This site contains links to various web database applications that I have created using PHP and MySQL.
My first creation is an application which displays the distances between various locations around the world in kilometres. At the moment I have 280 locations listed. You select a particular location from a drop down combo box, and then a display of all the distances from that selected location to all other locations on the database is displayed, as well as their angular separation in degrees. The angular separation is just that. For example, the circumference of the earth about the equator or any meridian of longitude is 40 000 Kilometres. (Approximating the earth to a perfect sphere, a reasonable approximation). Now the distance between the North and South Poles is 20 000 Kilometres, hence their angular separation (THETA):

THETA = (20000/40000) x 360 = 180 degrees

Of course, the distance can never be greater than 20 000 Kilometres, and THETA never greater than 180 degrees.

One other feature, is that you can pick just two locations to find the distance between, then you can ask to find the distance between another pair of locations. This is done by pressing the "VIEW SPECIFIC DISTANCES" button. This is particularly useful when you wish to find the length of a route between three or more locations. For example, you could find the length of the trip from Koahsiung Taiwan to Tokyo Japan, then Tokyo to Los Angeles California, then Los Angleles to Buenos Aires Argentina. The cumulative distance for this trip is equal to 21,024 Km or 13,064 miles.

Another interesting combination to try is Brisbane Queensland Australia to Bangkok Thailand to Cairo Egypt. What's special about that route?
My next project is one in which you can execute a number of different queries about the solar system. They can be placed into five broad categories such as:

Next is a database of 2888 isotopes.

I did NOT enter the data manually into the database, as that would have taken forever and a day. Instead, I was able to download in one hit multiple files of all the known isotopes, via a fairly simple PHP script (which I wrote) to my PC. Then, with another more complex PHP script, which I designed to read and extract the data, I was able to import all the data requried into my isotopes database. The data was obtained from KAERI, the Korean Atomic Energy Research Institute back in 2002. Their homepage is at

From here you can query a radioactive isotope's decay chain, along with other details, such as it's half life. For example, the isotope 92-Uranium-238 has a long decay chain where it passes through several isotopes before finishing at the stable isotope 82-Lead-206. The isotopes of elements in our everyday lives, for example Iron (Fe) and Carbon (C) are dominated by stable isotopes. However, all chemical elements have radioactive isotopes, but usually you don't see them in nature as their half-lives are so short when compared to the age of the Earth.

Some elements, such as Uranium, the heaviest naturally occurring chemical element, have no stable isotopes. However, some of their isotopes do occur in nature because their half-lives are comparable to the age of the Earth.

For example, the half life of 92-Uranium-238 is about 4.5 billion years. That means if we start with 1Kg of pure 92-Uranium-238, after 4.5 billion years, there will only be 0.5Kg of 92-Uranium-238 left. Then after another 4.5 billion years, only 0.25Kg, and so on. This half-life of 4.5 billion years is comparable to the estimated age of the Earth, namely 5 billion years, which means that significant amounts of Uranium exist naturally.

Other istopes of Uranium have half-lives not as long as 92-Uranium-238, but still long enough to exist in much smaller quantities naturally. As a result, there percentage abundance in a random sample of Uranium is much less, but still detectable. For example, 92-Uranium-235 which is required in the nuclear bomb and nuclear reactors has a half-life of 0.7038 billion years, which is about 1/6 the half-life of 92-Uranium-238. As a result, in a random sample of Uranium, 99.274498% of the Uranium atoms will be 92-Uranium-238, while only 0.720000% will be 92-Uranium-235. The only other naturally occurring Uranium isotope is 92-Uranium-234 with a half-life of 24.42 million years and a microscopic percentage abundance of only 0.0055% in any random sample of Uranium.

One interesting property of Uranium, enables one to calculate roughly the age of the Earth, since Uranium is the heaviest naturally occurring element on Earth, and all its isotopes are radioactive with three still in detectable amounts. Using the equations of radioactive exponential decay, this is possible and one arrives at a figure around the presently accepted figure of five billion years or so. The basic fundamental assumption made, is that the Uranium isotopes were all in equal amounts at the formation of the Earth. Furthermore, similar dating methods such as radio-carbon dating, based on 6-Carbon-14 (6-Carbon-12 is stable and the most abundant Carbon isotope) with a half-life of only 5,700 years, is used to date items less than 100,000 years old. The idea being, that when say an organism dies, it stops reproducing carbon, and thus over time, the percentage of 6-Carbon-14 will gradually decrease, and thus its time of death can be estimated.

When you hear the term "Uranium Enrichment Plant", the aim of that facility is to extract 92-Uranium-235, which is "fissionable", that is, its atom can be split to release nuclear energy which can be harnessed destructively as in a nuclear bomb, or used peacefully but still rather dangerously as the Japanese of Sendai will attest to, for nuclear power stations. Clearly, while nuclear power is perhaps the cheapest and most efficient form of power generation, it is also the most dangerous means of power generation, especially in earthquake prone countries like Japan.

Other isotopes, such as 32-Germanium-83, only have a half life of 1.85 seconds, while 38-Strontium-90, a product of radioactive waste, has a half life of just under 29 years. Thus, these isotopes don't occur naturally, and clearly, half life is a quantity that wildly varies from isotope to isotope.

The next link is a link to a database and lightcurves (brightness graphs) of cepheid variable stars in the LARGE & SMALL MAGELLANIC CLOUD galaxies. The lightcurves were drawn using the image creation capabilities of PHP.

Cepheid variable stars are quite luminous stars, in comparison to our star the Sun, but they vary in brightness over a given period in a cyclic fashion.

There are two main categories of cepheid variable stars, namely, "Fundamental-Classical", which I designate as "FU", and "Firstovertone", which I designate as type "FO".

Each main category has its own "period-luminosity law." Click here for more information.

Basically, this means that the longer a cepheid's period, the higher its average brightness, which makes cepheids useful calibraters of cosmic distance, or cosmic yardsticks. It was through the use of this characteristic that Edwin Hubble in the 1920's was able to prove the scale and expanding nature (big bang) of our universe.

However, there is one very important proviso. The "period-luminosity law" varies between "Fundamental-Classical" (FU) and "Firstovertone" (FO) types. From my graphs you will see that the lightcurves for type FU, resemble that of a "shark fin", while that of for type FO, resemble that of a "triangular wave" or "sine wave".

The vertical Y axis of the graph represents the cepheid brightness or "MAGNITUDE" Click here for more information., which is a logarithmic scale. Strangely,the higher the numerical value for the magnitude, the lower its luminosity, so hence the reverse scale on my graphs for the vertical axis, to represent increasing/decreasing luminosity.

The horizontal X axis represents "PHASE". It ranges in value from ZERO to 2, which means it covers a period in time equal to two periods of the cepheid. For example, if cepheid period = 3 days, then the horizontal axis covers a period of 2 X 3 = 6 days.

For each cepheid, a lightcurve is drawn in three different light bands, namely "I", "B", & "V".

The "V" band is in the visible-light range, which the human eye is most sensitive to. "I" is in the infra-red band, while "B" is in the low-energy ultra-violet band, which is responsible for giving us sunburn.

The cepheid lightcurves given, are for cepheids in the two satellite galaxies, called the LARGE & SMALL MAGELLANIC CLOUDS, (LMC & SMC) which are orbiting our very own MILKY WAY GALAXY. Hence the term "satellite galaxies". The data I use to draw the graphs is from the "OGLE WEBSITE (University of Warsaw)" Click here. These graphs are drawn by PHP on the fly in PNG format, which saves an enormous amount in disk storage space.

A galaxy is a family of stars orbiting a common center, like our solar system is a family of planets/asteroids/comets orbiting a common centre, namely our star, the Sun.

The LARGE MAGELLANIC CLOUD galaxy is approximately 169,000 light years distant from us, while the SMALL cloud is approximately 210,000 light years away. (One light year is the distance light travels in a year = 9.467 trillion Kilometers)

Our Sun lies 30,000 light years from the center of our own MILKY WAY GALAXY, and the MILKY WAY has a radius of about 50,000 light years. The Sun, being 30,000 light years from the galactic centre, means our Sun takes about 225 million years to complete an orbit around the centre of our Milky Way galaxy. This is known as a cosmic year, and one cosmic year ago, the dinosaurs first started walking the Earth. The Milky Way contains about 100,000 million stars.

Fortunately, at the moment anyway, our star the Sun, is not a cepheid, or anyother type of variable star. It is very uniform in luminosity, which allows for flourishing of life here on Earth. The tiniest drop in luminosity could bring about a devastating ice age, while the opposite could fry all life on earth.

As well as the lightcurves for individual cepheids just mentioned, I have now added a page which displays graphs for entire datasets of cepheids. "ALL CEPHEID PLOTS" Click here For example, you can obtain a plot of the logarithm10(period in days) versus apparent magnitude in the "V" band for all the cepheids in the small magellanic cloud. Dual plots are possible as well. For example you can compare plots from the same magellanic cloud in the same light band but for different cepheid types. One plot could be for first overtone cepheids in the small magellanic cloud in the "I" band, and the other on the same graph for fundamemtal cepheids in the small magellanic cloud in the "I" band. Another dual plot is where each plot graphs the same light band and cepheid type, but one plot is for the cepheids in the large magellanic cloud and the other for the corresponding cepheids and light band in the small magellanic cloud. This plot is useful for determining the distance ratio from us to each magellanic cloud. Bear in mind that all the cepheids in one particular magellanic cloud are more or less the same distance from us, in the sense that the length and breadth of each cloud is much much less than their respective distance from us.

You will find that the plots calculated are roughly linear. The Pearson correllation coefficients given tell us how close to a linear relationship the plot is. The closer the ABSOLUTE value of the Pearson correllation coefficient is to 1, the closer the plot is to being perfectly linear. A zero value means no relationship exists. Some have Pearson correllation coefficients above 0.96 while others are not so good. This linear relationship is what the cepheid period luminosity law is based upon.

This link "EXOPLANETS QUERY PAGE" Click here takes you to a page where you can query all the known exoplanets. Exoplanets are planets that orbit stars other than the Sun. The first one was discovered in 1989, but now 4805 have been discovered as of Saturday 17th of July 2021. This number now, from Sunday the 2nd July 2017, includes the nine planets of our Solar System, including the demoted Pluto, now being on this database. This I have found is most useful when we compare exoplanet systems to our own. In addition, there are pieces of valuable data called "Habitability Factors". There are three of them, namely "Habitability Factor Maximum Distance", "Habitability Factor Mean Distance" and "Habitability Factor Minimum Distance". As the orbits are often elliptical, these Habitability Factors have to be defined by when the planet is at its maximum, mean and minimum distance from its parent star. If the orbit is perfectly circular, that is with an orbital eccentricity = 0, then all these three Habitability Factors will be identical, otherwise, the "Habitability Factor Maximum Distance" will be the smallest, then the "Habitability Factor Mean Distance", then of course the "Habitability Factor Minimum Distance". The closer this value is to 1, the more possibly "Earth-like" this planet is, while if it is much more than 1, then the planet will be too hot, while if it is much less than 1, then it will be too cold. For a planet to be in the "Goldilocks" or "habitable" zone, this value, must be close to 1. Bear in mind, this is just a rough guide. These habitability factors only take into account the intensity of the star at these distances, compared to the intensity of our Sun at the mean Earth distance. Other important factors like the composition of the planet's atmosphere, or possible absence of one, are not, as this cannot be reliably determined at present. Nevertheless, it is a useful guide. The recently discovered and confirmed planet "Kepler-22 b", which is regarded as one of the most "Earth-like" planet discovered so far, has a Habitability Factor at its mean distance = 0.8238457596240227, with a radius of 2.37894839216 times that of Earth respectively. However two of the five planets in the confirmed "Kepler-20" system, namely 'e' and 'f', have radii of 0.86405201036 and 0.99870946652 times that of the Earth. Unfortunately their mean habitability factors are 13.036502807511969 and 5.9672817292264675 respectively, orbiting at 6.09852281 and 19.57758478 days respectively around a very "Sun like" star, making them way too hot for life. However, they are still very encouraging discoveries as they confirm that the Kepler craft can detect "Earth size" planets.

In March 2014, I added what I call "Bolometric Habitability Factors". They are similar to what I termed just "Habitability Factors", but the key difference is that the Bolometric ones take into account the entire spectrum of radiation emitted by the star, NOT JUST THE VISIBLE LIGHT, as is the case with the plain "Habitability Factors". For stars similar to the Sun, both sets of Habitability Factors will be quite close, but for for stars dissimilar to the Sun, they can vary markedly. For example, in the case of M type Red Dwarfs, which mostly emit Infra Red light, their Bolometric values will be higher than the plain visible light only Habitability Factors.

Breaking News Monday December 05th 2011--Kepler Confirms First Planet in Habitable Zone of Sun-like Star

Breaking News Monday December 19th 2011--Kepler Confirms First Planets of earth like size orbiting Sun-like Star

The data has been obtained from the The Extrasolar Planets Encyclopaedia, by importing the data from downloaded spreadsheets into the database, similar to what I did with the isotopes database. I find this site of Jean Schneider most up to date, and with the now continual and persistent new discoveries, that is most important. For example, from the 15th August 2011 to the 16th Septemeber 2011, that is in just over one month, the number of known exoplanets had increased from 573 to 684.

Most recently, in March 2014, an incredible 702 new exoplanets were added from the Kepler mission. The next month, Kepler discovered the most "Earth like" exoplanet so far, "Kepler-186 f" orbiting a dim M type Red dwarf star.

Nasa's Kepler discovers first earth size planet in the habitable zone of another star

However, this new discovery of "Kepler-452 b" on the 24th July 2015 is now the most earth like.

Breaking News Friday July 24th 2015--Kepler Confirms most earth like planet in Habitable Zone of Sun-like Star. Take note of Bolometric Habitability Factors just above 1 and radius of exoplanet PLUS spectral type of parent star "Kepler-452"

You can query them by spectral type where stars similar to our Sun have a general spectral type of "G" and are yellow in colour with a surface temperature of about 5800 deg celsius. Others like type "M" have a surface temperature of about 3000 deg celsius. Type "B" are very young hot stars with temperatures above 10000 deg celsius. The average distance of the exoplanets from their stars are given in AU (Astronomical Units) where the average Earth to Sun distance is 1 AU, which is equal to about 149 570 000 Km. Their masses are given in comparison to Jupiter and the Earth. Bear in mind Jupiter is 317.8 times the mass of the Earth, and in the early history of exoplanet hunting, nearly all the exoplanets had masses around that of Jupiter and much higher.

At the moment the lightest exoplanet discovered is "PSR 1257 12 b" at only 1/50 of the Earth's mass. However it orbits a PULSAR which is a heavy, extremely dense star which is the remains of a cataclysmic supernova, a typical fate for any star significantly heavier than the Sun. Furthermore, the environment around this star is saturated with dangerous gamma and X-radiation which would fry any life on this planet.

Another interesting planet, which is in the Gliese 581 system, is "Gliese 581 c" with a mass of 5.498807850693 times that of the Earth. Now, this planet has an orbital period of only 12.919 days, much much less than Earth's 365.2425 days, however it's star being a tiny COOL "M" type star with a luminosity, as already mentioned of only 1/500th compared to that of our Sun, puts it in the HABITABLE REGION WHERE LIQUID WATER COULD EXIST--a major precursor for the existence of life. It is more than twice the distance from its star as "Gliese 581 e", which is only around 1.9387739373 times the mass of the Earth, but even for this faint star, that would probably make "Gliese 581 e" too hot for life. However, techniques are becoming more accurate, and with the rate they are now finding new exoplanets, an Earth planet mark II may not be too far away. Red dwarf M type stars have a life span hundreds of times that of our Sun, so certainly that gives life plenty of time to form and evolve, unlike extremely massive stars with lifespans only 1/10 of that of the Sun.

Click here for more information on this intruiging exoplanet "Gliese 581 c".

Bear in mind, that even though this article states that "Gliese 581 c" is the smallest exoplanet to date, that was only true for the time the article was written, namely the 25th of April 2007. At the time of the last database update, namely Saturday 17th of July 2021, with a mass of over five times that of the Earth, it was ranked number 230 as the lightest known exoplanet. This is indicative of the greater accuracy of the detection instruments as time goes by.

As well, you can find information on the five various exoplanet detection methods, namely radial velocity, transit, gravitational microlensing, direct imaging and timing at

Methods of exoplanet detection

Back in late September 2010, an exoplanet in the Gliese 581 system, namely "Gliese 581 g" was reported. It was stated that it was the absolutely ideal distance from its star to support life, in other words, right in the middle of the so called "GOLDILOCKS ZONE". But two months later its existence was brought into serious question, and now it is officially listed as doubtful or questionable. As a result, it is listed in this database, but not in the main table. Rather it is listed in the table of 80 retracted exoplanets. Also, the following link provides more information on this nevertheless, intruiging exoplanet.

Unconfirmed "GOLDILOCKS" extrasolar planet "Gliese 581 g"

From the table created from the submitted query, two useful links, when available, are given. One is for the Open Exoplanet Catalogue website, where you can obtain more information on the planetary system of the star, such as its habitable zone and the location of its planet(s) orbits in relation to that habitable zone. The other, added in May 2019, is from the NASA EXOPLANET CATALOG where you can view orbital simulations of the exoplanets, comparing the exoplanetary system to our solar system, with the predicted habitable zone given in green. Moreover, size comparisons of the exoplanet to Earth and Jupiter are given, as well as size comparisons of the parent star with the Sun.

The habitable zones are also given for some pulsar stars, that is massive stars that have met their cataclysmic death. However, in these cases the GOLDILOCKS zone is a rather mute point, since the incredibly high levels of gamma and X-radiation would make life on these planets impossible. In fact, it is a wonder that planets could even exist after a cataclysmic supernova when at that moment of the supernova, the power output of that star is equal to the entire power output of all the stars (all 100,000 million of them) in the galaxy!!!! Most likely, they are "zombie" planets created in the aftermath of the supernova and are all detected by the timing method, as pulsars "pulse" a beacon of radiation like a lighthouse with incredible clocklike regularity. When the exoplanet passes in front of this beacon of radiation, it can be detected. These cataclysmic stars are incredibly dense from the cataclysmic IMPLOSION of their cores. For example, the pulsar with the lightest known exoplanet, namely "PSR 1257 12 b", is only about 1/450 the radius of the Earth, but is still 1.4339109962793022 times the mass of the Sun or more than 476,190 times the mass of the Earth!!!! This makes it about 45 trillion (million million) times more dense than the Earth!!! More information on this pulsar and its exoplanets can be found at the following link.

Pulsar PSR 1257 12

Stars which are heavier than stars which become pulsars, will also supernova, however they will become something even more extreme than pulsars. They will become "blackholes" which are regions of space from which light can't even escape. You can obtain the density for "PSR 1257 12" by ordering the query by Stellar Density, and you can also query by the Exoplanet Density, ie mass per unit volume. Water is 1 gram per cubic centimetre, while the average density of the Earth = 5.515 grams/cm 3, and for the Sun is 1.408 grams/cm 3, while Jupiter's density is slightly lower than the Sun at 1.35738 grams/ cm 3. Saturn, the second largest and most massive planet in our solar system is actually less dense than water, which means that on a vast ocean, Saturn would float. Density is an important quantity that is easy to overlook, but when looking for Earth like planets it is an important consideration. Unfortunately, only 25% of the planets have their radius given, and they are nearly always ones discovered by the transit method. The trouble with this method is that the planet's orbit must be edge on to our view for us to monitor the microscopic dip in the stars brightness as the planet passes in front of the star.

A note on the convention for naming exoplanets. The first exoplanet discovered orbiting a particular star is designated as "b" and all exoplanets discovered around that star afterwards are designated as "c", "d", "e" etc. So exoplanet Gliese 581 c is the second exoplanet discovered orbiting that star, while Gliese 581 e is the most recently discovered exoplanet orbiting Gliese 581. Even though it is at present, the inner-most exoplanet in this sytem, it is still designated as "e", since the convention goes in order of discovery, NOT IN ORDER OF DISTANCE FROM THE STAR. Also, some stars can be multiple star systems, where they orbit each other. For example star "HD 41004", has its exoplanet designated as "HD 41004 A b". The "A" designates it as the primary star in this multiple star system, while "HD 41004 B" would be the secondary star in this system. Thus "HD 41004 A b" is the first exoplanet discovered orbiting the primary star in this system.

However, one exception to this convention is the already mentioned pulsar star PSR 1257 12, which does in fact have its exoplanets designated in order of their mean distance from their star.

And another slight break with convention as of Thursday the 15th September 2011. The first ever circumbinary oribiting exoplanet has been discovered by NASA's Kepler mission. Also go to

The existence of a world with a double sunset/sunrise, like "Tatooine" from the 1970s movie "Star Wars", has now become fact, although it is expected that this world, unlike Tatooine would be a cold gas giant. But like Tatooine it orbits twin stars which in turn orbit each other. On the database the stellar mass of this circumbinary orbiting exoplanet, namely "Kepler-16 (AB) b" is given as the combined mass of the two stars. This combined mass is 89% the mass of the Sun. as Star A is an orange "K" type star, about 69% the mass of the Sun, while star B is a red dwarf "M" type star about 20% the mass of the Sun. Many astronomers have suspected the existence of such worlds orbiting two stars, but the proof has proven elusive until now. The great significance of such a discovery is that the majority of stars out their are not "lone wolves" like our Sun, but have companion stars. Thus, now given this most significant discovery, the chance of finding life has been significantly improved, as our pool of possible candidates has been significantly increased.

Bear in mind, this planet "Kepler-16 (AB) b" is different to "HD 41004 A b" just mentioned earlier, as while "HD 41004 A b" also lies in a double star system, the planet itself only orbits the primary star.

Added in June 2017 was the "EXOPLANET PLOT QUERY PAGE". On this page you can obtain plots/graphs of the various exoplanet/parent star data. The option of using logarithmic scales is available as quite often the logarithmic scale, with markedly varying plot values, renders a more useful and viewable plot. Bear in mind, this option is not available for the Fe_H (Stellar Metallicity) parameter as this parameter is already logarithmic. Also, with Right Ascension and Declination the LOG option is not available as Declination can be negative for southern declinations, and in any case, the range of these parameters is rather limted.

If you choose to query a single system of a particular star, you can plot it as well, and even include a plot alongside it of our Solar System. In this case, the Solar System plot points will appear white, while the plot points for the subject star will appear according to their spectral type. That will be Violet for Super Hot 'O' stars, down to Red for cool 'M' type, and Brown for even cooler Brown Dwarfs of type 'T'.

Overall, including the nine planets from our Solar System, including Pluto, we have 3614 stars with exoplanets, with 785 of these stars known to have multiple exoplanets orbiting them, with the grand total of known exoplanets being as mentioned before 4805, as of Saturday 17th of July 2021.
Another link is to a page that does not use a database, but makes use of sessions. When you start a session you are able to preserve variables across different web pages. A concept used frequently for example in "shopping carts".

This page is called "BLACKJACK". The game of Blackjack is similar to the card game 21, where you try and get as close to 21, without going over 21. You make bets against the dealer, and you can have up to 7 players. Of course, the bets are with "imaginary money". This game is still in the beta stage as you cannot take out insurance against the dealer getting Blackjack, namely an ACE and a TEN or PICTURE CARD, nor can you split a pair or double up on 9,10, or 11. However, you can do just about everything else.
The old HANGMAN favourite. I have just resurrected it after many years and again it uses no database but makes use of sessions. Various sounds are made use of to indicate various stages of the game, as well as success or failure. Good Luck!
A calculator to DETERMINE LINEAR AND ANGULAR DISTANCE FROM HORIZON FOR A GIVEN HEIGHT OR ELEVATION. The Earth is a spheroid with a slightly lesser polar radius than its equatorial radius due to the rotation on its polar axis. Measured around the equator, it is 40,075.017 km (24,901.461 miles). Measured passing through the poles, the circumference is 40,007.863 km (24,859.734 miles). This gives it an equatorial radius of (40,075.017 / (2 * 3.14159265359)) = 6378.13705004 Km and polar radius of (40,007.863 / (2 * 3.14159265359)) = 6367.44915899 Km. For my horizon distance calculator, I give a radius of 6366.19772367 Km or 6366197.72367 metres. This corresponds to a circumference of 40,000 Km. For low elevations for just up to a few metres, the linear distance is practically identical and only ever so slightly more than the angular distance along the surface from the point directly below the elevated observation point to the horizon. However, as the observation elevation increases, especially to that of satellite orbits, the angular distance approaches that of one-quarter of the circumference. Hence. if one uses a radius of 6366.19772367 Km, corresponding to a circumference of 40,000 Km, then at elevations for say satellite orbits, the angular distance approaches 0.25 x 40,000 = 10,000 Km. I derived my equations using the gradient of the tangent from the horizon to the elevated observation point, which in turn was determined by differential calculus, using the Cartesian equation for a circle: "x*x + y*y = radius*radius".