The last time Mercury made a planetary transit was in 2006, when it appeared as a small black dot passing across the face of the sun.
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On Monday, the Royal Astronomical Society of Canada (RASC) invited the public to watch the transit on Parliament Hill through solar telescopes.
Though temperatures on Mercury’s surface reach 800 degrees Fahrenheit (427 degrees Celsius) – hot enough to melt lead – the planet also has deep craters where the sun never shines.
The other important thing a planetarium program will tell you is exactly where on the sun’s limb to look for the first appearance of Mercury.
The next transit will occur in 2019, and the one after that in 2032. That’s because its orbit is inclined, or tilted, by seven degrees with respect to the Earth’s, so Mercury doesn’t usually intersect our line of sight to the Sun.
Around once in over a decade, Earth and Mercury align, giving amateur and professional astronomers a tiny chance to watch Mercury as it glides between the Sun and the Earth.
“Unfortunately we haven’t been able to find the sun yet this morning”, Shadick said.
Monday’s 7.5-hour transit gives researchers an opportunity to use the New Solar Telescope to catch a glimpse of sodium in Mercury’s thin atmosphere.
Suzanna Nagy, president of the society’s local chapter, said this was her first time viewing the transit, which happens about 13 times each century.
“You do need a telescope, but you should never point a telescope at the sun unless you have the proper solar filter”, Shadick said.
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NASA is broadcasting near-live images of the Mercury transit from the Solar Dynamics Observatory (SDO).
