Julianne Robertson investigates the world of snoozes, forty winks, cat naps and snoring. What is SLEEP, why do we need it, and how much sleep do kids need?
A couple of nights ago I was feeling really, really tired, so I went to bed early. I slept soundly, without even dreaming, until about 5am, when I woke up. It felt like I’d only been sleeping for about 5 minutes! After that, I fell back to sleep but had lots of vivid dreams and when I woke up a couple of hours later, it felt like I’d been asleep for a long time. After all that I still felt well-rested and was ready for the day.
All this made me wonder – what IS sleep? Why is it that some nights we feel like we’ve had a really good nights’ sleep, while other nights we still feel tired when we wake up in the morning? Here’s what I’ve discovered about sleep…
There has been a lot of excitement about the Juno probe this week, but what is it and what is its mission?
What is Juno?
Juno is a spacecraft designed and operated by NASA, the US space agency. It was launched from Cape Canaveral on the 5th August 2011 and has taken almost 5 years to travel the 716 million kilometres to Jupiter, the largest planet in our solar system. Juno is 3.5 metres in height, and when its solar arrays are extended it’s more than 20 metres across. These arrays are covered in more than 18,500 solar cells, which allows Juno to operate even when it’s at such a great distance from the Sun.
(Image: NASA)
Why is it called Juno?
In Roman mythology Juno was the Queen of the gods. She was married to the king, Jupiter, who wasn’t always well-behaved. Juno had to peer through the clouds to discover what he was up to; the spacecraft is called Juno because it will be looking beneath the clouds that cover the surface of the planet Jupiter.
Aboard the Juno craft are 3 models of Lego minifigures: Jupiter, Juno and Galileo, who discovered in 1610 that Jupiter had moons.
From left to right: Galileo, Juno and Jupiter. (Image: NASA/JPL-Caltech/LEGO).
What is it looking for?
Jupiter is enormous; it’s two and a half times larger than all the other planets in our solar system combined. It’s made entirely of gases and is believed to have no solid surface. The planet rotates at an immense speed, completing one rotation every ten hours, and telescopes have shown us that it has a cloudy atmosphere with colourful spots and stripes. The largest of these, known as the Great Red Spot, is a storm that is several times the size of Earth and has been raging for more than 300 years.
Jupiter. The Great Red Spot is clearly visible. (Image: NASA).
This mission is the first time that humans will be able to glimpse what lies beneath Jupiter’s cloudy atmosphere. The main objective is to understand how the planet formed and evolved, which will give us more information about the formation of gas giants as well as the rest of the solar system. Juno will also measure the quantities of water and ammonia within the atmosphere, examine the magnetic field that surrounds the planet, observe any polar auroras and measure the gravity to see whether a solid core may exist after all.
When we talk about electric batteries, we often talk about voltage. But did you know that this word is named after the person who invented the first electric battery? First, let’s take a look at what a volt is, and then we’ll find out more about the guy who gave the ‘volt’ its name.
What is a Volt?
A volt is defined as a unit of electric potential and electromotive force, and voltage refers to the number of those units. That sounds a lot more complicated than it is! If you think of the water in a tap being like the electricity running through a wire, the voltage means the amount of pressure. This video is quite long but explains it very well.
Why are Volts Called Volts?
Alessandro Volta
The term actually comes from a name. It was coined in honour of Italian physicist Alessandro Volta, who is recognised as the inventor of the first electric battery. During the 1790s, Volta worked on the theories of electricity of the day.
Volta disagreed with the theory proposed by fellow Italian scientist Galvani that electricity was generated by animal tissue. Instead of experimenting on frogs or other animals, Volta did experiment after experiment with metals.
His persistence paid off, and in 1800, he invented the world’s first battery, known as the ‘voltaic pile’.
The Voltaic Pile
This voltaic pile was simple but ingenious. It consisted of a pile of zinc and silver discs. But alternating between them was a piece of cardboard, or a piece of cloth, that had been soaked in saltwater.
There was a wire that connected the zinc disc on the bottom to the silver disc on the top, and this wire was capable of producing sparks.
What else Did Volta Invent?
The invention of the first electric battery brought Volta the most fame and recognition, but he also made other discoveries. He invented the electrophorus, a device that could transfer an electrical charge to other objects, as well as an electrical condensor, and the voltaic cell.
He is also known for having discovered and isolated methane gas. After his death, the volt and voltage were named in his memory.
What about Galvani?
Luigi Galvani
Yet there is one more twist to the tale. Volta’s longstanding colleague Galvani of the animal electricity theory also left his name in our language. When we say ‘galvanise’ or ‘galvanism’, that is where it comes from.
Despite their differing theories, there was no rivalry between the two scientists. They were both more concerned with the pursuit of knowledge than with whose theory would prove to be right, and it was Volta who first coined the word ‘galvanismo’ in Italian.
This October Earth will be passing through the tail of Halley’s comet, which will mean a shower of meteors flashing across the night sky. Our science editor Sam Gouldson explains.
What is Halley’s Comet?
A comet is a lump of rocky particles, ice and dust all bound together like a dirty snowball. When the comet nears a star, its surface transforms from a solid to a gas. The star’s light shines through these gases and makes them visible to observers as a fuzzy cloud around the comet’s centre, and a tail streaming out behind.
