Pluto was first referred to as Planet X by the astronomer Percival Lowell. He reasoned it existed
because something was causing slight variations in the orbits of the planets Neptune and Uranus.
He believed only another body large enough to exert a strong enough gravitational field could affect Neptune and Uranus' orbits.

Unfortunatley Percival Lowell died in 1916 without having proven the existence of Planet X. In 1930,
astronomer Clyde Tombaugh discovered "Planet X" 3.7 billion miles from our sun. He did this by
using an astronomical telescope to expose a series of photographic plates. The Plates clearly showed
a small object had moved against the background of distant stars.

This discovery turned out to be the result of a happy accident. The calculations that predicted
the existence of a planet beyond the orbit of Neptune later proved to be in error. The Voyager
2 spacecraft was able to measure the mass of the planet Neptune more accurately. When this new data
is used the variations in the orbits of Uranus and Neptune disappear.

None the less the new planet was dubbed Pluto. Several names were suggested including Zeus,
Cronus and Minerva. But in 1930 Pluto was officially labeled the ninth planet by the
International Astronomical Union and named for the Roman god of the underworld.

The axis of Pluto's poles do not point "up" and "down" out of the plane of the solar system
like planet Earth's. Instead the point more inward toward the Sun. Pluto is usually farther
from the Sun than any of the other planets. But due to it's eccentric orbit, it is closer to the
Sun than Neptune for 20 years out of its 249 year orbit. Pluto crossed inside Neptune's orbit
on January 21, 1979 and made its closest approach to the Sun on September 5, 1989. It remained
within the orbit of Neptune until February 11, 1999. This will not happen again until September 2226.
Pluto's odd orbit has lead some to say it is a "trans-Neptunian interloper". Which means it is
more like a Kuiper belt comet than a planet.

The composition of Pluto is unknown, but its density (about 2 gm/cm3) probably indicates it is a mixture
of and 30% water ice and 70% rock. The bright areas of the surface appear to be covered with ices of
nitrogen and smaller amounts of methane, ethane and carbon monoxide. The composition of the darker areas
on Pluto's surface is not known.

Pluto does have an atmosphere which probably consists mostly of nitrogen with some carbon monoxide
and methane. It is extremely thin with a surface pressure of only a few microbars. Pluto's atmosphere probably exist as
a gas only when Pluto is near the Sun. For the rest of Pluto's long orbit the atmospheric gases are frozen solid. Near the
Sun it is possible that some of the atmospheric gases escape into space. NASA mission planners hope to arrive at Pluto
while the atmosphere is still in gas form.

In 1978 it was discovered that pluto has a moon. Officially named Charon after the mythological
figure who ferried the dead across the River Acheron into the underworld. Charon was discovered
by Jim Christy and may have been named in honor of his wife Charlene. Before the discovery of
Charon it was believed Pluto was much larger since the images of the two were blurred together.

Pluto and Charon are unique in that they rotate synchronously with each other. Which means they
both keep the same face toward one another. It has been suggested that Charon was formed by a
giant impact against Pluto similar to the one that formed Earth's Moon. In 2005 a team using
the Hubble Space Telescope discovered two tiny moons orbiting around both Pluto and Charon.
They have been named Nix and Hydra. They are very small with diameters between 40 and 60 kilometers.

Recently there has been considerable debate about the classification of Pluto. It was classified as the a
planet just after its discovery and remained so for 75 years. But on 2006 Aug 24 the International
Astronomical Union decided to change the definition of a "planet". The new definition does not include Pluto.
Instead Pluto is now classified as a "dwarf planet". Personally I don't agree with taking away Pluto's
status as a planet. Maybe I am being superstitious, but as any sailor worth his salt will tell you it is
generally considered bad luck to change the name of a ship once she was been christened.

As of the writing of this article Pluto has not yet been explored by a space probe. On January 19, 2006
NASA launched New Horizons which will be the first spacecraft to visit Pluto in July 2015. New Horizons
is equipped with remote sensing devices that include imaging instruments, a radio science tool, a
spectroscopic sensor and other experiments. The tiny moons Nix and Hydra may present a certain
danger as their presence indicates the possibility of ring system similar to the one around Saturn,
though much smaller. Any ring system poses the threat of micrometeorite damage to the New Horizons
spacecraft as it flys past.

I hope very much that all goes well and the New Horizons space probe sends back a wealth of information about
"Planet X" or Pluto as it is known. Perhaps then we will be able to settle the debate as to whether
Pluto is really a planet or not.

Astronomy has to be one the most humbling of all subjects to study. Just the thought of our universe, being like a grain of sand in a sandy shore of universes, is enough to make me want to crawl back under the sheets. Everything just seems so immense, andbeyond comprehension. Where does it end? Is it possible to get to the end of space? Astronomy tries to come up those answers. Like any science, Astronomy asks far more questions then it can answer. But, that's part of what makes it so fascinating. Ever since the first adventurer wondered what was beyond the nexthorizon, humans have been trying to expand their boundaries. Astronomy is carrying on that fine tradition. It's a pretty big horizon, and maybe one that doesn't end? Who knows, only astronomers of the future will be able to answer that question.

Astronomy Begins At Home

We don't have to go that far with astronomy, to be truly fascinated. Our own friendly sun has some pretty interesting things going on. Did you know, that the sun moves at a rate of 12 miles per second. That's 720 miles per minute, or 43,200 miles per hour. Good thing it's got a big gas tank huh? And it's moving towards the constellation Hercules. Better get out of the way Herc! Another interesting astronomy tidbit here. I bet you thought the sun was about the hottest thing around. Well, not even close. The surface of the sun is hot, at about 10,000 degreesfarenheit . But, there is something here on earth that is 3 times hotter. Care to guess? Some people have even been touched by it, and lived to tell the story. Lightening is 30,000 degreesfarenheit . Cool huh? One more startling sun fact. There are 92 natural elements on earth. You remember that periodic table of elements from high school science, those elements. Well, two thirds of those elements have been identified in the sun. Not sure who checked, but they are there. And, scientists believe that the other third are most likely in the sun as well. Hard to believe our home planet full of water could be so closely related to that big fiery ball of gas. Astronomy spins a pretty fascinating tale.

Future Worlds

Like those adventurers who came before us and were drawn to venture beyond their horizon. I believe that star gazers of today will be our future boundary busters. It may have been a while since people have walked on the moon. But it's just a question of time. Human nature justdoesn't allow us to settle for what we have. We're always looking beyond. And astronomy is building that map, and trying to help break down those boundaries of today. It's not only fascinating to imagine where we will go next, but essential to our survival. We are spending the resources of this planet at an alarming rate, and sooner before later things will run out. The planet will survive of course, but we may not. It is time to venture out, and find another planet like earth. Not just for the sake of discovery, but because we need to. Soon. Hopefully, we will arrive there smarter, and a little more careful. In the mean time, astronomy is paving the path for ours and future generations to follow.

The stars have always been a fascinating subject. Perhaps that's one reason why astronomy is so popular these days.

In essence, Astronomy isn't just about studying stars, as most people think. It's actually a study of celestial objects, which includes not only stars but also planets, comets and entire galaxies. In fact, Astronomy also studies different phenomena that come from outside of the earth's atmosphere, such as auroras and cosmic background radiation.

In addition, Astronomy, is concerned with a host of other sciences, including physics, evolution, chemistry, how celestial objects move and how the universe was formed and developed. Scientists routinely use Astronomy to test some of the most fundamental theories in physics, such as general relativity. In attempting to explain astronomical phenomena, astronomy joins hands with astrophysics.

Overall, Astronomy is among the oldest sciences known to mankind. Records show that there were astronomers dating back to the days of ancient Greece and India. This is probably where advanced observation techniques originated. In addition, the scientific history of man shows how many amateur astronomers have contributed and played an active role in observing and discovering what is referred to as transient phenomena.

With the dawn of the 20th century, Astronomy was divided into two sciences. These are observational astronomy and theoretical astrophysics. The first one is concerned with getting data and this involves building and maintaining a host of different instruments as well as processing the results of the data it acquires. There are some who refer to this branch of science as "astrometry" or simply as "astronomy". On the other hand, theoretical astrophysics has to do with ascertaining the implications that can be observed through a computer or through analytical models.

There are those who confuse modern astronomy with astrology but they are two very different things. Astrology revolves around a belief system that presupposes that the different positions of celestial objects have a direct bearing on human affairs. In a nutshell, it is fortune telling with the aid of the stars. Astronomy and astrology obviously share the same common origins but most scientists and other knowledgeable observers know that both fields are clearly distinct.