Star date: 06:07:99

Mars, Spica and a Sombrero

This week offers us a variety of treats, from Mars to Spica to The Sombrero Galaxy.

Mars is one of the brightest planets in the sky, and was well known to all ancient people. In todays age, however, there is new knowledge and discoveries pouring in on an almost daily basis. One tool currently being used is the Mars Global Surveyor. Mars Global Surveyor carries five science instruments designed to generate a complete global portrait of Mars and its seasonal changes during a full Martian year, the equivalent of two Earth years. It is the first mission in a long-term program of Mars exploration known as the Mars Surveyor Program, which is managed by NASA's Jet Propulsion Laboratory (JPL), centered in Pasadena, California.

One of its recent discoveries is an impact basin deep enough to swallow Mount Everest. This discovery was made possible by a new 3D map generated by the Mars Orbiter Laser Altimeter (MOLA), an instrument aboard NASA's Mars Global Surveyor. The high- resolution map represents 27 million elevation measurements gathered in 1998 and 1999. The data were assembled into a global grid with each point spaced 37 miles (60 kilometers) apart at the equator, and less elsewhere.

Each elevation point is known with an accuracy of 13 meters (42 feet) on average, with large areas of the flat northern hemisphere known to better than two meters (a little over 6 feet). "This incredible database means that we now know the topography of Mars better than many continental regions on Earth," said Dr. Carl Pilcher, Science Director for Solar System Exploration at NASA Headquarters, Washington, DC.

MOLA topographic images may be viewed at the following web address: http://pao.gsfc.nasa.gov/gsfc/spacesci/pictures/mola/mars3d.html .

Mars will be just south/southeast at around 8 pm this week, and will be due south at 9:20pm. Look for it nearly 40 degrees above the horizon at this time. Mars will be less than two degrees from one of the brightest stars in the sky, Spica. At magnitude 1.2, it will be nearly seven times dimmer than Mars, but it is still an easy find. You will see it nearly due south of Mars.

From here, if you are using a pair of binoculars or a telescope, travel a total of 11 degrees until you are 10 degrees east of south, and 38 degrees above the horizon. This is the lair of M104, the Sombrero Galaxy. This spherical galaxy shines at magnitude 8.3, and spans about 1/7 of a degree across the sky. This may not sound large, but it is nearly 1/3 the diameter of the Sun or Moon as seen from the Earth.

Clear skies, and good viewing.

"Understanding is joyous" - Carl Sagan