..HH +6GzHH d'h,<KTLLF`F` 33of (aqHH L0@pjG H IJKLM!N%O )P-Q1R5S9T= Helvetica Helvetica 0d . . . . . . . . . . . . . . . . . . . . ,      HF}W-V6؇WmhRCR}8Po=oDO-@}TC@]ffty<ԗŇ:2o wu&}^Ŀ6 `H2r[/INovember 10, 1999. Copyright, 1999, Graphic News. All rights reserved MERCURY GRAZES THE SUN By Elisabeth Ribbans LONDON, November 10, Graphic News: MERCURY DRIFTING across the face of the Sun is a stunning and fairly uncommon celestial phenomenon. It happens only around 13 times each century. But when the tiny planet performs its solar stunt on November 15, it will be a particularly special event for stargazers in the South Pacific. Its passage will produce a rare grazing transit, which means Mercurys path will follow a short chord near the extreme north-eastern edge of the Suns visible disc. It is the first time such a transit has occurred since the invention of the telescope and will not happen again until at least the 23rd century. The effect of a transit that hovers so close to the Suns edge will be that southernmost observers will see only part of Mercury superimposed as a small notch along the solar rim. Further north, the planets entire disk will be visible as a small black dot silhouetted against the dazzling solar surface. The total transit, expected between about 21:10 and 22:10 UT, will be visible from Papua-New Guinea, northeastern Australia, the northern tip of New Zealand, Hawaii, western South America and most of North America, where it will be seen just before sunset local time. The partial transit will be seen from most of Australia, New Zealand, and Antarctica early in the morning of November 16. Because Mercury is the smallest of the terrestrial planets and measures only 1/194 the Suns apparent diameter, a telescope is needed to watch the event. As for a solar eclipse, the instruments must have proper filters to protect the eyes. Mercurys size and distance means that gathering detail by telescope is extremely difficult. And although the solar transit puts the planet closer to Earth than at any other time in its orbit, it is of little use to scientists firstly because it is largely obscured by the Suns glare and secondly because its illuminated hemisphere is turned away from us. The information we have about the Suns nearest neighbour comes from flybys of the Mariner 10 spacecraft during the 1970s. Its pictures produced a map of around 35 per cent of the planet, showing rocky, heavily cratered terrain similar to that of the Moon. We also know that Mercurys rotation makes a day last for two years and that its noontime temperature exceeds 400C at the equator and dips below 170C in the long night. The next transits of Mercury, which always take place in May or November, are due in 2003, 2006 and 2016. The last was in 1993. ENDS/ Sources: Nasa; Association of Lunar and Planetary Observers; Stars and Planets by Ridpath and Tirion (Collins); Penguin Dictionary of Astronomy8T8$HRgA|vyA8܀aT`@  ,t LLF` FY/ E 0%@,p%@ LLF` FY4/ @J(& C|R LLF`0 FYP/ PB9$@(@|$Uj u0@[vV=G@ <siam6"W'B0r[5y_(^"%q5Bs:gޏHbR.M^3E"E쭄J+fP 'i,Tۥ* 1r\)ODG.ubfH3mQBm