The phenomenon, known as the Transit of Mercury, takes place when the planet Mercury comes in between the Sun and the Earth and is seen as a small dot moving across the face of the Sun. This happens 12 to 13 times in a century, the last one being on November 8, 2006, and the next expected on November 11, 2019.
According to Omani scientist and astronomer Dr Saleh al Shidani, who works with the Department of Physics at Sultan Qaboos University, the best part of the current Transit of Mercury is the fact that the initial stage of the event will be visible in Oman from around 3pm onwards until sunset.
There are different ways how people here can view this interesting phenomenon, Saleh informed. The PDO planetarium will be conducting a free scientific demonstration and providing people an opportunity to view it via solar telescopes, so Saleh suggests a family outing at the planetarium on Monday afternoon.
Another way to view the Transit of Mercury is by projecting it via a homemade pin-hole camera onto a screen in a dark corner of your home, as done during solar eclipses. Also, some astronomy societies are planning to have webcasts of the Transit of Mercury which can be viewed on the Internet as it occurs.
Veteran Omani astrophotographer Dr Samir al Kharusi, said, "There are five planets that are visible to the naked eye - Mercury, Venus, Mars, Jupiter and Saturn. Since ancient times, people in all cultures noted that though these moved against fixed stellar background patterns, Mercury and Venus also had retrograde loops (backward movement). This had remained unexplained for centuries since many cultures considered the earth to be at the centre of the universe."
Samir further explained that the Earth's movement in an orbit around an 'insignificant star' - the Sun - as part of a galaxy among billions of galaxies, was established only recently. "When planetary orbits were finally deciphered in recent history, it became clear that Venus and Mercury had smaller orbits inside the Earth's orbit, which caused their retrograde loops."
As Oman has an ancient maritime tradition, the Omani sailors and fishermen of yore were aware about the planetary movements and never relied on them for navigation purposes in this celestial phase, Samir said.
Saleh further explained that the alignment of planets in between the Earth and the Sun are governed by a number of factors including their orbits and distance from the Sun which make them a rare occurrence. The Transit of Mercury used to occur in April and October but now it has slowly shifted to the months of May and November.
Countries in the Middle East, will get a chance to view the first part of the Transit of Mercury until sunset. The first point of contact of Mercury against the rim of the Sun will occur around 3.30pm as it progresses to the second point of contact concentric to the inner circumference of the Sun.
When asked about beliefs in Oman associated with the Transit of Mercury, Saleh said there are no specific stories among the older generation connected with this phenomenon. Since the transit does not cause any visible change in the light of the sun, as is the case of an eclipse, it did not attract attention.
"Fishermen and sailors in Oman in ancient times were more concerned with objects whose appearance in the sky could be used to date other events, like seasons, for timing agricultural tasks or to predict storms," Saleh said. They were able to identify planets as 'wandering stars' and did not find them useful for timing any of their activities due to their changing positions.
Meanwhile, Sulaiman al Busaidi, curator of the PDO Planetarium, informed that the Transit of Mercury, as seen in the sultanate will begin at 3.13pm and end at 10.42pm. "Note that the sun sets at 6.39pm on that day and the planet will be present in Aries and will cross the solar disk in the sky in a descending movement," he said The total time taken for the transit would be seven hours and 30 minutes.
Sulaiman also cautioned people against looking at the sun with naked eyes to avoid retinal damage. The best way to view the transit would be via a solar telescope equipped with solar filters, he said.
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