic "laboratories" for observing physical phenomena. It is unlikely that any laboratory on Earth will ever produce matter as dense as that of a neutron star, temperatures as hot as those inside a supernova, or gravity as strong as that of a black hole. Yet, astronomers can study the physics of such extreme conditions routinely with instruments such as the VLA and VLBA. Closer to home, the VLBA is a primary instrument providing valuable data on the drift of Earth's continents and the mechanisms of global climate.

What will this yield? It is the nature of basic research that we can't predict what will come of this work, except that we probably will be surprised. When Kepler and Newton labored to develop the science of orbital mechanics, they weren't thinking of weather satellites or CNN.

Finally, astronomy performs an important educational service for our nation. As an exciting, visual science easily accessible to amateur observers, astronomy stirs scientific curiosity in thousands of young people every year. These young people soon learn that astronomy involves nearly the whole range of the physical sciences, including mathematics, physics, chemistry, geology, engineering and computer science. Many professional scientists in these and other fields first became interested in their profession through astronomy. In today's world marketplace, a competitive nation needs for its entire population, not just its scientists, to have a basic level of scientific literacy. Astronomy, by providing the excitement of new knowledge about the fascinating variety of strange objects in the universe, can help communicate much basic science to all our people.

In sum, astronomy has been a cornerstone of technological progress throughout history, has much to contribute in the future, and offers all humans a fundamental sense of our place in an unimaginably vast and exciting universe.
(FC)


Q: Why do you need these telescopes when you have Hubble? Is Hubble going to make these telescopes useless?

RESPONSE A:

It’s true that many space telescopes can get better results than ground based telescopes, especially with certain studies in infrared, X-ray, UV.
However, there is a long wait for astronomers when applying for time on a space telescope. The ground-based telescopes are much more accessible.
That means you can do many more follow-up studies on ground-based telescopes in a shorter amount of time. Not to mention that space telescopes
are much more expensive to build and more difficult to maintain. So it’s good to have both types available for astronomers. (MC)

RESPONSE B:

There are more ground-based telescopes and lots of astronomers wanting to use them. The Hubble space telescope can only perform one project at a time so it is difficult to get enough time on it for research.

1b.“Is Hubble going to make these telescopes useless?” No. The Hubble and other space-based telescopes are additional resources that astronomers can use. The Hubble is not affected by atmospheric absorption and distortion that plague ground-base telescopes so the superb eyesight of this orbiting observatory ensures the demand for its instruments will always exceed its availability. Space telescopes are usually outfitted with a limited number of scientific instruments so one telescope may not be able to do everything an astronomer wants it to do. Space telescopes are very costly and can be difficult (if not impossible) to maintain once in orbit. Ground-based observatories greatly outnumber their space-based counterparts so availability is much less of an issue. Furthermore, adding additional instrumentation and servicing it is comparatively easy and cost effective. (SR)


Q: But my bible says the Earth is only XXXX years old…

R

RESPONSE A:

The age of the Earth is obtained through scientific methods. Current estimates place this age at around 4.54 billion years. This age is determined through a process called Radiometric dating. A chemical element consists of atoms with a specific number of protons in their nuclei but different atomic weights owing to variations in the number of neutrons. Atoms of the same element with differing atomic weights are called isotopes. Radioactive decay is a spontaneous process in which an isotope (the parent) loses particles from its nucleus to form an isotope of a new element (the daughter). The rate of decay is conveniently expressed in terms of an isotope's half-life, or the time it takes for one-half of a particular radioactive isotope in a sample to decay. Most radioactive isotopes have rapid rates of decay (that is, short half-lives) and lose their radioactivity within a few days or years. Some isotopes, however, decay slowly, and several of these are used as geologic clocks. The parent isotopes and corresponding daughter products most commonly used to determine the ages of ancient rocks are listed below:

 

Parent Isotope Stable Daughter Product Currently Accepted Half-Life Values

 

Uranium-238 Lead-206 4.5 billion years
Uranium-235 Lead-207 704 million years
Thorium-232 Lead-208 14.0 billion years
Rubidium-87 Strontium-87 48.8 billion years
Potassium-40 Argon-40 1.25 billion years
Samarium-147 Neodymium-143 106 billion years

 

Dating rocks by these radioactive timekeepers is simple in theory, but the laboratory procedures are complex. The numbers of parent and daughter isotopes in each specimen are determined by various kinds of analytical methods. The principal difficulty lies in measuring precisely very small amounts of isotopes.

 

The above information was obtained from the following web site: http://pubs.usgs.gov/gip/geotime/radiometric.html
More information about this topic can be found here:
http://en.wikipedia.org/wiki/Age_of_the_Earth (JW)

 

RESPONSE B:

McDonald Observatory is a scientific research institution investigating issues completely unrelated to matters of faith and, as such, has nothing to say about the nature of religion or of the veracity or lack thereof of any particular faith book. What we discuss at our public outreach programs is based on the latest scientifically accepted information about the universe we observe. Faith books are just that… books about faith. Faith books, while many times containing elements of history and historical events, are not themselves history books. Faith books, while sometimes containing elements of those scientific ideas known at the time, are not themselves science books. To insist that they are either or even both is to demean and degrade both the meaning of history and/or science and any remaining legitimacy of the faith book. It seems only fitting to quote Galileo’s council to the Grand Duchess Christina (de Medici) who was concerned that the growing popularity of the heliocentric model of the Solar System might undermine faith in such biblical stories as Joshua commanding the Sun to stand still. Galileo wrote the Grand Duchess, “It is clear from a churchman who has been elevated to a very eminent position(1) that the Holy Spirit’s intention is to teach us how to go to Heaven, and not how the heavens go.”(2) While Galileo was referring here to the X-ian bible, the same can certainly be said about any faith book. (FC)

 

1 He refers here to St. Augustine.
2 Letter to Madame Christine of Lorraine, Grand Duchess of Tuscany (1615)


Q: Do astronomers believe in god? Are all astronomers/scientists atheists?

RESPONSE A:

Some do...some don’t.  However, even those astronomers who do believe in a deity of some sort, believe the evidence is overwhelming that the earth is old, and that it was formed nearly 4.5 billion years ago. They also believe the evidence shows that the universe was formed nearly 14 billion years ago.

Since the bible is not a science book, astronomers do not use it as a scientific guide. They use the scientific method. (If they push further, I might even mention the paraphrase of Galileo’s remarks to the Grand Duchess: “The bible tells you how to go to heaven...not how the heavens go”.) (MC)

RESPONSE C:

Most recent polls find that the number of atheists among scientists is greater than in the general population. However, it would be incorrect to label the majority of scientists as atheists. A 1998 survey of scientists in the National Academy of Sciences did indeed find that just 7% of scientists claim belief in a god, while 21% percent have some doubt and 72% are atheists.(1) It is important to keep in mind that this was a very narrow sample of a very elite group of scientists, with only about 250 respondents. Using a larger sample size and polling a broader range of scientists, the very same authors found 40% of scientists believe in a “personal god” and 15% have some doubt but do not align themselves with atheism.(2) Furthermore, both of these surveys are limited in their ability to accurately gauge scientists’ attitudes toward religion because they rather narrowly define God as “a God in intellectual and affective communication with humankind, i.e. a God to whom one may pray in expectation of receiving an answer.” At least one respondent in this survey commented that the very narrow definition forced him to respond that he did not believe, while his personal beliefs were more in line with belief in an impersonal god than with atheism.

An even larger sampling (about 1000 respondents in the “hard sciences”) published in 2007 finds 38% of scientists report being atheists, 29% claim agnosticism and 33% believe in a god.(3) It is also interesting to note that this study found the number of scientists identifying with Judaism is actually greater than that in the general population.

The short answer to this question is that as in most disciplines, science is made up of individuals with a wide variety of backgrounds and personal beliefs. Scientists on the whole appear to be less religious than the general population and scientists who claim outright and devout belief are definitely in the minority, but it is a fallacy that the majority would label themselves atheists.

1) Larson, E and Witham, L 1998, Nature, Vol. 394, No. 6691.
2) Larson, E and Witham, L 1997, Nature, Vol. 386, No. 6624.
3) Ecklund, E and Scheitle, C 2007, Social Problems, Vol. 54, No. 2.


Q: Can we go online and see pictures of what your astronomers are looking at?

RESPONSE A:

No. The astronomers who use our telescopes are doing their research, studying stars (or galaxies or other astronomical objects) using instruments. Most of the time, the astronomers who use the telescopes here at McDonald are doing spectroscopy, where they collect light from an object, then spread that light into its spectrum, then analyze the spectrum. So what they are “looking at” is not a pretty star, but something that looks more like a bar code, or else a big group of numbers. The data that the astronomers collect belong to the astronomers, to analyze as they see fit, and then to publish. In some fields of astronomy, there is competition between research groups to be the first to publish a particular result. This is one reason that many researchers choose not to share the targets they are observing, or their preliminary results before those results are ready for publication. (JM)

 

RESPONSE B:

Information on the astronomers, our telescopes, scientific equipment, and current projects is available on our website (mcdonaldobservatory.org/research). A common misconception related to your question is that astronomers are either using eyepieces to look through the research telescopes or are using cameras to take pretty pictures of objects. As it turns out, nearly 80% or so of the projects conducted here are McDonald (and most observatories) are spectrographic in nature… meaning that the astronomers send the light collected by the telescopes through a scientific instrument called a spectrograph to analyze the individual wavelengths of light and features within the produced spectrum. Many times, the astronomers are analyzing the light of an individual star so, if we were to pipe a video image to the web or some other location, all you’d see would be a non-descript dot of light or, if we sent the spectrum, a B&W image showing strips of alternating light and dark areas that look something like a DNA sequencing image.

 

That’s not to say that you can’t find some fascinating things to see about research being conducted or things we’ve recently learned. The HETDEX site (hetdex.org) offers explanations and images about this latest effort by McDonald and its partners. StarDate.org is also a great resource to learn about what’s going on in the night sky.

For astounding images, go to the Hubble Space Telescope web site (hubblesite.org). Another resource for learning astronomy through images and text is the Astronomy Picture of the Day website.


Q: Can you show me this star that I bought for my dead Aunt Martha?

RESPONSE A:

This is a very tough one and one that is just fraught with emotional peril. All too often, people “buy” these for dying or already deceased loved ones. The last thing they want to hear, and certainly the last thing we want to tell them, is that they wasted their money or that doing something like this is silly. Even for those who have some idea that it may be a novelty, it’s still not our place to tell them they did something stupid.

 

So, what to say? If they have all the paperwork, have charts, catalogue numbers, and reasonably precise coordinates, I tell them that I would be willing to try but only at the end of the SP if they’re willing to stick around. I do warn them that it may not be possible to identify “their” particular star out of a field of stars or even that it is actually in the field due to inaccuracies in the telescope drive or with the coordinates they have.

 

If they don’t have the above mentioned paperwork, then I tell them that, without that, there’s really no way to attempt it. We simply don’t have the resources to do such a thing on the fly.

 

If they tell me that they’re considering “buying” a star, I do tell them several things:


Q: Can we see the flag/equipment left on the moon?

RESPONSE A:

Not with current technology. The resolving power of a telescope depends on the atmospheric conditions. Astronomers call this “seeing” The theoretical limit is determined through the Dawes Limit; simply divide the diameter of the mirror lens of your telescope into 4.5. For example, a telescope with an aperture of 4.5 inches would, in theory be able to detect details at an angular size of 1 arc second (4.5/4.5) and a 10 inch telescope would have a resolution of .45 arc seconds (4.5/10) An arc second is an angular measurement. There are 360 deg. in a circle, 60 min. in one deg. and 60 sec. in one min. To give you an idea how small these measurements are the apparent size of the full moon is about ½ deg. or 30 arc seconds. You might ask: “Well what about the HST?” While the HST is a remarkable instrument, the actual size of its mirror is relatively small 94.5 inches (2.4m) so its theoretical resolving power translates to 4.5/94.5 or about .05 arc seconds. This translates to a resolution of some 300 ft. You may also ask, “If the Hubble can take pictures of galaxies millions of light years away, why can’t it image the equipment left on the moon?” While the moon is much closer than these galaxies, the galaxies are many times larger!

More information about this topic can be found here: http://curious.astro.cornell.edu/question.php?number=134 (JW)

RESPONSE B:

Not from Earth. Not even from the Hubble Space Telescope. Since the moon is a quarter million miles away, it’s too difficult to see equipment left there.
You’d have to actually be there.  If you had something like a “spy” satellite orbiting the moon, you would be able to.

It’s like trying to see an ant on the sidewalk 20 feet away...very difficult. But if you are standing over it, you could. (MC)

The Lunar Reconnaissance Orbiter, which is currently orbiting the moon, has taken some nice images of the Apollo landing sites. Equipment left behind by the astronauts, as well as astronaut and rover tracks, are visible in these pictures.


Q: Did we really send men to the moon?

RESPONSE A:

Yes, we did. The arguments made to support the "moon landing hoax" are very easy to refute, and are mostly based upon a misunderstanding of various topics and processes. Tens of thousands of people were involved with placing 12 humans on the moon - mass conspiracies like that are impossible to maintain. Someone would have an incentive to spill the beans. Besides which, we have a special telescope here that fires a laser beam to the moon, which then reflects off specially designed retroreflectors placed on the moon my Apollo astronauts. (KM)

RESPONSE B:

Yes. Hundreds of pounds of lunar rocks were brought back; we have thousands of pictures so why do people question this? If you examine the Moon hoax believers (or HB’s ) all of their so-called “evidence” can be easily debunked. The most common argument is that there are no stars in the pictures. The photographs were taken using very short exposures. Stars would show up if longer exposures were taken. You can easily demonstrate this yourself. Go outside some night and point a camera at a bright star. Try to take a picture of it using an exposure setting you would use for daylight pictures, say 1/250 sec. When you examine the results I can guarantee the star will not show up in your picture!

Another argument the HB’s will make is: “The flag was waving, since the moon has no atmosphere it should not have been waving!” Well the moon does have a very thin atmosphere but this is not the reason. Not every waving flag needs a breeze -- at least not in space. When astronauts were planting the flagpole they rotated it back and forth to better penetrate the lunar soil (anyone who's set a blunt tent-post will know how this works). So of course the flag waved! Unfurling a piece of rolled-up cloth with stored angular momentum will naturally result in waves and ripples -- no breeze required!

There are many other so-called pieces of “evidence” that HB’s quote. More details can be found here:
http://www.clavius.org/
http://www.badastronomy.com/bad/tv/foxapollo.html (JW)


Q: How do we know all this?

RESPONSE A:

I would like to think that what is being asked here is this: How do scientists figure out the things that we say we “know” or we have “discovered”. That’s the question that I’ll try to answer here.

Scientists are people who study various parts of nature using a particular method called “the scientific method.” In the scientific method, scientists start with observations. After making many observations, a scientist will form a hypothesis, which is an educated guess based on observations. The hypothesis is an idea that can be tested, so the scientist tests the hypothesis by setting up experiments, or maybe further observations, to see if the hypothesis accurately predicts the outcome of the experiments. Basically, the scientist spends most of his or her time trying to disprove hypotheses. If the hypothesis is disproved, then the scientist will make more observations, and refine the original hypothesis (or change it totally), and test it again. If the hypothesis is not disproved, then the scientist may call the hypothesis a working scientific theory. A scientific theory is a very different thing from the word theory that is used in everyday life. A scientific theory is one that has been tested in many different ways, and has stood up to those tests.

So the things that we say that scientists have discovered or learned or know are actually scientific theories that have not yet been disproved. (JM)

RESPONSE B:

You're asking a very good question. Astronomers are using the 400 year old tool for answering questions, called science. Science is a method of learning that is evidence driven. We gather evidence, build tentative 'scientific theories' based on that evidence, and continually advance those theories as we forever explore. Astronomers are gathering evidence by spending long nights gathering light with these large telescopes. So when an astronomer claims to know something, they are really saying that what they "know" is supported by overwhelming evidence, and can't currently be disproven. (MW)


Q: Is global warming real? Is global warming man-made? Could the sun’s cycle cause global warming?

RESPONSE A:

Yes. In the most basic sense of the term, 'global warming' is a tested and proven fact. On average the temperatures around the planet are getting hotter over recent decades. We've had thermometers and pencils for 300 years, so there are lots of records to verify this (along with mountains of paleoclimate evidence).
It is EXTREMELY LIKELY that man is ACCELERATING the current warming trend, but we don't have sufficient evidence to say to what degree. The global climate is an extraordinarily complex system and there are many interacting influences driving climate change (volcanoes, ocean currents, atmospheric gases, % of earth's surface covered by ice, plate tectonics, cloud cover and types of clouds, etc...), so it is very hard to accurately say which influences are currently dominant. But according to a HUGE majority of the many scientists who have devoted their careers to answering this question, it is very likely that man's activities (creating excess greenhouse gases) are ACCELERATING the current warming trend, to what degree is debatable. (Don't use the word CAUSING, that's too simplistic). Yes, solar activity MAY ALSO INFLUENCE climate change along with other factors such as man-made greenhouse gases, but we don't have sufficient evidence to say to what degree. Solar activity is likely one of many influences on the climate. There is some circumstantial evidence showing a connection between sun-spot activity and climate (e.g. the Maunder Minimum coincides with the 'Little Ice Age'). However there isn't much (if any) real evidence of an 11 or 22 year pattern in the climate. This is still very new science, and there are some good hypotheses about how the sun's radiation output could influence earth's atmosphere. Some ideas involve the solar wind and heliosphere and cosmic rays. Others involve ozone production. (MW)

RESPONSE B:

The Earth’s climate is always changing. Many factors contribute to climate change, including:

a) Changes in Earth’s orbit.
b) Changes in the intensity of the sun.
c) Volcanic eruptions.
d) Changes in the levels of Greenhouse Gases in Earth’s atmosphere.
e) Changes in ocean currents.

The final two contributors are referred to as “feedback mechanisms” because changes in these factors can cause warming, which in turn causes changes in these factors. For example, changes in ocean currents could cause warming, which in turn causes further changes in ocean currents and so on.

Scientists agree that the global average temperature has increased by between 1 and 1.7 degrees Fahrenheit over the period from 1906 to 2005. Furthermore, the average temperature over the last few decades was warmer than any comparable period over the past 400 years. Evidence also suggests the average temperature was warmer over the past 25 years than any other 25-year period since 900 AD.

Scientists have measured increased levels of greenhouse gases in Earth’s atmosphere and attribute this change to human activity. It is also known that increased levels of greenhouse gases in the atmosphere tend to lead to warming. Most scientists agree that the warming trend exhibited over the past 100 years or so is due in part to human activity.

However, there are still many gaps in our knowledge of Earth’s climate and the natural processes that lead to warming. While there is overwhelming evidence of a global warming trend and most agree humans play a role, there is still a large amount of debate as to the relative impact of human activities and natural warming processes. Scientists do not agree on how much warming can be expected, how fast the warming will occur or what effect the warming will have on other climatological factors. There are a number of competing theories about these issues and much research needs to be done to narrow the field of ideas.

The sun’s activity cycle may play a role in global warming, but as with all of the other potential causes, it is still uncertain to what degree and in what proportion it affects our climate. Scientists attribute a period of slightly lower temperatures in North America and Europe between the 1400s and 1700s (called “The Little Ice Age” or Maunder Minimum) to reduced solar activity. So, there is evidence to suggest it plays a role, but the entire global warming trend cannot be attributed solely to the solar cycle, or indeed to any single cause.

The EPA, NOAA and NASA all maintain good websites related to climate change. (RF)


Q: How does air pollution affect viewing here? Is air pollution a problem here?

RESPONSE A:

Air pollution is detrimental to astronomy. The fine optical surfaces and delicate electrical components astronomers use to collect starlight can be ruined by corrosive particles in the air.

There are times of the year when air pollution, caused by forest fires, can cause astronomers to close all domes and lose valuable telescope time given them by the Telescope Allocation Committee. These bad times of year are primarily during the mid to late summer months, when lightning from more frequent thunderstorms sets off forest fires. Otherwise, our remote location keeps us far away from the adverse effects of big city air pollution. (MW)

RESPONSE B:

Air pollution is a concern here, as it is around the world. Overall levels have increased here in recent years and most is believed to originate in the power plants of east Texas. Pollutants in the air can affect the quality of astronomical images, specifically in decreasing the transparency of the atmosphere. Our main concern here at McDonald is dust. This can obscure our images and also cause problems for our equipment. In general, however, the air quality here is better than average most of the time. (RF)


Q: What was the Christmas Star?

RESPONSE A:

The Christmas “star”, according to one biblical account, was a celestial object that wise men from the east reported as heralding the birth of a Hebrew king. The astronomical origins of this event are uncertain, at best, and suggestions for the event include: the appearance of Halley’s comet in 12 B.C.; a conjunction of Jupiter and Saturn three times in 7 B.C.; a nova that appeared 5 B.C., and conjunctions of Jupiter and Venus in 3-2 B.C. More than one natural phenomenon may have been involved. (SR)

RESPONSE B:

The heralding of momentous events by celestial apparitions is a common enough literary device employed by ancient chroniclers. Many rulers/leaders both religious and secular even up through early-modern times have claimed that their births, ascensions to thrones, etc., were heralded by astral events. If, as believed by many in pre-modern times, the Earth was the center of the universe and Man the purpose of creation, then it made perfect sense for people to believe that great happenings on Earth should be announced by great happenings in the heavens … this is the essence of the pseudo-religion of astrology. As with all things astrological however, if one looks hard enough, long enough, and allows for a multitude of interpretations of the information, one can always find something that kind of, sort of can be made to fit the story. Thus, everything from comets, to planetary conjunctions, to various novae/supernovae have been put forth as possible candidates for the one mention of a celestial correspondent event to the story of the epiphany. In the end, however, with “his star” as the only description and the propensity of the ancients to use the word “star” to mean nearly anything astronomical, it’s impossible to say to what, if anything, the phrase refers. (FC)


Q: How much do astronomers pay to use the telescopes?

(Anita Cochran to Rachel) Astronomers are not charged as long as they apply to the TAC for time on the telescope. The costs of operating the telescope come out of the Observatory’s operating budget. If an astronomer wishes to bypass the TAC, they can contract directly for time on the telescope and in this case, they are charged. Because the amount charged varies with the individual contract, we are not able to quote a dollar value.”


Q: How far out can the telescopes see?

(Kevin): Our telescopes most distant targets are quasars, billions of light years away. The only limitation on range is the brightness of the object.


Q: What is the power of these telescopes?

(Kevin): The measure of a telescope's capability is the aperture, or diameter of the primary mirror or lens. The larger the aperture, the more light the telescope collects.

(Shannon): Power in the sense of magnification: Research telescopes cannot be directly compared to ordinary amateur telescopes in a magnifying (power) sense. Research telescopes typically do not have an attached eyepiece so professional astronomers do not speak of the telescope magnification. The instrument attached to the telescope will have definable field of view characteristics that are described as the instrument "plate scale". Plate scale may be defined as the observed angle of arc over a given measurable distance (arcsecs/mm, arcsecs/pixel, etc..)


Q: Why was 55 degrees chosen as the altitude angle for the HET?

(Kevin): It's a compromise between minimizing the zenith distance (looking through less atmosphere) and maximizing the sky coverage for the "ring" (which increases at increasing zenith distance).


Q: How large is the drive gear on the 107" telescope?

(From Dave Doss): The Polar drive gear of the 107" is 8 feet in diameter.


Q: When Betelgeuse dies, will its supernova effects threaten the Earth?

I haven't read through this yet, but: check this out: http://stupendous.rit.edu/richmond/answers/snrisks.txt. It was linked from this also rather interesting NASA "Ask a High Energy Astronomer" page: http://imagine.gsfc.nasa.gov/docs/ask_astro/ask_an_astronomer.html


Q: What happened to the guy that shot the mirror at the 107" telescope?

(From Dave Doss to Joe): The guy was put in jail that night, then sent to a mental institution in Big Spring. He was released 3 months later


Q: Why is there one segment missing from the HET mirror array?

(Dr. Shetrone to Visitor during HET special tour): The mirror cell for that segment is causing the segment to distort; therefore, a black cover was placed over the segment.


Q: What is the faintest object visible in the HET?

(Dr. Shetrone): The faintest objects we have setup on is a quasar (not a star) that was at a redshift of Z=6.4, which makes it the 7th most distant object ever observed. That target was very very red... I = 22.3 but V=26. The HET is completely limited by the darkness of the sky to image any target. We try to look where the object is the brightest and the sky is the faintest.


Q: What is the faintest object visible in the 107"?

(Dave Doss): This is highly dependent on whether your talking about imaging or spectra. Imaging I think they have gotten down to 22nd or 23rd magnitude with igi. Taking spectra with the lcs I believe that they have worked down to about 19th magnitude. Again this is all dependent on the signal to noise that the particular observer wants.


Q: What level of vacuum is pulled in the 107" and 82" Aluminizing Chambers?

(Dave Doss): We generally put down to 5 X 10-6 Torr. on both chambers.


Q: How much would a person weigh if they were standing on the surface of the sun?

(Kevin): I worked it out using F=GM(sun)m(person)/R(sun)^2 and came up with about 28x what you would weigh on the Earth.


Q: How many professional telescopes/observatories are there in the USA and worldwide?

(Kevin): Worldwide there are about 70 telescopes larger than 2 meters (80 inches) in size at about 30 separate observatories. Considering only the USA, there are about 30 telescopes larger than 2 meters at 11 sites. The USA sites are Mauna Kea (HI), McDonald, Mt. Hopkins (AZ), Palomar (CA), Kitt Peak (AZ), Apache Point (NM), Lick (CA), Jelm Mountain (WY), Maui/CFH (HI), Mt. Graham (AZ), and Mt. Wilson (CA). Not all telescopes on American soil are owned and/or operated by American institutions. Additionally, some telescopes on foreign soil are operated by American institutions. A complete listing from SEDS is here.


Q: How cold is liquid nitrogen?

(Kevin): While, like water, there is a range of temperatures over which Nitrogen is liquid, my sources state about
-200 degrees C. This is about -325 degrees Farenheit or about 73 Kelvin. For comparison, dry ice (frozen CO2) is about -80 degrees C (-110 F or 193 Kelvin). Remember that when stating temperatures on the Kelvin scale, don't say "degrees Kelvin"...it's just "Kelvin". There are no "degrees" on the Kelvin scale.


Q: How much torque does it take to rotate the HET once the air bearings have lifted it off the pier ring?

(Jim Fowler): I don't have an exact figure. However, recall that the air bearing creates an essentially frictionless surface (recall your air hockey tables) so the only friction in the system comes from the central bearing and the occasional drag on the air bearings. It takes some force to get things started, the moving weight is 80 tons (pre-HETDEX upgrade stats) after all, however, it is possible for one person to get it going and to push it around by hand.


Q: How powerful are the motors that move the 107" Harlan J. Smith Telescope, and what pressure is exerted by the hydraulic bearings?

(Dave Doss/Earl Green): Earl said that for slewing the motor runs at about 1/2 horse power. I think the bearing hydraulic pressure is around 900psi.


Q: I heard you are working with Texas A&M on a project. Can you tell me about it?

Texas A&M plays a crucial and growing role in Texas astronomy and we are proud to work with their talented scientists on not one, but two exciting projects.  First, an international team of academic institutions, including UT and Texas A&M, are working together to try to determine the nature of dark energy. The Hobby-Eberly Telescope Dark Energy Experiment, or HETDEX, will survey one million distant galaxies over three years using 150 specially designed spectrographs on the Hobby-Eberly Telescope. Scientists, engineers and graduate students from the six partners are working together to try to solve one of the biggest mysteries in the universe today. The other HETDEX partners are:  Pennsylvania State University, Universitats-Sternwarte Munich, Leibniz Institute for Astrophysics (AIP), Max Planck Institute for Extraterrestrial Physics, Institute for Astrophysics Gottingen, and the University of Oxford.  Second, UT, Texas A&M and several international partners are working together to build one of the world’s largest new telescopes. The Giant Magellan Telescope will be built at Las Campanas, Chile. When complete, the diameter of its primary mirror will be almost 25 meters! It will be able to produce images 10 times sharper than the Hubble Space Telescope and will be used to investigate a wide variety of astronomical phenomena, including dark matter, dark energy and the origins of stars, planets, galaxies and black holes. We hope to have the telescope completed by 2019. The other partners working with us are: University of Chicago, the Carnegie Institution for Science, Harvard University, the Smithsonian Institution, University of Arizona, Australian National University, Astronomy Australia Limited and the Korea Astronomy and Space Science Institute.We are also working with A&M on an outreach program to bring the wonders of the universe to the citizens of Texas.

 

IMPORTANT NOTE: The rivalry between UT and Texas A&M is well known and often comes up, especially if “Aggies” are present on the tour. Light-hearted banter with regard to this rivalry is okay. However, it is imperative that you avoid belittling the contribution of Texas A&M to these projects. Under no circumstances is it permissible to make derogatory statements regarding the contributions of Texas A&M to Texas astronomy in general or HETDEX/GMT in particular, such as implying their contribution is only monetary or is somehow inferior to the contributions of others. These statements are not only false, but they only serve to damage a valuable and productive working relationship between our two institutions. Have fun, but be respectful.


Standardized Tour Statistics (Revised September 20, 2011 for what undoubtedly will not be the last time)

About the Telescopes: 82" 107" HET
Cost of construction $375,000 $6.8 million $20 million + $42 million HETDEX upgrade = $62 million
Year construction began 1933 1966 1994
Year completed 1939 1968 1997
Diameter of primary mirror 82" or 2.1m 107" or 2.7m 433"x394" or 10mx11m
Effective 10m aperture (post HETDEX upgrade)
Weight of primary mirror 2.1 tons (4,200 lbs) 4 tons (7,800 lbs) Each segment is 250 pounds. The entire array including the truss is 26,000 pounds (13 tons)
Weight of telescope (moving parts) 45 tons 160 tons ~150? tons (post HETDEX upgrade)
Length of telescope tube 27' 32' about 50'
Who made the mirror Corning (fabrication)
Warner & Swasey (grind/figure)
Corning (fabrication)
Davidson Optronics (grind/figure)
Schott Glassworks (fabrication)
Eastman Kodak (grind/figure)
Who built the telescope Warner&Swasey Westinghouse UT/PSU engineering + contractors
Mirror material Pyrex Fused Silica Zerodur, a low-expansion ceramic composite
Past / current world ranking 2/60 3/41 tied for second (1=10.4m GTC/Canary Islands, then 2=10.0m HET/Keck1/Keck2)
Cost per night for science use See "*" below See "*" below See "**" below

About the Observatory in general:      
Why on Mount Locke? high altitude / southern latitude / dry climate / remote / high # of clear nights / access
How much land do we have? 640 acres (one section)    
How many employees? 80 (full and part time) at McDonald and another 100 in Austin
How many residents? 70, which includes (resident and transient) children and spouses
How many visitors per year? 70,000    
Average temperature 65F    
Average rainfall 20" annually since 1935    
How cold do winters get? teens to 20's, snow sometimes    
How far to Wal-Mart? 100 miles    
How far to Mexico? 100 miles    
Elevation of Mt. Locke? 6,791'    
Elevation of Mt. Fowlkes? 6,659'    
   
 
*UT Astronomy does not sell nights on any telescope and astronomers are not charged, unless there is a contract with an observer that guarantees their telescope time and permits them to bypass the peer review process (TAC) - which is rare. Astronomers are selected by TAC peer review.
   
 
** HET Astronomers are not charged nightly for use of the telescope. Astronomers using the HET are typically part of the consortium of 4 universities that funded the project. Consortium members are given time proportional to the percentage of the total amount that they contributed. The annual operation budget of the HET was $1.9 million in 2008.

General Inconsistencies:


1. Status of UT astronomy department in 1939: Some tours state UT had no department, some state it had only a small department.
• “The University of Texas had no working astronomers with which to staff an observatory.” Source: Big & Bright p. 22

2. 107” Completion date: Some say 1968, some 1969.
• Dedication 26 Nov 1968, first astronomical observations March 1969. Source: Big & Bright pp. 150, 152

3. Cost of Keck Telescopes: Various figures cited.
• “Construction of the twin Keck telescopes and domes was made possible with grants totaling more than $140 million from the W. M. Keck Foundation in Los Angeles”, Source: Keck Observatory website.
The total cost of construction was over $200 million for both telescopes.  About $100 million is a reasonable estimate for per telescope cost.  Source:  Craig Nance.

4. Shape of 107” Mirror: Some state parabolic, some state hyperbolic.
• The telescope is of the Ritchey-Chretien design, which employs a hyperbolic primary mirror. Source: Big & Bright p. 148 & website.

5. Accuracy of the LLR: Statements range from 1cm to a few inches.
• Initial Apollo measurements 10-15cm. McDonald Website. As of 1973, accuracy was about 15cm. Source: Bender et al., Science 19 Oct 1973.
• As of 1994, accuracy was about 3cm. Source: JPL PIO Press Release 21 July 1994.
• Currently, accuracy is about 1cm. Source: McDonald Website.

6. The Coke Cans: The 107” mirror can be coated 4 or 8 times with amount of aluminum in one coke can, depending on whom you ask.
• Assuming an average soda can mass of 15 grams, thickness of coating of 928 angstroms and a density of aluminum of 2.7 g/cc, the amount of aluminum in a single soda can should coat the mirror about 10 times.
• Another way to describe the thickness is that the coating is about 0.001 times as thick as the soda can skin.

7. Retroreflectors: Some tours state they are mirrors, some say prisms.
• The retro-reflectors are arrays of corner-cube prisms. The same effect can be created using mirrors, but the retro-reflectors on the Apollo missions used prisms. They were actually cubes of fused silica. Source: NASA website.

8. Air bearing capacity: Most tours cite a lifting capacity of 10 tons, which is fine if the speaker uses a modifier such as “about” or “over.”
• Based on the area of each bearing, the actual lifting capacity of a single air bearing is closer to 12-tons.

9. HET cost: Some state $13.5 million, others state $20 million.
• The lower figure is the cost before instrumentation was added. Twenty million is a good estimate of the total cost, but an exact figure including instruments is unavailable.

10. Power of 107” telescope vs. human eye: various figures given.
• One way to look at this is by comparing the light gathering power of the primary mirror to that of the human pupil. Using 5mm as a diameter of the human pupil, the 107” telescope comes out to be 291,600 times more powerful.
• Another way is to determine how much fainter the objects are that the telescope can see than those seen by the human eye. In this case, the telescope sees objects 13.7 magnitudes fainter than the human eye.

11. Distribution of HET Data: Many state that the data are e-mailed to researchers.
• HET Data are not e-mailed to researchers. At the conclusion of an observing program, a notification is sent by e-mail informing researchers that their data are ready to be retrieved. It is up to the researcher to transfer the data to their own server. Throughout the course of an observing program, the researcher can access a website that lists the dates and times of observations made for their project. This site also includes notes about the observations (e.g. cloudy skies on a given night, technical problems, etc.).

12. HET Operations I: Some tours state as many as 30 projects observed in a given night.
• The HET typically will work on roughly 7 different projects in the course of a night’s observations. That number can vary depending on telescope and/or instrument issues and weather conditions.

13. HET Operations II: Some tours mention a “team” of RA’s/TO’s working on a single night.
• Typically, only one RA and one TO work at the HET in the course of a night.

14. SALT: Many suggest the SALT is identical to HET or state that it is the “twin” of the HET.
• The two telescopes are based on the same design plan, but there are many differences between them. For example, the HET’s tube is set at 55 degrees above the horizon, while the SALT’s tube is set at 53 degrees above the horizon. This is to allow SALT to target the Magellanic Clouds. Many other differences exist as well. Basically, SALT’s design addresses many of the problems in the HET design and integrates several changes from the HET design specific to SALT’s location and scientific objectives.