Ahead of the upcoming passage of Mercury in front of the sun, UK astronomer and TV presenter Mark Thompson shows the shocking potential consequences of staring at the sun - using a real eye.

In the footage, Thompson uses a pig's eye to show the damage that can be caused to the eye's cornea, lens and retina.

He holds the eye close to the eyepiece of the telescope and - after just 20 seconds - smoke starts coming out of the eye and a hole is burnt through the cornea and the lens.

After dissecting it, Thompson also realises that the retina has a brown spot - likely to have been caused by the sun.

Mercury will transit the sun on May 9th.

TV astronomer and author Mark Thompson reveals the dangers of looking at the Sun with dramatic effect.