The Universe is a fascinating place. Our distant ancestors looked up in awe and, even for many people today, it can appear to be a magical cosmos. Therefore, those who understand it, or at least part of it, hold the key to explaining some wonderful sights.
Check out my top ten ways you can impress your friends with your new-found intimate knowledge of the vast Universe that stretches across heads.
Guiding Stars: To find our way around these days we rely on smartphones and a network of global positioning satellites in orbit around the Earth. But if you wanted to navigate your way around in the good old days you had to rely on the stars to help find your way.
A really simple way this can be done is to find Polaris, the "North Pole star." From anywhere in the Northern Hemisphere this star is visible (albeit on the horizon if you are very close to the equator) and can be found by following the two pointer stars in the front of the bowl of the Big Dipper, part of the constellation Ursa Major. Find Polaris and you have found north, from there, the rest is easy.
Galactic Guts: We live in the Milky Way Galaxy whose shape is thought to resemble a spiral with a loosely structured bar running across its middle. From our vantage point here on Earth, embedded inside the disk, we can see all of the Milky Way galaxy as it runs around our sky like some strange eerily glowing path of light. If we look in the direction of Sagittarius, which lies low on the western horizon after sunset, then we are looking toward the center of our galaxy, located 27,000 light-years away.
Planet Hunting: Aside from Planet Earth, you can see five planets in the sky over the coming months.
Look west just after sunset to see Venus shining brightly in the sky. It really cannot be missed as it is the brightest object in the sky after the sun has set. A couple of hours after Venus sets, Jupiter rises in the east and as it lies due south, the faint red glow of Mars can be seen in the south east in the constellation of Virgo.
As dawn breaks and the sky starts to brighten, Saturn can be seen low in the west with Mercury hiding in the glare of the sun. Great caution should be exercised when hunting for Mercury because of the intense light from the sun. If the sun has risen, end your search.
Stellar Light: Place a lump of metal in a furnace and, as it heats up, it will start to produce light. If you were 'lucky' enough to have a furnace to hand and watched the metal it would start to glow red, orange and yellow before turning white and blue. We can tell from this example that hotter things will give off blue light and cooler things red light.
Stars act in just the same way, so by looking at the color of a star we can tell what its temperature is; red stars are around 3000K, yellow stars like the sun are around 6,000K, white stars are about 9,000K and the hottest blue stars (like Spica in Virgo) are in excess of 20,000K. How cool (pardon the pun) is it that you can point at a star and tell them roughly how hot it is!
Really Far: All things take time to travel from A to B. Light is no exception as it travels at the finite speed of 300,000 kilometers per second. From the moon it takes just over one second to reach us; from the sun, it takes just over 8 minutes.
But that's nothing if you consider how long light takes to travel through intergalactic space -- from the Andromeda Galaxy, it takes light a whopping 2.3 million years to reach us! That means you are seeing Andromeda as it was 2.3 million years ago, so you are looking back in time. The galaxy can be seen to the upper left of the Square of Pegasus which is nicely placed for observation this time of year in the south.
Stellar Birthing: The birth of anything in nature is a truly magical moment, but the ultimate arrival must be the birth of a star.
In a process that takes millions of years, a cloud of gas slowly collapses under the force of gravity. Eventually, the pressures in the heart of the cloud become so extreme that nuclear fusion begins, transforming hydrogen atoms into helium. One of the byproducts of this transformation is the production of heat and light; a star is born.
Band of Light: On any clear, dark moonless night away from the intrusive glow of light pollution, an eery band can be seen stretching across the sky. This is the Milky Way, the combined light from the stars in our galaxy gently shining down on us. As you wander along its length you can see dark patches where ghostly clouds of dust are blocking the light from the stars.
A great example of stellar birth can be seen with the naked eye below the famous three star belt in Orion.
Seven? Or 20? The Pleiades star cluster, otherwise known as the Seven Sisters, is home to an estimated 1,000 stars. But, to the naked eye, only around seven can be seen. That is, if you have good eyesight. The Romans used the easily identifiable star cluster in Taurus as a test of eyesight and even today people will compare how many they can see for fun. Most people with average eyesight can see just about seven of them, hence its name, but a few with exceptional eyesight have reported up to 20!
Armchair Astronaut: We live on a planet, a planet that is revolving and completing one revolution every 24 hours. The circumference of Earth is a little over 40,000 kilometers, so from the time the sun sets to the time it rises again, without even moving, you would have traveled 20,000 kilometers in space. That's not even taking into account the movement of the Earth in its orbit around the sun.
There's nothing more amazing than staying up all night, watching the sun set in the west and then rise in the east, knowing that you have been able to gaze upon half of the entire Universe without even moving.
Shooting Stars: With Comet ISON fresh in our minds, it is a timely reminder that about 20 times each year our planet plows through the orbit of a comet. In doing so, it sweeps up debris that has been left by the comet, which then plunges through our atmosphere at speeds in excess of 90 kilometers per second. At these speeds it is only the largest of chunks that can survive the violent descent earthward.
This year, the Quadrantid meteor shower is one of these showers although it curiously seems to be the remains of an asteroid rather than a comet. It peaks overnight on Jan 3, 2014, so keep an eye on the sky for the debris as it falls to Earth.