Much of the subsurface soil of Greenland, Svalbard, and the northerly regions of Scandinavia, Russia, Alaska and Canada has been frozen since the last ice age. Continuous freezing and thawing in the top 20 centimetres (7.9 inches), known as cryoturbation, allows meltwater to circulate and keep the soil relatively fertile. But lower layers than this …
Insects and spiders are both arthropods with a chitin exoskeleton and segmented bodies, but the fossil record shows that their evolutionary trees separated around 420 to 450 million years ago. Insects all have six legs and three body segments: head, thorax and abdomen. They have a pair of antennae on the head and sideways-moving mandibles …
Astronomers estimate the distances to far-away galaxies by measuring the brightness of their stars. An easy way to do this is to find a type of star called a Cepheid variable, whose brightness varies overtime. Astronomer Henrietta Leavitt discovered over 100 years ago that the period of these fluctuations relates to Cepheid variable stars’ true …
Mirrors appear to reverse things from left to right because of our perceptions. Our bodies are roughly symmetrical, so the reflection of your left hand looks just like your right hand. For this reason, we tend to assume that mirrors reverse left and right. But if you hold up an asymmetric object in front of …
How Does Your Image Show Up Reversed In Mirrors? Read More »
It has been suggested that the River Nile was created in its modern incarnation approximately 25,000 years ago when Lake Victoria developed a northern outlet. In Ancient Egyptian times the River Nile was known as ‘Ar’, ‘Aur’, which as ‘black’, referring to the dark, fertile sediment that was left behind after it flooded. 3. While …
In order to withstand the high pressure as the heart beats, arteries need to be relatively thick and muscular. They resist stretching, helping to maintain enough pressure to push blood around the body without bursting under the strain. However, by the time the blood has travelled through the capillaries and into the veins, the pressure …
What’s The Difference Between Veins and Arteries? Read More »
Balloons retain a static electric charge due to the insulating properties of rubber. This material has a high electron affinity (likelihood of gaining electrons) relative to hair, so when you rub a balloon against your head, electrons easily come off your hair and build up on the surface of the balloon, and it acquires a …
Cats only meow at each other as kittens; adult cats only meow at humans. That’s because they’ve learned that we respond to it. Cats meow when they’re hungry, need to go out, want your attention, or just want to say hello. Older cats or cats with mental disorders may also meow for no apparent reason. …
Deep down, computer hardware can only understand very basic commands written in machine code. As machine code is basically just ones and zeros, it’s difficult for people to understand. Programming languages allow us to instruct computers using concepts and words more like human language, like LOAD and DO, and convert these to machine code that …
Although atmospheric pressure and density influence the speed of sound, the two effects essentially cancel each other out. In fact, the most noticeable factor affecting the speed of sound at high altitude is temperature. At colder temperatures, the molecules in the air carry less kinetic energy, making sound waves travel more slowly. At -1 degrees …
Does Music Sound Any Different At High Altitudes? Read More »
Paints vary depending on their use, but all types include three basic ingredients: a binder, a pigment and a solvent. The pigment will usually start off as a lump of rock, so it is first ground into a fine powder. It is then mixed with a binder, which coats the pigment, and a solvent, which …
With an automatic toilet, you’ll probably spot a small black circle nearby that looks a bit like a button – it’s an infra-red sensor. This detects body heat, and is connected to an electronic valve inside the water tank. The sensor is triggered when you wave your hand in front of it or move away …
Shampoo makes bubbles because it contains chemicals called surfactants. These are molecules that are part hydrophobic (water-hating), and part hydrophilic (water-loving). They help to pull oils from your hair because the water-loving ends all try to point towards the water, while the water-hating ends want to point towards the oils. This suspends tiny drops of …
What Causes More Shampoo Bubbles In Your Hair Than On The Body? Read More »
Muscle fibres come in two major types – fast-twitch and slow-twitch. Fast-twitch fibres are geared for bursts of energy (turkeys use their breast and wing muscles to escape predators), while slow-twitch fibres are adapted for sustained use (leg and thigh muscles are used constantly for standing and walking). The colour of meat is related to …
In 1970s France, an architect called Gilles Ebersolt was probably the first to create a giant inflatable plastic ball for people to get inside and roll around, which he named the ‘Ballule’. However, Zorbing as we know it today was created in 1994 in New Zealand by Dwane van der Sluis and Andrew Akers. At …