October 30, 2006. Copyright 2006, Graphic News. All rights reserved

Transit of Mercury visible from Pacific
By Mark Rutter

LONDON, October 30, Graphic News:  As the smallest planet in our solar system, and the closest to the sun, Mercury is difficult to view from Earth. On November 8, however, it will be in a position directly between Earth and the sun, allowing its silhouette to be seen clearly as it crosses the sun. Such an event is rare. This will be the second of only 14 occurrences expected this century, the first taking place in 2003.
 
Since the recent loss of PlutoÕs planetary status, Mercury is now the smallest planet in the solar system. It also has the widest temperature range of any planet, varying from around a freezing -180¡C at night to a flaming 450¡C at its peak, during the 4,223-hour day. With a sparse atmosphere, it is particularly susceptible to asteroids, which bombard the planet and give it its characteristic pockmarked surface. Mercury takes only 88 Earth days to orbit the Sun, and it was this rapid passage across the sky that led the Romans to name it after their messenger of the gods.
 
Although Mercury was first discovered thousands of years ago, it has not been easy to get useful information on the planet. As it is so close to the sun it is often masked by the sunÕs light. The best time to spot Mercury is near sunrise or sunset, when it is out of the light. Even then it is never directly overhead, which means that there can be up to eight times the atmospheric thickness to look through compared with a planet such as Mars, which does appear directly overhead. Most of our current knowledge on Mercury was gathered by the Mariner 10 mission, which flew past it three times in 1974 and 1975.
 
The point at which a planet can be seen crossing the sun from Earth is termed a transit, and only the transits of Mercury and Venus are ever apparent from our own planet. During its transit, Mercury is visible as a small spot, about 200 times smaller than the sun. This phenomenon can be observed with a telescope or binoculars, of at least 30 times magnification, using appropriate filters to avoid eye damage from looking at the sun.
 
The impending transit of Mercury will not be noticeable in Europe, Africa or western Asia, where it will be night-time when it occurs. But the entire transit -- lasting nearly five hours -- should be visible from the west coast of North America, Hawaii, New Zealand and the east coast of Australia. In the U.S. it will begin at 11:12 am Pacific Standard Time on the lower left edge or east of the sun, and finish on the right side. Some parts of the world, where sunrise or sunset occurs during the transit, will see only part of MercuryÕs passage across the sun.
 
You would be well advised to make the most of this transit. Although the next transit of Mercury will be visible from the Americas, Europe, Africa and central Asia, youÕll have to wait until May 9, 2016 to see it.
/ENDS