Mark Your Calendars! Rare Mercury Transit Happening on May 9

This May, mark your calendars for a rare cosmic affair that only happens 13 times in a century. On May 9, Mercury will transit and directly pass between the Sun and Earth.

According to the Royal Astronomical Society of Canada (RASC) handbook, the transit of Mercury will be seen in most parts of the globe including Western Europe, most parts of South America, eastern part of North America and western part of North and West Africa. However, this rare transit of Mercury will not be visible in other parts of East Asia as well as Japan. Antartic and Oceania will not be able to see this rare occurrence.

The transit of Mercury happens when the Earth's orbital plane intersects with that of Mercury. This usually occurs during early May or November, as per NASA's Goodard Space Flight Center. RASC notes that aside from Mercury, Venus also transits the Sun twice after every century.

The transit of Mercury on May 9 is mainly separated into five stages or periods characterized as contacts. Contact I (11:12:19 UT) occurs immediately when the planet passes through the solar limb. In Contact II (11:15:31 UT), Mercury will be internally tangent to the Sun and strolls through the solar disk. Then, the planet will reach the other side of the solar limb in Contact III (18:39:14 UT) and then exits the Sun's internal tangent in Contact IV (18:42:26 UT). The whole process will take 7.5 hours.

For amateur skywatchers, RASC recommends using a telescope equipped with a 50x magnification, considering that Mercury is a tiny planet compared to the Sun. Also, solar filters should be used in these telescopes to avoid ocular damage.

Washington Post notes that those in the U.S. interested to view the transit of Mercury can head over to Montgomery College (7:15 am to 2:15 pm), Air and Space Museum (7 am to 3 pm) or David M. Brown Planetarium in Arlington (10 am to 2 pm). The rare transit of Mercury can also be viewed online via live coverage on Slooh or VirtualTelescope.

NASA will also hold public viewing of the Mercury transit on NASA Television and will stream a live program on NASA TV and their Facebook page from 10:30 am to 11:30 am.

The last Mercury transit happened in 2006. Here's a refresher on what to expect on May 9.