Dark skies from Tubbenden Meadow by Trevor Morgan

When I was a young lad living in West Wales in the 1950s I had no problem finding a location without any light pollution as all I had to do was walk about half a mile from my village. It was easy to see the Milky Way and recognise the constellations. Orion in particular was a wonderful sight and you could easily see its nebula with the naked eye. The night sky was an inspirational sight and my sense of wonder and awe at seeing the heavens in their full glory has not diminished and it still stimulates my imagination.

Unfortunately it is not possible to see Orion in all its glory from anywhere near London and its beautiful apparition is severely diminished.

Nowadays you need to be way out in the country and about 100 km from the nearest city to find really dark skies. My childhood village is now covered with a red glow at night from the local oil refineries.

http://www.darkskydiscovery.org.uk/

Star gazing in Orpington and the difficulty of seeing stars.

Even though there is a paucity of stars visible from Orpington my imagination still runs wild when I gaze up to the heavens. I am Dan Dare chasing the Mekon across the solar system. I am travelling to Jupiter with only a HAL 9000 “series 2” computer for company but to find the creators of the Star Gate and how they made it. I am voyaging at the speed of a photon in a quantum mechanic powered spaceship with Erwin Schrödinger who is looking for his cat or perhaps his cat is already dead and buried.

My wife and I like to gaze at the heavens even though we are not avid astronomers. Our back garden is not a great place to look at the stars because of the light pollution. We can just about see the Plough, the Orion constellation and Cassiopeia. Most other constellations are hardly recognisable; we can only see the major stars of Gemini.  A latter day explorer would have real difficulty navigating by the stars in Greater London. However, going to Tubbenden Meadow improves the viewing conditions but not considerably. Readers who have been to dark sky locations may think that the night sky is full of stars but even under the best of viewing circumstances only 6,000 stars of the Milky Way are recognisable individually.  Our galaxy has about 200 billion stars.

It is possible to see most of the planets of the solar system with the naked eye: Mercury, Venus, Mars, Jupiter and Saturn are readily visible even from Orpington. The Earth, of course, is readily visible too!

You have got no chance of seeing Uranus from Orpington with the naked eye; for that you will need to go to a dark skies location with very good viewing conditions. My wife and I have only ever seen Uranus once but through a telescope.

One of our favourite sights is the Andromeda Galaxy which is visible through binoculars from Tubbenden Meadow.

http://www.universetoday.com/22285/facts-about-the-milky-way/

The brightness of celestial bodies

Astronomers, generally use the astronomical magnitude scale to measure the brightness of stars and other celestial bodies.  The scale is derived from Ancient Greek times when astronomers used 6 magnitudes to describe the apparent brightness of stars. Astronomers have modernised the system but the principles are similar. The scale is logarithmic. The lower the figure for magnitude the brighter the celestial object: the Sun is magnitude -26; the Moon is on average -12.7. Sirius which is the brightest star in the sky is magnitude -1.4.  A star with magnitude 1 is 100 times brighter than a star of magnitude 6. The apparent magnitude of Uranus is 5.8 and it is just about visible with the naked eye under very dark skies. Sirius appears over 100 times brighter than Uranus. It is all very complicated but it is all explained below.

In the suburbs of London it is difficult to see a celestial body of apparent magnitude 3.5 with the naked eye and that is why most stars are invisible. In theory you should be able to see the Andromeda Galaxy from your back garden in Orpington but in reality you need binoculars to get a really good view of this fascinating celestial object.

http://www.icq.eps.harvard.edu/MagScale.html

http://www.astronomynotes.com/starprop/s4.htm

The Andromeda Galaxy

We go to Tubbenden Meadow to gaze at the Andromeda Galaxy which with binoculars is an awesome sight. I find it hard to comprehend how far away it really is and how many stars it contains.

You cannot see its individual stars because it is so far away but you can see it as a milky oval shape of stars or a nebula which is appears bigger in your field of view than the Moon. The galaxy was described by the French Astronomer Charles Messier (1730 -1817) as a nebula and he catalogued it as M31. M31 has always been visible to the naked eye but before the 20th Century most astronomers believed that it was located in the Milky Way. In 1923 the astronomer Edwin Hubble discovered that M31 was in fact another galaxy. This discovery astonished the world as up until then scientists believed that the whole universe was contained in the Milky Way. The discovery of another galaxy changed science’s view of the origin, age and size of the Universe. It is really worth seeing M31 in all its glory as it is really a beautiful sight through binoculars.

M31 is the largest of the local cluster of galaxies of which the Milky Way is a member. It is estimated to be 2.5 million light years away. This is a mind boggling distance when you consider that light travels at a velocity of 300,000 km per second. M31 is estimated to have around 1 trillion stars and to be 140,000 light years in diameter. Our own Milky Way is about 100,000 light years in diameter. Our solar system is situated about 26,000 light years away from the galactic centre. These statistics are truly astonishing.  M31 is widely regarded to be the furthest object in the Universe which is visible with the naked eye.

Human beings in the form of Homo sapiens did not exist when the light that we see now started travelling towards us from M31. Equally, Homo sapiens will not exist when the light emitted now from our Milky Way reaches M31. We would either have become extinct or have evolved into another species. The distances and timescales are astounding and we may never ever be able to communicate with another sentient being from another galaxy even if such a being existed. But I can dream about extra-terrestrial communication while gazing up to the heavens.

What has this got to do with Tubbenden Meadow?

Our meadow, just like the rest of the Earth’s surface, is teeming with life. The Earth is the only celestial body that we know for certain supports life. We can only speculate that life exists elsewhere in our solar system or in the multitude of other star systems in our galaxy. Our planet could be unique to the Milky Way. However, the laws of physics and chemistry are universal and it is quite possible that life has evolved elsewhere but we have no hard evidence that this has happened.

Further more we have no evidence that life exists in another galaxy and the vast distances may prevent us from ever finding out. Our planet could be unique to the whole of the Universe and this is an intriguing possibility.

However, whenever I look up towards M31 I always imagine a planet like ours orbiting a star like ours. My extra solar planet has prolific plant and animal life living in forests and oceans similar to our own. Perhaps, an “extra-terrestrial shepherd” is gazing up at the heavens to see a nebula which is our Milky Way. Hopefully, the inhabitants of this distant world are looking after their planet better than we are looking after ours.

We might have a better chance of meeting an “extra-terrestrial shepherd” in our own Milky Way but my imagination is still running wild. We haven’t even visited Mars yet and it is only a few light minutes away: the nearest star, Proxima Centauri, is 4.24 light years distant and we may never be able to visit it and get back home within a human lifetime.

http://mkaku.org/home/articles/the-physics-of-interstellar-travel/

http://www.nasa.gov/centers/glenn/technology/warp/ipspaper.html

The Earth is probably the only living planet that we will ever be able to touch, feel and smell as the others are just too far away or they simply do not exist at all. This is all the more reason to look after Tubbenden Meadow and the rest of our planet; our world is precious.

How can you find the Andromeda Galaxy and when is the best time to see it?

The Andromeda galaxy is visible in the North Eastern Sky from August to March. Use a star chart to identify the constellations of Cassiopeia, Andromeda and Pegasus. Cassiopeia is relatively easy to find as it is shaped like an upside down “M” or a “W”. The square of Pegasus is also quite easy to find and it is to the East of Cassiopeia. The constellation of Andromeda stems from the square of Pegasus and appears like a horizontal “V” shape. The star charts below show you how to identify where the Andromeda Galaxy is situated at the intersection of imaginary lines drawn between the major stars of the three constellations.

It is best to identify exactly where the three constellations are located with the naked eye; luckily they are visible on a dark night from Tubbenden Meadow provided that the moon is not shining too strongly near its full phase.

I doubt that you will be able to find the Andromeda Galaxy with the naked eye even on the darkest of nights and with the clearest of atmosphere. With 8×30 or 10X50 binoculars you will get a good view provided that your lenses are not misted up!

You will be amazed how much of the sky that the galaxy covers when you consider the distance of 2.5 million light years. It really is difficult to appreciate how large the galaxy is as the human brain cannot fully comprehend the distances and time periods involved.

http://www.wikihow.com/Find-the-Andromeda-Galaxy

http://earthsky.org/tonight/star-hopping-to-the-andromeda-galaxy

In about 4 billion years the Milky Way and the Andromeda Galaxy are predicted to have a collision but by then our star and its planetary system will be in its death throes.  Just imagine the view in the sky after the merger; it will be full of stars and hopefully there will be some other sentient beings around to see it.  Perhaps beings from the Milky Way and the Andromeda galaxy will get to meet each other at last.

Preservation of dark skies

Bromley council is now installing improved street lighting which uses less electricity and which aims the light downwards. This move is to be applauded. It should improve the visibility of the stars and planets. If this policy were to be adapted on a nationwide basis then more dark sky locations will become available.

All of us can make a contribution to dark skies by pointing our security lights at the ground and minimizing the time they are left on.

The stars will become more visible and perhaps our young people will be able to get to know the constellations and appreciate the glory of the night sky. And then allow their imagination to run wild too- just like mine.