If you glance at the Sun today and notice a small black ‘dot’ moving across it, you may be interested to hear that that ‘dot’ is actually Mercury.
Mercury is crossing the sun today, in a rare event known as a Mercury Transit.
Mercury Transits take place just 13 times a century, when Mercury passes directly between Earth and the Sun. The next Mercury Transit won’t happen until 2032, so it’s an event you don’t want to miss!
Mitzi Adams, a solar scientist at NASA , said: “Viewing transits and eclipses provide opportunities to engage the public, to encourage one and all to experience the wonders of the universe and to appreciate how precisely science and mathematics can predict celestial events.
“Of course, safely viewing the Sun is one of my favourite things to do.”
How to see the Mercury Transit
For those of us based in the UK, the Mercury Transit will begin at around 12:35 GMT. However, Mercury will pass over the sun from 12:37-18:02, so look to the Sun any time between then.
Mercury’s tiny black disk will only cover a tiny fraction of the sun during the transit - only 1,283 of the Sun’s diameter!
Unfortunately, this means it’s pretty unlikely to be visible with the naked eyes. Instead, NASA recommends you use a telescope with at least 50x magnification.
It’s also very important that you use a solar filter when viewing the transit.
NASA explained: “Never look at the Sun directly or through a telescope without proper protection. It can lead to serious and permanent vision damage. Always use a safe Sun filter to protect your eyes!”
Is the Mercury Transit useful to scientists?
Scientists have been using transits for hundreds of years to study the way planets and stars move in space.
For example, back in 1761 and 1769, Edmund Halley used a Venus Transit to work out the absolute distance to the Sun!
NASA added: “Another use of transits is the dimming of Sun or star light as a planet crosses in front of it.
“This technique is one way planets circling other stars can be found. Scientists can measure brightness dips from these other stars (or from the Sun) to calculate sizes of planets, how far away the planets are from their stars, and even get hints of what they’re made of.”
