Administrator and Stuntman
Whoah! Very, very cool.
Magnetic sensing, perhaps because it is a type of sensory perception inaccessible to humans, has long captivated the human imagination. Over the past 50 years, scientific studies have shown that a wide variety of living organisms have the ability to perceive magnetic fields and can use information from the earth's magnetic field in orientation behavior.
The basis for the magnetic sense is located in the eye of the bird, and furthermore, it is light-dependent, ie, a bird can only sense the magnetic field if certain wavelengths of light are available. Specifically, many studies have shown that birds can only orient if blue light is present (although a recent study showed that they may orient in red light given sufficient accomodation time). The avian compass is also an inclination-only compass, meaning that it can sense changes in the inclination of magnetic field lines but is not sensitive to the polarity of the field lines.
The two main models for avian magnetoreception.
The former suggests that the compass has its foundation in small particles of magnetite located in the head of the bird.
The latter idea is that the avian compass may be produced in a chemical reaction in the eye of the bird, involving the production of a radical pair.
On July 12th 2011, Neptune is one year old - one Neptunian year that is. The furthest planet from the sun it's only now completed one solar orbit since its discovery in 1846, travelling so slowly each Neptunian season lasts forty Earth years.
Too distant to spot with the naked eye the ancients could never have known of Neptune's existence. Nineteenth century astronomers had to climb on the shoulders of scientific giants to see it. First a tiny blue disc now an ice giant whose strange atmospheric features send shivers down the spines of astronomers today.
It's late spring, early summer in Neptune today. It's been that way for decades.