4Stargazing

Comets have held a high fascination for all levels of astronomers all the way back to the first civilizations that provided a recorded history through writing or picture.  Ancient civilizations first mention the presence of comets associated with dark omens of death or destruction, and it was not until 350 BC when Aristotle offered his first book, “Meteorology,” and a basic scientific explanation of comets.  Within the texts he stated that comets were a phenomenon of the upper atmosphere, where hot, dry exhalations gathered and occasionally burst into flame.  Late in the seventeenth century Sir Iisac Newton added that comets were compact and durable solid bodies moving in oblique orbits, and their tails as thin streams of vapor emitted by their nuclei ignited or heated by the sun.  While today’s scientists have largely confirmed the hypothesis of these former scholars, much about comets is still largely unknown.

What is known about comets is that they follow a predetermined path, and their inner core is comprised of rock and forms of ice.  What exactly determines a comet’s course still remains largely a mystery; some pass by the Earth every few years while others may not return for hundreds of thousands of years or more.  Recent data from the Stardust spacecraft, which returned a core sample from Comet Wild 2 in 2004, verified that the interior makeup of comets were of crystaline form, which could only be produced by the intense heat of a star or another cosmic event.  The tail associated with comets is actually the visibility of gasses from within frozen ice particles when it passes close to our Sun, and once these gases are completely expelled the comet is simply a fast moving hunk of rock that closely resembles an asteroid.  It is also noted that the gravatitional pull of larger planets can alter a comet’s flight course, and even a differential of a few feet can equate to a massive trajectory change over the life of a comet.

Comets are classified by how often they pass into our solar system.  Short period comets pass by the Earth every two hundred years or less, and they are further divided into two subcatagories.  Jupiter comets are seen every twenty years or less while those belonging to the Halley family are spotted every twenty to two hundred years.  Long period comets are those that appear more than once within their lifetimes outside the two hundred year mark, and Single Appirition comets are those that travel an unknown course that will not bring them back into our solar system.  One of the problems with classifying a comet is that their orbits can last thousands or even millions of years, and the odds of not colliding with another object and being destroyed within that time period is infintisimal. 

Of course, another problem for astrologers is the formation of new comets from nearby celestial objects.  The Kuiper Belt, which resides beyond Neptune, is thought to create many short period comets while the Oort Cloud just outside our solar system is believed to be the creator of long period comets.  Since it is near impossible to predict how comets are formed or how many of them actually enter our various means of vision in space, it is difficult to make a reasonable hypothesis of their overall travel patterns.  As technology advances tracking long period comets will become a more resaonalbe expectation and hopefully science will finally be able to provide a definitive answer regarding their true origins.

By definition a satellite is any object placed in orbit due to a gravitational pull of a larger entity.  Since moons and some asteroids would fall under this description, the term artificial satellite was invented to describe man-made objects in space.  Sputnik 1 was the first of its kind and launched by Russia in 1957, primarily to identify proper the proper launch coordinates required for later missions.  Two months later Sputnik 2 successfully sent a dog named Lakia into space, and by this time the space race was fully ignited around the globe.  Since that time thousands of other launches have occurred by over fifty separate countries.  Only a few hundred of those artificial satellites are still operational, and within our orbit hundreds of partially damaged satellites continue to rotate around our planet as if they were inside a type of technological graveyard.  If aliens have in fact visited our planet as so many people have attested over time, we must be viewed as the hillbillies of the universe since our space garbage has been left to idly drift for everyone to see.

There are countless uses for artificial satellites and they are relied on at all levels of civil and public government.  Many will associate satellites for spying purposes, but they are also used for communication, global navigation, weather reporting, and other various types of research.  From internet access and cellular telephones to GPS devices and television, satellites empower modern living as much as any twentieth century invention.

As useful as the technology appears, satellites are unfortunately a common object of attack as well.  Militant groups will often hack into satellite transmissions in order to broadcast their own political views or to obtain classified secrets of another world nation.  While the technology behind a satellite may appear advanced, it is no more than a computer designed to accept a variety of commands.  Since communication requires a signal to be sent to and from Earth, it is relatively simple to block, intercept, or even take control of that transmission for personal gain.  More sophisticated monitoring equipment has become available within the past decade to assist satellite operators to avoid these issues and quickly track the parties responsible, but the problem is far from being solved.

In astronomy, satellites have been used to view distant objects that would otherwise be inaccessible.  The unmanned spacecrafts Pioneer and Voyager have been sent to the outer regions of our solar system and provided detailed analysis of Saturn, Uranus, Jupiter, and Neptune.  At a total one way distance in excess of over four billion miles, these epic journeys have provided countless data for scientists on Earth and have helped explain the makeup of our solar system.  A few examples of Voyager’s many scientific contributions are the discovery of water on one of Jupiter’s moons (Europa), erupting volcanoes on another (Lo), and a massive storm on Neptune that was previously undiscovered (the Great Dark Spot).  Many of the highest resolution pictures of the outer planets have been provided by one of these two satellites, and without them our solar system would still be largely considered a mystery.

The Hubble Space Telescope, designed by NASA and the European Space agency, has been capturing pictures of stunning celestial objects for the past two decades.  The concept of launching a telescope into orbit can not be fully accredited to our generation, however, since it was first proposed as early as 1923.  The Hubble project began in the late 1970’s with a proposed launch date of around 1983, but the Challenger incident and technical delays postponed the project’s completion until April of 1990.  Even then it was discovered that the main mirror had been attached incorrectly and the full capabilities of Hubble were not achieved until 1993.  Although not technically the first distant viewer in space, the Hubble Telescope is easily one of the largest and most versatile instruments of its kind and has provided more scientific data relating to astronomy than every other method used up until 1990. 

The idea of a telescope in space sounded good in theory; a good bit of sunlight reflects from the Earth’s surface and to gain a view without that interference was thought to be extremely beneficial.  Not only would clearer images be possible with such an instrument, but astronomers would also be able to view far outside of our solar system and gain a much more thorough knowledge of the universe.  Hubble’s Ultra Deep Field is the most technologically advanced system ever created and provides the most detailed visible light images ever witnessed.  By studying objects far distant from our own solar system scientists gain a more thorough understanding of how the universe was formed and at the rate it expands.

Not only has the Hubble Telescope validated or proven wrong countless hypothetical theories proposed by astronomers, but its discoveries have led to many other questions while trying to explain some of its discoveries.  Before the Hubble Telescope black holes were entirely theoretical, dark energy was not even expected,  and countless celestial bodies within our own solar system were not even known to exist.  Over eight thousand papers have been published within scientific journals with countless other observations reserved for lectures and background data. 

On top of launching Hubble in 1990 and the subsequent adjustment of the main mirror, several other modifiactions and adjustments have occurred over the years.  The last such mission was completed by the crew of Space Shuttle Atlantis in May of 2009.  Over the course of five spacewalks, Wide Field Camera 3 and the Cosmic Origins Spectrograph were installed to provide the Hubble Telescope even more viewing power.  The new systems allows astronomers a wider angle to study and up to thirty-five times more detailed viewing in ultraviolet and visible spectral ranges.  Although Hubble was originally designed to be returned to Earth for regular maintenance procedures, the retirement of the shuttle fleet make it an impossible task.  All future repairs and additions will have to be conducted from space.

Perhaps the best news about the Hubble Space Telescope is that anyone can gain access to its technology.  There is quite a waiting list and there is always more demand than actual usage time available, but all requests are considered based on the celestial object requested for viewing and the potential application for the research being conducted.  Amateur astronomers are not granted as much time now as they have been granted in previous years but the launch of Hubble’s successor, the James Webb Space Telescope, in 2014 should make it more readily available.