Astronomers Sun astronomy enthusiasts are excited about this event that happened only thirteen times in this century: the Mercury transit. This phenomenon occurs when Mercury crosses the Sun. This will happen only once this Nov. 11 and will not happen again until 2023.
ACROSS THE SUN
The Mercury transit happens when the planet Mercury passes between the Earth and the Sun. From the Earth's view, Mercury is a small blot against the Sun's massive size. This year, the planet Mercury will take at least five hours to complete its transit, making the first contact with the Sun at 7:15 AM. Mercury is expected to reach the midpoint by 10:20 AM, and the transit will finally come to an end by 1:04 PM. Astronomers would advise everyone to practice safe viewing and to not look directly at the Sun without wearing protection for the eyes.
In actuality, there is nothing much to see for the naked eye during the transit as Mercury will appear very small - just about 1/160th the width of the Sun. To be able to experience the transit, aid from high-powered telescopes are needed (these telescopes come with eye filters to protect the eyes. Experts also advise viewing the event in places where it occurs during daylight, specifically in North America.
A NEW OPPORTUNITY
Astronomers use events such as this to advance their knowledge about the planet. For instance, it was previously thought that Mercury could not possibly have an atmosphere, but because of phenomenon such as this when the planet Mercury came a bit closer to Earth did we able to confirm the presence of its atmosphere (with the help of the Mariner 10 at Messenger spacecraft). Mercury's transit provides a great opportunity to probe the thin atmosphere of the planet.
Mercury's orbital plane does not line up with Earth's so mostly, during transits, it appears below or above the Sun. Planetary transits are rare, and this is the only 14th Mercury transit that will happen this century. When transits occur, usually, astronomers measure when each side of the planet comes in contact with the 'solar limb.'
Mercury transit inspired a new way of hunting for exoplanets. Astronomers now use the transit method when finding exoplanets using the Kepler Space Telescope. In the transit method, astronomers observe a star system and take note of whether or not there will be a dip somewhere in the lower or upper part of the star - that would mean a planet is present. This method enabled the Kepler Space Telescope to discover thousands of exoplanets before its retirement in 2018.
