Readers' Feedback


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Generated : 21st June 2024


Robert Shaw


I only recently discovered your deeply engrossing and remarkably wide-ranging site. I have just finished traversing your entire section on Astronomy, and eagerly look forward to exploring the other topics, which are very appetizing - what a rich intellectual feast awaits me!. Your explanations are thoroughgoing but clear and concise, highly informative for a novice but equally useful for a more knowledgeable reader to brush up on aspects of the field which may be fuzzily recalled or incompletely grasped. I'm in awe of the effort in research and writing that went into producing such an extensive resource.

I know that you cannot possibly keep track of every correction that might be called for across so wide a range of subject matter, so here are a few suggested revisions or additions to the astronomical articles that you may wish to make when time permits.

KtyssTal Reply: Thank you for your enjoyable and informative email. As you so quite rightly say, it is difficult keeping up with all the corrections.

Although there is much on the web site, astronomy has always been my first love so I will be updating errors and new figures as soon as possible. See my notes among your email text.

We Are Stardust section (love the clever tribute to Joni Mitchell- nice touch): Antares is not classified merely as a red giant but a full-sized red supergiant like Betelgeuse (in fact, these two are the most commonly used examples in popular writing). Aldebaran or Arcturus are appropriate specimens of red giants, especially the former as it is conspicuously reddish-orange.

This is right.

Chemistry of the Universe: The total mass of all the solar system material aside from the Sun itself is 466 Earth masses. (Talk about information you'll never use!)

I used it - well nearly.

Measuring the Stars: The classic stellar spectral sequence O-B-A-F-G-K-M (no mention of the famous mnemonic, eh?) has lately been extended, adding classes L and T to cover brown dwarfs.

The mnemonic distracts and can be found elsewhere. Sorry. I wanted to keep the ideas simple so have omitted L, T, W, C, etc. I do say "Other spectral types exist but these will not be discussed here".

Epsilon Aurigae A is estimated at 100-200x the sun's diameter, not 2000x, which would make it even larger than the current record-holder VY Canis Majoris. Many older textbooks from the mid-1900s state that the unseen dim companion may be an enormous star which would then be the largest known; it is now suspected to be perhaps a disk of dust, but definitely not stellar in nature.

I've changed this.

Brightest Stars: Canopus is actually just 310 lyr away, as was determined by the Hipparcos probe in the 90s. Your listing of 1200lyr estimated distance & 200,000x solar luminosity is quite outdated (that would have made it one of the most luminous stars in the galaxy). Canopus is "only" 15,000 x the sun's brightness, very impressive indeed, but not comparable to Rigel or Deneb. Still, with such candlepower, i think it "deserves" to be the brightest star in the sky over Sirius, which has only the benefit of proximity, if such a preference even makes sense.

I've corrected this.

Scale of the Universe (beautifully done, btw -- love the images): Newer measurements give a greater distance for Betelgeuse - approximately 640lyr, not 429 (or 310, as your table says), making its luminosity a whopping 105,000 suns!

I have updated Beteljeux details.

The distance you list for the Magellanic Clouds - 160k lyr -- is for the Large MC; the Small MC is 200k lyr. And they are no longer the nearest external galaxies. Two closer dwarf galaxies are now known. The Andromeda Galaxy is 2,540,000 lyr away, not 2,900,000.

I have corrected these details.

The Calendar: The Anomalistic Year is 4 minutes longer than the Sidereal Year, not the Tropical Year (which, as stated earlier in the text, is 21 mins shorter than the Sidereal).


Solar System:

Minor Planets: You obviously wrote this essay after dwarf planet Makemake was named, but before the christening of 2003 EL61 as Haumea, which should now be substituted. 2002 AW197 still awaits a moniker.

I can't keep up with these ! I have updated Haumea.

Minor Planet tables: Since you are using the Moon for comparison here, i think it should be listed at the top, above Eros, which is a very minor body indeed. Nothing crucial, it just seems a little odd.

I agree - I hadn't noticed this before.

Satellites of Jupiter: Ganymede is indeed bigger than Mercury, but Callisto is not - it falls short by 1%. Ganymede and Titan are the only moons larger than Mercury.

Corrected. I should hire you as my editor.

Satellites of Saturn: Titan's rotation period is blank on your table; it is now known to be synchronous.


Satellites of Pluto: Since the barycenter of the Pluto/Charon system is outside the larger body, they should really be described as a double dwarf planet.

You could describe the Earth-Moon as a double planet because the Moon’s orbit is always concave towards the Sun. I'll leave this.

Eris has a small moon, Dysnomia, so they should get a brief mention.

I'll add it soon.

Observer's Glossary: You do a really good job here of making some potentially rather dry material interesting. Just a few small suggestions:

Inclination of Ecliptic: "The Ecliptic is the path in the sky that the Sun, Moon and planets appear to travel close to." To be precise, of course, the Sun's path defines the ecliptic, so its doesnt just "travel close" to it. Might seem trifling, but a naive reader could infer that this line has some independent existence apart from the bodies that "happen to" travel along it.

Well spotted. I've rephrased this.

Under Planets, the last sentence could read: "Since the invention of the telescope, two more major planets have been discovered, Uranus in 1781 and Neptune in 1846, as well as a number of minor planets (Ceres, Pluto, Eris, Sedna etc)." The etc makes it clear that these are not the only ones.


Under Inferior Planets, the text covers Inferior & Superior Conjunction, and Greatest Eastern & Western Elongation. Similarly, the segment on Superior Planets discusses Conjunction and Opposition, but there is no mention of Quadrature (E & W), which struck me as a puzzling if trivial omission.

Deliberate omission - I just don't rate Quadrature as a concept.

Asteroids: Normally, spelling errors are inconsequential, but in the case of the Centaur Chiron, misspelling it as "Charon" leads to major confusion, since it is Pluto's double-planet companion which actually bears that name. Charon also is roughly spherical and much larger than the irregular Chiron.


And "Icaros" should be corrected to Icarus.

That's the Greek in me using the OS rather than the US ending. I suppose etymologically OS is correct but I changed it.

It would be useful to have a separate table for major asteroids, showing Ceres, Vesta, Pallas & Hygeia to be the big four by size and mass.

True - one day.

Stars: Mira's period of variation is 332 days,not 400.


Brief History: Absorbing overview; i learned several facts i had not previously known.

Much of this uses a single date for simplicity. I am in the process of updating this section as you can see from the page formats being different and I'll take some of your suggestions on board.

Galileo 1610 -- he actually turned his telescope skyward for the first time in 1609, which is of course, the reason we are observing the 400th anniversary this year. It was in Jan 1610 that he discovered the Jovian moons. I know, picky picky.

Newton 1666 - yes, he achieved his great conceptual leaps in this milestone year, but did not publish the Principia until 1687, which has no separate entry in your timeline. Given its monumental impact on the world, i think its publication date merits a separate entry. Kind of picky, but not as much.

This is deliberate to keep the chronology more logical. I am basically following the story in logical order rather than giving an exact historical sequence.

Herschel 1780 -- he actually discovered Uranus in 1781, as correctly stated in other sections. Yeah, picky picky again.

1780 covers all his observations so perhaps I should add an s.

Einstein 1915 -- This one is NOT picky picky. No entry for 1905, the annus mirabulus that revolutionized physics! This was the year that the papers on special relativity, Brownian motion and the photoelectric effect were all published. You mention all of these in your description of Einsteins contributions, but only for the year he finished the General Theory of Relativity, his single greatest accomplishment. A newcomer would get the impression that all of them date from 1915.

Again I wanted to keep Einstein in one place. One day I will do something specific on the great man and 1905 will definitely be a key year. I have put a "between 1905 and 1915" in the text.

Hubble 1929 -- should be first 1925, Andromeda galaxy found to be a separate "island of stars" outside the Milky Way, THEN 1929, expansion of the universe, the two phenomenal discoveries which established Hubble as the 20th century's greatest observational astronomer.

Again, simplicity.

Your treatment of the properties of stars and of stellar evolution is so outstanding, i was rather disappointed that you dont have a similar lengthy section on galaxies, their characteristics and classification (ellipticals, lenticulars, spirals, barred spirals, irregulars), as well as the status of quasars as active cores of young galaxies. Will this be coming along sometime in the future, as time allows? A feature on the burgeoning study of exoplanets would likewise be most welcome. (Yes, i do realize you have a life!).

When I'm not travelling, eclipse chasing, living and working I would like to add more essays.

Well, i've obviously gone overboard with this laundry list of recommendations, but i hope you find portions of it useful in some fashion. None of it should imply anything but great admiration for the labor of love which resulted in this fascinating little corner of cyberspace and i will continue devouring more of it in the coming months. Thank you for your splendid efforts at public education,


Again thank you for taking the time to write.

Well, what can i say? Seldom has any humble communication of mine resulted in such immediate and fruitful results. I admire your responsiveness and your conscientious devotion to factual accuracy and currency. If only those traits were more ubiquitous in cyberspace!

Hi, Rob, More work for me?

I do try and keep up to date. See my notes below.

Re Icarus - aw, thanks for your solicitude. Well, the son of Daedalus can still be spelled Icaros, in keeping with his native origins, but I've only seen the sun-skirting asteroid in the Anglicized spelling. Of course, being an English speaker from the colonies, I suppose thats inevitable. The US journal of planetary science also uses the standard "Icarus" spelling. Certainly, few celestial objects have ever been more aptly christened!

Of course, here in the UK we spell it "Anglicised". Language differences, eh?

Speaking of Anglizing names from other languages -- JOHN Kepler? I've never encountered THAT version before ... (ellipsis, appropriately enough).

I take your point that Quadrature doesnt pass muster as a significant positional concept, but its one that people will encounter in planetary aspect tables along with the others, so i figured a one-line definition was in order. Its just the equivalent of first and last quarters for the moon, so it's not really esoteric, just less important for practical planet-hunting. But you are certainly allowed to omit it on your own web page!

Your point about readers coming across this term is a good one and I will add a note about it.

A couple more suggestions of far less than cosmic import:

Solar System Intro page:"Eight Major Planets (also known as Classical Planets)."

Perhaps this is another semantic quibble, but i tend to think of the Classical Planets as the seven "planets" known to the ancients - sun, moon and the five "wanderers", which gave us our days of the week. I know the IAU suggested this as an acceptable alternate designation for Mercury [to] Neptune, but to me, this simply underlines their narrow historical perspective. I cant really see Uranus & Neptune being considered as "classical" given that they were unknown just ten generations ago.

I think Major Planets is a sufficient label for the eight and all the others are Minor Planets down to point at which they become markedly irregular in shape. I rather like the classification suggested by Nathan Rogers - A planet is any substellar body massive enough to have achieved hydrostatic equilibrium ('roundness' in common language), and they can be divided into Primary Planets, which orbit a central star & have cleared their orbital region of other planetary bodies; Satellite Planets, which orbit another planet; Associate Planets, which are members of associated material groupings of greater mass than themselves, with which they orbit the star; and Free Planets, which have no host, either stellar or planetary.

By these criteria, the Sun's family consists of 8 Primary planets; 18 Satellite planets (Luna, the four Galilean moons, Saturn's seven largest, Uranus' five largest, and Triton); at least four dozen Associate planets: 1-4 in the asteroid belt (Ceres and probably Pallas, Vesta, Hygeia), a large and still growing number discovered in the Kuiper Belt and Scattered Disk (Eris, Pluto/Charon, Makemake, Haumea, Orcus, Quaoar, Varuna are the named ones to date), and one so far in the Inner Oort Cloud (Sedna).

This is a nice definition - I must say that Dwarf Planet is a poor definition. I will certainly look further at this.

BTW, Haumea. Its tiny moons are listed only as 1 & 2; their names are Hi'iaka and Namaka.

We might also add a special category called Fictional Planets, the leading example being Leverrier's second great "discovery", the infra-Mercurian world he dubbed Vulcan, which in the late 20th century was "transported" to 40 EridaniA by Star Trek fans. But that's drifting erratically into your Television section. ;-)

Vulcan was in the Dr Who story, Power of the Daleks, a few months before Star Trek began.

Thanx again for your prompt and generous reply to my message!



Jim Klingers

Dear webmaster,

In found some mistakes in your list of inventions: not Hans Lippershey was the inventor of the telescope, he only created the binocular. Most likely the basical techniques of both microscope and refractor-telescope were invented around 1590 by Zacharias Jansen, a very young spectaclemaker - some say he was only a child - from Middelburg in the Netherlands (not Denmark). Hans Lippershey was a competitive spectaclemaker from the same city of Middelburg who may have used the inventions of Jansen for his own sake. Anyway, his patent request in 1608 was not granted, because Maurits, the prince of Orange, allready posessed a telescope made by Jansen for many years. By the way, there was a third Dutch spectaclemaker, Jacob Adriaanszoon, who claimed the invention of the telescope, and there must be a few others. But Zacharias Jansen still holds the best cards.


Cindy McCarthy

You have a great and factual page. I found it a great deal of help, however I need more info on the Moon's temp! Can you help?!

KryssTal Reply: Thank you,

Try my page

There is a large difference between day and night temperatures because:

1 - the day / night period is 2 weeks for each.
2 - there is no atmosphere to soften the heat of the day or hold the heat at night.

Good luck.

Thank you soooo much for info.



can you tellme the age of the star of aries sharatan??? for a project for school???

KryssTal Reply: Hello,

I don't have any information about that particular star.

If you can look the star up in an astronomy book, you need to look up its SPECTRAL TYPE or SPECTRAL CLASS. This will be a letter (O, B, A, F, G, K, M) or a letter with a number (A7, G2, etc). Ignore the number and take the letter. The following table will give you a rough idea of the star's age:

Types: O, B - less than 100 million years old
Types: A, F - less than 1,000 million years old
Type G - about 5,000 million years old
Type K - about 15,000 million years old
Type M - about 30,000 million years

Hope that helps. Good luck with your project.


Bill Lindsay


If you want to know what astrology is REALLY about, why don't you correspond with a REAL astrologer, and not rely only upon popular belief. There are not many of us who take astrology seriously enough to look for the hows and whys. Thanks for a great website. I am open to any response.

KryssTal Reply: I am happy to correspond with you if you are a real astrologer.


Thanks for your response...I visited your website in the course of my research, and find it very informative.

You devote some space to your opinion on astrology and how it is practiced. I want you to know that few 'astrologers' know the mechanics behind it, and many actually don't know that they are doing it wrong. I would like to correct some of the assumptions about astrology. I know that you take it somewhat seriously because you write about it on your website and even include a link to others about it. One of my goals is not to prove that astrology 'works'...but to clarify it and explain how and why.

Let's start with the number one common assumption...true astrology is not based on the zodiac of the constellations. 'Sign energy' does not come from the stars in the constellations. That is a fallacy that is frequently supported by many uneducated astrologers in an attempt to explain their 'work' to an even less informed public. Our zodiac, which we call the 'zodiac of the signs' is actually the corona of force around the Earth, as she spins, and the point known as 0 Aries is located where the equator cuts the ecliptic plane.

The opposite point is, of course, 0 Libra. The point that the North Pole leans towards is 0 Cancer, while the opposite point is 0 Capricorn. If I diverge in any way from the astronomer's terminology, remember, astrology is not is a science of energy and in practice I deal with issues of behavior, not physics. In astrology, when we say 'zodiac', we don't mean the zodiacal belt of constellations, but the ring around the Earth at the ecliptic. The signs are named intuitively, according to the behavior orientation their energy supports, which is analogous to their positioning regarding the equator.

Many astrologers (some misinformed, some just trying to make a fast buck if they can) take on a fatalistic approach, and this has done more harm than good for us. Newspaper astrology only makes it worse. I have never been inclined to say that 'such and such will happen when this planet is in that sign'. In practice I am more inclined to take note of the energy that I see present in a look at transits for a future date, and what types of actions or events it would support. Even more inclined to see whether it would support what I had planned for that date.

We do take account of precession('we', meaning serious astrologers). The most commonly used reference work in astrology is called, as you know, an ephemeris, and mine (and most others published in the States) gets its data from the Jet Propulsion Lab in Pasadena, CA. Precession is indeed taken into account, and in fact my ephemeris includes data for those astrologers (though few) who do use the sidereal zodiac(ie zodiac of the constellations). But to me, that is energetically incorrect, but oh well.

Another common assumption is that we astrologers do not acknowledge the multitude of other influences present in the universe. That is only partly true. Us serious astrologers do. The thing is that there is just so many many of them. Could you write out an interpretation of the zodiacal positions of every star in a birth chart? The individual stars do have some influence on their own individual merit (though not as signs). But there are billions of them. In serious astrology, the forces that are most directly pertinent are the ones that have the most direct influence. Gravity-wise, the Earth (which determines the sign locations, not the stars) and the Moon are the top two, with the Sun contributing not only gravity but heat and light, which has astrological significance.

The planets each have their own fundamental meaning and pull on the Earth with various strengths. Not to mention the thousands of other objects. We just prefer to focus on the most powerful ones. Earth is the center (remember, this is not astronomy) because Earth is where we live. In making a birthchart (or any other chart) we use the local longitude and latitude, and use trigonometry to determine the rising degree (or 'rising sign' as most people would call it).

These are the most common points of contention that some astronomers have with our study, I think. There are probably more that have slipped my mind. I am just frustrated with seeing so many assumptions made about astrologers and how we think. I am an astrologer, but I am also math- and science-minded, this means I skip all the books about 'Love Signs', 'So-and-so's Moon Signs', etc. I have done astrology for 13 years, and these days, I am more of a writer on the subject. I use my intuition and other knowledge to guide me in my research.

I think that, more than anything else, astrologers who have not researched their methods and relied purely upon what they have read, have damaged the reputation of astrologers. Especially those who claim to practice it. My research has led me to change the way I practice, while others have held to fundamental beliefs (you called it a belief system, and that is often how it is taught). I am seeking a way to merge it with physics and that can only work by being willing to change, or correct, how I see it. Many others just won't see it that way, because it is a challenge.

We study astronomy, like other fields, as a means of understanding ourselves. Astrology is to the same end. I hope I have encouraged you somewhat to have a more open mind. I am not writing to sell you anything, I don't even advertise or sell my services anywhere. I am a researcher. I do charts and help people understand themselves through astrology, but I often do not charge. I earn my income as the second-highest paid stocker at a local supermarket. I am a college graduate, but money is only a peripheral concern, I am in search of some other purpose.

I am open to any further questions. I meant no resentment towards you, I just felt that you were serious enough about your work to receive better insights on how serious astrologers look at their subject. I guess I am more astronomy-geometry conscious than most of my 'colleagues'. If you have any questions about your chart, I'd be happy to take a look and offer an opinion (I would need the time, date and place of your birth).

Thanks for your time.

KryssTal Reply: I cannot say that I understand or believe your notes. However, I do believe in open debate. therefore I am publishing them in my feedback pages (under astronomy) so that others can read them.

You appear to be talking about imaginary entities called "signs" rather than the astronomical constellations. How would you measure these and what are their properties? You use the term "corona of force" which is scientifically meaningless.

It would not be a good test to produce predictions or personality based on my chart because we have communicated and that gives you information about me.


David Anderson

Dear Mr. Tal -

Are you aware of any scientific consensus on increases in the orbital path of the moon ?

KryssTal Reply: The Moon affects the Earth's tides. This causes the Earth to lose energy and slow down. The Moon gains energy by moving a way from the Earth.

That's a summary.


Jim Bell

Minto, New Brunswick, Canada


I have been traveling the www for years. Your site has to be one of the most interesting I've ever come across. I never email webmasters of sites, but in your case, I just had to say .... GREAT PAGE! ... it contains many fascinating and wondrous things.

I was looking for a scale of the Universe to understand the immensity of it all ... and happened upon your page. Seeing many things which interest me on your site, I'm sure to have some enjoyable reading.

Regards, Jim Bell

KryssTal Reply: Thank you for your kind comments.

I'm glad you found something useful.


Hannah Norton

Dear Sir,

your history of astronomy was very interesting and enjoyable to read. I found the information very useful. The information was presented in a very organized and easy to understand way. Thank you for your help.

I do have a problem, however, with your view of fundamentalists. I am a Bible-believing fundamentalist. That does not mean that I am stupid or close my eyes to observations or scientific data. I think that the recent discoveries in astronomy are wonderful. I acknowledge and understand the data that has been collected. I do not cling to the scientifically archaic ideas once held by the Catholic Church, or any other religious group for that matter. The subject of how the earth came into existence is not science. For something to meet the criteria of science, it must be measurable and repeatable. The formation of the earth is not measurable and repeatable. Scientists and church leaders can both guess by observing the universe around them. No one can say for definite, based on science alone, how the earth came into existence. It is outside of the realm of science. The process of the universe's formation would fit much better into the category of faith-that is, trusting in what we cannot see.

When astronomers observe and record data, they make guesses about why certain phenomenon occur. They do not, for instance, know that the gases and other phenomena in the heavens will eventually evolve into another galaxy. They do not know that the earth came into existence that way. They are only guessing. There are certain things science will never tell us. Thank you again for your history of astronomy.

KryssTal Reply: Thank you for your thought-provoking email. I will attempt to respond to your points as well as I can.

The essay mentions fundamentalists after the entry for 1200. These were certainly the views of the Vatican until very recently. Galileo's books were on the Index of Forbidden Books until the 1980s. In addition there are many people around the world (not necessary all Christians) whose view of the Universe is along these lines. I was referring to these events and not calling anybody stupid. The need to believe in a religion is nothing to do with stupidity. But I don't look at those issues.

The essays do not actually go that much into the origin of the Universe except to describe the Big Bang and the Steady State theories. It is an account of how our position in the Universe was slowly worked out.

Obviously, the origin of the Universe is not a repeatable phenomenon. However, any explanation of its origin has to account for the existing properties of the Universe and make predictions that are measurable. The Big Bang theory is the best explanation for the observations at present. But remember, science works on evidence and is continuously changing - it is not absolute truth. However long or strongly a theory is accepted, new evidence may arrive that disproves it. This is the fundamental difference between science and religion: the latter talks of absolute truth.

Science looks at observations, proposes hypotheses (what you call guesses) consistent with the observations, tests the hypotheses until they are accepted as theories, but is always open to changing even its most established theories. Religion has a given truth which does not depend on evidence but rather on faith. The two work in totally different ways. Different religions will tell us different things about origins and it is by faith that one or other of their models is accepted.

Thank you for writing and I am glad you enjoyed the history.


Arrow (Navarro)

In the studying of geocentric cosmology which celestial bodies are considered planets, which are not, and why?


KryssTal Reply: In geocentric cosmology, the planets are the moving objects as opposed to the fixed stars. They consist of the sun, moon and traditional five "naked eye" planets (Mercury, Venus, Mars, Jupiter, Saturn). The Greek word planet means "wanderer".


Jan Tessem


My name is Jacob and I am interested in doing a science fair project on planet x or the 10th planet. I have been searching the internet for info but have not been able to find much. Can you tell me where I might go to find current info about planet x? Thank you.

KryssTal Reply: Hello there

Planet X has yet to be discovered.

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