Check out Mercury transit at IU Kokomo Observatory
November 2, 2006
KOKOMO, Ind.—Maybe it’s interplanetary jealousy. In early fall, solar system watchers focused on the farthest planet from the sun, Pluto, when it was demoted to “dwarf planet” status. Now, the planet closest to the sun, Mercury, will be drawing attention to itself on Wednesday, November 8.
For approximately five hours that day, starting at 2:12 p.m. local time, the planet Mercury will transit the sun. That is, Mercury’s orbit will bring it between the sun and Earth so that, from Earth, Mercury will appear as a silhouetted black dot moving at a slight diagonal across the sun’ surface. Approximately 13 transits of Mercury happen each century. The last occurred in 2003, and almost another decade will pass before the next one on May 9, 2016.
Clear skies permitting, the public can view this year’s transit of Mercury at the IU Kokomo Observatory. Doors will be open from 2–7 p.m.; admission is free.
Since Mercury is only 1/194 of the sun’s diameter, the transit will not be visible without significant magnification through a telescope. And, because viewing the transit means looking directly at the sun, a telescope must be equipped with adequate filtration to ensure safe viewing. IU Kokomo’s Takahashi refractor telescope has a solar filter that fits the bill, said Associate Professor of Physics Frank Steldt, Ph.D., who oversees the observatory. According to industry experts as well as Steldt, the Takahashi is perhaps the finest six-inch refractor telescope in the world.
Comparatively little is known about Mercury, our solar system’s smallest planet. The closest look Earthlings have ever gotten was in 1974–75, when Mariner 10 approached Mercury and mapped about 40–45 percent of the planet’s heavily cratered surface. Mercury has no moons or other large satellites and little atmosphere. Its diameter is about 1/3 the size of Earth’s. According to Wikipedia, Mercury has a large iron core that generates a magnetic field about 1 percent as strong as that of the Earth. Surface temperatures on Mercury range from lows around –700 degrees Kelvin (–298 Fahrenheit) and highs of 700 degrees Kelvin (800 Fahrenheit).
As with all events at the IU Kokomo Observatory, the November 8 open house will be canceled if skies over Kokomo are overcast one hour before the start time of 2 p.m.
