How To Observe The Mercury Transit Using Projection Methods

HOW TO OBSERVE THE MERCURY TRANSIT SAFELY USING PROJECTION METHODS

On Monday 9^th May, Mercury will transit the Sun. The entire transit event will last around 7 and a half hours. It begins at 12:12pm BST and ends at 7:42pm BST.  During this event, Mercury will be visible as a tiny, round black spot which slowly moves across the disc of the Sun.  It will be darker in colour than any sunspots which may be visible on Monday. Mercury will be so small that you will not be able to observe it with eclipse glasses. You will need large binoculars or a telescope, fitted with a white light solar filter.  If you have left it too late to get hold of a solar filter and want to safely observe the transit, then don’t panic! You can safely observe the event using a projection method. 

SAFETY NOTICE: NEVER EVER ATTEMPT TO LOOK AT THE SUN EITHER DIRECTLY, OR THROUGH BINOCULARS OR A TELESCOPE WITHOUT THE CORRECT EQUIPMENT. YOU WILL GO BLIND! DO NOT UNDER ANY CIRCUMSTANCES TRY TO USE ECLIPSE GLASSES WITH BINOCULARS OR A TELESCOPE; THE MAGNIFICATION OF THE SUN WILL BURN STRAIGHT THROUGH THE GLASSES AND CAUSE PERMANENT DAMAGE TO YOUR EYES. IF YOU ARE USING A TELECOPE, MAKE SURE YOU KEEP THE CAPS ON THE FINDERSCOPE. EVEN THAT LOW MAGNIFICATION IS ENOUGH TO BURN YOUR EYES AND CAUSE PERMANENT DAMAGE.

Telescope Projection Method:
First of all, you need a piece of white card, or white paper glued onto a piece or card, or a piece of white board. This will be your projection board. If you can, try to find a way of mounting it onto a tripod or broom handle so it is free standing. It will help you greatly later on if it can stand up by itself.

Begin by lining up your telescope with the Sun.  Place your projection board behind the eye piece to help you get things lined up properly. If you are using a refractor, your projection board will be behind the telescope, but if you are using a reflector it will be at the side. When everything is in place, you will see a large bright disc on your projection board. Adjust the focus on your telescope until the disc is nice and sharp. You should easily be able to see any sunspots which are currently visible. During the eclipse, you will see the tiny black dot that is Mercury passing across the disc. If you want to take a photograph of the projection on the white board, it is safe to do so. Do not try to take a photography by holding your camera up to the eye piece - it will burn your camera sensor!

Binocular projection method:
Begin by placing your projection board facing the Sun. Point your binoculars at the Sun and angle them until you see 2 bright discs on your projection board. Adjust the focus of the binoculars until you get nice sharp discs. As with the telescope projection, you may be able to see sunspots using this method. During the transit, you will see Mercury as a tiny dot moving across the Sun. Once again, if you wish to photograph the image on the projection board, it is safe to do so, but you may need an extra pair of hands to hold everything in place if you don’t have a tripod for your binoculars!

 

I hope this blog helps you to observe Monday’s transit event safely. If you have any doubts then please do not take any chances with your eyes. There are lots of local astronomy societies who are doing outreach events on Monday, so find one of those and observe it safely with them. Now we just have to hope that we get some clear skies. Good luck and happy observing!