Mercury Rising

From the evening of February 1st, people in the Northern Hemisphere should be able to see Mercury with the naked eye. Until February 4th the bleak, sun-dried planet will be visible in the post-sunset sky. So with a passion in photography I grabbed my camera and tripod, and headed out to the Dunstable Downs in Bedfordshire, UK. I set up my camera about 30 minutes before sunset, and started taking a few shots of the setting sun while waiting for the appearance of Mercury.

As the sun dropped towards, then below, the horizon a thin sliver of silver moon began to rise. Knowing that Mercury should appear somewhere below and just off the side of the moon, I stayed where I was, on an exposed hilltop with strong gusts and biting wind chill. As the moon rose, clouds moved in obscuring much of the sky, including where Mercury would show. Needless to say, I never got to see the planet closest to the sun.

On the plus side, I did get to see a different astronomical phenomenon. Given the time of year, and position of the Earth and moon in relation to the sun, there is currently a very narrow crescent moon. Sunlight reflected off the surface of the earth, very faintly lights up the dark side of the moon (no not the Pink Floyd album!). This phenomenon is called Earthshine, and allows us to see the outline of the entirety of the Moon beyond the crescent in the sunlight.

So I stood in the biting wind to catch a glimpse of Mercury which was obscured by cloud, but I did at least manage to snap a few shots of the crescent moon and Earthshine, so it wasn’t a total bust!

Crescent moon and Earthshine

Crescent moon and Earthshine

Death by Rainbow – Killer Crustaceans

Mantis shrimp1

Take a look at the picture above. What do you see? A fantastically multichromatic sea creature? Close. What you are looking at is kaleidoscopic, rainbow-coloured harbinger of death in crustacean from. This is the peacock mantis shrimp (Odontodactylus scyllarus). This brightly coloured, vicious sea dweller is by far the most impressive of crustaceans. I referred to them as harbingers of death, and they are a lethal animal among the sea floor residents, but they are impressive for another reason, too.

The peacock mantis shrimp is widely considered to have the most complex visual system within the animal kingdom. To start with, each eye sits on the end of its own eye stalk. This allows each eye to work and move independently from each other. The peacock mantis shrimp has compound eyes capable of viewing light waves beyond the visual range of many creatures. Humans can see light, with the 3 receptors in our eyes that have wavelengths above ultraviolet and below infrared (between 400 and 700nm). The mantis shrimp eye has more receptors, allowing it to see light across the whole spectrum. They can even see linear and circular polarised light. To put it in to context, humans can only see linear polarised light, and only if they are wearing polarised sunglasses.

Anyway, enough of that, what about the harbinger of death bit? Well the mantis shrimp has a pair of claw-like appendages. These claws can strike at around 50mph in water, with acceleration close to that of a .22 calibre bullet. In larger species these appendages end with a kind of club. This allows them to smash open the shells of crabs to feed on the soft flesh inside. In some cases, they can hit hard enough to break the glass of an aquarium. It isn’t just the blow itself that causes damage. The speed and force of the blows creates a cavitation bubble between the limb and the surface it hits. The bubbles form in an area of low pressure. As the pressure levels out, the bubbles collapse creating a shockwave of high force, in addition to the 1,500 Newton strike force. A double strike effect. If the physical blow misses, the effect of the collapse of bubbles can stun prey. Check out the video to see these amazing creatures in action.

For an alternative view on why the mantis shrimp is such a spectacular creature, check out this cartoon by The Oatmeal as to why it is his new favourite animal!

What is the most impressive creature you have seen? Or what is your favourite animal? Let me know in the comments section! 🙂