The Transit of Mercury on November 9

Carter Observatory

The National Observatory of New Zealand

MEDIA RELEASE
(Date November 3. For immediate release)

The Transit of Mercury on November 9

The whole of the transit of Mercury on November 9 will be visible from New Zealand. Its duration is slightly under 5 hours, starting at ~08 12 and finishing at ~13 10. A transit is when a planet, in this case Mercury (and occasionally Venus) passes in front of the Sun. Mercury will enter the disk of the Sun to the right rim or about 3 o’clock on a clock face and leave the Sun’s face towards the left rim.

The diameter of the Sun, as we see it, is ½° but Mercury is only ~10 seconds of arc or 180 times smaller. For this reason a small telescope fitted with a solar filter, will be needed to “view” the event.

Brian Carter, Senior Astronomer at Carter Observatory says, “It is imperative that you do not look directly at the Sun though binoculars or a telescope as very serious eye damage will occur. To observe the Sun safely the telescope needs to be fitted with a special solar filter or the image needs to be projected onto a white card”.

The Earth orbits the Sun once a year. Mercury orbits closer to the Sun so its orbit is much shorter than the Earths. In addition Mercury is travelling faster than the Earth, which means that it orbits the Sun every 88 days or put simply its year is only 88 days. Both planets are travelling in the same direction around the Sun, which means that Mercury ‘overtakes on the inside’ 3 or sometimes 4 times a year. Because Mercury’s orbit is slightly tilted to that of the Earth’s, we do not get to view a transit every time. It usually passes to the North (below) or to the South (above) of the Sun. All Mercury transits occur in either May or November as these are the months when the planes of the orbits of the Earth and Mercury cross.

There are only 14 transits of Mercury in the twenty first century. The next Mercury transit that can be fully seen from New Zealand is in 2052 November (although some areas in New Zealand will see the very end and the very beginning of the transits in 2019 and 2032 respectively).

The Carter Observatory will be open for viewing of the event from about 8 am. We will use solar filters to SAFELY view the transit. This always assumes that the weather conditions are favourable and the sky is not cloudy.

Auckland’s Stardome will be running SAFE observing sessions and it is probably that local astronomical societies and observatories around the country will also be in operation, so please contact your local facility.

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