The-Spring-Night-Sky

The Spring Night Sky

When we gaze up at the night sky, at first there appears to be a random collection of pinholes in the curtain of night; but look again and you start to see definite patterns begin to emerge. We refer to these patterns as constellations, and the pinholes are actually Suns, billions of miles away.

The ancient Greeks first formed the constellations thousands of years ago by making up stories about the star patterns they could see; stories about their gods and heroes and great feats of bravery; stories about magical animals, tales of forbidden love and stories about of evil creatures.

The names of individual stars mostly have Arabic origins, while the planets have Roman names.

As we move around the Sun, the angle of the earths tilt causes our seasonal changes, and we see different constellations in the night sky throughout these seasons.

For instance during the winter months the constellation of Orion stands proudly on guard in the night sky but during summer he is nowhere to be seen. Orion hasn’t really gone anywhere he just makes his way across the sky during the daytime so we can’t see him because of the suns glare.

We can always see fascinating objects in the night sky no matter what season we’re in, so as it is now spring lets take a look at some of the wonderful celestial objects on offer in the spring night sky.

But before we begin, a word about light pollution; light pollution is wasted light-glare which shines upwards from things like street and road lamps and there is only around 2% of the UK which is free from light pollution. This is what the sky looks like from built up areas. This is what we should be seeing.

We start off with one of the most well known star patterns of them all the Plough. This constellation looks like a saucepan, here is the curved handle and here is the pan. The Plough makes a perfect pointer-constellation to find our way around the night sky. Always use a star map which will show you names and shapes of constellations; one of our monthly night-watch sheets will help you with this.

These two stars are called the pointers and if you draw an imaginary line through them they lead to the North star or Polaris which is situated directly above the north pole, and always points in the direction north.

A common misconception is that the north star is the brightest star in the night sky when actually it is quite dim and is only 48th on the list of brightest stars. Even so it is a huge star shining over 2000 times brighter than our own star the sun. Polaris only appears so dim because it is roughly 430 light years away.

A light year is the distance light travels in a single year which is 6 trillion miles and to give you some idea of the distance we’re talking about, the furthest probe sent into space, Voyager 1 launched over 30 years ago, is double the distance of Pluto from Earth, and travelling at its current speed of 36,000 mph it would still take another 18,000 years to travel 1 light year.

The Plough is actually part of a larger constellation called Ursa Major meaning Great Bear but the Plough is easily recognisable, and as it is a circumpolar constellation it never sets below the horizon.

Continue past the north star and we come to this ‘W’ shaped star pattern called Cassiopeia (Cassio-payer) who according to Greek myth was an Ethiopian queen who was punished for comparing her beauty to that of the Gods. This constellation is easy to recognise because of its distinctive shape. This is as close as Cassiopeia comes to the horizon making this a circumpolar constellation also.

Come back to the Plough and strike a line away from these two stars and eventually you will come to this bright star called Capella in the constellation of Auriga, which is Latin for ‘The Charioteer’.

According to Greek myth Auriga represents Hephaestus, the blacksmith of the gods and because he was disabled Hephaestus was said to have invented the chariot to make travelling easier.

Capella is the third brightest star in the northern hemisphere and although it appears to be a single star, it actually consists of two pairs of double or Binary stars. The two stars in each binary orbit each other, and in turn the two binaries orbit around the same point in space.

Again starting from the Plough, continue a line away from the handle and we eventually come to this bright star Arcturus, in the constellation of Boötes the herdsman.

Arcturus is the brightest star in the northern sky and is an orange giant over 100 times more luminous than the sun.

The name Arcturus comes from the ancient Greek word for Bear, “Arctos” and this is also where we derive the name of ‘Arctic’ from.

Carry on our line and we come to the second largest and one of the most interesting constellations in the whole night sky, Virgo.

Because of the presence of a galaxy cluster within its borders, this constellation is especially rich with galaxies. He said “galactic” instead of “galaxy”.

For most of the year we can’t see Virgo as it disappears below the horizon but if you look through a small telescope you should be able to see a myriad of celestial gems. Virgo also has more confirmed Exoplanets than any other constellation, 22 in all. Exoplanets are new planets orbiting distant stars and in 2009 alone 9 planets were discovered in this constellation, which is the most discovered in one constellation in a single year.

Come back to the Plough one last time and strike a line through the pointers in the opposite direction from Polaris and you eventually come to the constellation of Leo, meaning Lion.

This star at the Lions tail is called Denebola (deneb-bowler) and is a relatively young star with an estimated age of less than 400 million years. It has 75% more mass than the Sun which results in a much higher luminosity but a shorter life span.

This star called Regulus meaning ‘little king’ is the brightest star in Leo and is spinning so fast that it is wider at its equator than at its poles and if it were to rotate just 16% faster, centrifugal force would overcome gravity and the star would tear itself apart.

If the sky is dark enough and you are away from city lights, you may just be able to make out a misty faint band of stars extending across the sky; this is our home galaxy, the Milky Way.

The Milky Way is a spiral galaxy with over 100 billion stars and our sun is just one of those stars. It is estimated that there are over 100 billion galaxies just in the observable universe and probably billions more which we can’t see.

It is also estimated that there are more stars in the universe than grains of sand on the beaches of the earth. Occasionally we see a streak of light flash through the sky at night; this is a shooting star or meteor. Meteors are usually tiny pieces of material left in space by a comets tail.

While this material is travelling through space at incredible speeds it comes into contact with our atmosphere which causes friction which in turn heats up these tiny rocks until they start to burn. Periodically we have annual meteor showers with hundreds of meteors emanating from the same apparent point in space. Sometimes these meteors survive to hit the ground and we call these meteorites; you can see some meteorites on the space gallery after the show.

The world turns and the night gives way to the daytime once more and the only star that we can see now is the source of all life, the Sun.

The Sun burns hydrogen at the rate of 700 million tonnes per second and this one second of energy output would be enough to power the whole of the United States for 900 years.

Our Sun has been burning for about 4.5 billion years, and given the incredible energy output every second, the sun will still continue unchanged for another 5 billion years. After this it will start to inflate and eventually swallow up the inner planets including the earth.

But don’t worry, by that time we may have the technology to travel to distant galaxies and visit hundreds of worlds.