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Mars, the fourth planet from the Sun was named after the Roman god of war and is sometimes called the "red Planet" due to its reddish appearance. This is due to the iron oxide (rust) dust covering the surface of the planet.

Mars has a very thin atmosphere and has surface features like the impact craters of the Moon and volcanos, valleys, deserts and polar ice caps like the Earth. It has the highest mountain known in the solar system, Olympus Mons at 26 km. (three times the height of Mount Everest) as well as the largest canyon, Valles Marineris at 4,000 km long and 7 km deep compared to the Grand Canyon at 700 km long and 2 km deep.

Mars has two Moons, Phobos (larger) and Deimos (smaller). They are very small, misshaped and orbit very close to Mars itself. They are probably captured asteroids.

Mars can be seen by the naked eye from Earth, and when closest to Earth, (every two years) it is brighter than any other body in the solar system except Venus, the Moon and the Sun.

Finally there is some evidence that life once existed on Mars. The Mars Pathfinder and the robot Sojourner discovered evidence for large amounts of water on ancient Mars. This was confirmed by the Mars Global Surveyor. Scientists have also found evidence for fossil life in an SNC meteorite, discovered in an antarctic ice field in 1984. It was ejected into space by the impact of an asteroid about 15 million years ago, travelled around the Sun in an elliptical orbit until it crashed in the ice about 13 thousand years ago. It is labelled, ALH 84001 and contains fossils-like objects similar to the single celled organisms once existed on Earth. Until next time, have the happiest of Holidays!

Special Bonus for 2009!

By this time in our journey together, you are probably somewhat familiar with some of the methods used to locate celestial objects. The most commonly used method is a Celestial Coordinate System based on Right Ascension (RA), measured in hours, minutes and seconds and equivalent to Earthly longitude, and Declination (Dec), measured in degrees and equivalent to Earthly latitude. It is interesting to note that the 0/24 hour point of Right Ascension is also called "the first point of Aries" or the Vernal Equinox, the beginning of spring, and is equivalent to the Earthly Prime Meridian.

Next year we will become familiar with the most ancient coordinate system known to man, the Ecliptic Coordinate System. This system was first described in the Rigveda, puported to be the oldest book in the world. It is known to have been in use by the Roman era and was based on Hellenistic (Greek) astronomy. The Greeks "inherited" it from the Babylonians (Chaldean period, around the middle of the first millennium BC.) The construction of the zodiac was described by Ptolemy in his book, Almagest.

In astronomy, the zodiac is a "ring" of constellations that lie within the ecliptic. The ecliptic is the apparent path followed by the Sun, Moon and the Planets throughout the year. The Ecliptic coordinate system uses the plane of the ecliptic as its reference. Its latitudinal angle is called the ecliptic latitude and is measured + towards the north. Its longitudinal angle is called its ecliptic longitude and is measured in degrees eastward from 0 to 360.

Now observe a child's spinning top. You will notice it wobbles and, in addition to its spinning motion, there is a slow pivot of its upper "pole" around in a circle. This movement is called precession, and the Earth does the same thing as it spins on its axis. Due to precession, the first point of Aries is now somewhere in the Constellation Pisces! This wobble repeats every 26,700 years.

You may have noticed that the same bright stars of the same constellations keep appearing throughout the year as part of a pseudo-conjunctions. Technically a conjunction occurs when two or more solar system objects appear, from our vantage point, to be very close to each other. Remember that this is usually an optical illusion and these objects are not really that close together!

On the other hand, sometimes solar system objects appear to be very close to a deep space object. It looks like a "conjunction" but, technically it is not. Thus my use of the term: pseudo or false - conjunction.

The Ecliptic coordinate system is very useful for charting solar system objects. Most of the planets and other smaller bodies have orbits with very small inclinations to the ecliptic plane so these coordinates have been used historically to compute their positions.

--A very happy New Year to you and yours!
Ron, the star geezer